LCOV - code coverage report
Current view: top level - pageserver/src/tenant - timeline.rs (source / functions) Coverage Total Hit
Test: c8f8d331b83562868d9054d9e0e68f866772aeaa.info Lines: 62.4 % 4517 2819
Test Date: 2025-07-26 17:20:05 Functions: 57.8 % 403 233

            Line data    Source code
       1              : pub(crate) mod analysis;
       2              : pub(crate) mod compaction;
       3              : pub mod delete;
       4              : pub(crate) mod detach_ancestor;
       5              : mod eviction_task;
       6              : pub(crate) mod handle;
       7              : mod heatmap_layers_downloader;
       8              : pub(crate) mod import_pgdata;
       9              : mod init;
      10              : pub mod layer_manager;
      11              : pub(crate) mod logical_size;
      12              : pub mod offload;
      13              : pub mod span;
      14              : pub mod uninit;
      15              : mod walreceiver;
      16              : 
      17              : use hashlink::LruCache;
      18              : use std::array;
      19              : use std::cmp::{max, min};
      20              : use std::collections::btree_map::Entry;
      21              : use std::collections::{BTreeMap, HashMap, HashSet};
      22              : use std::ops::{ControlFlow, Deref, Range};
      23              : use std::sync::atomic::{AtomicBool, AtomicU64, Ordering as AtomicOrdering};
      24              : use std::sync::{Arc, Mutex, OnceLock, RwLock, Weak};
      25              : use std::time::{Duration, Instant, SystemTime};
      26              : 
      27              : use anyhow::{Context, Result, anyhow, bail, ensure};
      28              : use arc_swap::{ArcSwap, ArcSwapOption};
      29              : use bytes::Bytes;
      30              : use camino::Utf8Path;
      31              : use chrono::{DateTime, Utc};
      32              : use compaction::{CompactionOutcome, GcCompactionCombinedSettings};
      33              : use enumset::EnumSet;
      34              : use fail::fail_point;
      35              : use futures::stream::FuturesUnordered;
      36              : use futures::{FutureExt, StreamExt};
      37              : use handle::ShardTimelineId;
      38              : use layer_manager::{
      39              :     LayerManagerLockHolder, LayerManagerReadGuard, LayerManagerWriteGuard, LockedLayerManager,
      40              :     Shutdown,
      41              : };
      42              : 
      43              : use once_cell::sync::Lazy;
      44              : use pageserver_api::config::tenant_conf_defaults::DEFAULT_PITR_INTERVAL;
      45              : use pageserver_api::key::{
      46              :     KEY_SIZE, Key, METADATA_KEY_BEGIN_PREFIX, METADATA_KEY_END_PREFIX, NON_INHERITED_RANGE,
      47              :     SPARSE_RANGE,
      48              : };
      49              : use pageserver_api::keyspace::{KeySpaceAccum, KeySpaceRandomAccum, SparseKeyPartitioning};
      50              : use pageserver_api::models::{
      51              :     CompactKeyRange, CompactLsnRange, CompactionAlgorithm, CompactionAlgorithmSettings,
      52              :     DetachBehavior, DownloadRemoteLayersTaskInfo, DownloadRemoteLayersTaskSpawnRequest,
      53              :     EvictionPolicy, InMemoryLayerInfo, LayerMapInfo, LsnLease, PageTraceEvent, RelSizeMigration,
      54              :     TimelineState,
      55              : };
      56              : use pageserver_api::reltag::{BlockNumber, RelTag};
      57              : use pageserver_api::shard::{ShardIdentity, ShardIndex, ShardNumber, TenantShardId};
      58              : use postgres_connection::PgConnectionConfig;
      59              : use postgres_ffi::v14::xlog_utils;
      60              : use postgres_ffi::{PgMajorVersion, WAL_SEGMENT_SIZE, to_pg_timestamp};
      61              : use rand::Rng;
      62              : use remote_storage::DownloadError;
      63              : use serde_with::serde_as;
      64              : use storage_broker::BrokerClientChannel;
      65              : use tokio::runtime::Handle;
      66              : use tokio::sync::mpsc::Sender;
      67              : use tokio::sync::{Notify, oneshot, watch};
      68              : use tokio_util::sync::CancellationToken;
      69              : use tracing::*;
      70              : use utils::generation::Generation;
      71              : use utils::guard_arc_swap::GuardArcSwap;
      72              : use utils::id::TimelineId;
      73              : use utils::logging::{MonitorSlowFutureCallback, log_slow, monitor_slow_future};
      74              : use utils::lsn::{AtomicLsn, Lsn, RecordLsn};
      75              : use utils::postgres_client::PostgresClientProtocol;
      76              : use utils::rate_limit::RateLimit;
      77              : use utils::seqwait::SeqWait;
      78              : use utils::simple_rcu::{Rcu, RcuReadGuard};
      79              : use utils::sync::gate::{Gate, GateGuard};
      80              : use utils::{completion, critical_timeline, fs_ext, pausable_failpoint};
      81              : #[cfg(test)]
      82              : use wal_decoder::models::value::Value;
      83              : use wal_decoder::serialized_batch::{SerializedValueBatch, ValueMeta};
      84              : 
      85              : use self::delete::DeleteTimelineFlow;
      86              : pub(super) use self::eviction_task::EvictionTaskTenantState;
      87              : use self::eviction_task::EvictionTaskTimelineState;
      88              : use self::logical_size::LogicalSize;
      89              : use self::walreceiver::{WalReceiver, WalReceiverConf};
      90              : use super::remote_timeline_client::RemoteTimelineClient;
      91              : use super::remote_timeline_client::index::{GcCompactionState, IndexPart};
      92              : use super::secondary::heatmap::HeatMapLayer;
      93              : use super::storage_layer::{LayerFringe, LayerVisibilityHint, ReadableLayer};
      94              : use super::tasks::log_compaction_error;
      95              : use super::upload_queue::NotInitialized;
      96              : use super::{
      97              :     AttachedTenantConf, GcError, HeatMapTimeline, MaybeOffloaded,
      98              :     debug_assert_current_span_has_tenant_and_timeline_id,
      99              : };
     100              : use crate::PERF_TRACE_TARGET;
     101              : use crate::aux_file::AuxFileSizeEstimator;
     102              : use crate::basebackup_cache::BasebackupCache;
     103              : use crate::config::PageServerConf;
     104              : use crate::context::{
     105              :     DownloadBehavior, PerfInstrumentFutureExt, RequestContext, RequestContextBuilder,
     106              : };
     107              : use crate::disk_usage_eviction_task::{DiskUsageEvictionInfo, EvictionCandidate, finite_f32};
     108              : use crate::feature_resolver::TenantFeatureResolver;
     109              : use crate::keyspace::{KeyPartitioning, KeySpace};
     110              : use crate::l0_flush::{self, L0FlushGlobalState};
     111              : use crate::metrics::{
     112              :     DELTAS_PER_READ_GLOBAL, LAYERS_PER_READ_AMORTIZED_GLOBAL, LAYERS_PER_READ_BATCH_GLOBAL,
     113              :     LAYERS_PER_READ_GLOBAL, ScanLatencyOngoingRecording, TimelineMetrics,
     114              : };
     115              : use crate::page_service::TenantManagerTypes;
     116              : use crate::pgdatadir_mapping::{
     117              :     CalculateLogicalSizeError, CollectKeySpaceError, DirectoryKind, LsnForTimestamp,
     118              :     MAX_AUX_FILE_V2_DELTAS, MetricsUpdate,
     119              : };
     120              : use crate::task_mgr::TaskKind;
     121              : use crate::tenant::gc_result::GcResult;
     122              : use crate::tenant::layer_map::LayerMap;
     123              : use crate::tenant::metadata::TimelineMetadata;
     124              : use crate::tenant::storage_layer::delta_layer::DeltaEntry;
     125              : use crate::tenant::storage_layer::inmemory_layer::IndexEntry;
     126              : use crate::tenant::storage_layer::{
     127              :     AsLayerDesc, BatchLayerWriter, DeltaLayerWriter, EvictionError, ImageLayerName,
     128              :     ImageLayerWriter, InMemoryLayer, IoConcurrency, Layer, LayerAccessStatsReset, LayerName,
     129              :     PersistentLayerDesc, PersistentLayerKey, ResidentLayer, ValueReconstructSituation,
     130              :     ValueReconstructState, ValuesReconstructState,
     131              : };
     132              : use crate::tenant::tasks::BackgroundLoopKind;
     133              : use crate::tenant::timeline::logical_size::CurrentLogicalSize;
     134              : use crate::virtual_file::{MaybeFatalIo, VirtualFile};
     135              : use crate::walingest::WalLagCooldown;
     136              : use crate::walredo::RedoAttemptType;
     137              : use crate::{ZERO_PAGE, task_mgr, walredo};
     138              : 
     139              : #[derive(Debug, PartialEq, Eq, Clone, Copy)]
     140              : pub(crate) enum FlushLoopState {
     141              :     NotStarted,
     142              :     Running {
     143              :         #[cfg(test)]
     144              :         expect_initdb_optimization: bool,
     145              :         #[cfg(test)]
     146              :         initdb_optimization_count: usize,
     147              :     },
     148              :     Exited,
     149              : }
     150              : 
     151              : #[derive(Debug, Copy, Clone, PartialEq, Eq)]
     152              : pub enum ImageLayerCreationMode {
     153              :     /// Try to create image layers based on `time_for_new_image_layer`. Used in compaction code path.
     154              :     Try,
     155              :     /// Force creating the image layers if possible. For now, no image layers will be created
     156              :     /// for metadata keys. Used in compaction code path with force flag enabled.
     157              :     Force,
     158              :     /// Initial ingestion of the data, and no data should be dropped in this function. This
     159              :     /// means that no metadata keys should be included in the partitions. Used in flush frozen layer
     160              :     /// code path.
     161              :     Initial,
     162              : }
     163              : 
     164              : #[derive(Clone, Debug, Default)]
     165              : pub enum LastImageLayerCreationStatus {
     166              :     Incomplete {
     167              :         /// The last key of the partition (exclusive) that was processed in the last
     168              :         /// image layer creation attempt. We will continue from this key in the next
     169              :         /// attempt.
     170              :         last_key: Key,
     171              :     },
     172              :     Complete,
     173              :     #[default]
     174              :     Initial,
     175              : }
     176              : 
     177              : impl std::fmt::Display for ImageLayerCreationMode {
     178          191 :     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
     179          191 :         write!(f, "{self:?}")
     180          191 :     }
     181              : }
     182              : 
     183              : /// Temporary function for immutable storage state refactor, ensures we are dropping mutex guard instead of other things.
     184              : /// Can be removed after all refactors are done.
     185           23 : fn drop_layer_manager_rlock(rlock: LayerManagerReadGuard<'_>) {
     186           23 :     drop(rlock)
     187           23 : }
     188              : 
     189              : /// Temporary function for immutable storage state refactor, ensures we are dropping mutex guard instead of other things.
     190              : /// Can be removed after all refactors are done.
     191          214 : fn drop_layer_manager_wlock(rlock: LayerManagerWriteGuard<'_>) {
     192          214 :     drop(rlock)
     193          214 : }
     194              : 
     195              : /// The outward-facing resources required to build a Timeline
     196              : pub struct TimelineResources {
     197              :     pub remote_client: RemoteTimelineClient,
     198              :     pub pagestream_throttle: Arc<crate::tenant::throttle::Throttle>,
     199              :     pub pagestream_throttle_metrics: Arc<crate::metrics::tenant_throttling::Pagestream>,
     200              :     pub l0_compaction_trigger: Arc<Notify>,
     201              :     pub l0_flush_global_state: l0_flush::L0FlushGlobalState,
     202              :     pub basebackup_cache: Arc<BasebackupCache>,
     203              :     pub feature_resolver: Arc<TenantFeatureResolver>,
     204              : }
     205              : 
     206              : pub struct Timeline {
     207              :     pub(crate) conf: &'static PageServerConf,
     208              :     tenant_conf: Arc<ArcSwap<AttachedTenantConf>>,
     209              : 
     210              :     myself: Weak<Self>,
     211              : 
     212              :     pub(crate) tenant_shard_id: TenantShardId,
     213              :     pub timeline_id: TimelineId,
     214              : 
     215              :     /// The generation of the tenant that instantiated us: this is used for safety when writing remote objects.
     216              :     /// Never changes for the lifetime of this [`Timeline`] object.
     217              :     ///
     218              :     /// This duplicates the generation stored in LocationConf, but that structure is mutable:
     219              :     /// this copy enforces the invariant that generatio doesn't change during a Tenant's lifetime.
     220              :     pub(crate) generation: Generation,
     221              : 
     222              :     /// The detailed sharding information from our parent Tenant.  This enables us to map keys
     223              :     /// to shards, and is constant through the lifetime of this Timeline.
     224              :     shard_identity: ShardIdentity,
     225              : 
     226              :     pub pg_version: PgMajorVersion,
     227              : 
     228              :     /// The tuple has two elements.
     229              :     /// 1. `LayerFileManager` keeps track of the various physical representations of the layer files (inmem, local, remote).
     230              :     /// 2. `LayerMap`, the acceleration data structure for `get_reconstruct_data`.
     231              :     ///
     232              :     /// `LayerMap` maps out the `(PAGE,LSN) / (KEY,LSN)` space, which is composed of `(KeyRange, LsnRange)` rectangles.
     233              :     /// We describe these rectangles through the `PersistentLayerDesc` struct.
     234              :     ///
     235              :     /// When we want to reconstruct a page, we first find the `PersistentLayerDesc`'s that we need for page reconstruction,
     236              :     /// using `LayerMap`. Then, we use `LayerFileManager` to get the `PersistentLayer`'s that correspond to the
     237              :     /// `PersistentLayerDesc`'s.
     238              :     ///
     239              :     /// Hence, it's important to keep things coherent. The `LayerFileManager` must always have an entry for all
     240              :     /// `PersistentLayerDesc`'s in the `LayerMap`. If it doesn't, `LayerFileManager::get_from_desc` will panic at
     241              :     /// runtime, e.g., during page reconstruction.
     242              :     ///
     243              :     /// In the future, we'll be able to split up the tuple of LayerMap and `LayerFileManager`,
     244              :     /// so that e.g. on-demand-download/eviction, and layer spreading, can operate just on `LayerFileManager`.
     245              :     pub(crate) layers: LockedLayerManager,
     246              : 
     247              :     last_freeze_at: AtomicLsn,
     248              :     // Atomic would be more appropriate here.
     249              :     last_freeze_ts: RwLock<Instant>,
     250              : 
     251              :     pub(crate) standby_horizon: AtomicLsn,
     252              : 
     253              :     // WAL redo manager. `None` only for broken tenants.
     254              :     walredo_mgr: Option<Arc<super::WalRedoManager>>,
     255              : 
     256              :     /// Remote storage client.
     257              :     /// See [`remote_timeline_client`](super::remote_timeline_client) module comment for details.
     258              :     pub(crate) remote_client: Arc<RemoteTimelineClient>,
     259              : 
     260              :     // What page versions do we hold in the repository? If we get a
     261              :     // request > last_record_lsn, we need to wait until we receive all
     262              :     // the WAL up to the request. The SeqWait provides functions for
     263              :     // that. TODO: If we get a request for an old LSN, such that the
     264              :     // versions have already been garbage collected away, we should
     265              :     // throw an error, but we don't track that currently.
     266              :     //
     267              :     // last_record_lsn.load().last points to the end of last processed WAL record.
     268              :     //
     269              :     // We also remember the starting point of the previous record in
     270              :     // 'last_record_lsn.load().prev'. It's used to set the xl_prev pointer of the
     271              :     // first WAL record when the node is started up. But here, we just
     272              :     // keep track of it.
     273              :     last_record_lsn: SeqWait<RecordLsn, Lsn>,
     274              : 
     275              :     // All WAL records have been processed and stored durably on files on
     276              :     // local disk, up to this LSN. On crash and restart, we need to re-process
     277              :     // the WAL starting from this point.
     278              :     //
     279              :     // Some later WAL records might have been processed and also flushed to disk
     280              :     // already, so don't be surprised to see some, but there's no guarantee on
     281              :     // them yet.
     282              :     disk_consistent_lsn: AtomicLsn,
     283              : 
     284              :     // Parent timeline that this timeline was branched from, and the LSN
     285              :     // of the branch point.
     286              :     ancestor_timeline: Option<Arc<Timeline>>,
     287              :     ancestor_lsn: Lsn,
     288              : 
     289              :     // The LSN of gc-compaction that was last applied to this timeline.
     290              :     gc_compaction_state: ArcSwapOption<GcCompactionState>,
     291              : 
     292              :     pub(crate) metrics: Arc<TimelineMetrics>,
     293              : 
     294              :     // `Timeline` doesn't write these metrics itself, but it manages the lifetime.  Code
     295              :     // in `crate::page_service` writes these metrics.
     296              :     pub(crate) query_metrics: crate::metrics::SmgrQueryTimePerTimeline,
     297              : 
     298              :     directory_metrics_inited: [AtomicBool; DirectoryKind::KINDS_NUM],
     299              :     directory_metrics: [AtomicU64; DirectoryKind::KINDS_NUM],
     300              : 
     301              :     /// Ensures layers aren't frozen by checkpointer between
     302              :     /// [`Timeline::get_layer_for_write`] and layer reads.
     303              :     /// Locked automatically by [`TimelineWriter`] and checkpointer.
     304              :     /// Must always be acquired before the layer map/individual layer lock
     305              :     /// to avoid deadlock.
     306              :     ///
     307              :     /// The state is cleared upon freezing.
     308              :     write_lock: tokio::sync::Mutex<Option<TimelineWriterState>>,
     309              : 
     310              :     /// Used to avoid multiple `flush_loop` tasks running
     311              :     pub(super) flush_loop_state: Mutex<FlushLoopState>,
     312              : 
     313              :     /// layer_flush_start_tx can be used to wake up the layer-flushing task.
     314              :     /// - The u64 value is a counter, incremented every time a new flush cycle is requested.
     315              :     ///   The flush cycle counter is sent back on the layer_flush_done channel when
     316              :     ///   the flush finishes. You can use that to wait for the flush to finish.
     317              :     /// - The LSN is updated to max() of its current value and the latest disk_consistent_lsn
     318              :     ///   read by whoever sends an update
     319              :     layer_flush_start_tx: tokio::sync::watch::Sender<(u64, Lsn)>,
     320              :     /// to be notified when layer flushing has finished, subscribe to the layer_flush_done channel
     321              :     layer_flush_done_tx: tokio::sync::watch::Sender<(u64, Result<(), FlushLayerError>)>,
     322              : 
     323              :     // The LSN at which we have executed GC: whereas [`Self::gc_info`] records the LSN at which
     324              :     // we _intend_ to GC (i.e. the PITR cutoff), this LSN records where we actually last did it.
     325              :     // Because PITR interval is mutable, it's possible for this LSN to be earlier or later than
     326              :     // the planned GC cutoff.
     327              :     pub applied_gc_cutoff_lsn: Rcu<Lsn>,
     328              : 
     329              :     pub(crate) gc_compaction_layer_update_lock: tokio::sync::RwLock<()>,
     330              : 
     331              :     // List of child timelines and their branch points. This is needed to avoid
     332              :     // garbage collecting data that is still needed by the child timelines.
     333              :     pub(crate) gc_info: std::sync::RwLock<GcInfo>,
     334              : 
     335              :     pub(crate) last_image_layer_creation_status: ArcSwap<LastImageLayerCreationStatus>,
     336              : 
     337              :     // It may change across major versions so for simplicity
     338              :     // keep it after running initdb for a timeline.
     339              :     // It is needed in checks when we want to error on some operations
     340              :     // when they are requested for pre-initdb lsn.
     341              :     // It can be unified with latest_gc_cutoff_lsn under some "first_valid_lsn",
     342              :     // though let's keep them both for better error visibility.
     343              :     pub initdb_lsn: Lsn,
     344              : 
     345              :     /// The repartitioning result. Allows a single writer and multiple readers.
     346              :     pub(crate) partitioning: GuardArcSwap<((KeyPartitioning, SparseKeyPartitioning), Lsn)>,
     347              : 
     348              :     /// Configuration: how often should the partitioning be recalculated.
     349              :     repartition_threshold: u64,
     350              : 
     351              :     last_image_layer_creation_check_at: AtomicLsn,
     352              :     last_image_layer_creation_check_instant: std::sync::Mutex<Option<Instant>>,
     353              : 
     354              :     /// Current logical size of the "datadir", at the last LSN.
     355              :     current_logical_size: LogicalSize,
     356              : 
     357              :     /// Information about the last processed message by the WAL receiver,
     358              :     /// or None if WAL receiver has not received anything for this timeline
     359              :     /// yet.
     360              :     pub last_received_wal: Mutex<Option<WalReceiverInfo>>,
     361              :     pub walreceiver: Mutex<Option<WalReceiver>>,
     362              : 
     363              :     /// Relation size cache
     364              :     pub(crate) rel_size_latest_cache: RwLock<HashMap<RelTag, (Lsn, BlockNumber)>>,
     365              :     pub(crate) rel_size_snapshot_cache: Mutex<LruCache<(Lsn, RelTag), BlockNumber>>,
     366              : 
     367              :     download_all_remote_layers_task_info: RwLock<Option<DownloadRemoteLayersTaskInfo>>,
     368              : 
     369              :     state: watch::Sender<TimelineState>,
     370              : 
     371              :     /// Prevent two tasks from deleting the timeline at the same time. If held, the
     372              :     /// timeline is being deleted. If 'true', the timeline has already been deleted.
     373              :     pub delete_progress: TimelineDeleteProgress,
     374              : 
     375              :     eviction_task_timeline_state: tokio::sync::Mutex<EvictionTaskTimelineState>,
     376              : 
     377              :     /// Load or creation time information about the disk_consistent_lsn and when the loading
     378              :     /// happened. Used for consumption metrics.
     379              :     pub(crate) loaded_at: (Lsn, SystemTime),
     380              : 
     381              :     /// Gate to prevent shutdown completing while I/O is still happening to this timeline's data
     382              :     pub(crate) gate: Gate,
     383              : 
     384              :     /// Cancellation token scoped to this timeline: anything doing long-running work relating
     385              :     /// to the timeline should drop out when this token fires.
     386              :     pub(crate) cancel: CancellationToken,
     387              : 
     388              :     /// Make sure we only have one running compaction at a time in tests.
     389              :     ///
     390              :     /// Must only be taken in two places:
     391              :     /// - [`Timeline::compact`] (this file)
     392              :     /// - [`delete::delete_local_timeline_directory`]
     393              :     ///
     394              :     /// Timeline deletion will acquire both compaction and gc locks in whatever order.
     395              :     compaction_lock: tokio::sync::Mutex<()>,
     396              : 
     397              :     /// If true, the last compaction failed.
     398              :     compaction_failed: AtomicBool,
     399              : 
     400              :     /// Notifies the tenant compaction loop that there is pending L0 compaction work.
     401              :     l0_compaction_trigger: Arc<Notify>,
     402              : 
     403              :     /// Make sure we only have one running gc at a time.
     404              :     ///
     405              :     /// Must only be taken in two places:
     406              :     /// - [`Timeline::gc`] (this file)
     407              :     /// - [`delete::delete_local_timeline_directory`]
     408              :     ///
     409              :     /// Timeline deletion will acquire both compaction and gc locks in whatever order.
     410              :     gc_lock: tokio::sync::Mutex<()>,
     411              : 
     412              :     /// Cloned from [`super::TenantShard::pagestream_throttle`] on construction.
     413              :     pub(crate) pagestream_throttle: Arc<crate::tenant::throttle::Throttle>,
     414              : 
     415              :     /// Size estimator for aux file v2
     416              :     pub(crate) aux_file_size_estimator: AuxFileSizeEstimator,
     417              : 
     418              :     /// Some test cases directly place keys into the timeline without actually modifying the directory
     419              :     /// keys (i.e., DB_DIR). The test cases creating such keys will put the keyspaces here, so that
     420              :     /// these keys won't get garbage-collected during compaction/GC. This field only modifies the dense
     421              :     /// keyspace return value of `collect_keyspace`. For sparse keyspaces, use AUX keys for testing, and
     422              :     /// in the future, add `extra_test_sparse_keyspace` if necessary.
     423              :     #[cfg(test)]
     424              :     pub(crate) extra_test_dense_keyspace: ArcSwap<KeySpace>,
     425              : 
     426              :     pub(crate) l0_flush_global_state: L0FlushGlobalState,
     427              : 
     428              :     pub(crate) handles: handle::PerTimelineState<TenantManagerTypes>,
     429              : 
     430              :     pub(crate) attach_wal_lag_cooldown: Arc<OnceLock<WalLagCooldown>>,
     431              : 
     432              :     /// Cf. [`crate::tenant::CreateTimelineIdempotency`].
     433              :     pub(crate) create_idempotency: crate::tenant::CreateTimelineIdempotency,
     434              : 
     435              :     /// If Some, collects GetPage metadata for an ongoing PageTrace.
     436              :     pub(crate) page_trace: ArcSwapOption<Sender<PageTraceEvent>>,
     437              : 
     438              :     pub(super) previous_heatmap: ArcSwapOption<PreviousHeatmap>,
     439              : 
     440              :     /// May host a background Tokio task which downloads all the layers from the current
     441              :     /// heatmap on demand.
     442              :     heatmap_layers_downloader: Mutex<Option<heatmap_layers_downloader::HeatmapLayersDownloader>>,
     443              : 
     444              :     pub(crate) rel_size_v2_status: ArcSwap<(Option<RelSizeMigration>, Option<Lsn>)>,
     445              : 
     446              :     wait_lsn_log_slow: tokio::sync::Semaphore,
     447              : 
     448              :     /// A channel to send async requests to prepare a basebackup for the basebackup cache.
     449              :     basebackup_cache: Arc<BasebackupCache>,
     450              : 
     451              :     #[expect(dead_code)]
     452              :     feature_resolver: Arc<TenantFeatureResolver>,
     453              : 
     454              :     /// Basebackup will collect the count and store it here. Used for reldirv2 rollout.
     455              :     pub(crate) db_rel_count: ArcSwapOption<(usize, usize)>,
     456              : }
     457              : 
     458              : pub(crate) enum PreviousHeatmap {
     459              :     Active {
     460              :         heatmap: HeatMapTimeline,
     461              :         read_at: std::time::Instant,
     462              :         // End LSN covered by the heatmap if known
     463              :         end_lsn: Option<Lsn>,
     464              :     },
     465              :     Obsolete,
     466              : }
     467              : 
     468              : pub type TimelineDeleteProgress = Arc<tokio::sync::Mutex<DeleteTimelineFlow>>;
     469              : 
     470              : pub struct WalReceiverInfo {
     471              :     pub wal_source_connconf: PgConnectionConfig,
     472              :     pub last_received_msg_lsn: Lsn,
     473              :     pub last_received_msg_ts: u128,
     474              : }
     475              : 
     476              : /// Information about how much history needs to be retained, needed by
     477              : /// Garbage Collection.
     478              : #[derive(Default)]
     479              : pub(crate) struct GcInfo {
     480              :     /// Specific LSNs that are needed.
     481              :     ///
     482              :     /// Currently, this includes all points where child branches have
     483              :     /// been forked off from. In the future, could also include
     484              :     /// explicit user-defined snapshot points.
     485              :     pub(crate) retain_lsns: Vec<(Lsn, TimelineId, MaybeOffloaded)>,
     486              : 
     487              :     /// The cutoff coordinates, which are combined by selecting the minimum.
     488              :     pub(crate) cutoffs: GcCutoffs,
     489              : 
     490              :     /// Leases granted to particular LSNs.
     491              :     pub(crate) leases: BTreeMap<Lsn, LsnLease>,
     492              : 
     493              :     /// Whether our branch point is within our ancestor's PITR interval (for cost estimation)
     494              :     pub(crate) within_ancestor_pitr: bool,
     495              : }
     496              : 
     497              : impl GcInfo {
     498          154 :     pub(crate) fn min_cutoff(&self) -> Lsn {
     499          154 :         self.cutoffs.select_min()
     500          154 :     }
     501              : 
     502          119 :     pub(super) fn insert_child(
     503          119 :         &mut self,
     504          119 :         child_id: TimelineId,
     505          119 :         child_lsn: Lsn,
     506          119 :         is_offloaded: MaybeOffloaded,
     507          119 :     ) {
     508          119 :         self.retain_lsns.push((child_lsn, child_id, is_offloaded));
     509          119 :         self.retain_lsns.sort_by_key(|i| i.0);
     510          119 :     }
     511              : 
     512            2 :     pub(super) fn remove_child_maybe_offloaded(
     513            2 :         &mut self,
     514            2 :         child_id: TimelineId,
     515            2 :         maybe_offloaded: MaybeOffloaded,
     516            2 :     ) -> bool {
     517              :         // Remove at most one element. Needed for correctness if there is two live `Timeline` objects referencing
     518              :         // the same timeline. Shouldn't but maybe can occur when Arc's live longer than intended.
     519            2 :         let mut removed = false;
     520            3 :         self.retain_lsns.retain(|i| {
     521            3 :             if removed {
     522            1 :                 return true;
     523            2 :             }
     524            2 :             let remove = i.1 == child_id && i.2 == maybe_offloaded;
     525            2 :             removed |= remove;
     526            2 :             !remove
     527            3 :         });
     528            2 :         removed
     529            2 :     }
     530              : 
     531            2 :     pub(super) fn remove_child_not_offloaded(&mut self, child_id: TimelineId) -> bool {
     532            2 :         self.remove_child_maybe_offloaded(child_id, MaybeOffloaded::No)
     533            2 :     }
     534              : 
     535            0 :     pub(super) fn remove_child_offloaded(&mut self, child_id: TimelineId) -> bool {
     536            0 :         self.remove_child_maybe_offloaded(child_id, MaybeOffloaded::Yes)
     537            0 :     }
     538          119 :     pub(crate) fn lsn_covered_by_lease(&self, lsn: Lsn) -> bool {
     539          119 :         self.leases.contains_key(&lsn)
     540          119 :     }
     541              : }
     542              : 
     543              : /// The `GcInfo` component describing which Lsns need to be retained.  Functionally, this
     544              : /// is a single number (the oldest LSN which we must retain), but it internally distinguishes
     545              : /// between time-based and space-based retention for observability and consumption metrics purposes.
     546              : #[derive(Clone, Debug, Default)]
     547              : pub(crate) struct GcCutoffs {
     548              :     /// Calculated from the [`pageserver_api::models::TenantConfig::gc_horizon`], this LSN indicates how much
     549              :     /// history we must keep to retain a specified number of bytes of WAL.
     550              :     pub(crate) space: Lsn,
     551              : 
     552              :     /// Calculated from [`pageserver_api::models::TenantConfig::pitr_interval`], this LSN indicates
     553              :     /// how much history we must keep to enable reading back at least the PITR interval duration.
     554              :     ///
     555              :     /// None indicates that the PITR cutoff has not been computed. A PITR interval of 0 will yield
     556              :     /// Some(last_record_lsn).
     557              :     pub(crate) time: Option<Lsn>,
     558              : }
     559              : 
     560              : impl GcCutoffs {
     561          154 :     fn select_min(&self) -> Lsn {
     562              :         // NB: if we haven't computed the PITR cutoff yet, we can't GC anything.
     563          154 :         self.space.min(self.time.unwrap_or_default())
     564          154 :     }
     565              : }
     566              : 
     567              : pub(crate) struct TimelineVisitOutcome {
     568              :     completed_keyspace: KeySpace,
     569              :     image_covered_keyspace: KeySpace,
     570              : }
     571              : 
     572              : /// An error happened in a get() operation.
     573              : #[derive(thiserror::Error, Debug)]
     574              : pub(crate) enum PageReconstructError {
     575              :     #[error(transparent)]
     576              :     Other(anyhow::Error),
     577              : 
     578              :     #[error("Ancestor LSN wait error: {0}")]
     579              :     AncestorLsnTimeout(WaitLsnError),
     580              : 
     581              :     #[error("timeline shutting down")]
     582              :     Cancelled,
     583              : 
     584              :     /// An error happened replaying WAL records
     585              :     #[error(transparent)]
     586              :     WalRedo(anyhow::Error),
     587              : 
     588              :     #[error("{0}")]
     589              :     MissingKey(Box<MissingKeyError>),
     590              : }
     591              : 
     592              : impl PageReconstructError {
     593            0 :     pub(crate) fn is_cancel(&self) -> bool {
     594            0 :         match self {
     595            0 :             PageReconstructError::Other(_) => false,
     596            0 :             PageReconstructError::AncestorLsnTimeout(e) => e.is_cancel(),
     597            0 :             PageReconstructError::Cancelled => true,
     598            0 :             PageReconstructError::WalRedo(_) => false,
     599            0 :             PageReconstructError::MissingKey(_) => false,
     600              :         }
     601            0 :     }
     602              :     #[allow(dead_code)] // we use the is_cancel + into_anyhow pattern in quite a few places, this one will follow soon enough
     603            0 :     pub(crate) fn into_anyhow(self) -> anyhow::Error {
     604            0 :         match self {
     605            0 :             PageReconstructError::Other(e) => e,
     606            0 :             PageReconstructError::AncestorLsnTimeout(e) => e.into_anyhow(),
     607            0 :             PageReconstructError::Cancelled => anyhow::Error::new(self),
     608            0 :             PageReconstructError::WalRedo(e) => e,
     609            0 :             PageReconstructError::MissingKey(_) => anyhow::Error::new(self),
     610              :         }
     611            0 :     }
     612              : }
     613              : 
     614              : impl From<anyhow::Error> for PageReconstructError {
     615            1 :     fn from(value: anyhow::Error) -> Self {
     616              :         // with walingest.rs many PageReconstructError are wrapped in as anyhow::Error
     617            1 :         match value.downcast::<PageReconstructError>() {
     618            0 :             Ok(pre) => pre,
     619            1 :             Err(other) => PageReconstructError::Other(other),
     620              :         }
     621            1 :     }
     622              : }
     623              : 
     624              : impl From<utils::bin_ser::DeserializeError> for PageReconstructError {
     625            0 :     fn from(value: utils::bin_ser::DeserializeError) -> Self {
     626            0 :         PageReconstructError::Other(anyhow::Error::new(value).context("deserialization failure"))
     627            0 :     }
     628              : }
     629              : 
     630              : impl From<layer_manager::Shutdown> for PageReconstructError {
     631            0 :     fn from(_: layer_manager::Shutdown) -> Self {
     632            0 :         PageReconstructError::Cancelled
     633            0 :     }
     634              : }
     635              : 
     636              : impl GetVectoredError {
     637              :     #[cfg(test)]
     638            3 :     pub(crate) fn is_missing_key_error(&self) -> bool {
     639            3 :         matches!(self, Self::MissingKey(_))
     640            3 :     }
     641              : }
     642              : 
     643              : impl From<layer_manager::Shutdown> for GetVectoredError {
     644            0 :     fn from(_: layer_manager::Shutdown) -> Self {
     645            0 :         GetVectoredError::Cancelled
     646            0 :     }
     647              : }
     648              : 
     649              : /// A layer identifier when used in the [`ReadPath`] structure. This enum is for observability purposes
     650              : /// only and not used by the "real read path".
     651              : pub enum ReadPathLayerId {
     652              :     PersistentLayer(PersistentLayerKey),
     653              :     InMemoryLayer(Range<Lsn>),
     654              : }
     655              : 
     656              : impl std::fmt::Display for ReadPathLayerId {
     657            0 :     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
     658            0 :         match self {
     659            0 :             ReadPathLayerId::PersistentLayer(key) => write!(f, "{key}"),
     660            0 :             ReadPathLayerId::InMemoryLayer(range) => {
     661            0 :                 write!(f, "in-mem {}..{}", range.start, range.end)
     662              :             }
     663              :         }
     664            0 :     }
     665              : }
     666              : pub struct ReadPath {
     667              :     keyspace: KeySpace,
     668              :     lsn: Lsn,
     669              :     path: Vec<(ReadPathLayerId, KeySpace, Range<Lsn>)>,
     670              : }
     671              : 
     672              : impl ReadPath {
     673       312438 :     pub fn new(keyspace: KeySpace, lsn: Lsn) -> Self {
     674       312438 :         Self {
     675       312438 :             keyspace,
     676       312438 :             lsn,
     677       312438 :             path: Vec::new(),
     678       312438 :         }
     679       312438 :     }
     680              : 
     681       446988 :     pub fn record_layer_visit(
     682       446988 :         &mut self,
     683       446988 :         layer_to_read: &ReadableLayer,
     684       446988 :         keyspace_to_read: &KeySpace,
     685       446988 :         lsn_range: &Range<Lsn>,
     686       446988 :     ) {
     687       446988 :         let id = match layer_to_read {
     688       139728 :             ReadableLayer::PersistentLayer(layer) => {
     689       139728 :                 ReadPathLayerId::PersistentLayer(layer.layer_desc().key())
     690              :             }
     691       307260 :             ReadableLayer::InMemoryLayer(layer) => {
     692       307260 :                 ReadPathLayerId::InMemoryLayer(layer.get_lsn_range())
     693              :             }
     694              :         };
     695       446988 :         self.path
     696       446988 :             .push((id, keyspace_to_read.clone(), lsn_range.clone()));
     697       446988 :     }
     698              : }
     699              : 
     700              : impl std::fmt::Display for ReadPath {
     701            0 :     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
     702            0 :         writeln!(f, "Read path for {} at lsn {}:", self.keyspace, self.lsn)?;
     703            0 :         for (idx, (layer_id, keyspace, lsn_range)) in self.path.iter().enumerate() {
     704            0 :             writeln!(
     705            0 :                 f,
     706            0 :                 "{}: {} {}..{} {}",
     707              :                 idx, layer_id, lsn_range.start, lsn_range.end, keyspace
     708            0 :             )?;
     709              :         }
     710            0 :         Ok(())
     711            0 :     }
     712              : }
     713              : 
     714              : #[derive(thiserror::Error)]
     715              : pub struct MissingKeyError {
     716              :     keyspace: KeySpace,
     717              :     shard: ShardNumber,
     718              :     query: Option<VersionedKeySpaceQuery>,
     719              :     // This is largest request LSN from the get page request batch
     720              :     original_hwm_lsn: Lsn,
     721              :     ancestor_lsn: Option<Lsn>,
     722              :     /// Debug information about the read path if there's an error
     723              :     read_path: Option<ReadPath>,
     724              :     backtrace: Option<std::backtrace::Backtrace>,
     725              : }
     726              : 
     727              : impl MissingKeyError {
     728            7 :     fn enrich(&mut self, query: VersionedKeySpaceQuery) {
     729            7 :         self.query = Some(query);
     730            7 :     }
     731              : }
     732              : 
     733              : impl std::fmt::Debug for MissingKeyError {
     734            0 :     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
     735            0 :         write!(f, "{self}")
     736            0 :     }
     737              : }
     738              : 
     739              : impl std::fmt::Display for MissingKeyError {
     740            0 :     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
     741            0 :         write!(
     742            0 :             f,
     743            0 :             "could not find data for key {} (shard {:?}), original HWM LSN {}",
     744              :             self.keyspace, self.shard, self.original_hwm_lsn
     745            0 :         )?;
     746              : 
     747            0 :         if let Some(ref ancestor_lsn) = self.ancestor_lsn {
     748            0 :             write!(f, ", ancestor {ancestor_lsn}")?;
     749            0 :         }
     750              : 
     751            0 :         if let Some(ref query) = self.query {
     752            0 :             write!(f, ", query {query}")?;
     753            0 :         }
     754              : 
     755            0 :         if let Some(ref read_path) = self.read_path {
     756            0 :             write!(f, "\n{read_path}")?;
     757            0 :         }
     758              : 
     759            0 :         if let Some(ref backtrace) = self.backtrace {
     760            0 :             write!(f, "\n{backtrace}")?;
     761            0 :         }
     762              : 
     763            0 :         Ok(())
     764            0 :     }
     765              : }
     766              : 
     767              : #[derive(thiserror::Error, Debug)]
     768              : pub(crate) enum CreateImageLayersError {
     769              :     #[error("timeline shutting down")]
     770              :     Cancelled,
     771              : 
     772              :     #[error("read failed")]
     773              :     GetVectoredError(#[source] GetVectoredError),
     774              : 
     775              :     #[error("reconstruction failed")]
     776              :     PageReconstructError(#[source] PageReconstructError),
     777              : 
     778              :     #[error(transparent)]
     779              :     Other(anyhow::Error),
     780              : }
     781              : 
     782              : impl From<layer_manager::Shutdown> for CreateImageLayersError {
     783            0 :     fn from(_: layer_manager::Shutdown) -> Self {
     784            0 :         CreateImageLayersError::Cancelled
     785            0 :     }
     786              : }
     787              : 
     788              : #[derive(thiserror::Error, Debug, Clone)]
     789              : pub(crate) enum FlushLayerError {
     790              :     /// Timeline cancellation token was cancelled
     791              :     #[error("timeline shutting down")]
     792              :     Cancelled,
     793              : 
     794              :     /// We tried to flush a layer while the Timeline is in an unexpected state
     795              :     #[error("cannot flush frozen layers when flush_loop is not running, state is {0:?}")]
     796              :     NotRunning(FlushLoopState),
     797              : 
     798              :     // Arc<> the following non-clonable error types: we must be Clone-able because the flush error is propagated from the flush
     799              :     // loop via a watch channel, where we can only borrow it.
     800              :     #[error("create image layers (shared)")]
     801              :     CreateImageLayersError(Arc<CreateImageLayersError>),
     802              : 
     803              :     #[error("other (shared)")]
     804              :     Other(#[from] Arc<anyhow::Error>),
     805              : }
     806              : 
     807              : impl FlushLayerError {
     808              :     // When crossing from generic anyhow errors to this error type, we explicitly check
     809              :     // for timeline cancellation to avoid logging inoffensive shutdown errors as warn/err.
     810            0 :     fn from_anyhow(timeline: &Timeline, err: anyhow::Error) -> Self {
     811            0 :         let cancelled = timeline.cancel.is_cancelled()
     812              :             // The upload queue might have been shut down before the official cancellation of the timeline.
     813            0 :             || err
     814            0 :                 .downcast_ref::<NotInitialized>()
     815            0 :                 .map(NotInitialized::is_stopping)
     816            0 :                 .unwrap_or_default();
     817            0 :         if cancelled {
     818            0 :             Self::Cancelled
     819              :         } else {
     820            0 :             Self::Other(Arc::new(err))
     821              :         }
     822            0 :     }
     823              : }
     824              : 
     825              : impl From<layer_manager::Shutdown> for FlushLayerError {
     826            0 :     fn from(_: layer_manager::Shutdown) -> Self {
     827            0 :         FlushLayerError::Cancelled
     828            0 :     }
     829              : }
     830              : 
     831              : #[derive(thiserror::Error, Debug)]
     832              : pub enum GetVectoredError {
     833              :     #[error("timeline shutting down")]
     834              :     Cancelled,
     835              : 
     836              :     #[error("requested too many keys: {0} > {1}")]
     837              :     Oversized(u64, u64),
     838              : 
     839              :     #[error("requested at invalid LSN: {0}")]
     840              :     InvalidLsn(Lsn),
     841              : 
     842              :     #[error("requested key not found: {0}")]
     843              :     MissingKey(Box<MissingKeyError>),
     844              : 
     845              :     #[error("ancestry walk")]
     846              :     GetReadyAncestorError(#[source] GetReadyAncestorError),
     847              : 
     848              :     #[error(transparent)]
     849              :     Other(#[from] anyhow::Error),
     850              : }
     851              : 
     852              : impl From<GetReadyAncestorError> for GetVectoredError {
     853            1 :     fn from(value: GetReadyAncestorError) -> Self {
     854              :         use GetReadyAncestorError::*;
     855            1 :         match value {
     856            0 :             Cancelled => GetVectoredError::Cancelled,
     857              :             AncestorLsnTimeout(_) | BadState { .. } => {
     858            1 :                 GetVectoredError::GetReadyAncestorError(value)
     859              :             }
     860              :         }
     861            1 :     }
     862              : }
     863              : 
     864              : #[derive(thiserror::Error, Debug)]
     865              : pub enum GetReadyAncestorError {
     866              :     #[error("ancestor LSN wait error")]
     867              :     AncestorLsnTimeout(#[from] WaitLsnError),
     868              : 
     869              :     #[error("bad state on timeline {timeline_id}: {state:?}")]
     870              :     BadState {
     871              :         timeline_id: TimelineId,
     872              :         state: TimelineState,
     873              :     },
     874              : 
     875              :     #[error("cancelled")]
     876              :     Cancelled,
     877              : }
     878              : 
     879              : #[derive(Clone, Copy)]
     880              : pub enum LogicalSizeCalculationCause {
     881              :     Initial,
     882              :     ConsumptionMetricsSyntheticSize,
     883              :     EvictionTaskImitation,
     884              :     TenantSizeHandler,
     885              : }
     886              : 
     887              : pub enum GetLogicalSizePriority {
     888              :     User,
     889              :     Background,
     890              : }
     891              : 
     892              : #[derive(Debug, enumset::EnumSetType)]
     893              : pub(crate) enum CompactFlags {
     894              :     ForceRepartition,
     895              :     ForceImageLayerCreation,
     896              :     ForceL0Compaction,
     897              :     OnlyL0Compaction,
     898              :     EnhancedGcBottomMostCompaction,
     899              :     DryRun,
     900              :     /// Makes image compaction yield if there's pending L0 compaction. This should always be used in
     901              :     /// the background compaction task, since we want to aggressively compact down L0 to bound
     902              :     /// read amplification.
     903              :     ///
     904              :     /// It only makes sense to use this when `compaction_l0_first` is enabled (such that we yield to
     905              :     /// an L0 compaction pass), and without `OnlyL0Compaction` (L0 compaction shouldn't yield for L0
     906              :     /// compaction).
     907              :     YieldForL0,
     908              : }
     909              : 
     910              : #[serde_with::serde_as]
     911            0 : #[derive(Debug, Clone, serde::Deserialize)]
     912              : pub(crate) struct CompactRequest {
     913              :     pub compact_key_range: Option<CompactKeyRange>,
     914              :     pub compact_lsn_range: Option<CompactLsnRange>,
     915              :     /// Whether the compaction job should be scheduled.
     916              :     #[serde(default)]
     917              :     pub scheduled: bool,
     918              :     /// Whether the compaction job should be split across key ranges.
     919              :     #[serde(default)]
     920              :     pub sub_compaction: bool,
     921              :     /// Max job size for each subcompaction job.
     922              :     pub sub_compaction_max_job_size_mb: Option<u64>,
     923              : }
     924              : 
     925            0 : #[derive(Debug, Clone, serde::Deserialize)]
     926              : pub(crate) struct MarkInvisibleRequest {
     927              :     #[serde(default)]
     928              :     pub is_visible: Option<bool>,
     929              : }
     930              : 
     931              : #[derive(Debug, Clone, Default)]
     932              : pub(crate) struct CompactOptions {
     933              :     pub flags: EnumSet<CompactFlags>,
     934              :     /// If set, the compaction will only compact the key range specified by this option.
     935              :     /// This option is only used by GC compaction. For the full explanation, see [`compaction::GcCompactJob`].
     936              :     pub compact_key_range: Option<CompactKeyRange>,
     937              :     /// If set, the compaction will only compact the LSN within this value.
     938              :     /// This option is only used by GC compaction. For the full explanation, see [`compaction::GcCompactJob`].
     939              :     pub compact_lsn_range: Option<CompactLsnRange>,
     940              :     /// Enable sub-compaction (split compaction job across key ranges).
     941              :     /// This option is only used by GC compaction.
     942              :     pub sub_compaction: bool,
     943              :     /// Set job size for the GC compaction.
     944              :     /// This option is only used by GC compaction.
     945              :     pub sub_compaction_max_job_size_mb: Option<u64>,
     946              :     /// Only for GC compaction.
     947              :     /// If set, the compaction will compact the metadata layers. Should be only set to true in unit tests
     948              :     /// because metadata compaction is not fully supported yet.
     949              :     pub gc_compaction_do_metadata_compaction: bool,
     950              : }
     951              : 
     952              : impl CompactOptions {
     953              :     #[cfg(test)]
     954           28 :     pub fn default_for_gc_compaction_unit_tests() -> Self {
     955           28 :         Self {
     956           28 :             gc_compaction_do_metadata_compaction: true,
     957           28 :             ..Default::default()
     958           28 :         }
     959           28 :     }
     960              : }
     961              : 
     962              : impl std::fmt::Debug for Timeline {
     963            0 :     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
     964            0 :         write!(f, "Timeline<{}>", self.timeline_id)
     965            0 :     }
     966              : }
     967              : 
     968              : #[derive(thiserror::Error, Debug, Clone)]
     969              : pub enum WaitLsnError {
     970              :     // Called on a timeline which is shutting down
     971              :     #[error("Shutdown")]
     972              :     Shutdown,
     973              : 
     974              :     // Called on an timeline not in active state or shutting down
     975              :     #[error("Bad timeline state: {0:?}")]
     976              :     BadState(TimelineState),
     977              : 
     978              :     // Timeout expired while waiting for LSN to catch up with goal.
     979              :     #[error("{0}")]
     980              :     Timeout(String),
     981              : }
     982              : 
     983              : impl WaitLsnError {
     984            0 :     pub(crate) fn is_cancel(&self) -> bool {
     985            0 :         match self {
     986            0 :             WaitLsnError::Shutdown => true,
     987            0 :             WaitLsnError::BadState(timeline_state) => match timeline_state {
     988            0 :                 TimelineState::Loading => false,
     989            0 :                 TimelineState::Active => false,
     990            0 :                 TimelineState::Stopping => true,
     991            0 :                 TimelineState::Broken { .. } => false,
     992              :             },
     993            0 :             WaitLsnError::Timeout(_) => false,
     994              :         }
     995            0 :     }
     996            0 :     pub(crate) fn into_anyhow(self) -> anyhow::Error {
     997            0 :         match self {
     998            0 :             WaitLsnError::Shutdown => anyhow::Error::new(self),
     999            0 :             WaitLsnError::BadState(_) => anyhow::Error::new(self),
    1000            0 :             WaitLsnError::Timeout(_) => anyhow::Error::new(self),
    1001              :         }
    1002            0 :     }
    1003              : }
    1004              : 
    1005              : impl From<WaitLsnError> for tonic::Status {
    1006            0 :     fn from(err: WaitLsnError) -> Self {
    1007              :         use tonic::Code;
    1008            0 :         let code = if err.is_cancel() {
    1009            0 :             Code::Unavailable
    1010              :         } else {
    1011            0 :             Code::Internal
    1012              :         };
    1013            0 :         tonic::Status::new(code, err.to_string())
    1014            0 :     }
    1015              : }
    1016              : 
    1017              : // The impls below achieve cancellation mapping for errors.
    1018              : // Perhaps there's a way of achieving this with less cruft.
    1019              : 
    1020              : impl From<CreateImageLayersError> for CompactionError {
    1021            0 :     fn from(e: CreateImageLayersError) -> Self {
    1022            0 :         match e {
    1023            0 :             CreateImageLayersError::Cancelled => CompactionError::new_cancelled(),
    1024            0 :             CreateImageLayersError::Other(e) => {
    1025            0 :                 CompactionError::Other(e.context("create image layers"))
    1026              :             }
    1027            0 :             _ => CompactionError::Other(e.into()),
    1028              :         }
    1029            0 :     }
    1030              : }
    1031              : 
    1032              : impl From<CreateImageLayersError> for FlushLayerError {
    1033            0 :     fn from(e: CreateImageLayersError) -> Self {
    1034            0 :         match e {
    1035            0 :             CreateImageLayersError::Cancelled => FlushLayerError::Cancelled,
    1036            0 :             any => FlushLayerError::CreateImageLayersError(Arc::new(any)),
    1037              :         }
    1038            0 :     }
    1039              : }
    1040              : 
    1041              : impl From<PageReconstructError> for CreateImageLayersError {
    1042            0 :     fn from(e: PageReconstructError) -> Self {
    1043            0 :         match e {
    1044            0 :             PageReconstructError::Cancelled => CreateImageLayersError::Cancelled,
    1045            0 :             _ => CreateImageLayersError::PageReconstructError(e),
    1046              :         }
    1047            0 :     }
    1048              : }
    1049              : 
    1050              : impl From<super::storage_layer::errors::PutError> for CreateImageLayersError {
    1051            0 :     fn from(e: super::storage_layer::errors::PutError) -> Self {
    1052            0 :         if e.is_cancel() {
    1053            0 :             CreateImageLayersError::Cancelled
    1054              :         } else {
    1055            0 :             CreateImageLayersError::Other(e.into_anyhow())
    1056              :         }
    1057            0 :     }
    1058              : }
    1059              : 
    1060              : impl From<GetVectoredError> for CreateImageLayersError {
    1061            0 :     fn from(e: GetVectoredError) -> Self {
    1062            0 :         match e {
    1063            0 :             GetVectoredError::Cancelled => CreateImageLayersError::Cancelled,
    1064            0 :             _ => CreateImageLayersError::GetVectoredError(e),
    1065              :         }
    1066            0 :     }
    1067              : }
    1068              : 
    1069              : impl From<GetVectoredError> for PageReconstructError {
    1070            3 :     fn from(e: GetVectoredError) -> Self {
    1071            3 :         match e {
    1072            0 :             GetVectoredError::Cancelled => PageReconstructError::Cancelled,
    1073            0 :             GetVectoredError::InvalidLsn(_) => PageReconstructError::Other(anyhow!("Invalid LSN")),
    1074            0 :             err @ GetVectoredError::Oversized(_, _) => PageReconstructError::Other(err.into()),
    1075            2 :             GetVectoredError::MissingKey(err) => PageReconstructError::MissingKey(err),
    1076            1 :             GetVectoredError::GetReadyAncestorError(err) => PageReconstructError::from(err),
    1077            0 :             GetVectoredError::Other(err) => PageReconstructError::Other(err),
    1078              :         }
    1079            3 :     }
    1080              : }
    1081              : 
    1082              : impl From<GetReadyAncestorError> for PageReconstructError {
    1083            1 :     fn from(e: GetReadyAncestorError) -> Self {
    1084              :         use GetReadyAncestorError::*;
    1085            1 :         match e {
    1086            0 :             AncestorLsnTimeout(wait_err) => PageReconstructError::AncestorLsnTimeout(wait_err),
    1087            1 :             bad_state @ BadState { .. } => PageReconstructError::Other(anyhow::anyhow!(bad_state)),
    1088            0 :             Cancelled => PageReconstructError::Cancelled,
    1089              :         }
    1090            1 :     }
    1091              : }
    1092              : 
    1093              : pub(crate) enum WaitLsnTimeout {
    1094              :     Custom(Duration),
    1095              :     // Use the [`PageServerConf::wait_lsn_timeout`] default
    1096              :     Default,
    1097              : }
    1098              : 
    1099              : pub(crate) enum WaitLsnWaiter<'a> {
    1100              :     Timeline(&'a Timeline),
    1101              :     Tenant,
    1102              :     PageService,
    1103              :     HttpEndpoint,
    1104              :     BaseBackupCache,
    1105              : }
    1106              : 
    1107              : /// Argument to [`Timeline::shutdown`].
    1108              : #[derive(Debug, Clone, Copy)]
    1109              : pub(crate) enum ShutdownMode {
    1110              :     /// Graceful shutdown, may do a lot of I/O as we flush any open layers to disk. This method can
    1111              :     /// take multiple seconds for a busy timeline.
    1112              :     ///
    1113              :     /// While we are flushing, we continue to accept read I/O for LSNs ingested before
    1114              :     /// the call to [`Timeline::shutdown`].
    1115              :     FreezeAndFlush,
    1116              :     /// Only flush the layers to the remote storage without freezing any open layers. Flush the deletion
    1117              :     /// queue. This is the mode used by ancestor detach and any other operations that reloads a tenant
    1118              :     /// but not increasing the generation number. Note that this mode cannot be used at tenant shutdown,
    1119              :     /// as flushing the deletion queue at that time will cause shutdown-in-progress errors.
    1120              :     Reload,
    1121              :     /// Shut down immediately, without waiting for any open layers to flush.
    1122              :     Hard,
    1123              : }
    1124              : 
    1125              : #[allow(clippy::large_enum_variant, reason = "TODO")]
    1126              : enum ImageLayerCreationOutcome {
    1127              :     /// We generated an image layer
    1128              :     Generated {
    1129              :         unfinished_image_layer: ImageLayerWriter,
    1130              :     },
    1131              :     /// The key range is empty
    1132              :     Empty,
    1133              :     /// (Only used in metadata image layer creation), after reading the metadata keys, we decide to skip
    1134              :     /// the image layer creation.
    1135              :     Skip,
    1136              : }
    1137              : 
    1138              : enum RepartitionError {
    1139              :     Other(anyhow::Error),
    1140              :     CollectKeyspace(CollectKeySpaceError),
    1141              : }
    1142              : 
    1143              : impl RepartitionError {
    1144            0 :     fn is_cancel(&self) -> bool {
    1145            0 :         match self {
    1146            0 :             RepartitionError::Other(_) => false,
    1147            0 :             RepartitionError::CollectKeyspace(e) => e.is_cancel(),
    1148              :         }
    1149            0 :     }
    1150            0 :     fn into_anyhow(self) -> anyhow::Error {
    1151            0 :         match self {
    1152            0 :             RepartitionError::Other(e) => e,
    1153            0 :             RepartitionError::CollectKeyspace(e) => e.into_anyhow(),
    1154              :         }
    1155            0 :     }
    1156              : }
    1157              : 
    1158              : /// Public interface functions
    1159              : impl Timeline {
    1160              :     /// Get the LSN where this branch was created
    1161           80 :     pub(crate) fn get_ancestor_lsn(&self) -> Lsn {
    1162           80 :         self.ancestor_lsn
    1163           80 :     }
    1164              : 
    1165              :     /// Get the ancestor's timeline id
    1166          416 :     pub(crate) fn get_ancestor_timeline_id(&self) -> Option<TimelineId> {
    1167          416 :         self.ancestor_timeline
    1168          416 :             .as_ref()
    1169          416 :             .map(|ancestor| ancestor.timeline_id)
    1170          416 :     }
    1171              : 
    1172              :     /// Get the ancestor timeline
    1173            1 :     pub(crate) fn ancestor_timeline(&self) -> Option<&Arc<Timeline>> {
    1174            1 :         self.ancestor_timeline.as_ref()
    1175            1 :     }
    1176              : 
    1177              :     /// Get the bytes written since the PITR cutoff on this branch, and
    1178              :     /// whether this branch's ancestor_lsn is within its parent's PITR.
    1179            0 :     pub(crate) fn get_pitr_history_stats(&self) -> (u64, bool) {
    1180              :         // TODO: for backwards compatibility, we return the full history back to 0 when the PITR
    1181              :         // cutoff has not yet been initialized. This should return None instead, but this is exposed
    1182              :         // in external HTTP APIs and callers may not handle a null value.
    1183            0 :         let gc_info = self.gc_info.read().unwrap();
    1184            0 :         let history = self
    1185            0 :             .get_last_record_lsn()
    1186            0 :             .checked_sub(gc_info.cutoffs.time.unwrap_or_default())
    1187            0 :             .unwrap_or_default()
    1188            0 :             .0;
    1189            0 :         (history, gc_info.within_ancestor_pitr)
    1190            0 :     }
    1191              : 
    1192              :     /// Read timeline's GC cutoff: this is the LSN at which GC has started to happen
    1193       427459 :     pub(crate) fn get_applied_gc_cutoff_lsn(&self) -> RcuReadGuard<Lsn> {
    1194       427459 :         self.applied_gc_cutoff_lsn.read()
    1195       427459 :     }
    1196              : 
    1197              :     /// Read timeline's planned GC cutoff: this is the logical end of history that users are allowed
    1198              :     /// to read (based on configured PITR), even if physically we have more history. Returns None
    1199              :     /// if the PITR cutoff has not yet been initialized.
    1200            0 :     pub(crate) fn get_gc_cutoff_lsn(&self) -> Option<Lsn> {
    1201            0 :         self.gc_info.read().unwrap().cutoffs.time
    1202            0 :     }
    1203              : 
    1204              :     /// Look up given page version.
    1205              :     ///
    1206              :     /// If a remote layer file is needed, it is downloaded as part of this
    1207              :     /// call.
    1208              :     ///
    1209              :     /// This method enforces [`Self::pagestream_throttle`] internally.
    1210              :     ///
    1211              :     /// NOTE: It is considered an error to 'get' a key that doesn't exist. The
    1212              :     /// abstraction above this needs to store suitable metadata to track what
    1213              :     /// data exists with what keys, in separate metadata entries. If a
    1214              :     /// non-existent key is requested, we may incorrectly return a value from
    1215              :     /// an ancestor branch, for example, or waste a lot of cycles chasing the
    1216              :     /// non-existing key.
    1217              :     ///
    1218              :     /// # Cancel-Safety
    1219              :     ///
    1220              :     /// This method is cancellation-safe.
    1221              :     #[inline(always)]
    1222       301300 :     pub(crate) async fn get(
    1223       301300 :         &self,
    1224       301300 :         key: Key,
    1225       301300 :         lsn: Lsn,
    1226       301300 :         ctx: &RequestContext,
    1227       301300 :     ) -> Result<Bytes, PageReconstructError> {
    1228       301300 :         if !lsn.is_valid() {
    1229            0 :             return Err(PageReconstructError::Other(anyhow::anyhow!("Invalid LSN")));
    1230       301300 :         }
    1231              : 
    1232              :         // This check is debug-only because of the cost of hashing, and because it's a double-check: we
    1233              :         // already checked the key against the shard_identity when looking up the Timeline from
    1234              :         // page_service.
    1235       301300 :         debug_assert!(!self.shard_identity.is_key_disposable(&key));
    1236              : 
    1237       301300 :         let mut reconstruct_state = ValuesReconstructState::new(IoConcurrency::sequential());
    1238              : 
    1239       301300 :         let query = VersionedKeySpaceQuery::uniform(KeySpace::single(key..key.next()), lsn);
    1240              : 
    1241       301300 :         let vectored_res = self
    1242       301300 :             .get_vectored_impl(query, &mut reconstruct_state, ctx)
    1243       301300 :             .await;
    1244              : 
    1245       301300 :         let key_value = vectored_res?.pop_first();
    1246       301297 :         match key_value {
    1247       301291 :             Some((got_key, value)) => {
    1248       301291 :                 if got_key != key {
    1249            0 :                     error!(
    1250            0 :                         "Expected {}, but singular vectored get returned {}",
    1251              :                         key, got_key
    1252              :                     );
    1253            0 :                     Err(PageReconstructError::Other(anyhow!(
    1254            0 :                         "Singular vectored get returned wrong key"
    1255            0 :                     )))
    1256              :                 } else {
    1257       301291 :                     value
    1258              :                 }
    1259              :             }
    1260            6 :             None => Err(PageReconstructError::MissingKey(Box::new(
    1261            6 :                 MissingKeyError {
    1262            6 :                     keyspace: KeySpace::single(key..key.next()),
    1263            6 :                     shard: self.shard_identity.get_shard_number(&key),
    1264            6 :                     original_hwm_lsn: lsn,
    1265            6 :                     ancestor_lsn: None,
    1266            6 :                     backtrace: None,
    1267            6 :                     read_path: None,
    1268            6 :                     query: None,
    1269            6 :                 },
    1270            6 :             ))),
    1271              :         }
    1272       301300 :     }
    1273              : 
    1274              :     #[inline(always)]
    1275            0 :     pub(crate) async fn debug_get(
    1276            0 :         &self,
    1277            0 :         key: Key,
    1278            0 :         lsn: Lsn,
    1279            0 :         ctx: &RequestContext,
    1280            0 :         reconstruct_state: &mut ValuesReconstructState,
    1281            0 :     ) -> Result<Bytes, PageReconstructError> {
    1282            0 :         if !lsn.is_valid() {
    1283            0 :             return Err(PageReconstructError::Other(anyhow::anyhow!("Invalid LSN")));
    1284            0 :         }
    1285              : 
    1286              :         // This check is debug-only because of the cost of hashing, and because it's a double-check: we
    1287              :         // already checked the key against the shard_identity when looking up the Timeline from
    1288              :         // page_service.
    1289            0 :         debug_assert!(!self.shard_identity.is_key_disposable(&key));
    1290              : 
    1291            0 :         let query = VersionedKeySpaceQuery::uniform(KeySpace::single(key..key.next()), lsn);
    1292            0 :         let vectored_res = self
    1293            0 :             .debug_get_vectored_impl(query, reconstruct_state, ctx)
    1294            0 :             .await;
    1295              : 
    1296            0 :         let key_value = vectored_res?.pop_first();
    1297            0 :         match key_value {
    1298            0 :             Some((got_key, value)) => {
    1299            0 :                 if got_key != key {
    1300            0 :                     error!(
    1301            0 :                         "Expected {}, but singular vectored get returned {}",
    1302              :                         key, got_key
    1303              :                     );
    1304            0 :                     Err(PageReconstructError::Other(anyhow!(
    1305            0 :                         "Singular vectored get returned wrong key"
    1306            0 :                     )))
    1307              :                 } else {
    1308            0 :                     value
    1309              :                 }
    1310              :             }
    1311            0 :             None => Err(PageReconstructError::MissingKey(Box::new(
    1312            0 :                 MissingKeyError {
    1313            0 :                     keyspace: KeySpace::single(key..key.next()),
    1314            0 :                     shard: self.shard_identity.get_shard_number(&key),
    1315            0 :                     original_hwm_lsn: lsn,
    1316            0 :                     ancestor_lsn: None,
    1317            0 :                     backtrace: None,
    1318            0 :                     read_path: None,
    1319            0 :                     query: None,
    1320            0 :                 },
    1321            0 :             ))),
    1322              :         }
    1323            0 :     }
    1324              : 
    1325              :     pub(crate) const LAYERS_VISITED_WARN_THRESHOLD: u32 = 100;
    1326              : 
    1327              :     /// Look up multiple page versions at a given LSN
    1328              :     ///
    1329              :     /// This naive implementation will be replaced with a more efficient one
    1330              :     /// which actually vectorizes the read path.
    1331              :     ///
    1332              :     /// NB: the read path must be cancellation-safe. The Tonic gRPC service will drop the future
    1333              :     /// if the client goes away (e.g. due to timeout or cancellation).
    1334        10894 :     pub(crate) async fn get_vectored(
    1335        10894 :         &self,
    1336        10894 :         query: VersionedKeySpaceQuery,
    1337        10894 :         io_concurrency: super::storage_layer::IoConcurrency,
    1338        10894 :         ctx: &RequestContext,
    1339        10894 :     ) -> Result<BTreeMap<Key, Result<Bytes, PageReconstructError>>, GetVectoredError> {
    1340        10894 :         let total_keyspace = query.total_keyspace();
    1341              : 
    1342        10894 :         let key_count = total_keyspace.total_raw_size();
    1343        10894 :         if key_count > self.conf.max_get_vectored_keys.get() {
    1344            0 :             return Err(GetVectoredError::Oversized(
    1345            0 :                 key_count as u64,
    1346            0 :                 self.conf.max_get_vectored_keys.get() as u64,
    1347            0 :             ));
    1348        10894 :         }
    1349              : 
    1350        34113 :         for range in &total_keyspace.ranges {
    1351        23219 :             let mut key = range.start;
    1352        65248 :             while key != range.end {
    1353        42029 :                 assert!(!self.shard_identity.is_key_disposable(&key));
    1354        42029 :                 key = key.next();
    1355              :             }
    1356              :         }
    1357              : 
    1358        10894 :         trace!(
    1359            0 :             "get vectored query {} from task kind {:?}",
    1360              :             query,
    1361            0 :             ctx.task_kind(),
    1362              :         );
    1363              : 
    1364        10894 :         let start = crate::metrics::GET_VECTORED_LATENCY
    1365        10894 :             .for_task_kind(ctx.task_kind())
    1366        10894 :             .map(|metric| (metric, Instant::now()));
    1367              : 
    1368        10894 :         let res = self
    1369        10894 :             .get_vectored_impl(query, &mut ValuesReconstructState::new(io_concurrency), ctx)
    1370        10894 :             .await;
    1371              : 
    1372        10894 :         if let Some((metric, start)) = start {
    1373            0 :             let elapsed = start.elapsed();
    1374            0 :             metric.observe(elapsed.as_secs_f64());
    1375        10894 :         }
    1376              : 
    1377        10894 :         res
    1378        10894 :     }
    1379              : 
    1380              :     /// Scan the keyspace and return all existing key-values in the keyspace. This currently uses vectored
    1381              :     /// get underlying. Normal vectored get would throw an error when a key in the keyspace is not found
    1382              :     /// during the search, but for the scan interface, it returns all existing key-value pairs, and does
    1383              :     /// not expect each single key in the key space will be found. The semantics is closer to the RocksDB
    1384              :     /// scan iterator interface. We could optimize this interface later to avoid some checks in the vectored
    1385              :     /// get path to maintain and split the probing and to-be-probe keyspace. We also need to ensure that
    1386              :     /// the scan operation will not cause OOM in the future.
    1387            8 :     pub(crate) async fn scan(
    1388            8 :         &self,
    1389            8 :         keyspace: KeySpace,
    1390            8 :         lsn: Lsn,
    1391            8 :         ctx: &RequestContext,
    1392            8 :         io_concurrency: super::storage_layer::IoConcurrency,
    1393            8 :     ) -> Result<BTreeMap<Key, Result<Bytes, PageReconstructError>>, GetVectoredError> {
    1394            8 :         if !lsn.is_valid() {
    1395            0 :             return Err(GetVectoredError::InvalidLsn(lsn));
    1396            8 :         }
    1397              : 
    1398            8 :         trace!(
    1399            0 :             "key-value scan request for {:?}@{} from task kind {:?}",
    1400              :             keyspace,
    1401              :             lsn,
    1402            0 :             ctx.task_kind()
    1403              :         );
    1404              : 
    1405              :         // We should generalize this into Keyspace::contains in the future.
    1406           16 :         for range in &keyspace.ranges {
    1407            8 :             if range.start.field1 < METADATA_KEY_BEGIN_PREFIX
    1408            8 :                 || range.end.field1 > METADATA_KEY_END_PREFIX
    1409              :             {
    1410            0 :                 return Err(GetVectoredError::Other(anyhow::anyhow!(
    1411            0 :                     "only metadata keyspace can be scanned"
    1412            0 :                 )));
    1413            8 :             }
    1414              :         }
    1415              : 
    1416            8 :         let start = crate::metrics::SCAN_LATENCY
    1417            8 :             .for_task_kind(ctx.task_kind())
    1418            8 :             .map(ScanLatencyOngoingRecording::start_recording);
    1419              : 
    1420            8 :         let query = VersionedKeySpaceQuery::uniform(keyspace, lsn);
    1421              : 
    1422            8 :         let vectored_res = self
    1423            8 :             .get_vectored_impl(query, &mut ValuesReconstructState::new(io_concurrency), ctx)
    1424            8 :             .await;
    1425              : 
    1426            8 :         if let Some(recording) = start {
    1427            0 :             recording.observe();
    1428            8 :         }
    1429              : 
    1430            8 :         vectored_res
    1431            8 :     }
    1432              : 
    1433       312438 :     pub(super) async fn get_vectored_impl(
    1434       312438 :         &self,
    1435       312438 :         query: VersionedKeySpaceQuery,
    1436       312438 :         reconstruct_state: &mut ValuesReconstructState,
    1437       312438 :         ctx: &RequestContext,
    1438       312438 :     ) -> Result<BTreeMap<Key, Result<Bytes, PageReconstructError>>, GetVectoredError> {
    1439       312438 :         if query.is_empty() {
    1440            0 :             return Ok(BTreeMap::default());
    1441       312438 :         }
    1442              : 
    1443       312438 :         let read_path = if self.conf.enable_read_path_debugging || ctx.read_path_debug() {
    1444       312438 :             Some(ReadPath::new(
    1445       312438 :                 query.total_keyspace(),
    1446       312438 :                 query.high_watermark_lsn()?,
    1447              :             ))
    1448              :         } else {
    1449            0 :             None
    1450              :         };
    1451              : 
    1452       312438 :         reconstruct_state.read_path = read_path;
    1453              : 
    1454       312438 :         let redo_attempt_type = if ctx.task_kind() == TaskKind::Compaction {
    1455            0 :             RedoAttemptType::LegacyCompaction
    1456              :         } else {
    1457       312438 :             RedoAttemptType::ReadPage
    1458              :         };
    1459              : 
    1460       312438 :         let traversal_res: Result<(), _> = {
    1461       312438 :             let ctx = RequestContextBuilder::from(ctx)
    1462       312438 :                 .perf_span(|crnt_perf_span| {
    1463            0 :                     info_span!(
    1464              :                         target: PERF_TRACE_TARGET,
    1465            0 :                         parent: crnt_perf_span,
    1466              :                         "PLAN_IO",
    1467              :                     )
    1468            0 :                 })
    1469       312438 :                 .attached_child();
    1470              : 
    1471       312438 :             self.get_vectored_reconstruct_data(query.clone(), reconstruct_state, &ctx)
    1472       312438 :                 .maybe_perf_instrument(&ctx, |crnt_perf_span| crnt_perf_span.clone())
    1473       312438 :                 .await
    1474              :         };
    1475              : 
    1476       312438 :         if let Err(err) = traversal_res {
    1477              :             // Wait for all the spawned IOs to complete.
    1478              :             // See comments on `spawn_io` inside `storage_layer` for more details.
    1479            8 :             let mut collect_futs = std::mem::take(&mut reconstruct_state.keys)
    1480            8 :                 .into_values()
    1481            8 :                 .map(|state| state.collect_pending_ios())
    1482            8 :                 .collect::<FuturesUnordered<_>>();
    1483            8 :             while collect_futs.next().await.is_some() {}
    1484              : 
    1485              :             // Enrich the missing key error with the original query.
    1486            8 :             if let GetVectoredError::MissingKey(mut missing_err) = err {
    1487            7 :                 missing_err.enrich(query.clone());
    1488            7 :                 return Err(GetVectoredError::MissingKey(missing_err));
    1489            1 :             }
    1490              : 
    1491            1 :             return Err(err);
    1492       312430 :         };
    1493              : 
    1494       312430 :         let layers_visited = reconstruct_state.get_layers_visited();
    1495              : 
    1496       312430 :         let ctx = RequestContextBuilder::from(ctx)
    1497       312430 :             .perf_span(|crnt_perf_span| {
    1498            0 :                 info_span!(
    1499              :                     target: PERF_TRACE_TARGET,
    1500            0 :                     parent: crnt_perf_span,
    1501              :                     "RECONSTRUCT",
    1502              :                 )
    1503            0 :             })
    1504       312430 :             .attached_child();
    1505              : 
    1506       312430 :         let futs = FuturesUnordered::new();
    1507       363559 :         for (key, state) in std::mem::take(&mut reconstruct_state.keys) {
    1508       363559 :             let req_lsn_for_key = query.map_key_to_lsn(&key);
    1509              : 
    1510       363559 :             futs.push({
    1511       363559 :                 let walredo_self = self.myself.upgrade().expect("&self method holds the arc");
    1512       363559 :                 let ctx = RequestContextBuilder::from(&ctx)
    1513       363559 :                     .perf_span(|crnt_perf_span| {
    1514            0 :                         info_span!(
    1515              :                             target: PERF_TRACE_TARGET,
    1516            0 :                             parent: crnt_perf_span,
    1517              :                             "RECONSTRUCT_KEY",
    1518              :                             key = %key,
    1519              :                         )
    1520            0 :                     })
    1521       363559 :                     .attached_child();
    1522              : 
    1523       363559 :                 async move {
    1524       363559 :                     assert_eq!(state.situation, ValueReconstructSituation::Complete);
    1525              : 
    1526       363559 :                     let res = state
    1527       363559 :                         .collect_pending_ios()
    1528       363559 :                         .maybe_perf_instrument(&ctx, |crnt_perf_span| {
    1529            0 :                             info_span!(
    1530              :                                 target: PERF_TRACE_TARGET,
    1531            0 :                                 parent: crnt_perf_span,
    1532              :                                 "WAIT_FOR_IO_COMPLETIONS",
    1533              :                             )
    1534            0 :                         })
    1535       363559 :                         .await;
    1536              : 
    1537       363559 :                     let converted = match res {
    1538       363559 :                         Ok(ok) => ok,
    1539            0 :                         Err(err) => {
    1540            0 :                             return (key, Err(err));
    1541              :                         }
    1542              :                     };
    1543       363559 :                     DELTAS_PER_READ_GLOBAL.observe(converted.num_deltas() as f64);
    1544              : 
    1545              :                     // The walredo module expects the records to be descending in terms of Lsn.
    1546              :                     // And we submit the IOs in that order, so, there shuold be no need to sort here.
    1547       363559 :                     debug_assert!(
    1548       363559 :                         converted
    1549       363559 :                             .records
    1550      1401588 :                             .is_sorted_by_key(|(lsn, _)| std::cmp::Reverse(*lsn)),
    1551            0 :                         "{converted:?}"
    1552              :                     );
    1553              : 
    1554       363559 :                     let walredo_deltas = converted.num_deltas();
    1555       363559 :                     let walredo_res = walredo_self
    1556       363559 :                         .reconstruct_value(key, req_lsn_for_key, converted, redo_attempt_type)
    1557       363559 :                         .maybe_perf_instrument(&ctx, |crnt_perf_span| {
    1558            0 :                             info_span!(
    1559              :                                 target: PERF_TRACE_TARGET,
    1560            0 :                                 parent: crnt_perf_span,
    1561              :                                 "WALREDO",
    1562              :                                 deltas = %walredo_deltas,
    1563              :                             )
    1564            0 :                         })
    1565       363559 :                         .await;
    1566              : 
    1567       363559 :                     (key, walredo_res)
    1568       363559 :                 }
    1569              :             });
    1570              :         }
    1571              : 
    1572       312430 :         let results = futs
    1573       312430 :             .collect::<BTreeMap<Key, Result<Bytes, PageReconstructError>>>()
    1574       312430 :             .maybe_perf_instrument(&ctx, |crnt_perf_span| crnt_perf_span.clone())
    1575       312430 :             .await;
    1576              : 
    1577              :         // For aux file keys (v1 or v2) the vectored read path does not return an error
    1578              :         // when they're missing. Instead they are omitted from the resulting btree
    1579              :         // (this is a requirement, not a bug). Skip updating the metric in these cases
    1580              :         // to avoid infinite results.
    1581       312430 :         if !results.is_empty() {
    1582       312251 :             if layers_visited >= Self::LAYERS_VISITED_WARN_THRESHOLD {
    1583            0 :                 let total_keyspace = query.total_keyspace();
    1584            0 :                 let max_request_lsn = query.high_watermark_lsn().expect("Validated previously");
    1585              : 
    1586              :                 static LOG_PACER: Lazy<Mutex<RateLimit>> =
    1587            0 :                     Lazy::new(|| Mutex::new(RateLimit::new(Duration::from_secs(60))));
    1588            0 :                 LOG_PACER.lock().unwrap().call(|| {
    1589            0 :                     let num_keys = total_keyspace.total_raw_size();
    1590            0 :                     let num_pages = results.len();
    1591            0 :                     tracing::info!(
    1592            0 :                       shard_id = %self.tenant_shard_id.shard_slug(),
    1593              :                       lsn = %max_request_lsn,
    1594            0 :                       "Vectored read for {total_keyspace} visited {layers_visited} layers. Returned {num_pages}/{num_keys} pages.",
    1595              :                     );
    1596            0 :                 });
    1597       312251 :             }
    1598              : 
    1599              :             // Records the number of layers visited in a few different ways:
    1600              :             //
    1601              :             // * LAYERS_PER_READ: all layers count towards every read in the batch, because each
    1602              :             //   layer directly affects its observed latency.
    1603              :             //
    1604              :             // * LAYERS_PER_READ_BATCH: all layers count towards each batch, to get the per-batch
    1605              :             //   layer visits and access cost.
    1606              :             //
    1607              :             // * LAYERS_PER_READ_AMORTIZED: the average layer count per read, to get the amortized
    1608              :             //   read amplification after batching.
    1609       312251 :             let layers_visited = layers_visited as f64;
    1610       312251 :             let avg_layers_visited = layers_visited / results.len() as f64;
    1611       312251 :             LAYERS_PER_READ_BATCH_GLOBAL.observe(layers_visited);
    1612       675810 :             for _ in &results {
    1613       363559 :                 self.metrics.layers_per_read.observe(layers_visited);
    1614       363559 :                 LAYERS_PER_READ_GLOBAL.observe(layers_visited);
    1615       363559 :                 LAYERS_PER_READ_AMORTIZED_GLOBAL.observe(avg_layers_visited);
    1616       363559 :             }
    1617          179 :         }
    1618              : 
    1619       312430 :         Ok(results)
    1620       312438 :     }
    1621              : 
    1622              :     // A copy of the get_vectored_impl method except that we store the image and wal records into `reconstruct_state`.
    1623              :     // This is only used in the http getpage call for debugging purpose.
    1624            0 :     pub(super) async fn debug_get_vectored_impl(
    1625            0 :         &self,
    1626            0 :         query: VersionedKeySpaceQuery,
    1627            0 :         reconstruct_state: &mut ValuesReconstructState,
    1628            0 :         ctx: &RequestContext,
    1629            0 :     ) -> Result<BTreeMap<Key, Result<Bytes, PageReconstructError>>, GetVectoredError> {
    1630            0 :         if query.is_empty() {
    1631            0 :             return Ok(BTreeMap::default());
    1632            0 :         }
    1633              : 
    1634            0 :         let read_path = if self.conf.enable_read_path_debugging || ctx.read_path_debug() {
    1635            0 :             Some(ReadPath::new(
    1636            0 :                 query.total_keyspace(),
    1637            0 :                 query.high_watermark_lsn()?,
    1638              :             ))
    1639              :         } else {
    1640            0 :             None
    1641              :         };
    1642              : 
    1643            0 :         reconstruct_state.read_path = read_path;
    1644              : 
    1645            0 :         let traversal_res: Result<(), _> = self
    1646            0 :             .get_vectored_reconstruct_data(query.clone(), reconstruct_state, ctx)
    1647            0 :             .await;
    1648              : 
    1649            0 :         if let Err(err) = traversal_res {
    1650              :             // Wait for all the spawned IOs to complete.
    1651              :             // See comments on `spawn_io` inside `storage_layer` for more details.
    1652            0 :             let mut collect_futs = std::mem::take(&mut reconstruct_state.keys)
    1653            0 :                 .into_values()
    1654            0 :                 .map(|state| state.collect_pending_ios())
    1655            0 :                 .collect::<FuturesUnordered<_>>();
    1656            0 :             while collect_futs.next().await.is_some() {}
    1657            0 :             return Err(err);
    1658            0 :         };
    1659              : 
    1660            0 :         let reconstruct_state = Arc::new(Mutex::new(reconstruct_state));
    1661            0 :         let futs = FuturesUnordered::new();
    1662              : 
    1663            0 :         for (key, state) in std::mem::take(&mut reconstruct_state.lock().unwrap().keys) {
    1664            0 :             let req_lsn_for_key = query.map_key_to_lsn(&key);
    1665            0 :             futs.push({
    1666            0 :                 let walredo_self = self.myself.upgrade().expect("&self method holds the arc");
    1667            0 :                 let rc_clone = Arc::clone(&reconstruct_state);
    1668              : 
    1669            0 :                 async move {
    1670            0 :                     assert_eq!(state.situation, ValueReconstructSituation::Complete);
    1671              : 
    1672            0 :                     let converted = match state.collect_pending_ios().await {
    1673            0 :                         Ok(ok) => ok,
    1674            0 :                         Err(err) => {
    1675            0 :                             return (key, Err(err));
    1676              :                         }
    1677              :                     };
    1678            0 :                     DELTAS_PER_READ_GLOBAL.observe(converted.num_deltas() as f64);
    1679              : 
    1680              :                     // The walredo module expects the records to be descending in terms of Lsn.
    1681              :                     // And we submit the IOs in that order, so, there shuold be no need to sort here.
    1682            0 :                     debug_assert!(
    1683            0 :                         converted
    1684            0 :                             .records
    1685            0 :                             .is_sorted_by_key(|(lsn, _)| std::cmp::Reverse(*lsn)),
    1686            0 :                         "{converted:?}"
    1687              :                     );
    1688            0 :                     {
    1689            0 :                         let mut guard = rc_clone.lock().unwrap();
    1690            0 :                         guard.set_debug_state(&converted);
    1691            0 :                     }
    1692              :                     (
    1693            0 :                         key,
    1694            0 :                         walredo_self
    1695            0 :                             .reconstruct_value(
    1696            0 :                                 key,
    1697            0 :                                 req_lsn_for_key,
    1698            0 :                                 converted,
    1699            0 :                                 RedoAttemptType::ReadPage,
    1700            0 :                             )
    1701            0 :                             .await,
    1702              :                     )
    1703            0 :                 }
    1704              :             });
    1705              :         }
    1706              : 
    1707            0 :         let results = futs
    1708            0 :             .collect::<BTreeMap<Key, Result<Bytes, PageReconstructError>>>()
    1709            0 :             .await;
    1710              : 
    1711            0 :         Ok(results)
    1712            0 :     }
    1713              : 
    1714              :     /// Get last or prev record separately. Same as get_last_record_rlsn().last/prev.
    1715       138202 :     pub(crate) fn get_last_record_lsn(&self) -> Lsn {
    1716       138202 :         self.last_record_lsn.load().last
    1717       138202 :     }
    1718              : 
    1719            0 :     pub(crate) fn get_prev_record_lsn(&self) -> Lsn {
    1720            0 :         self.last_record_lsn.load().prev
    1721            0 :     }
    1722              : 
    1723              :     /// Atomically get both last and prev.
    1724          117 :     pub(crate) fn get_last_record_rlsn(&self) -> RecordLsn {
    1725          117 :         self.last_record_lsn.load()
    1726          117 :     }
    1727              : 
    1728              :     /// Subscribe to callers of wait_lsn(). The value of the channel is None if there are no
    1729              :     /// wait_lsn() calls in progress, and Some(Lsn) if there is an active waiter for wait_lsn().
    1730            0 :     pub(crate) fn subscribe_for_wait_lsn_updates(&self) -> watch::Receiver<Option<Lsn>> {
    1731            0 :         self.last_record_lsn.status_receiver()
    1732            0 :     }
    1733              : 
    1734          610 :     pub(crate) fn get_disk_consistent_lsn(&self) -> Lsn {
    1735          610 :         self.disk_consistent_lsn.load()
    1736          610 :     }
    1737              : 
    1738              :     /// remote_consistent_lsn from the perspective of the tenant's current generation,
    1739              :     /// not validated with control plane yet.
    1740              :     /// See [`Self::get_remote_consistent_lsn_visible`].
    1741            2 :     pub(crate) fn get_remote_consistent_lsn_projected(&self) -> Option<Lsn> {
    1742            2 :         self.remote_client.remote_consistent_lsn_projected()
    1743            2 :     }
    1744              : 
    1745              :     /// remote_consistent_lsn which the tenant is guaranteed not to go backward from,
    1746              :     /// i.e. a value of remote_consistent_lsn_projected which has undergone
    1747              :     /// generation validation in the deletion queue.
    1748            0 :     pub(crate) fn get_remote_consistent_lsn_visible(&self) -> Option<Lsn> {
    1749            0 :         self.remote_client.remote_consistent_lsn_visible()
    1750            0 :     }
    1751              : 
    1752              :     /// The sum of the file size of all historic layers in the layer map.
    1753              :     /// This method makes no distinction between local and remote layers.
    1754              :     /// Hence, the result **does not represent local filesystem usage**.
    1755            0 :     pub(crate) async fn layer_size_sum(&self) -> u64 {
    1756            0 :         let guard = self
    1757            0 :             .layers
    1758            0 :             .read(LayerManagerLockHolder::GetLayerMapInfo)
    1759            0 :             .await;
    1760            0 :         guard.layer_size_sum()
    1761            0 :     }
    1762              : 
    1763            0 :     pub(crate) fn resident_physical_size(&self) -> u64 {
    1764            0 :         self.metrics.resident_physical_size_get()
    1765            0 :     }
    1766              : 
    1767            0 :     pub(crate) fn get_directory_metrics(&self) -> [u64; DirectoryKind::KINDS_NUM] {
    1768            0 :         array::from_fn(|idx| self.directory_metrics[idx].load(AtomicOrdering::Relaxed))
    1769            0 :     }
    1770              : 
    1771              :     ///
    1772              :     /// Wait until WAL has been received and processed up to this LSN.
    1773              :     ///
    1774              :     /// You should call this before any of the other get_* or list_* functions. Calling
    1775              :     /// those functions with an LSN that has been processed yet is an error.
    1776              :     ///
    1777       114483 :     pub(crate) async fn wait_lsn(
    1778       114483 :         &self,
    1779       114483 :         lsn: Lsn,
    1780       114483 :         who_is_waiting: WaitLsnWaiter<'_>,
    1781       114483 :         timeout: WaitLsnTimeout,
    1782       114483 :         ctx: &RequestContext, /* Prepare for use by cancellation */
    1783       114483 :     ) -> Result<(), WaitLsnError> {
    1784       114483 :         let state = self.current_state();
    1785       114483 :         if self.cancel.is_cancelled() || matches!(state, TimelineState::Stopping) {
    1786            0 :             return Err(WaitLsnError::Shutdown);
    1787       114483 :         } else if !matches!(state, TimelineState::Active) {
    1788            0 :             return Err(WaitLsnError::BadState(state));
    1789       114483 :         }
    1790              : 
    1791       114483 :         if cfg!(debug_assertions) {
    1792       114483 :             match ctx.task_kind() {
    1793              :                 TaskKind::WalReceiverManager
    1794              :                 | TaskKind::WalReceiverConnectionHandler
    1795              :                 | TaskKind::WalReceiverConnectionPoller => {
    1796            0 :                     let is_myself = match who_is_waiting {
    1797            0 :                         WaitLsnWaiter::Timeline(waiter) => {
    1798            0 :                             Weak::ptr_eq(&waiter.myself, &self.myself)
    1799              :                         }
    1800              :                         WaitLsnWaiter::Tenant
    1801              :                         | WaitLsnWaiter::PageService
    1802              :                         | WaitLsnWaiter::HttpEndpoint
    1803            0 :                         | WaitLsnWaiter::BaseBackupCache => unreachable!(
    1804              :                             "tenant or page_service context are not expected to have task kind {:?}",
    1805            0 :                             ctx.task_kind()
    1806              :                         ),
    1807              :                     };
    1808            0 :                     if is_myself {
    1809            0 :                         if let Err(current) = self.last_record_lsn.would_wait_for(lsn) {
    1810              :                             // walingest is the only one that can advance last_record_lsn; it should make sure to never reach here
    1811            0 :                             panic!(
    1812            0 :                                 "this timeline's walingest task is calling wait_lsn({lsn}) but we only have last_record_lsn={current}; would deadlock"
    1813              :                             );
    1814            0 :                         }
    1815            0 :                     } else {
    1816            0 :                         // if another  timeline's  is waiting for us, there's no deadlock risk because
    1817            0 :                         // our walreceiver task can make progress independent of theirs
    1818            0 :                     }
    1819              :                 }
    1820       114483 :                 _ => {}
    1821              :             }
    1822            0 :         }
    1823              : 
    1824       114483 :         let timeout = match timeout {
    1825            0 :             WaitLsnTimeout::Custom(t) => t,
    1826       114483 :             WaitLsnTimeout::Default => self.conf.wait_lsn_timeout,
    1827              :         };
    1828              : 
    1829       114483 :         let timer = crate::metrics::WAIT_LSN_TIME.start_timer();
    1830       114483 :         let start_finish_counterpair_guard = self.metrics.wait_lsn_start_finish_counterpair.guard();
    1831              : 
    1832       114483 :         let wait_for_timeout = self.last_record_lsn.wait_for_timeout(lsn, timeout);
    1833       114483 :         let wait_for_timeout = std::pin::pin!(wait_for_timeout);
    1834              :         // Use threshold of 1 because even 1 second of wait for ingest is very much abnormal.
    1835       114483 :         let log_slow_threshold = Duration::from_secs(1);
    1836              :         // Use period of 10 to avoid flooding logs during an outage that affects all timelines.
    1837       114483 :         let log_slow_period = Duration::from_secs(10);
    1838       114483 :         let mut logging_permit = None;
    1839       114483 :         let wait_for_timeout = monitor_slow_future(
    1840       114483 :             log_slow_threshold,
    1841       114483 :             log_slow_period,
    1842       114483 :             wait_for_timeout,
    1843              :             |MonitorSlowFutureCallback {
    1844              :                  ready,
    1845              :                  is_slow,
    1846              :                  elapsed_total,
    1847              :                  elapsed_since_last_callback,
    1848       114483 :              }| {
    1849       114483 :                 self.metrics
    1850       114483 :                     .wait_lsn_in_progress_micros
    1851       114483 :                     .inc_by(u64::try_from(elapsed_since_last_callback.as_micros()).unwrap());
    1852       114483 :                 if !is_slow {
    1853       114483 :                     return;
    1854            0 :                 }
    1855              :                 // It's slow, see if we should log it.
    1856              :                 // (We limit the logging to one per invocation per timeline to avoid excessive
    1857              :                 // logging during an extended broker / networking outage that affects all timelines.)
    1858            0 :                 if logging_permit.is_none() {
    1859            0 :                     logging_permit = self.wait_lsn_log_slow.try_acquire().ok();
    1860            0 :                 }
    1861            0 :                 if logging_permit.is_none() {
    1862            0 :                     return;
    1863            0 :                 }
    1864              :                 // We log it.
    1865            0 :                 if ready {
    1866            0 :                     info!(
    1867            0 :                         "slow wait_lsn completed after {:.3}s",
    1868            0 :                         elapsed_total.as_secs_f64()
    1869              :                     );
    1870              :                 } else {
    1871            0 :                     info!(
    1872            0 :                         "slow wait_lsn still running for {:.3}s",
    1873            0 :                         elapsed_total.as_secs_f64()
    1874              :                     );
    1875              :                 }
    1876       114483 :             },
    1877              :         );
    1878       114483 :         let res = wait_for_timeout.await;
    1879              :         // don't count the time spent waiting for lock below, and also in walreceiver.status(), towards the wait_lsn_time_histo
    1880       114483 :         drop(logging_permit);
    1881       114483 :         drop(start_finish_counterpair_guard);
    1882       114483 :         drop(timer);
    1883       114483 :         match res {
    1884       114483 :             Ok(()) => Ok(()),
    1885            0 :             Err(e) => {
    1886              :                 use utils::seqwait::SeqWaitError::*;
    1887            0 :                 match e {
    1888            0 :                     Shutdown => Err(WaitLsnError::Shutdown),
    1889              :                     Timeout => {
    1890            0 :                         let walreceiver_status = self.walreceiver_status();
    1891            0 :                         Err(WaitLsnError::Timeout(format!(
    1892            0 :                             "Timed out while waiting for WAL record at LSN {} to arrive, last_record_lsn {} disk consistent LSN={}, WalReceiver status: {}",
    1893            0 :                             lsn,
    1894            0 :                             self.get_last_record_lsn(),
    1895            0 :                             self.get_disk_consistent_lsn(),
    1896            0 :                             walreceiver_status,
    1897            0 :                         )))
    1898              :                     }
    1899              :                 }
    1900              :             }
    1901              :         }
    1902       114483 :     }
    1903              : 
    1904            0 :     pub(crate) fn walreceiver_status(&self) -> String {
    1905            0 :         match &*self.walreceiver.lock().unwrap() {
    1906            0 :             None => "stopping or stopped".to_string(),
    1907            0 :             Some(walreceiver) => match walreceiver.status() {
    1908            0 :                 Some(status) => status.to_human_readable_string(),
    1909            0 :                 None => "Not active".to_string(),
    1910              :             },
    1911              :         }
    1912            0 :     }
    1913              : 
    1914              :     /// Check that it is valid to request operations with that lsn.
    1915          119 :     pub(crate) fn check_lsn_is_in_scope(
    1916          119 :         &self,
    1917          119 :         lsn: Lsn,
    1918          119 :         latest_gc_cutoff_lsn: &RcuReadGuard<Lsn>,
    1919          119 :     ) -> anyhow::Result<()> {
    1920          119 :         ensure!(
    1921          119 :             lsn >= **latest_gc_cutoff_lsn,
    1922            2 :             "LSN {} is earlier than latest GC cutoff {} (we might've already garbage collected needed data)",
    1923              :             lsn,
    1924            2 :             **latest_gc_cutoff_lsn,
    1925              :         );
    1926          117 :         Ok(())
    1927          119 :     }
    1928              : 
    1929              :     /// Initializes an LSN lease. The function will return an error if the requested LSN is less than the `latest_gc_cutoff_lsn`.
    1930            5 :     pub(crate) fn init_lsn_lease(
    1931            5 :         &self,
    1932            5 :         lsn: Lsn,
    1933            5 :         length: Duration,
    1934            5 :         ctx: &RequestContext,
    1935            5 :     ) -> anyhow::Result<LsnLease> {
    1936            5 :         self.make_lsn_lease(lsn, length, true, ctx)
    1937            5 :     }
    1938              : 
    1939              :     /// Renews a lease at a particular LSN. The requested LSN is not validated against the `latest_gc_cutoff_lsn` when we are in the grace period.
    1940            2 :     pub(crate) fn renew_lsn_lease(
    1941            2 :         &self,
    1942            2 :         lsn: Lsn,
    1943            2 :         length: Duration,
    1944            2 :         ctx: &RequestContext,
    1945            2 :     ) -> anyhow::Result<LsnLease> {
    1946            2 :         self.make_lsn_lease(lsn, length, false, ctx)
    1947            2 :     }
    1948              : 
    1949              :     /// Obtains a temporary lease blocking garbage collection for the given LSN.
    1950              :     ///
    1951              :     /// If we are in `AttachedSingle` mode and is not blocked by the lsn lease deadline, this function will error
    1952              :     /// if the requesting LSN is less than the `latest_gc_cutoff_lsn` and there is no existing request present.
    1953              :     ///
    1954              :     /// If there is an existing lease in the map, the lease will be renewed only if the request extends the lease.
    1955              :     /// The returned lease is therefore the maximum between the existing lease and the requesting lease.
    1956            7 :     fn make_lsn_lease(
    1957            7 :         &self,
    1958            7 :         lsn: Lsn,
    1959            7 :         length: Duration,
    1960            7 :         init: bool,
    1961            7 :         _ctx: &RequestContext,
    1962            7 :     ) -> anyhow::Result<LsnLease> {
    1963            6 :         let lease = {
    1964              :             // Normalize the requested LSN to be aligned, and move to the first record
    1965              :             // if it points to the beginning of the page (header).
    1966            7 :             let lsn = xlog_utils::normalize_lsn(lsn, WAL_SEGMENT_SIZE);
    1967              : 
    1968            7 :             let mut gc_info = self.gc_info.write().unwrap();
    1969            7 :             let planned_cutoff = gc_info.min_cutoff();
    1970              : 
    1971            7 :             let valid_until = SystemTime::now() + length;
    1972              : 
    1973            7 :             let entry = gc_info.leases.entry(lsn);
    1974              : 
    1975            7 :             match entry {
    1976            3 :                 Entry::Occupied(mut occupied) => {
    1977            3 :                     let existing_lease = occupied.get_mut();
    1978            3 :                     if valid_until > existing_lease.valid_until {
    1979            1 :                         existing_lease.valid_until = valid_until;
    1980            1 :                         let dt: DateTime<Utc> = valid_until.into();
    1981            1 :                         info!("lease extended to {}", dt);
    1982              :                     } else {
    1983            2 :                         let dt: DateTime<Utc> = existing_lease.valid_until.into();
    1984            2 :                         info!("existing lease covers greater length, valid until {}", dt);
    1985              :                     }
    1986              : 
    1987            3 :                     existing_lease.clone()
    1988              :                 }
    1989            4 :                 Entry::Vacant(vacant) => {
    1990              :                     // Never allow a lease to be requested for an LSN below the applied GC cutoff. The data could have been deleted.
    1991            4 :                     let latest_gc_cutoff_lsn = self.get_applied_gc_cutoff_lsn();
    1992            4 :                     if lsn < *latest_gc_cutoff_lsn {
    1993            1 :                         bail!(
    1994            1 :                             "tried to request an lsn lease for an lsn below the latest gc cutoff. requested at {} gc cutoff {}",
    1995              :                             lsn,
    1996            1 :                             *latest_gc_cutoff_lsn
    1997              :                         );
    1998            3 :                     }
    1999              : 
    2000              :                     // We allow create lease for those below the planned gc cutoff if we are still within the grace period
    2001              :                     // of GC blocking.
    2002            3 :                     let validate = {
    2003            3 :                         let conf = self.tenant_conf.load();
    2004            3 :                         !conf.is_gc_blocked_by_lsn_lease_deadline()
    2005              :                     };
    2006              : 
    2007              :                     // Do not allow initial lease creation to be below the planned gc cutoff. The client (compute_ctl) determines
    2008              :                     // whether it is a initial lease creation or a renewal.
    2009            3 :                     if (init || validate) && lsn < planned_cutoff {
    2010            0 :                         bail!(
    2011            0 :                             "tried to request an lsn lease for an lsn below the planned gc cutoff. requested at {} planned gc cutoff {}",
    2012              :                             lsn,
    2013              :                             planned_cutoff
    2014              :                         );
    2015            3 :                     }
    2016              : 
    2017            3 :                     let dt: DateTime<Utc> = valid_until.into();
    2018            3 :                     info!("lease created, valid until {}", dt);
    2019            3 :                     vacant.insert(LsnLease { valid_until }).clone()
    2020              :                 }
    2021              :             }
    2022              :         };
    2023              : 
    2024            6 :         Ok(lease)
    2025            7 :     }
    2026              : 
    2027              :     /// Freeze the current open in-memory layer. It will be written to disk on next iteration.
    2028              :     /// Returns the flush request ID which can be awaited with wait_flush_completion().
    2029              :     #[instrument(skip(self), fields(tenant_id=%self.tenant_shard_id.tenant_id, shard_id=%self.tenant_shard_id.shard_slug(), timeline_id=%self.timeline_id))]
    2030              :     pub(crate) async fn freeze(&self) -> Result<u64, FlushLayerError> {
    2031              :         self.freeze0().await
    2032              :     }
    2033              : 
    2034              :     /// Freeze and flush the open in-memory layer, waiting for it to be written to disk.
    2035              :     #[instrument(skip(self), fields(tenant_id=%self.tenant_shard_id.tenant_id, shard_id=%self.tenant_shard_id.shard_slug(), timeline_id=%self.timeline_id))]
    2036              :     pub(crate) async fn freeze_and_flush(&self) -> Result<(), FlushLayerError> {
    2037              :         self.freeze_and_flush0().await
    2038              :     }
    2039              : 
    2040              :     /// Freeze the current open in-memory layer. It will be written to disk on next iteration.
    2041              :     /// Returns the flush request ID which can be awaited with wait_flush_completion().
    2042          571 :     pub(crate) async fn freeze0(&self) -> Result<u64, FlushLayerError> {
    2043          571 :         let mut g = self.write_lock.lock().await;
    2044          571 :         let to_lsn = self.get_last_record_lsn();
    2045          571 :         self.freeze_inmem_layer_at(to_lsn, &mut g).await
    2046          571 :     }
    2047              : 
    2048              :     // This exists to provide a non-span creating version of `freeze_and_flush` we can call without
    2049              :     // polluting the span hierarchy.
    2050          571 :     pub(crate) async fn freeze_and_flush0(&self) -> Result<(), FlushLayerError> {
    2051          571 :         let token = self.freeze0().await?;
    2052          571 :         self.wait_flush_completion(token).await
    2053          571 :     }
    2054              : 
    2055              :     // Check if an open ephemeral layer should be closed: this provides
    2056              :     // background enforcement of checkpoint interval if there is no active WAL receiver, to avoid keeping
    2057              :     // an ephemeral layer open forever when idle.  It also freezes layers if the global limit on
    2058              :     // ephemeral layer bytes has been breached.
    2059            0 :     pub(super) async fn maybe_freeze_ephemeral_layer(&self) {
    2060            0 :         debug_assert_current_span_has_tenant_and_timeline_id();
    2061              : 
    2062            0 :         let Ok(mut write_guard) = self.write_lock.try_lock() else {
    2063              :             // If the write lock is held, there is an active wal receiver: rolling open layers
    2064              :             // is their responsibility while they hold this lock.
    2065            0 :             return;
    2066              :         };
    2067              : 
    2068              :         // FIXME: why not early exit? because before #7927 the state would had been cleared every
    2069              :         // time, and this was missed.
    2070              :         // if write_guard.is_none() { return; }
    2071              : 
    2072            0 :         let Ok(layers_guard) = self.layers.try_read(LayerManagerLockHolder::TryFreezeLayer) else {
    2073              :             // Don't block if the layer lock is busy
    2074            0 :             return;
    2075              :         };
    2076              : 
    2077            0 :         let Ok(lm) = layers_guard.layer_map() else {
    2078            0 :             return;
    2079              :         };
    2080              : 
    2081            0 :         let Some(open_layer) = &lm.open_layer else {
    2082              :             // If there is no open layer, we have no layer freezing to do.  However, we might need to generate
    2083              :             // some updates to disk_consistent_lsn and remote_consistent_lsn, in case we ingested some WAL regions
    2084              :             // that didn't result in writes to this shard.
    2085              : 
    2086              :             // Must not hold the layers lock while waiting for a flush.
    2087            0 :             drop(layers_guard);
    2088              : 
    2089            0 :             let last_record_lsn = self.get_last_record_lsn();
    2090            0 :             let disk_consistent_lsn = self.get_disk_consistent_lsn();
    2091            0 :             if last_record_lsn > disk_consistent_lsn {
    2092              :                 // We have no open layer, but disk_consistent_lsn is behind the last record: this indicates
    2093              :                 // we are a sharded tenant and have skipped some WAL
    2094            0 :                 let last_freeze_ts = *self.last_freeze_ts.read().unwrap();
    2095            0 :                 if last_freeze_ts.elapsed() >= self.get_checkpoint_timeout() {
    2096              :                     // Only do this if have been layer-less longer than get_checkpoint_timeout, so that a shard
    2097              :                     // without any data ingested (yet) doesn't write a remote index as soon as it
    2098              :                     // sees its LSN advance: we only do this if we've been layer-less
    2099              :                     // for some time.
    2100            0 :                     tracing::debug!(
    2101            0 :                         "Advancing disk_consistent_lsn past WAL ingest gap {} -> {}",
    2102              :                         disk_consistent_lsn,
    2103              :                         last_record_lsn
    2104              :                     );
    2105              : 
    2106              :                     // The flush loop will update remote consistent LSN as well as disk consistent LSN.
    2107              :                     // We know there is no open layer, so we can request freezing without actually
    2108              :                     // freezing anything. This is true even if we have dropped the layers_guard, we
    2109              :                     // still hold the write_guard.
    2110            0 :                     let _ = async {
    2111            0 :                         let token = self
    2112            0 :                             .freeze_inmem_layer_at(last_record_lsn, &mut write_guard)
    2113            0 :                             .await?;
    2114            0 :                         self.wait_flush_completion(token).await
    2115            0 :                     }
    2116            0 :                     .await;
    2117            0 :                 }
    2118            0 :             }
    2119              : 
    2120            0 :             return;
    2121              :         };
    2122              : 
    2123            0 :         let current_size = open_layer.len();
    2124              : 
    2125            0 :         let current_lsn = self.get_last_record_lsn();
    2126              : 
    2127            0 :         let checkpoint_distance_override = open_layer.tick();
    2128              : 
    2129            0 :         if let Some(size_override) = checkpoint_distance_override {
    2130            0 :             if current_size > size_override {
    2131              :                 // This is not harmful, but it only happens in relatively rare cases where
    2132              :                 // time-based checkpoints are not happening fast enough to keep the amount of
    2133              :                 // ephemeral data within configured limits.  It's a sign of stress on the system.
    2134            0 :                 tracing::info!(
    2135            0 :                     "Early-rolling open layer at size {current_size} (limit {size_override}) due to dirty data pressure"
    2136              :                 );
    2137            0 :             }
    2138            0 :         }
    2139              : 
    2140            0 :         let checkpoint_distance =
    2141            0 :             checkpoint_distance_override.unwrap_or(self.get_checkpoint_distance());
    2142              : 
    2143            0 :         if self.should_roll(
    2144            0 :             current_size,
    2145            0 :             current_size,
    2146            0 :             checkpoint_distance,
    2147            0 :             self.get_last_record_lsn(),
    2148            0 :             self.last_freeze_at.load(),
    2149            0 :             open_layer.get_opened_at(),
    2150              :         ) {
    2151            0 :             match open_layer.info() {
    2152            0 :                 InMemoryLayerInfo::Frozen { lsn_start, lsn_end } => {
    2153              :                     // We may reach this point if the layer was already frozen by not yet flushed: flushing
    2154              :                     // happens asynchronously in the background.
    2155            0 :                     tracing::debug!(
    2156            0 :                         "Not freezing open layer, it's already frozen ({lsn_start}..{lsn_end})"
    2157              :                     );
    2158              :                 }
    2159              :                 InMemoryLayerInfo::Open { .. } => {
    2160              :                     // Upgrade to a write lock and freeze the layer
    2161            0 :                     drop(layers_guard);
    2162            0 :                     let res = self
    2163            0 :                         .freeze_inmem_layer_at(current_lsn, &mut write_guard)
    2164            0 :                         .await;
    2165              : 
    2166            0 :                     if let Err(e) = res {
    2167            0 :                         tracing::info!(
    2168            0 :                             "failed to flush frozen layer after background freeze: {e:#}"
    2169              :                         );
    2170            0 :                     }
    2171              :                 }
    2172              :             }
    2173            0 :         }
    2174            0 :     }
    2175              : 
    2176              :     /// Checks if the internal state of the timeline is consistent with it being able to be offloaded.
    2177              :     ///
    2178              :     /// This is neccessary but not sufficient for offloading of the timeline as it might have
    2179              :     /// child timelines that are not offloaded yet.
    2180            0 :     pub(crate) fn can_offload(&self) -> (bool, &'static str) {
    2181            0 :         if self.remote_client.is_archived() != Some(true) {
    2182            0 :             return (false, "the timeline is not archived");
    2183            0 :         }
    2184            0 :         if !self.remote_client.no_pending_work() {
    2185              :             // if the remote client is still processing some work, we can't offload
    2186            0 :             return (false, "the upload queue is not drained yet");
    2187            0 :         }
    2188              : 
    2189            0 :         (true, "ok")
    2190            0 :     }
    2191              : 
    2192              :     /// Outermost timeline compaction operation; downloads needed layers. Returns whether we have pending
    2193              :     /// compaction tasks.
    2194          192 :     pub(crate) async fn compact(
    2195          192 :         self: &Arc<Self>,
    2196          192 :         cancel: &CancellationToken,
    2197          192 :         flags: EnumSet<CompactFlags>,
    2198          192 :         ctx: &RequestContext,
    2199          192 :     ) -> Result<CompactionOutcome, CompactionError> {
    2200          192 :         let res = self
    2201          192 :             .compact_with_options(
    2202          192 :                 cancel,
    2203          192 :                 CompactOptions {
    2204          192 :                     flags,
    2205          192 :                     compact_key_range: None,
    2206          192 :                     compact_lsn_range: None,
    2207          192 :                     sub_compaction: false,
    2208          192 :                     sub_compaction_max_job_size_mb: None,
    2209          192 :                     gc_compaction_do_metadata_compaction: false,
    2210          192 :                 },
    2211          192 :                 ctx,
    2212          192 :             )
    2213          192 :             .await;
    2214          192 :         if let Err(err) = &res {
    2215            0 :             log_compaction_error(err, None, cancel.is_cancelled(), false);
    2216          192 :         }
    2217          192 :         res
    2218          192 :     }
    2219              : 
    2220              :     /// Outermost timeline compaction operation; downloads needed layers.
    2221              :     ///
    2222              :     /// NB: the cancellation token is usually from a background task, but can also come from a
    2223              :     /// request task.
    2224          192 :     pub(crate) async fn compact_with_options(
    2225          192 :         self: &Arc<Self>,
    2226          192 :         cancel: &CancellationToken,
    2227          192 :         options: CompactOptions,
    2228          192 :         ctx: &RequestContext,
    2229          192 :     ) -> Result<CompactionOutcome, CompactionError> {
    2230              :         // Acquire the compaction lock and task semaphore.
    2231              :         //
    2232              :         // L0-only compaction uses a separate semaphore (if enabled) to make sure it isn't starved
    2233              :         // out by other background tasks (including image compaction). We request this via
    2234              :         // `BackgroundLoopKind::L0Compaction`.
    2235              :         //
    2236              :         // Yield for pending L0 compaction while waiting for the semaphore.
    2237          192 :         let is_l0_only = options.flags.contains(CompactFlags::OnlyL0Compaction);
    2238          192 :         let semaphore_kind = match is_l0_only && self.get_compaction_l0_semaphore() {
    2239            0 :             true => BackgroundLoopKind::L0Compaction,
    2240          192 :             false => BackgroundLoopKind::Compaction,
    2241              :         };
    2242          192 :         let yield_for_l0 = options.flags.contains(CompactFlags::YieldForL0);
    2243          192 :         if yield_for_l0 {
    2244              :             // If this is an L0 pass, it doesn't make sense to yield for L0.
    2245            0 :             debug_assert!(!is_l0_only, "YieldForL0 during L0 pass");
    2246              :             // If `compaction_l0_first` is disabled, there's no point yielding.
    2247            0 :             debug_assert!(self.get_compaction_l0_first(), "YieldForL0 without L0 pass");
    2248          192 :         }
    2249              : 
    2250          192 :         let acquire = async move {
    2251          192 :             let guard = self.compaction_lock.lock().await;
    2252          192 :             let permit = super::tasks::acquire_concurrency_permit(semaphore_kind, ctx).await;
    2253          192 :             (guard, permit)
    2254          192 :         };
    2255              : 
    2256          192 :         let (_guard, _permit) = tokio::select! {
    2257          192 :             (guard, permit) = acquire => (guard, permit),
    2258          192 :             _ = self.l0_compaction_trigger.notified(), if yield_for_l0 => {
    2259            0 :                 return Ok(CompactionOutcome::YieldForL0);
    2260              :             }
    2261          192 :             _ = self.cancel.cancelled() => return Ok(CompactionOutcome::Skipped),
    2262          192 :             _ = cancel.cancelled() => return Ok(CompactionOutcome::Skipped),
    2263              :         };
    2264              : 
    2265          192 :         let last_record_lsn = self.get_last_record_lsn();
    2266              : 
    2267              :         // Last record Lsn could be zero in case the timeline was just created
    2268          192 :         if !last_record_lsn.is_valid() {
    2269            0 :             warn!(
    2270            0 :                 "Skipping compaction for potentially just initialized timeline, it has invalid last record lsn: {last_record_lsn}"
    2271              :             );
    2272            0 :             return Ok(CompactionOutcome::Skipped);
    2273          192 :         }
    2274              : 
    2275          192 :         let result = match self.get_compaction_algorithm_settings().kind {
    2276              :             CompactionAlgorithm::Tiered => {
    2277            0 :                 self.compact_tiered(cancel, ctx).await?;
    2278            0 :                 Ok(CompactionOutcome::Done)
    2279              :             }
    2280          192 :             CompactionAlgorithm::Legacy => self.compact_legacy(cancel, options, ctx).await,
    2281              :         };
    2282              : 
    2283              :         // Signal compaction failure to avoid L0 flush stalls when it's broken.
    2284            0 :         match &result {
    2285          192 :             Ok(_) => self.compaction_failed.store(false, AtomicOrdering::Relaxed),
    2286            0 :             Err(e) if e.is_cancel() => {}
    2287            0 :             Err(_) => self.compaction_failed.store(true, AtomicOrdering::Relaxed),
    2288              :         };
    2289              : 
    2290          192 :         result
    2291          192 :     }
    2292              : 
    2293              :     /// Mutate the timeline with a [`TimelineWriter`].
    2294      2566609 :     pub(crate) async fn writer(&self) -> TimelineWriter<'_> {
    2295              :         TimelineWriter {
    2296      2566609 :             tl: self,
    2297      2566609 :             write_guard: self.write_lock.lock().await,
    2298              :         }
    2299      2566609 :     }
    2300              : 
    2301            0 :     pub(crate) fn activate(
    2302            0 :         self: &Arc<Self>,
    2303            0 :         parent: Arc<crate::tenant::TenantShard>,
    2304            0 :         broker_client: BrokerClientChannel,
    2305            0 :         background_jobs_can_start: Option<&completion::Barrier>,
    2306            0 :         ctx: &RequestContext,
    2307            0 :     ) {
    2308            0 :         if self.tenant_shard_id.is_shard_zero() {
    2309            0 :             // Logical size is only maintained accurately on shard zero.
    2310            0 :             self.spawn_initial_logical_size_computation_task(ctx);
    2311            0 :         }
    2312            0 :         self.launch_wal_receiver(ctx, broker_client);
    2313            0 :         self.set_state(TimelineState::Active);
    2314            0 :         self.launch_eviction_task(parent, background_jobs_can_start);
    2315            0 :     }
    2316              : 
    2317              :     /// After this function returns, there are no timeline-scoped tasks are left running.
    2318              :     ///
    2319              :     /// The preferred pattern for is:
    2320              :     /// - in any spawned tasks, keep Timeline::guard open + Timeline::cancel / child token
    2321              :     /// - if early shutdown (not just cancellation) of a sub-tree of tasks is required,
    2322              :     ///   go the extra mile and keep track of JoinHandles
    2323              :     /// - Keep track of JoinHandles using a passed-down `Arc<Mutex<Option<JoinSet>>>` or similar,
    2324              :     ///   instead of spawning directly on a runtime. It is a more composable / testable pattern.
    2325              :     ///
    2326              :     /// For legacy reasons, we still have multiple tasks spawned using
    2327              :     /// `task_mgr::spawn(X, Some(tenant_id), Some(timeline_id))`.
    2328              :     /// We refer to these as "timeline-scoped task_mgr tasks".
    2329              :     /// Some of these tasks are already sensitive to Timeline::cancel while others are
    2330              :     /// not sensitive to Timeline::cancel and instead respect [`task_mgr::shutdown_token`]
    2331              :     /// or [`task_mgr::shutdown_watcher`].
    2332              :     /// We want to gradually convert the code base away from these.
    2333              :     ///
    2334              :     /// Here is an inventory of timeline-scoped task_mgr tasks that are still sensitive to
    2335              :     /// `task_mgr::shutdown_{token,watcher}` (there are also tenant-scoped and global-scoped
    2336              :     /// ones that aren't mentioned here):
    2337              :     /// - [`TaskKind::TimelineDeletionWorker`]
    2338              :     ///    - NB: also used for tenant deletion
    2339              :     /// - [`TaskKind::RemoteUploadTask`]`
    2340              :     /// - [`TaskKind::InitialLogicalSizeCalculation`]
    2341              :     /// - [`TaskKind::DownloadAllRemoteLayers`] (can we get rid of it?)
    2342              :     // Inventory of timeline-scoped task_mgr tasks that use spawn but aren't sensitive:
    2343              :     /// - [`TaskKind::Eviction`]
    2344              :     /// - [`TaskKind::LayerFlushTask`]
    2345              :     /// - [`TaskKind::OndemandLogicalSizeCalculation`]
    2346              :     /// - [`TaskKind::GarbageCollector`] (immediate_gc is timeline-scoped)
    2347            5 :     pub(crate) async fn shutdown(&self, mode: ShutdownMode) {
    2348            5 :         debug_assert_current_span_has_tenant_and_timeline_id();
    2349              : 
    2350              :         // Regardless of whether we're going to try_freeze_and_flush
    2351              :         // cancel walreceiver to stop ingesting more data asap.
    2352              :         //
    2353              :         // Note that we're accepting a race condition here where we may
    2354              :         // do the final flush below, before walreceiver observes the
    2355              :         // cancellation and exits.
    2356              :         // This means we may open a new InMemoryLayer after the final flush below.
    2357              :         // Flush loop is also still running for a short while, so, in theory, it
    2358              :         // could also make its way into the upload queue.
    2359              :         //
    2360              :         // If we wait for the shutdown of the walreceiver before moving on to the
    2361              :         // flush, then that would be avoided. But we don't do it because the
    2362              :         // walreceiver entertains reads internally, which means that it possibly
    2363              :         // depends on the download of layers. Layer download is only sensitive to
    2364              :         // the cancellation of the entire timeline, so cancelling the walreceiver
    2365              :         // will have no effect on the individual get requests.
    2366              :         // This would cause problems when there is a lot of ongoing downloads or
    2367              :         // there is S3 unavailabilities, i.e. detach, deletion, etc would hang,
    2368              :         // and we can't deallocate resources of the timeline, etc.
    2369            5 :         let walreceiver = self.walreceiver.lock().unwrap().take();
    2370            5 :         tracing::debug!(
    2371            0 :             is_some = walreceiver.is_some(),
    2372            0 :             "Waiting for WalReceiverManager..."
    2373              :         );
    2374            5 :         if let Some(walreceiver) = walreceiver {
    2375            0 :             walreceiver.cancel().await;
    2376            5 :         }
    2377              :         // ... and inform any waiters for newer LSNs that there won't be any.
    2378            5 :         self.last_record_lsn.shutdown();
    2379              : 
    2380            5 :         if let ShutdownMode::FreezeAndFlush = mode {
    2381            3 :             let do_flush = if let Some((open, frozen)) = self
    2382            3 :                 .layers
    2383            3 :                 .read(LayerManagerLockHolder::Shutdown)
    2384            3 :                 .await
    2385            3 :                 .layer_map()
    2386            3 :                 .map(|lm| (lm.open_layer.is_some(), lm.frozen_layers.len()))
    2387            3 :                 .ok()
    2388            3 :                 .filter(|(open, frozen)| *open || *frozen > 0)
    2389              :             {
    2390            0 :                 if self.remote_client.is_archived() == Some(true) {
    2391              :                     // No point flushing on shutdown for an archived timeline: it is not important
    2392              :                     // to have it nice and fresh after our restart, and trying to flush here might
    2393              :                     // race with trying to offload it (which also stops the flush loop)
    2394            0 :                     false
    2395              :                 } else {
    2396            0 :                     tracing::info!(?open, frozen, "flushing and freezing on shutdown");
    2397            0 :                     true
    2398              :                 }
    2399              :             } else {
    2400              :                 // this is double-shutdown, it'll be a no-op
    2401            3 :                 true
    2402              :             };
    2403              : 
    2404              :             // we shut down walreceiver above, so, we won't add anything more
    2405              :             // to the InMemoryLayer; freeze it and wait for all frozen layers
    2406              :             // to reach the disk & upload queue, then shut the upload queue and
    2407              :             // wait for it to drain.
    2408            3 :             if do_flush {
    2409            3 :                 match self.freeze_and_flush().await {
    2410              :                     Ok(_) => {
    2411              :                         // drain the upload queue
    2412              :                         // if we did not wait for completion here, it might be our shutdown process
    2413              :                         // didn't wait for remote uploads to complete at all, as new tasks can forever
    2414              :                         // be spawned.
    2415              :                         //
    2416              :                         // what is problematic is the shutting down of RemoteTimelineClient, because
    2417              :                         // obviously it does not make sense to stop while we wait for it, but what
    2418              :                         // about corner cases like s3 suddenly hanging up?
    2419            3 :                         self.remote_client.shutdown().await;
    2420              :                     }
    2421              :                     Err(FlushLayerError::Cancelled) => {
    2422              :                         // this is likely the second shutdown, ignore silently.
    2423              :                         // TODO: this can be removed once https://github.com/neondatabase/neon/issues/5080
    2424            0 :                         debug_assert!(self.cancel.is_cancelled());
    2425              :                     }
    2426            0 :                     Err(e) => {
    2427              :                         // Non-fatal.  Shutdown is infallible.  Failures to flush just mean that
    2428              :                         // we have some extra WAL replay to do next time the timeline starts.
    2429            0 :                         warn!("failed to freeze and flush: {e:#}");
    2430              :                     }
    2431              :                 }
    2432              : 
    2433              :                 // `self.remote_client.shutdown().await` above should have already flushed everything from the queue, but
    2434              :                 // we also do a final check here to ensure that the queue is empty.
    2435            3 :                 if !self.remote_client.no_pending_work() {
    2436            0 :                     warn!(
    2437            0 :                         "still have pending work in remote upload queue, but continuing shutting down anyways"
    2438              :                     );
    2439            3 :                 }
    2440            0 :             }
    2441            2 :         }
    2442              : 
    2443            5 :         if let ShutdownMode::Reload = mode {
    2444              :             // drain the upload queue
    2445            1 :             self.remote_client.shutdown().await;
    2446            1 :             if !self.remote_client.no_pending_work() {
    2447            0 :                 warn!(
    2448            0 :                     "still have pending work in remote upload queue, but continuing shutting down anyways"
    2449              :                 );
    2450            1 :             }
    2451            4 :         }
    2452              : 
    2453              :         // Signal any subscribers to our cancellation token to drop out
    2454            5 :         tracing::debug!("Cancelling CancellationToken");
    2455            5 :         self.cancel.cancel();
    2456              : 
    2457              :         // If we have a background task downloading heatmap layers stop it.
    2458              :         // The background downloads are sensitive to timeline cancellation (done above),
    2459              :         // so the drain will be immediate.
    2460            5 :         self.stop_and_drain_heatmap_layers_download().await;
    2461              : 
    2462              :         // Ensure Prevent new page service requests from starting.
    2463            5 :         self.handles.shutdown();
    2464              : 
    2465              :         // Transition the remote_client into a state where it's only useful for timeline deletion.
    2466              :         // (The deletion use case is why we can't just hook up remote_client to Self::cancel).)
    2467            5 :         self.remote_client.stop();
    2468              : 
    2469              :         // As documented in remote_client.stop()'s doc comment, it's our responsibility
    2470              :         // to shut down the upload queue tasks.
    2471              :         // TODO: fix that, task management should be encapsulated inside remote_client.
    2472            5 :         task_mgr::shutdown_tasks(
    2473            5 :             Some(TaskKind::RemoteUploadTask),
    2474            5 :             Some(self.tenant_shard_id),
    2475            5 :             Some(self.timeline_id),
    2476            5 :         )
    2477            5 :         .await;
    2478              : 
    2479              :         // TODO: work toward making this a no-op. See this function's doc comment for more context.
    2480            5 :         tracing::debug!("Waiting for tasks...");
    2481            5 :         task_mgr::shutdown_tasks(None, Some(self.tenant_shard_id), Some(self.timeline_id)).await;
    2482              : 
    2483              :         {
    2484              :             // Allow any remaining in-memory layers to do cleanup -- until that, they hold the gate
    2485              :             // open.
    2486            5 :             let mut write_guard = self.write_lock.lock().await;
    2487            5 :             self.layers
    2488            5 :                 .write(LayerManagerLockHolder::Shutdown)
    2489            5 :                 .await
    2490            5 :                 .shutdown(&mut write_guard);
    2491              :         }
    2492              : 
    2493              :         // Finally wait until any gate-holders are complete.
    2494              :         //
    2495              :         // TODO: once above shutdown_tasks is a no-op, we can close the gate before calling shutdown_tasks
    2496              :         // and use a TBD variant of shutdown_tasks that asserts that there were no tasks left.
    2497            5 :         self.gate.close().await;
    2498              : 
    2499            5 :         self.metrics.shutdown();
    2500            5 :     }
    2501              : 
    2502          236 :     pub(crate) fn set_state(&self, new_state: TimelineState) {
    2503          236 :         match (self.current_state(), new_state) {
    2504          236 :             (equal_state_1, equal_state_2) if equal_state_1 == equal_state_2 => {
    2505            1 :                 info!("Ignoring new state, equal to the existing one: {equal_state_2:?}");
    2506              :             }
    2507            0 :             (st, TimelineState::Loading) => {
    2508            0 :                 error!("ignoring transition from {st:?} into Loading state");
    2509              :             }
    2510            0 :             (TimelineState::Broken { .. }, new_state) => {
    2511            0 :                 error!("Ignoring state update {new_state:?} for broken timeline");
    2512              :             }
    2513              :             (TimelineState::Stopping, TimelineState::Active) => {
    2514            0 :                 error!("Not activating a Stopping timeline");
    2515              :             }
    2516          235 :             (_, new_state) => {
    2517          235 :                 self.state.send_replace(new_state);
    2518          235 :             }
    2519              :         }
    2520          236 :     }
    2521              : 
    2522            1 :     pub(crate) fn set_broken(&self, reason: String) {
    2523            1 :         let backtrace_str: String = format!("{}", std::backtrace::Backtrace::force_capture());
    2524            1 :         let broken_state = TimelineState::Broken {
    2525            1 :             reason,
    2526            1 :             backtrace: backtrace_str,
    2527            1 :         };
    2528            1 :         self.set_state(broken_state);
    2529              : 
    2530              :         // Although the Broken state is not equivalent to shutdown() (shutdown will be called
    2531              :         // later when this tenant is detach or the process shuts down), firing the cancellation token
    2532              :         // here avoids the need for other tasks to watch for the Broken state explicitly.
    2533            1 :         self.cancel.cancel();
    2534            1 :     }
    2535              : 
    2536       115414 :     pub(crate) fn current_state(&self) -> TimelineState {
    2537       115414 :         self.state.borrow().clone()
    2538       115414 :     }
    2539              : 
    2540            3 :     pub(crate) fn is_broken(&self) -> bool {
    2541            3 :         matches!(&*self.state.borrow(), TimelineState::Broken { .. })
    2542            3 :     }
    2543              : 
    2544          126 :     pub(crate) fn is_active(&self) -> bool {
    2545          126 :         self.current_state() == TimelineState::Active
    2546          126 :     }
    2547              : 
    2548            8 :     pub(crate) fn is_archived(&self) -> Option<bool> {
    2549            8 :         self.remote_client.is_archived()
    2550            8 :     }
    2551              : 
    2552            8 :     pub(crate) fn is_invisible(&self) -> Option<bool> {
    2553            8 :         self.remote_client.is_invisible()
    2554            8 :     }
    2555              : 
    2556          569 :     pub(crate) fn is_stopping(&self) -> bool {
    2557          569 :         self.current_state() == TimelineState::Stopping
    2558          569 :     }
    2559              : 
    2560            0 :     pub(crate) fn subscribe_for_state_updates(&self) -> watch::Receiver<TimelineState> {
    2561            0 :         self.state.subscribe()
    2562            0 :     }
    2563              : 
    2564       114484 :     pub(crate) async fn wait_to_become_active(
    2565       114484 :         &self,
    2566       114484 :         _ctx: &RequestContext, // Prepare for use by cancellation
    2567       114484 :     ) -> Result<(), TimelineState> {
    2568       114484 :         let mut receiver = self.state.subscribe();
    2569              :         loop {
    2570       114484 :             let current_state = receiver.borrow().clone();
    2571       114484 :             match current_state {
    2572              :                 TimelineState::Loading => {
    2573            0 :                     receiver
    2574            0 :                         .changed()
    2575            0 :                         .await
    2576            0 :                         .expect("holding a reference to self");
    2577              :                 }
    2578              :                 TimelineState::Active => {
    2579       114483 :                     return Ok(());
    2580              :                 }
    2581              :                 TimelineState::Broken { .. } | TimelineState::Stopping => {
    2582              :                     // There's no chance the timeline can transition back into ::Active
    2583            1 :                     return Err(current_state);
    2584              :                 }
    2585              :             }
    2586              :         }
    2587       114484 :     }
    2588              : 
    2589            0 :     pub(crate) async fn layer_map_info(
    2590            0 :         &self,
    2591            0 :         reset: LayerAccessStatsReset,
    2592            0 :     ) -> Result<LayerMapInfo, layer_manager::Shutdown> {
    2593            0 :         let guard = self
    2594            0 :             .layers
    2595            0 :             .read(LayerManagerLockHolder::GetLayerMapInfo)
    2596            0 :             .await;
    2597            0 :         let layer_map = guard.layer_map()?;
    2598            0 :         let mut in_memory_layers = Vec::with_capacity(layer_map.frozen_layers.len() + 1);
    2599            0 :         if let Some(open_layer) = &layer_map.open_layer {
    2600            0 :             in_memory_layers.push(open_layer.info());
    2601            0 :         }
    2602            0 :         for frozen_layer in &layer_map.frozen_layers {
    2603            0 :             in_memory_layers.push(frozen_layer.info());
    2604            0 :         }
    2605              : 
    2606            0 :         let historic_layers = layer_map
    2607            0 :             .iter_historic_layers()
    2608            0 :             .map(|desc| guard.get_from_desc(&desc).info(reset))
    2609            0 :             .collect();
    2610              : 
    2611            0 :         Ok(LayerMapInfo {
    2612            0 :             in_memory_layers,
    2613            0 :             historic_layers,
    2614            0 :         })
    2615            0 :     }
    2616              : 
    2617              :     #[instrument(skip_all, fields(tenant_id = %self.tenant_shard_id.tenant_id, shard_id = %self.tenant_shard_id.shard_slug(), timeline_id = %self.timeline_id))]
    2618              :     pub(crate) async fn download_layer(
    2619              :         &self,
    2620              :         layer_file_name: &LayerName,
    2621              :         ctx: &RequestContext,
    2622              :     ) -> Result<Option<bool>, super::storage_layer::layer::DownloadError> {
    2623              :         let Some(layer) = self
    2624              :             .find_layer(layer_file_name)
    2625              :             .await
    2626            0 :             .map_err(|e| match e {
    2627              :                 layer_manager::Shutdown => {
    2628            0 :                     super::storage_layer::layer::DownloadError::TimelineShutdown
    2629              :                 }
    2630            0 :             })?
    2631              :         else {
    2632              :             return Ok(None);
    2633              :         };
    2634              : 
    2635              :         layer.download(ctx).await?;
    2636              : 
    2637              :         Ok(Some(true))
    2638              :     }
    2639              : 
    2640              :     /// Evict just one layer.
    2641              :     ///
    2642              :     /// Returns `Ok(None)` in the case where the layer could not be found by its `layer_file_name`.
    2643            0 :     pub(crate) async fn evict_layer(
    2644            0 :         &self,
    2645            0 :         layer_file_name: &LayerName,
    2646            0 :     ) -> anyhow::Result<Option<bool>> {
    2647            0 :         let _gate = self
    2648            0 :             .gate
    2649            0 :             .enter()
    2650            0 :             .map_err(|_| anyhow::anyhow!("Shutting down"))?;
    2651              : 
    2652            0 :         let Some(local_layer) = self.find_layer(layer_file_name).await? else {
    2653            0 :             return Ok(None);
    2654              :         };
    2655              : 
    2656              :         // curl has this by default
    2657            0 :         let timeout = std::time::Duration::from_secs(120);
    2658              : 
    2659            0 :         match local_layer.evict_and_wait(timeout).await {
    2660            0 :             Ok(()) => Ok(Some(true)),
    2661            0 :             Err(EvictionError::NotFound) => Ok(Some(false)),
    2662            0 :             Err(EvictionError::Downloaded) => Ok(Some(false)),
    2663            0 :             Err(EvictionError::Timeout) => Ok(Some(false)),
    2664              :         }
    2665            0 :     }
    2666              : 
    2667      2401506 :     fn should_roll(
    2668      2401506 :         &self,
    2669      2401506 :         layer_size: u64,
    2670      2401506 :         projected_layer_size: u64,
    2671      2401506 :         checkpoint_distance: u64,
    2672      2401506 :         projected_lsn: Lsn,
    2673      2401506 :         last_freeze_at: Lsn,
    2674      2401506 :         opened_at: Instant,
    2675      2401506 :     ) -> bool {
    2676      2401506 :         let distance = projected_lsn.widening_sub(last_freeze_at);
    2677              : 
    2678              :         // Rolling the open layer can be triggered by:
    2679              :         // 1. The distance from the last LSN we rolled at. This bounds the amount of WAL that
    2680              :         //    the safekeepers need to store.  For sharded tenants, we multiply by shard count to
    2681              :         //    account for how writes are distributed across shards: we expect each node to consume
    2682              :         //    1/count of the LSN on average.
    2683              :         // 2. The size of the currently open layer.
    2684              :         // 3. The time since the last roll. It helps safekeepers to regard pageserver as caught
    2685              :         //    up and suspend activity.
    2686      2401506 :         if distance >= checkpoint_distance as i128 * self.shard_identity.count.count() as i128 {
    2687            0 :             info!(
    2688            0 :                 "Will roll layer at {} with layer size {} due to LSN distance ({})",
    2689              :                 projected_lsn, layer_size, distance
    2690              :             );
    2691              : 
    2692            0 :             true
    2693      2401506 :         } else if projected_layer_size >= checkpoint_distance {
    2694              :             // NB: this check is relied upon by:
    2695           40 :             let _ = IndexEntry::validate_checkpoint_distance;
    2696           40 :             info!(
    2697            0 :                 "Will roll layer at {} with layer size {} due to layer size ({})",
    2698              :                 projected_lsn, layer_size, projected_layer_size
    2699              :             );
    2700              : 
    2701           40 :             true
    2702      2401466 :         } else if distance > 0 && opened_at.elapsed() >= self.get_checkpoint_timeout() {
    2703            0 :             info!(
    2704            0 :                 "Will roll layer at {} with layer size {} due to time since first write to the layer ({:?})",
    2705              :                 projected_lsn,
    2706              :                 layer_size,
    2707            0 :                 opened_at.elapsed()
    2708              :             );
    2709              : 
    2710            0 :             true
    2711              :         } else {
    2712      2401466 :             false
    2713              :         }
    2714      2401506 :     }
    2715              : 
    2716            1 :     pub(crate) fn is_basebackup_cache_enabled(&self) -> bool {
    2717            1 :         let tenant_conf = self.tenant_conf.load();
    2718            1 :         tenant_conf
    2719            1 :             .tenant_conf
    2720            1 :             .basebackup_cache_enabled
    2721            1 :             .unwrap_or(self.conf.default_tenant_conf.basebackup_cache_enabled)
    2722            1 :     }
    2723              : 
    2724              :     /// Try to get a basebackup from the on-disk cache.
    2725            0 :     pub(crate) async fn get_cached_basebackup(&self, lsn: Lsn) -> Option<tokio::fs::File> {
    2726            0 :         self.basebackup_cache
    2727            0 :             .get(self.tenant_shard_id.tenant_id, self.timeline_id, lsn)
    2728            0 :             .await
    2729            0 :     }
    2730              : 
    2731              :     /// Convenience method to attempt fetching a basebackup for the timeline if enabled and safe for
    2732              :     /// the given request parameters.
    2733              :     ///
    2734              :     /// TODO: consider moving this onto GrpcPageServiceHandler once the libpq handler is gone.
    2735            0 :     pub async fn get_cached_basebackup_if_enabled(
    2736            0 :         &self,
    2737            0 :         lsn: Option<Lsn>,
    2738            0 :         prev_lsn: Option<Lsn>,
    2739            0 :         full: bool,
    2740            0 :         replica: bool,
    2741            0 :         gzip: bool,
    2742            0 :     ) -> Option<tokio::fs::File> {
    2743            0 :         if !self.is_basebackup_cache_enabled() || !self.basebackup_cache.is_enabled() {
    2744            0 :             return None;
    2745            0 :         }
    2746              :         // We have to know which LSN to fetch the basebackup for.
    2747            0 :         let lsn = lsn?;
    2748              :         // We only cache gzipped, non-full basebackups for primary computes with automatic prev_lsn.
    2749            0 :         if prev_lsn.is_some() || full || replica || !gzip {
    2750            0 :             return None;
    2751            0 :         }
    2752            0 :         self.get_cached_basebackup(lsn).await
    2753            0 :     }
    2754              : 
    2755              :     /// Prepare basebackup for the given LSN and store it in the basebackup cache.
    2756              :     /// The method is asynchronous and returns immediately.
    2757              :     /// The actual basebackup preparation is performed in the background
    2758              :     /// by the basebackup cache on a best-effort basis.
    2759            1 :     pub(crate) fn prepare_basebackup(&self, lsn: Lsn) {
    2760            1 :         if !self.is_basebackup_cache_enabled() {
    2761            1 :             return;
    2762            0 :         }
    2763            0 :         if !self.tenant_shard_id.is_shard_zero() {
    2764              :             // In theory we should never get here, but just in case check it.
    2765              :             // Preparing basebackup doesn't make sense for shards other than shard zero.
    2766            0 :             return;
    2767            0 :         }
    2768            0 :         if !self.is_active() {
    2769              :             // May happen during initial timeline creation.
    2770              :             // Such timeline is not in the global timeline map yet,
    2771              :             // so basebackup cache will not be able to find it.
    2772              :             // TODO(diko): We can prepare such timelines in finish_creation().
    2773            0 :             return;
    2774            0 :         }
    2775              : 
    2776            0 :         self.basebackup_cache
    2777            0 :             .send_prepare(self.tenant_shard_id, self.timeline_id, lsn);
    2778            1 :     }
    2779              : }
    2780              : 
    2781              : /// Number of times we will compute partition within a checkpoint distance.
    2782              : const REPARTITION_FREQ_IN_CHECKPOINT_DISTANCE: u64 = 10;
    2783              : 
    2784              : // Private functions
    2785              : impl Timeline {
    2786            6 :     pub(crate) fn get_lsn_lease_length(&self) -> Duration {
    2787            6 :         let tenant_conf = self.tenant_conf.load();
    2788            6 :         tenant_conf
    2789            6 :             .tenant_conf
    2790            6 :             .lsn_lease_length
    2791            6 :             .unwrap_or(self.conf.default_tenant_conf.lsn_lease_length)
    2792            6 :     }
    2793              : 
    2794            0 :     pub(crate) fn get_lsn_lease_length_for_ts(&self) -> Duration {
    2795            0 :         let tenant_conf = self.tenant_conf.load();
    2796            0 :         tenant_conf
    2797            0 :             .tenant_conf
    2798            0 :             .lsn_lease_length_for_ts
    2799            0 :             .unwrap_or(self.conf.default_tenant_conf.lsn_lease_length_for_ts)
    2800            0 :     }
    2801              : 
    2802            0 :     pub(crate) fn is_gc_blocked_by_lsn_lease_deadline(&self) -> bool {
    2803            0 :         let tenant_conf = self.tenant_conf.load();
    2804            0 :         tenant_conf.is_gc_blocked_by_lsn_lease_deadline()
    2805            0 :     }
    2806              : 
    2807            0 :     pub(crate) fn get_lazy_slru_download(&self) -> bool {
    2808            0 :         let tenant_conf = self.tenant_conf.load();
    2809            0 :         tenant_conf
    2810            0 :             .tenant_conf
    2811            0 :             .lazy_slru_download
    2812            0 :             .unwrap_or(self.conf.default_tenant_conf.lazy_slru_download)
    2813            0 :     }
    2814              : 
    2815              :     /// Checks if a get page request should get perf tracing
    2816              :     ///
    2817              :     /// The configuration priority is: tenant config override, default tenant config,
    2818              :     /// pageserver config.
    2819            0 :     pub(crate) fn is_get_page_request_sampled(&self) -> bool {
    2820            0 :         let tenant_conf = self.tenant_conf.load();
    2821            0 :         let ratio = tenant_conf
    2822            0 :             .tenant_conf
    2823            0 :             .sampling_ratio
    2824            0 :             .flatten()
    2825            0 :             .or(self.conf.default_tenant_conf.sampling_ratio)
    2826            0 :             .or(self.conf.tracing.as_ref().map(|t| t.sampling_ratio));
    2827              : 
    2828            0 :         match ratio {
    2829            0 :             Some(r) => {
    2830            0 :                 if r.numerator == 0 {
    2831            0 :                     false
    2832              :                 } else {
    2833            0 :                     rand::rng().random_range(0..r.denominator) < r.numerator
    2834              :                 }
    2835              :             }
    2836            0 :             None => false,
    2837              :         }
    2838            0 :     }
    2839              : 
    2840      2402187 :     fn get_checkpoint_distance(&self) -> u64 {
    2841      2402187 :         let tenant_conf = self.tenant_conf.load();
    2842      2402187 :         tenant_conf
    2843      2402187 :             .tenant_conf
    2844      2402187 :             .checkpoint_distance
    2845      2402187 :             .unwrap_or(self.conf.default_tenant_conf.checkpoint_distance)
    2846      2402187 :     }
    2847              : 
    2848      2401522 :     fn get_checkpoint_timeout(&self) -> Duration {
    2849      2401522 :         let tenant_conf = self.tenant_conf.load();
    2850      2401522 :         tenant_conf
    2851      2401522 :             .tenant_conf
    2852      2401522 :             .checkpoint_timeout
    2853      2401522 :             .unwrap_or(self.conf.default_tenant_conf.checkpoint_timeout)
    2854      2401522 :     }
    2855              : 
    2856            1 :     pub(crate) fn get_pitr_interval(&self) -> Duration {
    2857            1 :         let tenant_conf = &self.tenant_conf.load().tenant_conf;
    2858            1 :         tenant_conf
    2859            1 :             .pitr_interval
    2860            1 :             .unwrap_or(self.conf.default_tenant_conf.pitr_interval)
    2861            1 :     }
    2862              : 
    2863         1273 :     fn get_compaction_period(&self) -> Duration {
    2864         1273 :         let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
    2865         1273 :         tenant_conf
    2866         1273 :             .compaction_period
    2867         1273 :             .unwrap_or(self.conf.default_tenant_conf.compaction_period)
    2868         1273 :     }
    2869              : 
    2870          352 :     fn get_compaction_target_size(&self) -> u64 {
    2871          352 :         let tenant_conf = self.tenant_conf.load();
    2872          352 :         tenant_conf
    2873          352 :             .tenant_conf
    2874          352 :             .compaction_target_size
    2875          352 :             .unwrap_or(self.conf.default_tenant_conf.compaction_target_size)
    2876          352 :     }
    2877              : 
    2878          820 :     fn get_compaction_threshold(&self) -> usize {
    2879          820 :         let tenant_conf = self.tenant_conf.load();
    2880          820 :         tenant_conf
    2881          820 :             .tenant_conf
    2882          820 :             .compaction_threshold
    2883          820 :             .unwrap_or(self.conf.default_tenant_conf.compaction_threshold)
    2884          820 :     }
    2885              : 
    2886              :     /// Returns `true` if the rel_size_v2 config is enabled. NOTE: the write path and read path
    2887              :     /// should look at `get_rel_size_v2_status()` to get the actual status of the timeline. It is
    2888              :     /// possible that the index part persists the state while the config doesn't get persisted.
    2889          973 :     pub(crate) fn get_rel_size_v2_enabled(&self) -> bool {
    2890          973 :         let tenant_conf = self.tenant_conf.load();
    2891          973 :         tenant_conf
    2892          973 :             .tenant_conf
    2893          973 :             .rel_size_v2_enabled
    2894          973 :             .unwrap_or(self.conf.default_tenant_conf.rel_size_v2_enabled)
    2895          973 :     }
    2896              : 
    2897         1099 :     pub(crate) fn get_rel_size_v2_status(&self) -> (RelSizeMigration, Option<Lsn>) {
    2898         1099 :         let (status, migrated_at) = self.rel_size_v2_status.load().as_ref().clone();
    2899         1099 :         (status.unwrap_or(RelSizeMigration::Legacy), migrated_at)
    2900         1099 :     }
    2901              : 
    2902           23 :     fn get_compaction_upper_limit(&self) -> usize {
    2903           23 :         let tenant_conf = self.tenant_conf.load();
    2904           23 :         tenant_conf
    2905           23 :             .tenant_conf
    2906           23 :             .compaction_upper_limit
    2907           23 :             .unwrap_or(self.conf.default_tenant_conf.compaction_upper_limit)
    2908           23 :     }
    2909              : 
    2910            0 :     pub fn get_compaction_l0_first(&self) -> bool {
    2911            0 :         let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
    2912            0 :         tenant_conf
    2913            0 :             .compaction_l0_first
    2914            0 :             .unwrap_or(self.conf.default_tenant_conf.compaction_l0_first)
    2915            0 :     }
    2916              : 
    2917            0 :     pub fn get_compaction_l0_semaphore(&self) -> bool {
    2918            0 :         let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
    2919            0 :         tenant_conf
    2920            0 :             .compaction_l0_semaphore
    2921            0 :             .unwrap_or(self.conf.default_tenant_conf.compaction_l0_semaphore)
    2922            0 :     }
    2923              : 
    2924          636 :     fn get_l0_flush_delay_threshold(&self) -> Option<usize> {
    2925              :         // By default, delay L0 flushes at 3x the compaction threshold. The compaction threshold
    2926              :         // defaults to 10, and L0 compaction is generally able to keep L0 counts below 30.
    2927              :         const DEFAULT_L0_FLUSH_DELAY_FACTOR: usize = 3;
    2928              : 
    2929              :         // If compaction is disabled, don't delay.
    2930          636 :         if self.get_compaction_period() == Duration::ZERO {
    2931          632 :             return None;
    2932            4 :         }
    2933              : 
    2934            4 :         let compaction_threshold = self.get_compaction_threshold();
    2935            4 :         let tenant_conf = self.tenant_conf.load();
    2936            4 :         let l0_flush_delay_threshold = tenant_conf
    2937            4 :             .tenant_conf
    2938            4 :             .l0_flush_delay_threshold
    2939            4 :             .or(self.conf.default_tenant_conf.l0_flush_delay_threshold)
    2940            4 :             .unwrap_or(DEFAULT_L0_FLUSH_DELAY_FACTOR * compaction_threshold);
    2941              : 
    2942              :         // 0 disables backpressure.
    2943            4 :         if l0_flush_delay_threshold == 0 {
    2944            0 :             return None;
    2945            4 :         }
    2946              : 
    2947              :         // Clamp the flush delay threshold to the compaction threshold; it doesn't make sense to
    2948              :         // backpressure flushes below this.
    2949              :         // TODO: the tenant config should have validation to prevent this instead.
    2950            4 :         debug_assert!(l0_flush_delay_threshold >= compaction_threshold);
    2951            4 :         Some(max(l0_flush_delay_threshold, compaction_threshold))
    2952          636 :     }
    2953              : 
    2954          637 :     fn get_l0_flush_stall_threshold(&self) -> Option<usize> {
    2955              :         // Disable L0 stalls by default. Stalling can cause unavailability if L0 compaction isn't
    2956              :         // responsive, and it can e.g. block on other compaction via the compaction semaphore or
    2957              :         // sibling timelines. We need more confidence before enabling this.
    2958              :         const DEFAULT_L0_FLUSH_STALL_FACTOR: usize = 0; // TODO: default to e.g. 5
    2959              : 
    2960              :         // If compaction is disabled, don't stall.
    2961          637 :         if self.get_compaction_period() == Duration::ZERO {
    2962          632 :             return None;
    2963            5 :         }
    2964              : 
    2965              :         // If compaction is failing, don't stall and try to keep the tenant alive. This may not be a
    2966              :         // good idea: read amp can grow unbounded, leading to terrible performance, and we may take
    2967              :         // on unbounded compaction debt that can take a long time to fix once compaction comes back
    2968              :         // online. At least we'll delay flushes, slowing down the growth and buying some time.
    2969            5 :         if self.compaction_failed.load(AtomicOrdering::Relaxed) {
    2970            0 :             return None;
    2971            5 :         }
    2972              : 
    2973            5 :         let compaction_threshold = self.get_compaction_threshold();
    2974            5 :         let tenant_conf = self.tenant_conf.load();
    2975            5 :         let l0_flush_stall_threshold = tenant_conf
    2976            5 :             .tenant_conf
    2977            5 :             .l0_flush_stall_threshold
    2978            5 :             .or(self.conf.default_tenant_conf.l0_flush_stall_threshold);
    2979              : 
    2980              :         // Tests sometimes set compaction_threshold=1 to generate lots of layer files, and don't
    2981              :         // handle the 20-second compaction delay. Some (e.g. `test_backward_compatibility`) can't
    2982              :         // easily adjust the L0 backpressure settings, so just disable stalls in this case.
    2983            5 :         if cfg!(feature = "testing")
    2984            5 :             && compaction_threshold == 1
    2985            0 :             && l0_flush_stall_threshold.is_none()
    2986              :         {
    2987            0 :             return None;
    2988            5 :         }
    2989              : 
    2990            5 :         let l0_flush_stall_threshold = l0_flush_stall_threshold
    2991            5 :             .unwrap_or(DEFAULT_L0_FLUSH_STALL_FACTOR * compaction_threshold);
    2992              : 
    2993              :         // 0 disables backpressure.
    2994            5 :         if l0_flush_stall_threshold == 0 {
    2995            5 :             return None;
    2996            0 :         }
    2997              : 
    2998              :         // Clamp the flush stall threshold to the compaction threshold; it doesn't make sense to
    2999              :         // backpressure flushes below this.
    3000              :         // TODO: the tenant config should have validation to prevent this instead.
    3001            0 :         debug_assert!(l0_flush_stall_threshold >= compaction_threshold);
    3002            0 :         Some(max(l0_flush_stall_threshold, compaction_threshold))
    3003          637 :     }
    3004              : 
    3005           57 :     fn get_image_creation_threshold(&self) -> usize {
    3006           57 :         let tenant_conf = self.tenant_conf.load();
    3007           57 :         tenant_conf
    3008           57 :             .tenant_conf
    3009           57 :             .image_creation_threshold
    3010           57 :             .unwrap_or(self.conf.default_tenant_conf.image_creation_threshold)
    3011           57 :     }
    3012              : 
    3013              :     // HADRON
    3014          193 :     fn get_image_layer_force_creation_period(&self) -> Option<Duration> {
    3015          193 :         let tenant_conf = self.tenant_conf.load();
    3016          193 :         tenant_conf
    3017          193 :             .tenant_conf
    3018          193 :             .image_layer_force_creation_period
    3019          193 :             .or(self
    3020          193 :                 .conf
    3021          193 :                 .default_tenant_conf
    3022          193 :                 .image_layer_force_creation_period)
    3023          193 :     }
    3024              : 
    3025          192 :     fn get_compaction_algorithm_settings(&self) -> CompactionAlgorithmSettings {
    3026          192 :         let tenant_conf = &self.tenant_conf.load();
    3027          192 :         tenant_conf
    3028          192 :             .tenant_conf
    3029          192 :             .compaction_algorithm
    3030          192 :             .as_ref()
    3031          192 :             .unwrap_or(&self.conf.default_tenant_conf.compaction_algorithm)
    3032          192 :             .clone()
    3033          192 :     }
    3034              : 
    3035          192 :     pub fn get_compaction_shard_ancestor(&self) -> bool {
    3036          192 :         let tenant_conf = self.tenant_conf.load();
    3037          192 :         tenant_conf
    3038          192 :             .tenant_conf
    3039          192 :             .compaction_shard_ancestor
    3040          192 :             .unwrap_or(self.conf.default_tenant_conf.compaction_shard_ancestor)
    3041          192 :     }
    3042              : 
    3043            0 :     fn get_eviction_policy(&self) -> EvictionPolicy {
    3044            0 :         let tenant_conf = self.tenant_conf.load();
    3045            0 :         tenant_conf
    3046            0 :             .tenant_conf
    3047            0 :             .eviction_policy
    3048            0 :             .unwrap_or(self.conf.default_tenant_conf.eviction_policy)
    3049            0 :     }
    3050              : 
    3051          235 :     fn get_evictions_low_residence_duration_metric_threshold(
    3052          235 :         tenant_conf: &pageserver_api::models::TenantConfig,
    3053          235 :         default_tenant_conf: &pageserver_api::config::TenantConfigToml,
    3054          235 :     ) -> Duration {
    3055          235 :         tenant_conf
    3056          235 :             .evictions_low_residence_duration_metric_threshold
    3057          235 :             .unwrap_or(default_tenant_conf.evictions_low_residence_duration_metric_threshold)
    3058          235 :     }
    3059              : 
    3060          191 :     fn get_image_layer_creation_check_threshold(&self) -> u8 {
    3061          191 :         let tenant_conf = self.tenant_conf.load();
    3062          191 :         tenant_conf
    3063          191 :             .tenant_conf
    3064          191 :             .image_layer_creation_check_threshold
    3065          191 :             .unwrap_or(
    3066          191 :                 self.conf
    3067          191 :                     .default_tenant_conf
    3068          191 :                     .image_layer_creation_check_threshold,
    3069              :             )
    3070          191 :     }
    3071              : 
    3072           27 :     fn get_gc_compaction_settings(&self) -> GcCompactionCombinedSettings {
    3073           27 :         let tenant_conf = &self.tenant_conf.load();
    3074           27 :         let gc_compaction_enabled = tenant_conf
    3075           27 :             .tenant_conf
    3076           27 :             .gc_compaction_enabled
    3077           27 :             .unwrap_or(self.conf.default_tenant_conf.gc_compaction_enabled);
    3078           27 :         let gc_compaction_verification = tenant_conf
    3079           27 :             .tenant_conf
    3080           27 :             .gc_compaction_verification
    3081           27 :             .unwrap_or(self.conf.default_tenant_conf.gc_compaction_verification);
    3082           27 :         let gc_compaction_initial_threshold_kb = tenant_conf
    3083           27 :             .tenant_conf
    3084           27 :             .gc_compaction_initial_threshold_kb
    3085           27 :             .unwrap_or(
    3086           27 :                 self.conf
    3087           27 :                     .default_tenant_conf
    3088           27 :                     .gc_compaction_initial_threshold_kb,
    3089              :             );
    3090           27 :         let gc_compaction_ratio_percent = tenant_conf
    3091           27 :             .tenant_conf
    3092           27 :             .gc_compaction_ratio_percent
    3093           27 :             .unwrap_or(self.conf.default_tenant_conf.gc_compaction_ratio_percent);
    3094           27 :         GcCompactionCombinedSettings {
    3095           27 :             gc_compaction_enabled,
    3096           27 :             gc_compaction_verification,
    3097           27 :             gc_compaction_initial_threshold_kb,
    3098           27 :             gc_compaction_ratio_percent,
    3099           27 :         }
    3100           27 :     }
    3101              : 
    3102            0 :     fn get_image_creation_preempt_threshold(&self) -> usize {
    3103            0 :         let tenant_conf = self.tenant_conf.load();
    3104            0 :         tenant_conf
    3105            0 :             .tenant_conf
    3106            0 :             .image_creation_preempt_threshold
    3107            0 :             .unwrap_or(
    3108            0 :                 self.conf
    3109            0 :                     .default_tenant_conf
    3110            0 :                     .image_creation_preempt_threshold,
    3111              :             )
    3112            0 :     }
    3113              : 
    3114            0 :     pub(super) fn tenant_conf_updated(&self, new_conf: &AttachedTenantConf) {
    3115              :         // NB: Most tenant conf options are read by background loops, so,
    3116              :         // changes will automatically be picked up.
    3117              : 
    3118              :         // The threshold is embedded in the metric. So, we need to update it.
    3119              :         {
    3120            0 :             let new_threshold = Self::get_evictions_low_residence_duration_metric_threshold(
    3121            0 :                 &new_conf.tenant_conf,
    3122            0 :                 &self.conf.default_tenant_conf,
    3123              :             );
    3124              : 
    3125            0 :             let tenant_id_str = self.tenant_shard_id.tenant_id.to_string();
    3126            0 :             let shard_id_str = format!("{}", self.tenant_shard_id.shard_slug());
    3127              : 
    3128            0 :             let timeline_id_str = self.timeline_id.to_string();
    3129              : 
    3130            0 :             self.remote_client.update_config(&new_conf.location);
    3131              : 
    3132            0 :             let mut rel_size_cache = self.rel_size_snapshot_cache.lock().unwrap();
    3133            0 :             if let Some(new_capacity) = new_conf.tenant_conf.relsize_snapshot_cache_capacity {
    3134            0 :                 if new_capacity != rel_size_cache.capacity() {
    3135            0 :                     rel_size_cache.set_capacity(new_capacity);
    3136            0 :                 }
    3137            0 :             }
    3138              : 
    3139            0 :             self.metrics
    3140            0 :                 .evictions_with_low_residence_duration
    3141            0 :                 .write()
    3142            0 :                 .unwrap()
    3143            0 :                 .change_threshold(
    3144            0 :                     &tenant_id_str,
    3145            0 :                     &shard_id_str,
    3146            0 :                     &timeline_id_str,
    3147            0 :                     new_threshold,
    3148            0 :                 );
    3149              :         }
    3150            0 :     }
    3151              : 
    3152              :     /// Open a Timeline handle.
    3153              :     ///
    3154              :     /// Loads the metadata for the timeline into memory, but not the layer map.
    3155              :     #[allow(clippy::too_many_arguments)]
    3156          235 :     pub(super) fn new(
    3157          235 :         conf: &'static PageServerConf,
    3158          235 :         tenant_conf: Arc<ArcSwap<AttachedTenantConf>>,
    3159          235 :         metadata: &TimelineMetadata,
    3160          235 :         previous_heatmap: Option<PreviousHeatmap>,
    3161          235 :         ancestor: Option<Arc<Timeline>>,
    3162          235 :         timeline_id: TimelineId,
    3163          235 :         tenant_shard_id: TenantShardId,
    3164          235 :         generation: Generation,
    3165          235 :         shard_identity: ShardIdentity,
    3166          235 :         walredo_mgr: Option<Arc<super::WalRedoManager>>,
    3167          235 :         resources: TimelineResources,
    3168          235 :         pg_version: PgMajorVersion,
    3169          235 :         state: TimelineState,
    3170          235 :         attach_wal_lag_cooldown: Arc<OnceLock<WalLagCooldown>>,
    3171          235 :         create_idempotency: crate::tenant::CreateTimelineIdempotency,
    3172          235 :         gc_compaction_state: Option<GcCompactionState>,
    3173          235 :         rel_size_v2_status: Option<RelSizeMigration>,
    3174          235 :         rel_size_migrated_at: Option<Lsn>,
    3175          235 :         cancel: CancellationToken,
    3176          235 :     ) -> Arc<Self> {
    3177          235 :         let disk_consistent_lsn = metadata.disk_consistent_lsn();
    3178          235 :         let (state, _) = watch::channel(state);
    3179              : 
    3180          235 :         let (layer_flush_start_tx, _) = tokio::sync::watch::channel((0, disk_consistent_lsn));
    3181          235 :         let (layer_flush_done_tx, _) = tokio::sync::watch::channel((0, Ok(())));
    3182              : 
    3183          235 :         let evictions_low_residence_duration_metric_threshold = {
    3184          235 :             let loaded_tenant_conf = tenant_conf.load();
    3185          235 :             Self::get_evictions_low_residence_duration_metric_threshold(
    3186          235 :                 &loaded_tenant_conf.tenant_conf,
    3187          235 :                 &conf.default_tenant_conf,
    3188              :             )
    3189              :         };
    3190              : 
    3191          235 :         if let Some(ancestor) = &ancestor {
    3192          118 :             let mut ancestor_gc_info = ancestor.gc_info.write().unwrap();
    3193          118 :             // If we construct an explicit timeline object, it's obviously not offloaded
    3194          118 :             let is_offloaded = MaybeOffloaded::No;
    3195          118 :             ancestor_gc_info.insert_child(timeline_id, metadata.ancestor_lsn(), is_offloaded);
    3196          118 :         }
    3197              : 
    3198          235 :         let relsize_snapshot_cache_capacity = {
    3199          235 :             let loaded_tenant_conf = tenant_conf.load();
    3200          235 :             loaded_tenant_conf
    3201          235 :                 .tenant_conf
    3202          235 :                 .relsize_snapshot_cache_capacity
    3203          235 :                 .unwrap_or(conf.default_tenant_conf.relsize_snapshot_cache_capacity)
    3204              :         };
    3205              : 
    3206          235 :         Arc::new_cyclic(|myself| {
    3207          235 :             let metrics = Arc::new(TimelineMetrics::new(
    3208          235 :                 &tenant_shard_id,
    3209          235 :                 &timeline_id,
    3210          235 :                 crate::metrics::EvictionsWithLowResidenceDurationBuilder::new(
    3211              :                     "mtime",
    3212          235 :                     evictions_low_residence_duration_metric_threshold,
    3213              :                 ),
    3214              :             ));
    3215          235 :             let aux_file_metrics = metrics.aux_file_size_gauge.clone();
    3216              : 
    3217          235 :             let mut result = Timeline {
    3218          235 :                 conf,
    3219          235 :                 tenant_conf,
    3220          235 :                 myself: myself.clone(),
    3221          235 :                 timeline_id,
    3222          235 :                 tenant_shard_id,
    3223          235 :                 generation,
    3224          235 :                 shard_identity,
    3225          235 :                 pg_version,
    3226          235 :                 layers: Default::default(),
    3227          235 :                 gc_compaction_layer_update_lock: tokio::sync::RwLock::new(()),
    3228              : 
    3229          235 :                 walredo_mgr,
    3230          235 :                 walreceiver: Mutex::new(None),
    3231              : 
    3232          235 :                 remote_client: Arc::new(resources.remote_client),
    3233              : 
    3234              :                 // initialize in-memory 'last_record_lsn' from 'disk_consistent_lsn'.
    3235          235 :                 last_record_lsn: SeqWait::new(RecordLsn {
    3236          235 :                     last: disk_consistent_lsn,
    3237          235 :                     prev: metadata.prev_record_lsn().unwrap_or(Lsn(0)),
    3238          235 :                 }),
    3239          235 :                 disk_consistent_lsn: AtomicLsn::new(disk_consistent_lsn.0),
    3240              : 
    3241          235 :                 gc_compaction_state: ArcSwapOption::from_pointee(gc_compaction_state),
    3242              : 
    3243          235 :                 last_freeze_at: AtomicLsn::new(disk_consistent_lsn.0),
    3244          235 :                 last_freeze_ts: RwLock::new(Instant::now()),
    3245              : 
    3246          235 :                 loaded_at: (disk_consistent_lsn, SystemTime::now()),
    3247              : 
    3248          235 :                 ancestor_timeline: ancestor,
    3249          235 :                 ancestor_lsn: metadata.ancestor_lsn(),
    3250              : 
    3251          235 :                 metrics,
    3252              : 
    3253          235 :                 query_metrics: crate::metrics::SmgrQueryTimePerTimeline::new(
    3254          235 :                     &tenant_shard_id,
    3255          235 :                     &timeline_id,
    3256          235 :                     resources.pagestream_throttle_metrics,
    3257              :                 ),
    3258              : 
    3259         1880 :                 directory_metrics: array::from_fn(|_| AtomicU64::new(0)),
    3260         1880 :                 directory_metrics_inited: array::from_fn(|_| AtomicBool::new(false)),
    3261              : 
    3262          235 :                 flush_loop_state: Mutex::new(FlushLoopState::NotStarted),
    3263              : 
    3264          235 :                 layer_flush_start_tx,
    3265          235 :                 layer_flush_done_tx,
    3266              : 
    3267          235 :                 write_lock: tokio::sync::Mutex::new(None),
    3268              : 
    3269          235 :                 gc_info: std::sync::RwLock::new(GcInfo::default()),
    3270              : 
    3271          235 :                 last_image_layer_creation_status: ArcSwap::new(Arc::new(
    3272          235 :                     LastImageLayerCreationStatus::default(),
    3273              :                 )),
    3274              : 
    3275          235 :                 applied_gc_cutoff_lsn: Rcu::new(metadata.latest_gc_cutoff_lsn()),
    3276          235 :                 initdb_lsn: metadata.initdb_lsn(),
    3277              : 
    3278          235 :                 current_logical_size: if disk_consistent_lsn.is_valid() {
    3279              :                     // we're creating timeline data with some layer files existing locally,
    3280              :                     // need to recalculate timeline's logical size based on data in the layers.
    3281          120 :                     LogicalSize::deferred_initial(disk_consistent_lsn)
    3282              :                 } else {
    3283              :                     // we're creating timeline data without any layers existing locally,
    3284              :                     // initial logical size is 0.
    3285          115 :                     LogicalSize::empty_initial()
    3286              :                 },
    3287              : 
    3288          235 :                 partitioning: GuardArcSwap::new((
    3289          235 :                     (KeyPartitioning::new(), KeyPartitioning::new().into_sparse()),
    3290          235 :                     Lsn(0),
    3291          235 :                 )),
    3292              :                 repartition_threshold: 0,
    3293          235 :                 last_image_layer_creation_check_at: AtomicLsn::new(0),
    3294          235 :                 last_image_layer_creation_check_instant: Mutex::new(None),
    3295          235 :                 last_received_wal: Mutex::new(None),
    3296          235 :                 rel_size_latest_cache: RwLock::new(HashMap::new()),
    3297          235 :                 rel_size_snapshot_cache: Mutex::new(LruCache::new(relsize_snapshot_cache_capacity)),
    3298              : 
    3299          235 :                 download_all_remote_layers_task_info: RwLock::new(None),
    3300              : 
    3301          235 :                 state,
    3302              : 
    3303          235 :                 eviction_task_timeline_state: tokio::sync::Mutex::new(
    3304          235 :                     EvictionTaskTimelineState::default(),
    3305              :                 ),
    3306          235 :                 delete_progress: TimelineDeleteProgress::default(),
    3307              : 
    3308          235 :                 cancel,
    3309          235 :                 gate: Gate::default(),
    3310              : 
    3311          235 :                 compaction_lock: tokio::sync::Mutex::default(),
    3312          235 :                 compaction_failed: AtomicBool::default(),
    3313          235 :                 l0_compaction_trigger: resources.l0_compaction_trigger,
    3314          235 :                 gc_lock: tokio::sync::Mutex::default(),
    3315              : 
    3316          235 :                 standby_horizon: AtomicLsn::new(0),
    3317              : 
    3318          235 :                 pagestream_throttle: resources.pagestream_throttle,
    3319              : 
    3320          235 :                 aux_file_size_estimator: AuxFileSizeEstimator::new(aux_file_metrics),
    3321              : 
    3322              :                 #[cfg(test)]
    3323          235 :                 extra_test_dense_keyspace: ArcSwap::new(Arc::new(KeySpace::default())),
    3324              : 
    3325          235 :                 l0_flush_global_state: resources.l0_flush_global_state,
    3326              : 
    3327          235 :                 handles: Default::default(),
    3328              : 
    3329          235 :                 attach_wal_lag_cooldown,
    3330              : 
    3331          235 :                 create_idempotency,
    3332              : 
    3333          235 :                 page_trace: Default::default(),
    3334              : 
    3335          235 :                 previous_heatmap: ArcSwapOption::from_pointee(previous_heatmap),
    3336              : 
    3337          235 :                 heatmap_layers_downloader: Mutex::new(None),
    3338              : 
    3339          235 :                 rel_size_v2_status: ArcSwap::from_pointee((
    3340          235 :                     rel_size_v2_status,
    3341          235 :                     rel_size_migrated_at,
    3342          235 :                 )),
    3343              : 
    3344          235 :                 wait_lsn_log_slow: tokio::sync::Semaphore::new(1),
    3345              : 
    3346          235 :                 basebackup_cache: resources.basebackup_cache,
    3347              : 
    3348          235 :                 feature_resolver: resources.feature_resolver.clone(),
    3349              : 
    3350          235 :                 db_rel_count: ArcSwapOption::from_pointee(None),
    3351              :             };
    3352              : 
    3353          235 :             result.repartition_threshold =
    3354          235 :                 result.get_checkpoint_distance() / REPARTITION_FREQ_IN_CHECKPOINT_DISTANCE;
    3355              : 
    3356          235 :             result
    3357          235 :                 .metrics
    3358          235 :                 .last_record_lsn_gauge
    3359          235 :                 .set(disk_consistent_lsn.0 as i64);
    3360          235 :             result
    3361          235 :         })
    3362          235 :     }
    3363              : 
    3364          343 :     pub(super) fn maybe_spawn_flush_loop(self: &Arc<Self>) {
    3365          343 :         let Ok(guard) = self.gate.enter() else {
    3366            0 :             info!("cannot start flush loop when the timeline gate has already been closed");
    3367            0 :             return;
    3368              :         };
    3369          343 :         let mut flush_loop_state = self.flush_loop_state.lock().unwrap();
    3370          343 :         match *flush_loop_state {
    3371          232 :             FlushLoopState::NotStarted => (),
    3372              :             FlushLoopState::Running { .. } => {
    3373          111 :                 info!(
    3374            0 :                     "skipping attempt to start flush_loop twice {}/{}",
    3375            0 :                     self.tenant_shard_id, self.timeline_id
    3376              :                 );
    3377          111 :                 return;
    3378              :             }
    3379              :             FlushLoopState::Exited => {
    3380            0 :                 info!(
    3381            0 :                     "ignoring attempt to restart exited flush_loop {}/{}",
    3382            0 :                     self.tenant_shard_id, self.timeline_id
    3383              :                 );
    3384            0 :                 return;
    3385              :             }
    3386              :         }
    3387              : 
    3388          232 :         let layer_flush_start_rx = self.layer_flush_start_tx.subscribe();
    3389          232 :         let self_clone = Arc::clone(self);
    3390              : 
    3391          232 :         debug!("spawning flush loop");
    3392          232 :         *flush_loop_state = FlushLoopState::Running {
    3393          232 :             #[cfg(test)]
    3394          232 :             expect_initdb_optimization: false,
    3395          232 :             #[cfg(test)]
    3396          232 :             initdb_optimization_count: 0,
    3397          232 :         };
    3398          232 :         task_mgr::spawn(
    3399          232 :             task_mgr::BACKGROUND_RUNTIME.handle(),
    3400          232 :             task_mgr::TaskKind::LayerFlushTask,
    3401          232 :             self.tenant_shard_id,
    3402          232 :             Some(self.timeline_id),
    3403          232 :             "layer flush task",
    3404          232 :             async move {
    3405          232 :                 let _guard = guard;
    3406          232 :                 let background_ctx = RequestContext::todo_child(TaskKind::LayerFlushTask, DownloadBehavior::Error).with_scope_timeline(&self_clone);
    3407          232 :                 self_clone.flush_loop(layer_flush_start_rx, &background_ctx).await;
    3408            5 :                 let mut flush_loop_state = self_clone.flush_loop_state.lock().unwrap();
    3409            5 :                 assert!(matches!(*flush_loop_state, FlushLoopState::Running{..}));
    3410            5 :                 *flush_loop_state  = FlushLoopState::Exited;
    3411            5 :                 Ok(())
    3412            5 :             }
    3413          232 :             .instrument(info_span!(parent: None, "layer flush task", tenant_id = %self.tenant_shard_id.tenant_id, shard_id = %self.tenant_shard_id.shard_slug(), timeline_id = %self.timeline_id))
    3414              :         );
    3415          343 :     }
    3416              : 
    3417            0 :     pub(crate) fn update_gc_compaction_state(
    3418            0 :         &self,
    3419            0 :         gc_compaction_state: GcCompactionState,
    3420            0 :     ) -> anyhow::Result<()> {
    3421            0 :         self.gc_compaction_state
    3422            0 :             .store(Some(Arc::new(gc_compaction_state.clone())));
    3423            0 :         self.remote_client
    3424            0 :             .schedule_index_upload_for_gc_compaction_state_update(gc_compaction_state)
    3425            0 :     }
    3426              : 
    3427            0 :     pub(crate) fn update_rel_size_v2_status(
    3428            0 :         &self,
    3429            0 :         rel_size_v2_status: RelSizeMigration,
    3430            0 :         rel_size_migrated_at: Option<Lsn>,
    3431            0 :     ) -> anyhow::Result<()> {
    3432            0 :         self.rel_size_v2_status.store(Arc::new((
    3433            0 :             Some(rel_size_v2_status.clone()),
    3434            0 :             rel_size_migrated_at,
    3435            0 :         )));
    3436            0 :         self.remote_client
    3437            0 :             .schedule_index_upload_for_rel_size_v2_status_update(
    3438            0 :                 rel_size_v2_status,
    3439            0 :                 rel_size_migrated_at,
    3440              :             )
    3441            0 :     }
    3442              : 
    3443            0 :     pub(crate) fn get_gc_compaction_state(&self) -> Option<GcCompactionState> {
    3444            0 :         self.gc_compaction_state
    3445            0 :             .load()
    3446            0 :             .as_ref()
    3447            0 :             .map(|x| x.as_ref().clone())
    3448            0 :     }
    3449              : 
    3450              :     /// Creates and starts the wal receiver.
    3451              :     ///
    3452              :     /// This function is expected to be called at most once per Timeline's lifecycle
    3453              :     /// when the timeline is activated.
    3454            0 :     fn launch_wal_receiver(
    3455            0 :         self: &Arc<Self>,
    3456            0 :         ctx: &RequestContext,
    3457            0 :         broker_client: BrokerClientChannel,
    3458            0 :     ) {
    3459            0 :         info!(
    3460            0 :             "launching WAL receiver for timeline {} of tenant {}",
    3461            0 :             self.timeline_id, self.tenant_shard_id
    3462              :         );
    3463              : 
    3464            0 :         let tenant_conf = self.tenant_conf.load();
    3465            0 :         let wal_connect_timeout = tenant_conf
    3466            0 :             .tenant_conf
    3467            0 :             .walreceiver_connect_timeout
    3468            0 :             .unwrap_or(self.conf.default_tenant_conf.walreceiver_connect_timeout);
    3469            0 :         let lagging_wal_timeout = tenant_conf
    3470            0 :             .tenant_conf
    3471            0 :             .lagging_wal_timeout
    3472            0 :             .unwrap_or(self.conf.default_tenant_conf.lagging_wal_timeout);
    3473            0 :         let max_lsn_wal_lag = tenant_conf
    3474            0 :             .tenant_conf
    3475            0 :             .max_lsn_wal_lag
    3476            0 :             .unwrap_or(self.conf.default_tenant_conf.max_lsn_wal_lag);
    3477              : 
    3478            0 :         let mut guard = self.walreceiver.lock().unwrap();
    3479            0 :         assert!(
    3480            0 :             guard.is_none(),
    3481            0 :             "multiple launches / re-launches of WAL receiver are not supported"
    3482              :         );
    3483              : 
    3484            0 :         let protocol = PostgresClientProtocol::Interpreted {
    3485            0 :             format: utils::postgres_client::InterpretedFormat::Protobuf,
    3486            0 :             compression: Some(utils::postgres_client::Compression::Zstd { level: 1 }),
    3487            0 :         };
    3488              : 
    3489            0 :         *guard = Some(WalReceiver::start(
    3490            0 :             Arc::clone(self),
    3491            0 :             WalReceiverConf {
    3492            0 :                 protocol,
    3493            0 :                 wal_connect_timeout,
    3494            0 :                 lagging_wal_timeout,
    3495            0 :                 max_lsn_wal_lag,
    3496            0 :                 auth_token: crate::config::SAFEKEEPER_AUTH_TOKEN.get().cloned(),
    3497            0 :                 availability_zone: self.conf.availability_zone.clone(),
    3498            0 :                 ingest_batch_size: self.conf.ingest_batch_size,
    3499            0 :                 validate_wal_contiguity: self.conf.validate_wal_contiguity,
    3500            0 :             },
    3501            0 :             broker_client,
    3502            0 :             ctx,
    3503            0 :         ));
    3504            0 :     }
    3505              : 
    3506              :     /// Initialize with an empty layer map. Used when creating a new timeline.
    3507          232 :     pub(super) fn init_empty_layer_map(&self, start_lsn: Lsn) {
    3508          232 :         let mut layers = self.layers.try_write(LayerManagerLockHolder::Init).expect(
    3509          232 :             "in the context where we call this function, no other task has access to the object",
    3510              :         );
    3511          232 :         layers
    3512          232 :             .open_mut()
    3513          232 :             .expect("in this context the LayerManager must still be open")
    3514          232 :             .initialize_empty(Lsn(start_lsn.0));
    3515          232 :     }
    3516              : 
    3517              :     /// Scan the timeline directory, cleanup, populate the layer map, and schedule uploads for local-only
    3518              :     /// files.
    3519            3 :     pub(super) async fn load_layer_map(
    3520            3 :         &self,
    3521            3 :         disk_consistent_lsn: Lsn,
    3522            3 :         index_part: IndexPart,
    3523            3 :     ) -> anyhow::Result<()> {
    3524              :         use LayerName::*;
    3525              :         use init::Decision::*;
    3526              :         use init::{Discovered, DismissedLayer};
    3527              : 
    3528            3 :         let mut guard = self
    3529            3 :             .layers
    3530            3 :             .write(LayerManagerLockHolder::LoadLayerMap)
    3531            3 :             .await;
    3532              : 
    3533            3 :         let timer = self.metrics.load_layer_map_histo.start_timer();
    3534              : 
    3535              :         // Scan timeline directory and create ImageLayerName and DeltaFilename
    3536              :         // structs representing all files on disk
    3537            3 :         let timeline_path = self
    3538            3 :             .conf
    3539            3 :             .timeline_path(&self.tenant_shard_id, &self.timeline_id);
    3540            3 :         let conf = self.conf;
    3541            3 :         let span = tracing::Span::current();
    3542              : 
    3543              :         // Copy to move into the task we're about to spawn
    3544            3 :         let this = self.myself.upgrade().expect("&self method holds the arc");
    3545              : 
    3546            3 :         let (loaded_layers, needs_cleanup, total_physical_size) = tokio::task::spawn_blocking({
    3547            3 :             move || {
    3548            3 :                 let _g = span.entered();
    3549            3 :                 let discovered = init::scan_timeline_dir(&timeline_path)?;
    3550            3 :                 let mut discovered_layers = Vec::with_capacity(discovered.len());
    3551            3 :                 let mut unrecognized_files = Vec::new();
    3552              : 
    3553            3 :                 let mut path = timeline_path;
    3554              : 
    3555           11 :                 for discovered in discovered {
    3556            8 :                     let (name, kind) = match discovered {
    3557            8 :                         Discovered::Layer(layer_file_name, local_metadata) => {
    3558            8 :                             discovered_layers.push((layer_file_name, local_metadata));
    3559            8 :                             continue;
    3560              :                         }
    3561            0 :                         Discovered::IgnoredBackup(path) => {
    3562            0 :                             std::fs::remove_file(path)
    3563            0 :                                 .or_else(fs_ext::ignore_not_found)
    3564            0 :                                 .fatal_err("Removing .old file");
    3565            0 :                             continue;
    3566              :                         }
    3567            0 :                         Discovered::Unknown(file_name) => {
    3568              :                             // we will later error if there are any
    3569            0 :                             unrecognized_files.push(file_name);
    3570            0 :                             continue;
    3571              :                         }
    3572            0 :                         Discovered::Ephemeral(name) => (name, "old ephemeral file"),
    3573            0 :                         Discovered::Temporary(name) => (name, "temporary timeline file"),
    3574            0 :                         Discovered::TemporaryDownload(name) => (name, "temporary download"),
    3575              :                     };
    3576            0 :                     path.push(Utf8Path::new(&name));
    3577            0 :                     init::cleanup(&path, kind)?;
    3578            0 :                     path.pop();
    3579              :                 }
    3580              : 
    3581            3 :                 if !unrecognized_files.is_empty() {
    3582              :                     // assume that if there are any there are many many.
    3583            0 :                     let n = unrecognized_files.len();
    3584            0 :                     let first = &unrecognized_files[..n.min(10)];
    3585            0 :                     anyhow::bail!(
    3586            0 :                         "unrecognized files in timeline dir (total {n}), first 10: {first:?}"
    3587              :                     );
    3588            3 :                 }
    3589              : 
    3590            3 :                 let decided = init::reconcile(discovered_layers, &index_part, disk_consistent_lsn);
    3591              : 
    3592            3 :                 let mut loaded_layers = Vec::new();
    3593            3 :                 let mut needs_cleanup = Vec::new();
    3594            3 :                 let mut total_physical_size = 0;
    3595              : 
    3596           11 :                 for (name, decision) in decided {
    3597            8 :                     let decision = match decision {
    3598            8 :                         Ok(decision) => decision,
    3599            0 :                         Err(DismissedLayer::Future { local }) => {
    3600            0 :                             if let Some(local) = local {
    3601            0 :                                 init::cleanup_future_layer(
    3602            0 :                                     &local.local_path,
    3603            0 :                                     &name,
    3604            0 :                                     disk_consistent_lsn,
    3605            0 :                                 )?;
    3606            0 :                             }
    3607            0 :                             needs_cleanup.push(name);
    3608            0 :                             continue;
    3609              :                         }
    3610            0 :                         Err(DismissedLayer::LocalOnly(local)) => {
    3611            0 :                             init::cleanup_local_only_file(&name, &local)?;
    3612              :                             // this file never existed remotely, we will have to do rework
    3613            0 :                             continue;
    3614              :                         }
    3615            0 :                         Err(DismissedLayer::BadMetadata(local)) => {
    3616            0 :                             init::cleanup_local_file_for_remote(&local)?;
    3617              :                             // this file never existed remotely, we will have to do rework
    3618            0 :                             continue;
    3619              :                         }
    3620              :                     };
    3621              : 
    3622            8 :                     match &name {
    3623            6 :                         Delta(d) => assert!(d.lsn_range.end <= disk_consistent_lsn + 1),
    3624            2 :                         Image(i) => assert!(i.lsn <= disk_consistent_lsn),
    3625              :                     }
    3626              : 
    3627            8 :                     tracing::debug!(layer=%name, ?decision, "applied");
    3628              : 
    3629            8 :                     let layer = match decision {
    3630            8 :                         Resident { local, remote } => {
    3631            8 :                             total_physical_size += local.file_size;
    3632            8 :                             Layer::for_resident(conf, &this, local.local_path, name, remote)
    3633            8 :                                 .drop_eviction_guard()
    3634              :                         }
    3635            0 :                         Evicted(remote) => Layer::for_evicted(conf, &this, name, remote),
    3636              :                     };
    3637              : 
    3638            8 :                     loaded_layers.push(layer);
    3639              :                 }
    3640            3 :                 Ok((loaded_layers, needs_cleanup, total_physical_size))
    3641            3 :             }
    3642              :         })
    3643            3 :         .await
    3644            3 :         .map_err(anyhow::Error::new)
    3645            3 :         .and_then(|x| x)?;
    3646              : 
    3647            3 :         let num_layers = loaded_layers.len();
    3648              : 
    3649            3 :         guard
    3650            3 :             .open_mut()
    3651            3 :             .expect("layermanager must be open during init")
    3652            3 :             .initialize_local_layers(loaded_layers, disk_consistent_lsn + 1);
    3653              : 
    3654            3 :         self.remote_client
    3655            3 :             .schedule_layer_file_deletion(&needs_cleanup)?;
    3656            3 :         self.remote_client
    3657            3 :             .schedule_index_upload_for_file_changes()?;
    3658              :         // This barrier orders above DELETEs before any later operations.
    3659              :         // This is critical because code executing after the barrier might
    3660              :         // create again objects with the same key that we just scheduled for deletion.
    3661              :         // For example, if we just scheduled deletion of an image layer "from the future",
    3662              :         // later compaction might run again and re-create the same image layer.
    3663              :         // "from the future" here means an image layer whose LSN is > IndexPart::disk_consistent_lsn.
    3664              :         // "same" here means same key range and LSN.
    3665              :         //
    3666              :         // Without a barrier between above DELETEs and the re-creation's PUTs,
    3667              :         // the upload queue may execute the PUT first, then the DELETE.
    3668              :         // In our example, we will end up with an IndexPart referencing a non-existent object.
    3669              :         //
    3670              :         // 1. a future image layer is created and uploaded
    3671              :         // 2. ps restart
    3672              :         // 3. the future layer from (1) is deleted during load layer map
    3673              :         // 4. image layer is re-created and uploaded
    3674              :         // 5. deletion queue would like to delete (1) but actually deletes (4)
    3675              :         // 6. delete by name works as expected, but it now deletes the wrong (later) version
    3676              :         //
    3677              :         // See https://github.com/neondatabase/neon/issues/5878
    3678              :         //
    3679              :         // NB: generation numbers naturally protect against this because they disambiguate
    3680              :         //     (1) and (4)
    3681              :         // TODO: this is basically a no-op now, should we remove it?
    3682            3 :         self.remote_client.schedule_barrier()?;
    3683              :         // TenantShard::create_timeline will wait for these uploads to happen before returning, or
    3684              :         // on retry.
    3685              : 
    3686            3 :         info!(
    3687            0 :             "loaded layer map with {} layers at {}, total physical size: {}",
    3688              :             num_layers, disk_consistent_lsn, total_physical_size
    3689              :         );
    3690              : 
    3691            3 :         timer.stop_and_record();
    3692            3 :         Ok(())
    3693            3 :     }
    3694              : 
    3695              :     /// Retrieve current logical size of the timeline.
    3696              :     ///
    3697              :     /// The size could be lagging behind the actual number, in case
    3698              :     /// the initial size calculation has not been run (gets triggered on the first size access).
    3699              :     ///
    3700              :     /// return size and boolean flag that shows if the size is exact
    3701            0 :     pub(crate) fn get_current_logical_size(
    3702            0 :         self: &Arc<Self>,
    3703            0 :         priority: GetLogicalSizePriority,
    3704            0 :         ctx: &RequestContext,
    3705            0 :     ) -> logical_size::CurrentLogicalSize {
    3706            0 :         if !self.tenant_shard_id.is_shard_zero() {
    3707              :             // Logical size is only accurately maintained on shard zero: when called elsewhere, for example
    3708              :             // when HTTP API is serving a GET for timeline zero, return zero
    3709            0 :             return logical_size::CurrentLogicalSize::Approximate(logical_size::Approximate::zero());
    3710            0 :         }
    3711              : 
    3712            0 :         let current_size = self.current_logical_size.current_size();
    3713            0 :         debug!("Current size: {current_size:?}");
    3714              : 
    3715            0 :         match (current_size.accuracy(), priority) {
    3716            0 :             (logical_size::Accuracy::Exact, _) => (), // nothing to do
    3717            0 :             (logical_size::Accuracy::Approximate, GetLogicalSizePriority::Background) => {
    3718            0 :                 // background task will eventually deliver an exact value, we're in no rush
    3719            0 :             }
    3720              :             (logical_size::Accuracy::Approximate, GetLogicalSizePriority::User) => {
    3721              :                 // background task is not ready, but user is asking for it now;
    3722              :                 // => make the background task skip the line
    3723              :                 // (The alternative would be to calculate the size here, but,
    3724              :                 //  it can actually take a long time if the user has a lot of rels.
    3725              :                 //  And we'll inevitable need it again; So, let the background task do the work.)
    3726            0 :                 match self
    3727            0 :                     .current_logical_size
    3728            0 :                     .cancel_wait_for_background_loop_concurrency_limit_semaphore
    3729            0 :                     .get()
    3730              :                 {
    3731            0 :                     Some(cancel) => cancel.cancel(),
    3732              :                     None => {
    3733            0 :                         match self.current_state() {
    3734            0 :                             TimelineState::Broken { .. } | TimelineState::Stopping => {
    3735            0 :                                 // Can happen when timeline detail endpoint is used when deletion is ongoing (or its broken).
    3736            0 :                                 // Don't make noise.
    3737            0 :                             }
    3738              :                             TimelineState::Loading => {
    3739              :                                 // Import does not return an activated timeline.
    3740            0 :                                 info!(
    3741            0 :                                     "discarding priority boost for logical size calculation because timeline is not yet active"
    3742              :                                 );
    3743              :                             }
    3744              :                             TimelineState::Active => {
    3745              :                                 // activation should be setting the once cell
    3746            0 :                                 warn!(
    3747            0 :                                     "unexpected: cancel_wait_for_background_loop_concurrency_limit_semaphore not set, priority-boosting of logical size calculation will not work"
    3748              :                                 );
    3749            0 :                                 debug_assert!(false);
    3750              :                             }
    3751              :                         }
    3752              :                     }
    3753              :                 }
    3754              :             }
    3755              :         }
    3756              : 
    3757            0 :         if let CurrentLogicalSize::Approximate(_) = &current_size {
    3758            0 :             if ctx.task_kind() == TaskKind::WalReceiverConnectionHandler {
    3759            0 :                 let first = self
    3760            0 :                     .current_logical_size
    3761            0 :                     .did_return_approximate_to_walreceiver
    3762            0 :                     .compare_exchange(
    3763            0 :                         false,
    3764            0 :                         true,
    3765            0 :                         AtomicOrdering::Relaxed,
    3766            0 :                         AtomicOrdering::Relaxed,
    3767            0 :                     )
    3768            0 :                     .is_ok();
    3769            0 :                 if first {
    3770            0 :                     crate::metrics::initial_logical_size::TIMELINES_WHERE_WALRECEIVER_GOT_APPROXIMATE_SIZE.inc();
    3771            0 :                 }
    3772            0 :             }
    3773            0 :         }
    3774              : 
    3775            0 :         current_size
    3776            0 :     }
    3777              : 
    3778            0 :     fn spawn_initial_logical_size_computation_task(self: &Arc<Self>, ctx: &RequestContext) {
    3779            0 :         let Some(initial_part_end) = self.current_logical_size.initial_part_end else {
    3780              :             // nothing to do for freshly created timelines;
    3781            0 :             assert_eq!(
    3782            0 :                 self.current_logical_size.current_size().accuracy(),
    3783              :                 logical_size::Accuracy::Exact,
    3784              :             );
    3785            0 :             self.current_logical_size.initialized.add_permits(1);
    3786            0 :             return;
    3787              :         };
    3788              : 
    3789            0 :         let cancel_wait_for_background_loop_concurrency_limit_semaphore = CancellationToken::new();
    3790            0 :         let token = cancel_wait_for_background_loop_concurrency_limit_semaphore.clone();
    3791            0 :         self.current_logical_size
    3792            0 :             .cancel_wait_for_background_loop_concurrency_limit_semaphore.set(token)
    3793            0 :             .expect("initial logical size calculation task must be spawned exactly once per Timeline object");
    3794              : 
    3795            0 :         let self_clone = Arc::clone(self);
    3796            0 :         let background_ctx = ctx.detached_child(
    3797            0 :             TaskKind::InitialLogicalSizeCalculation,
    3798            0 :             DownloadBehavior::Download,
    3799              :         );
    3800            0 :         task_mgr::spawn(
    3801            0 :             task_mgr::BACKGROUND_RUNTIME.handle(),
    3802            0 :             task_mgr::TaskKind::InitialLogicalSizeCalculation,
    3803            0 :             self.tenant_shard_id,
    3804            0 :             Some(self.timeline_id),
    3805            0 :             "initial size calculation",
    3806              :             // NB: don't log errors here, task_mgr will do that.
    3807            0 :             async move {
    3808            0 :                 self_clone
    3809            0 :                     .initial_logical_size_calculation_task(
    3810            0 :                         initial_part_end,
    3811            0 :                         cancel_wait_for_background_loop_concurrency_limit_semaphore,
    3812            0 :                         background_ctx,
    3813            0 :                     )
    3814            0 :                     .await;
    3815            0 :                 Ok(())
    3816            0 :             }
    3817            0 :             .instrument(info_span!(parent: None, "initial_size_calculation", tenant_id=%self.tenant_shard_id.tenant_id, shard_id=%self.tenant_shard_id.shard_slug(), timeline_id=%self.timeline_id)),
    3818              :         );
    3819            0 :     }
    3820              : 
    3821              :     /// # Cancellation
    3822              :     ///
    3823              :     /// This method is sensitive to `Timeline::cancel`.
    3824              :     ///
    3825              :     /// It is _not_ sensitive to task_mgr::shutdown_token().
    3826              :     ///
    3827              :     /// # Cancel-Safety
    3828              :     ///
    3829              :     /// It does Timeline IO, hence this should be polled to completion because
    3830              :     /// we could be leaving in-flight IOs behind, which is safe, but annoying
    3831              :     /// to reason about.
    3832            0 :     async fn initial_logical_size_calculation_task(
    3833            0 :         self: Arc<Self>,
    3834            0 :         initial_part_end: Lsn,
    3835            0 :         skip_concurrency_limiter: CancellationToken,
    3836            0 :         background_ctx: RequestContext,
    3837            0 :     ) {
    3838            0 :         scopeguard::defer! {
    3839              :             // Irrespective of the outcome of this operation, we should unblock anyone waiting for it.
    3840              :             self.current_logical_size.initialized.add_permits(1);
    3841              :         }
    3842              : 
    3843            0 :         let try_once = |attempt: usize| {
    3844            0 :             let background_ctx = &background_ctx;
    3845            0 :             let self_ref = &self;
    3846            0 :             let skip_concurrency_limiter = &skip_concurrency_limiter;
    3847            0 :             async move {
    3848            0 :                 let wait_for_permit = super::tasks::acquire_concurrency_permit(
    3849            0 :                     BackgroundLoopKind::InitialLogicalSizeCalculation,
    3850            0 :                     background_ctx,
    3851              :                 );
    3852              : 
    3853              :                 use crate::metrics::initial_logical_size::StartCircumstances;
    3854            0 :                 let (_maybe_permit, circumstances) = tokio::select! {
    3855            0 :                     permit = wait_for_permit => {
    3856            0 :                         (Some(permit), StartCircumstances::AfterBackgroundTasksRateLimit)
    3857              :                     }
    3858            0 :                     _ = self_ref.cancel.cancelled() => {
    3859            0 :                         return Err(CalculateLogicalSizeError::Cancelled);
    3860              :                     }
    3861            0 :                     () = skip_concurrency_limiter.cancelled() => {
    3862              :                         // Some action that is part of a end user interaction requested logical size
    3863              :                         // => break out of the rate limit
    3864              :                         // TODO: ideally we'd not run on BackgroundRuntime but the requester's runtime;
    3865              :                         // but then again what happens if they cancel; also, we should just be using
    3866              :                         // one runtime across the entire process, so, let's leave this for now.
    3867            0 :                         (None, StartCircumstances::SkippedConcurrencyLimiter)
    3868              :                     }
    3869              :                 };
    3870              : 
    3871            0 :                 let metrics_guard = if attempt == 1 {
    3872            0 :                     crate::metrics::initial_logical_size::START_CALCULATION.first(circumstances)
    3873              :                 } else {
    3874            0 :                     crate::metrics::initial_logical_size::START_CALCULATION.retry(circumstances)
    3875              :                 };
    3876              : 
    3877            0 :                 let io_concurrency = IoConcurrency::spawn_from_conf(
    3878            0 :                     self_ref.conf.get_vectored_concurrent_io,
    3879            0 :                     self_ref
    3880            0 :                         .gate
    3881            0 :                         .enter()
    3882            0 :                         .map_err(|_| CalculateLogicalSizeError::Cancelled)?,
    3883              :                 );
    3884              : 
    3885            0 :                 let calculated_size = self_ref
    3886            0 :                     .logical_size_calculation_task(
    3887            0 :                         initial_part_end,
    3888            0 :                         LogicalSizeCalculationCause::Initial,
    3889            0 :                         background_ctx,
    3890            0 :                     )
    3891            0 :                     .await?;
    3892              : 
    3893            0 :                 self_ref
    3894            0 :                     .trigger_aux_file_size_computation(
    3895            0 :                         initial_part_end,
    3896            0 :                         background_ctx,
    3897            0 :                         io_concurrency,
    3898            0 :                     )
    3899            0 :                     .await?;
    3900              : 
    3901              :                 // TODO: add aux file size to logical size
    3902              : 
    3903            0 :                 Ok((calculated_size, metrics_guard))
    3904            0 :             }
    3905            0 :         };
    3906              : 
    3907            0 :         let retrying = async {
    3908            0 :             let mut attempt = 0;
    3909              :             loop {
    3910            0 :                 attempt += 1;
    3911              : 
    3912            0 :                 match try_once(attempt).await {
    3913            0 :                     Ok(res) => return ControlFlow::Continue(res),
    3914            0 :                     Err(CalculateLogicalSizeError::Cancelled) => return ControlFlow::Break(()),
    3915              :                     Err(
    3916            0 :                         e @ (CalculateLogicalSizeError::Decode(_)
    3917              :                         | CalculateLogicalSizeError::PageRead(_)),
    3918              :                     ) => {
    3919            0 :                         warn!(attempt, "initial size calculation failed: {e:?}");
    3920              :                         // exponential back-off doesn't make sense at these long intervals;
    3921              :                         // use fixed retry interval with generous jitter instead
    3922            0 :                         let sleep_duration = Duration::from_secs(
    3923            0 :                             u64::try_from(
    3924              :                                 // 1hour base
    3925            0 :                                 (60_i64 * 60_i64)
    3926            0 :                                     // 10min jitter
    3927            0 :                                     + rand::rng().random_range(-10 * 60..10 * 60),
    3928              :                             )
    3929            0 :                             .expect("10min < 1hour"),
    3930              :                         );
    3931            0 :                         tokio::select! {
    3932            0 :                             _ = tokio::time::sleep(sleep_duration) => {}
    3933            0 :                             _ = self.cancel.cancelled() => return ControlFlow::Break(()),
    3934              :                         }
    3935              :                     }
    3936              :                 }
    3937              :             }
    3938            0 :         };
    3939              : 
    3940            0 :         let (calculated_size, metrics_guard) = match retrying.await {
    3941            0 :             ControlFlow::Continue(calculated_size) => calculated_size,
    3942            0 :             ControlFlow::Break(()) => return,
    3943              :         };
    3944              : 
    3945              :         // we cannot query current_logical_size.current_size() to know the current
    3946              :         // *negative* value, only truncated to u64.
    3947            0 :         let added = self
    3948            0 :             .current_logical_size
    3949            0 :             .size_added_after_initial
    3950            0 :             .load(AtomicOrdering::Relaxed);
    3951              : 
    3952            0 :         let sum = calculated_size.saturating_add_signed(added);
    3953              : 
    3954              :         // set the gauge value before it can be set in `update_current_logical_size`.
    3955            0 :         self.metrics.current_logical_size_gauge.set(sum);
    3956              : 
    3957            0 :         self.current_logical_size
    3958            0 :             .initial_logical_size
    3959            0 :             .set((calculated_size, metrics_guard.calculation_result_saved()))
    3960            0 :             .ok()
    3961            0 :             .expect("only this task sets it");
    3962            0 :     }
    3963              : 
    3964            7 :     pub(crate) fn spawn_ondemand_logical_size_calculation(
    3965            7 :         self: &Arc<Self>,
    3966            7 :         lsn: Lsn,
    3967            7 :         cause: LogicalSizeCalculationCause,
    3968            7 :         ctx: RequestContext,
    3969            7 :     ) -> oneshot::Receiver<Result<u64, CalculateLogicalSizeError>> {
    3970            7 :         let (sender, receiver) = oneshot::channel();
    3971            7 :         let self_clone = Arc::clone(self);
    3972              :         // XXX if our caller loses interest, i.e., ctx is cancelled,
    3973              :         // we should stop the size calculation work and return an error.
    3974              :         // That would require restructuring this function's API to
    3975              :         // return the result directly, instead of a Receiver for the result.
    3976            7 :         let ctx = ctx.detached_child(
    3977            7 :             TaskKind::OndemandLogicalSizeCalculation,
    3978            7 :             DownloadBehavior::Download,
    3979              :         );
    3980            7 :         task_mgr::spawn(
    3981            7 :             task_mgr::BACKGROUND_RUNTIME.handle(),
    3982            7 :             task_mgr::TaskKind::OndemandLogicalSizeCalculation,
    3983            7 :             self.tenant_shard_id,
    3984            7 :             Some(self.timeline_id),
    3985            7 :             "ondemand logical size calculation",
    3986            7 :             async move {
    3987            7 :                 let res = self_clone
    3988            7 :                     .logical_size_calculation_task(lsn, cause, &ctx)
    3989            7 :                     .await;
    3990            7 :                 let _ = sender.send(res).ok();
    3991            7 :                 Ok(()) // Receiver is responsible for handling errors
    3992            7 :             }
    3993            7 :             .in_current_span(),
    3994              :         );
    3995            7 :         receiver
    3996            7 :     }
    3997              : 
    3998              :     #[instrument(skip_all)]
    3999              :     async fn logical_size_calculation_task(
    4000              :         self: &Arc<Self>,
    4001              :         lsn: Lsn,
    4002              :         cause: LogicalSizeCalculationCause,
    4003              :         ctx: &RequestContext,
    4004              :     ) -> Result<u64, CalculateLogicalSizeError> {
    4005              :         crate::span::debug_assert_current_span_has_tenant_and_timeline_id();
    4006              :         // We should never be calculating logical sizes on shard !=0, because these shards do not have
    4007              :         // accurate relation sizes, and they do not emit consumption metrics.
    4008              :         debug_assert!(self.tenant_shard_id.is_shard_zero());
    4009              : 
    4010              :         let guard = self
    4011              :             .gate
    4012              :             .enter()
    4013              :             .map_err(|_| CalculateLogicalSizeError::Cancelled)?;
    4014              : 
    4015              :         self.calculate_logical_size(lsn, cause, &guard, ctx).await
    4016              :     }
    4017              : 
    4018              :     /// Calculate the logical size of the database at the latest LSN.
    4019              :     ///
    4020              :     /// NOTE: counted incrementally, includes ancestors. This can be a slow operation,
    4021              :     /// especially if we need to download remote layers.
    4022            7 :     async fn calculate_logical_size(
    4023            7 :         &self,
    4024            7 :         up_to_lsn: Lsn,
    4025            7 :         cause: LogicalSizeCalculationCause,
    4026            7 :         _guard: &GateGuard,
    4027            7 :         ctx: &RequestContext,
    4028            7 :     ) -> Result<u64, CalculateLogicalSizeError> {
    4029            7 :         info!(
    4030            0 :             "Calculating logical size for timeline {} at {}",
    4031              :             self.timeline_id, up_to_lsn
    4032              :         );
    4033              : 
    4034            7 :         if let Err(()) = pausable_failpoint!("timeline-calculate-logical-size-pause", &self.cancel)
    4035              :         {
    4036            0 :             return Err(CalculateLogicalSizeError::Cancelled);
    4037            7 :         }
    4038              : 
    4039              :         // See if we've already done the work for initial size calculation.
    4040              :         // This is a short-cut for timelines that are mostly unused.
    4041            7 :         if let Some(size) = self.current_logical_size.initialized_size(up_to_lsn) {
    4042            0 :             return Ok(size);
    4043            7 :         }
    4044            7 :         let storage_time_metrics = match cause {
    4045              :             LogicalSizeCalculationCause::Initial
    4046              :             | LogicalSizeCalculationCause::ConsumptionMetricsSyntheticSize
    4047            0 :             | LogicalSizeCalculationCause::TenantSizeHandler => &self.metrics.logical_size_histo,
    4048              :             LogicalSizeCalculationCause::EvictionTaskImitation => {
    4049            7 :                 &self.metrics.imitate_logical_size_histo
    4050              :             }
    4051              :         };
    4052            7 :         let timer = storage_time_metrics.start_timer();
    4053            7 :         let logical_size = self
    4054            7 :             .get_current_logical_size_non_incremental(up_to_lsn, ctx)
    4055            7 :             .await?;
    4056            7 :         debug!("calculated logical size: {logical_size}");
    4057            7 :         timer.stop_and_record();
    4058            7 :         Ok(logical_size)
    4059            7 :     }
    4060              : 
    4061              :     /// Update current logical size, adding `delta' to the old value.
    4062       135285 :     fn update_current_logical_size(&self, delta: i64) {
    4063       135285 :         let logical_size = &self.current_logical_size;
    4064       135285 :         logical_size.increment_size(delta);
    4065              : 
    4066              :         // Also set the value in the prometheus gauge. Note that
    4067              :         // there is a race condition here: if this is is called by two
    4068              :         // threads concurrently, the prometheus gauge might be set to
    4069              :         // one value while current_logical_size is set to the
    4070              :         // other.
    4071       135285 :         match logical_size.current_size() {
    4072       135285 :             CurrentLogicalSize::Exact(ref new_current_size) => self
    4073       135285 :                 .metrics
    4074       135285 :                 .current_logical_size_gauge
    4075       135285 :                 .set(new_current_size.into()),
    4076            0 :             CurrentLogicalSize::Approximate(_) => {
    4077            0 :                 // don't update the gauge yet, this allows us not to update the gauge back and
    4078            0 :                 // forth between the initial size calculation task.
    4079            0 :             }
    4080              :         }
    4081       135285 :     }
    4082              : 
    4083         1527 :     pub(crate) fn update_directory_entries_count(&self, kind: DirectoryKind, count: MetricsUpdate) {
    4084              :         // TODO: this directory metrics is not correct -- we could have multiple reldirs in the system
    4085              :         // for each of the database, but we only store one value, and therefore each pgdirmodification
    4086              :         // would overwrite the previous value if they modify different databases.
    4087              : 
    4088         1527 :         match count {
    4089          566 :             MetricsUpdate::Set(count) => {
    4090          566 :                 self.directory_metrics[kind.offset()].store(count, AtomicOrdering::Relaxed);
    4091          566 :                 self.directory_metrics_inited[kind.offset()].store(true, AtomicOrdering::Relaxed);
    4092          566 :             }
    4093          960 :             MetricsUpdate::Add(count) => {
    4094              :                 // TODO: these operations are not atomic; but we only have one writer to the metrics, so
    4095              :                 // it's fine.
    4096          960 :                 if self.directory_metrics_inited[kind.offset()].load(AtomicOrdering::Relaxed) {
    4097          960 :                     // The metrics has been initialized with `MetricsUpdate::Set` before, so we can add/sub
    4098          960 :                     // the value reliably.
    4099          960 :                     self.directory_metrics[kind.offset()].fetch_add(count, AtomicOrdering::Relaxed);
    4100          960 :                 }
    4101              :                 // Otherwise, ignore this update
    4102              :             }
    4103            1 :             MetricsUpdate::Sub(count) => {
    4104              :                 // TODO: these operations are not atomic; but we only have one writer to the metrics, so
    4105              :                 // it's fine.
    4106            1 :                 if self.directory_metrics_inited[kind.offset()].load(AtomicOrdering::Relaxed) {
    4107            1 :                     // The metrics has been initialized with `MetricsUpdate::Set` before.
    4108            1 :                     // The operation could overflow so we need to normalize the value.
    4109            1 :                     let prev_val =
    4110            1 :                         self.directory_metrics[kind.offset()].load(AtomicOrdering::Relaxed);
    4111            1 :                     let res = prev_val.saturating_sub(count);
    4112            1 :                     self.directory_metrics[kind.offset()].store(res, AtomicOrdering::Relaxed);
    4113            1 :                 }
    4114              :                 // Otherwise, ignore this update
    4115              :             }
    4116              :         };
    4117              : 
    4118              :         // TODO: remove this, there's no place in the code that updates this aux metrics.
    4119         1527 :         let aux_metric =
    4120         1527 :             self.directory_metrics[DirectoryKind::AuxFiles.offset()].load(AtomicOrdering::Relaxed);
    4121              : 
    4122         1527 :         let sum_of_entries = self
    4123         1527 :             .directory_metrics
    4124         1527 :             .iter()
    4125        12216 :             .map(|v| v.load(AtomicOrdering::Relaxed))
    4126         1527 :             .sum();
    4127              :         // Set a high general threshold and a lower threshold for the auxiliary files,
    4128              :         // as we can have large numbers of relations in the db directory.
    4129              :         const SUM_THRESHOLD: u64 = 5000;
    4130              :         const AUX_THRESHOLD: u64 = 1000;
    4131         1527 :         if sum_of_entries >= SUM_THRESHOLD || aux_metric >= AUX_THRESHOLD {
    4132            0 :             self.metrics
    4133            0 :                 .directory_entries_count_gauge
    4134            0 :                 .set(sum_of_entries);
    4135         1527 :         } else if let Some(metric) = Lazy::get(&self.metrics.directory_entries_count_gauge) {
    4136            0 :             metric.set(sum_of_entries);
    4137         1527 :         }
    4138         1527 :     }
    4139              : 
    4140            0 :     async fn find_layer(
    4141            0 :         &self,
    4142            0 :         layer_name: &LayerName,
    4143            0 :     ) -> Result<Option<Layer>, layer_manager::Shutdown> {
    4144            0 :         let guard = self
    4145            0 :             .layers
    4146            0 :             .read(LayerManagerLockHolder::GetLayerMapInfo)
    4147            0 :             .await;
    4148            0 :         let layer = guard
    4149            0 :             .layer_map()?
    4150            0 :             .iter_historic_layers()
    4151            0 :             .find(|l| &l.layer_name() == layer_name)
    4152            0 :             .map(|found| guard.get_from_desc(&found));
    4153            0 :         Ok(layer)
    4154            0 :     }
    4155              : 
    4156            0 :     pub(super) fn should_keep_previous_heatmap(&self, new_heatmap_end_lsn: Lsn) -> bool {
    4157            0 :         let crnt = self.previous_heatmap.load();
    4158            0 :         match crnt.as_deref() {
    4159            0 :             Some(PreviousHeatmap::Active { end_lsn, .. }) => match end_lsn {
    4160            0 :                 Some(crnt_end_lsn) => *crnt_end_lsn > new_heatmap_end_lsn,
    4161            0 :                 None => true,
    4162              :             },
    4163            0 :             Some(PreviousHeatmap::Obsolete) => false,
    4164            0 :             None => false,
    4165              :         }
    4166            0 :     }
    4167              : 
    4168              :     /// The timeline heatmap is a hint to secondary locations from the primary location,
    4169              :     /// indicating which layers are currently on-disk on the primary.
    4170              :     ///
    4171              :     /// None is returned if the Timeline is in a state where uploading a heatmap
    4172              :     /// doesn't make sense, such as shutting down or initializing.  The caller
    4173              :     /// should treat this as a cue to simply skip doing any heatmap uploading
    4174              :     /// for this timeline.
    4175            8 :     pub(crate) async fn generate_heatmap(&self) -> Option<HeatMapTimeline> {
    4176            8 :         if !self.is_active() {
    4177            0 :             return None;
    4178            8 :         }
    4179              : 
    4180            8 :         let guard = self
    4181            8 :             .layers
    4182            8 :             .read(LayerManagerLockHolder::GenerateHeatmap)
    4183            8 :             .await;
    4184              : 
    4185              :         // Firstly, if there's any heatmap left over from when this location
    4186              :         // was a secondary, take that into account. Keep layers that are:
    4187              :         // * present in the layer map
    4188              :         // * visible
    4189              :         // * non-resident
    4190              :         // * not evicted since we read the heatmap
    4191              :         //
    4192              :         // Without this, a new cold, attached location would clobber the previous
    4193              :         // heatamp.
    4194            8 :         let previous_heatmap = self.previous_heatmap.load();
    4195            8 :         let visible_non_resident = match previous_heatmap.as_deref() {
    4196              :             Some(PreviousHeatmap::Active {
    4197            6 :                 heatmap, read_at, ..
    4198           23 :             }) => Some(heatmap.all_layers().filter_map(|hl| {
    4199           23 :                 let desc: PersistentLayerDesc = hl.name.clone().into();
    4200           23 :                 let layer = guard.try_get_from_key(&desc.key())?;
    4201              : 
    4202           23 :                 if layer.visibility() == LayerVisibilityHint::Covered {
    4203            0 :                     return None;
    4204           23 :                 }
    4205              : 
    4206           23 :                 if layer.is_likely_resident() {
    4207           10 :                     return None;
    4208           13 :                 }
    4209              : 
    4210           13 :                 if layer.last_evicted_at().happened_after(*read_at) {
    4211            3 :                     return None;
    4212           10 :                 }
    4213              : 
    4214           10 :                 Some((desc, hl.metadata.clone(), hl.access_time, hl.cold))
    4215           23 :             })),
    4216            0 :             Some(PreviousHeatmap::Obsolete) => None,
    4217            2 :             None => None,
    4218              :         };
    4219              : 
    4220              :         // Secondly, all currently visible, resident layers are included.
    4221           18 :         let resident = guard.likely_resident_layers().filter_map(|layer| {
    4222           18 :             match layer.visibility() {
    4223              :                 LayerVisibilityHint::Visible => {
    4224              :                     // Layer is visible to one or more read LSNs: elegible for inclusion in layer map
    4225           17 :                     let last_activity_ts = layer.latest_activity();
    4226           17 :                     Some((
    4227           17 :                         layer.layer_desc().clone(),
    4228           17 :                         layer.metadata(),
    4229           17 :                         last_activity_ts,
    4230           17 :                         false, // these layers are not cold
    4231           17 :                     ))
    4232              :                 }
    4233              :                 LayerVisibilityHint::Covered => {
    4234              :                     // Layer is resident but unlikely to be read: not elegible for inclusion in heatmap.
    4235            1 :                     None
    4236              :                 }
    4237              :             }
    4238           18 :         });
    4239              : 
    4240            8 :         let mut layers = match visible_non_resident {
    4241            6 :             Some(non_resident) => {
    4242            6 :                 let mut non_resident = non_resident.peekable();
    4243            6 :                 if non_resident.peek().is_none() {
    4244            2 :                     tracing::info!(timeline_id=%self.timeline_id, "Previous heatmap now obsolete");
    4245            2 :                     self.previous_heatmap
    4246            2 :                         .store(Some(PreviousHeatmap::Obsolete.into()));
    4247            4 :                 }
    4248              : 
    4249            6 :                 non_resident.chain(resident).collect::<Vec<_>>()
    4250              :             }
    4251            2 :             None => resident.collect::<Vec<_>>(),
    4252              :         };
    4253              : 
    4254              :         // Sort layers in order of which to download first.  For a large set of layers to download, we
    4255              :         // want to prioritize those layers which are most likely to still be in the resident many minutes
    4256              :         // or hours later:
    4257              :         // - Cold layers go last for convenience when a human inspects the heatmap.
    4258              :         // - Download L0s last, because they churn the fastest: L0s on a fast-writing tenant might
    4259              :         //   only exist for a few minutes before being compacted into L1s.
    4260              :         // - For L1 & image layers, download most recent LSNs first: the older the LSN, the sooner
    4261              :         //   the layer is likely to be covered by an image layer during compaction.
    4262           60 :         layers.sort_by_key(|(desc, _meta, _atime, cold)| {
    4263           60 :             std::cmp::Reverse((
    4264           60 :                 *cold,
    4265           60 :                 !LayerMap::is_l0(&desc.key_range, desc.is_delta),
    4266           60 :                 desc.lsn_range.end,
    4267           60 :             ))
    4268           60 :         });
    4269              : 
    4270            8 :         let layers = layers
    4271            8 :             .into_iter()
    4272           27 :             .map(|(desc, meta, atime, cold)| {
    4273           27 :                 HeatMapLayer::new(desc.layer_name(), meta, atime, cold)
    4274           27 :             })
    4275            8 :             .collect();
    4276              : 
    4277            8 :         Some(HeatMapTimeline::new(self.timeline_id, layers))
    4278            8 :     }
    4279              : 
    4280            0 :     pub(super) async fn generate_unarchival_heatmap(&self, end_lsn: Lsn) -> PreviousHeatmap {
    4281            0 :         let guard = self
    4282            0 :             .layers
    4283            0 :             .read(LayerManagerLockHolder::GenerateHeatmap)
    4284            0 :             .await;
    4285              : 
    4286            0 :         let now = SystemTime::now();
    4287            0 :         let mut heatmap_layers = Vec::default();
    4288            0 :         for vl in guard.visible_layers() {
    4289            0 :             if vl.layer_desc().get_lsn_range().start >= end_lsn {
    4290            0 :                 continue;
    4291            0 :             }
    4292              : 
    4293            0 :             let hl = HeatMapLayer {
    4294            0 :                 name: vl.layer_desc().layer_name(),
    4295            0 :                 metadata: vl.metadata(),
    4296            0 :                 access_time: now,
    4297            0 :                 cold: true,
    4298            0 :             };
    4299            0 :             heatmap_layers.push(hl);
    4300              :         }
    4301              : 
    4302            0 :         tracing::info!(
    4303            0 :             "Generating unarchival heatmap with {} layers",
    4304            0 :             heatmap_layers.len()
    4305              :         );
    4306              : 
    4307            0 :         let heatmap = HeatMapTimeline::new(self.timeline_id, heatmap_layers);
    4308            0 :         PreviousHeatmap::Active {
    4309            0 :             heatmap,
    4310            0 :             read_at: Instant::now(),
    4311            0 :             end_lsn: Some(end_lsn),
    4312            0 :         }
    4313            0 :     }
    4314              : 
    4315              :     /// Returns true if the given lsn is or was an ancestor branchpoint.
    4316            0 :     pub(crate) fn is_ancestor_lsn(&self, lsn: Lsn) -> bool {
    4317              :         // upon timeline detach, we set the ancestor_lsn to Lsn::INVALID and the store the original
    4318              :         // branchpoint in the value in IndexPart::lineage
    4319            0 :         self.ancestor_lsn == lsn
    4320            0 :             || (self.ancestor_lsn == Lsn::INVALID
    4321            0 :                 && self.remote_client.is_previous_ancestor_lsn(lsn))
    4322            0 :     }
    4323              : }
    4324              : 
    4325              : #[derive(Clone)]
    4326              : /// Type representing a query in the ([`Lsn`], [`Key`]) space.
    4327              : /// In other words, a set of segments in a 2D space.
    4328              : ///
    4329              : /// This representation has the advatange of avoiding hash map
    4330              : /// allocations for uniform queries.
    4331              : pub(crate) enum VersionedKeySpaceQuery {
    4332              :     /// Variant for queries at a single [`Lsn`]
    4333              :     Uniform { keyspace: KeySpace, lsn: Lsn },
    4334              :     /// Variant for queries at multiple [`Lsn`]s
    4335              :     Scattered {
    4336              :         keyspaces_at_lsn: Vec<(Lsn, KeySpace)>,
    4337              :     },
    4338              : }
    4339              : 
    4340              : impl VersionedKeySpaceQuery {
    4341       302246 :     pub(crate) fn uniform(keyspace: KeySpace, lsn: Lsn) -> Self {
    4342       302246 :         Self::Uniform { keyspace, lsn }
    4343       302246 :     }
    4344              : 
    4345        10192 :     pub(crate) fn scattered(keyspaces_at_lsn: Vec<(Lsn, KeySpace)>) -> Self {
    4346        10192 :         Self::Scattered { keyspaces_at_lsn }
    4347        10192 :     }
    4348              : 
    4349              :     /// Returns the most recent (largest) LSN included in the query.
    4350              :     /// If any of the LSNs included in the query are invalid, returns
    4351              :     /// an error instead.
    4352       624876 :     fn high_watermark_lsn(&self) -> Result<Lsn, GetVectoredError> {
    4353       624876 :         match self {
    4354       604492 :             Self::Uniform { lsn, .. } => {
    4355       604492 :                 if !lsn.is_valid() {
    4356            0 :                     return Err(GetVectoredError::InvalidLsn(*lsn));
    4357       604492 :                 }
    4358              : 
    4359       604492 :                 Ok(*lsn)
    4360              :             }
    4361        20384 :             Self::Scattered { keyspaces_at_lsn } => {
    4362        20384 :                 let mut max_lsn = None;
    4363        42216 :                 for (lsn, _keyspace) in keyspaces_at_lsn.iter() {
    4364        42216 :                     if !lsn.is_valid() {
    4365            0 :                         return Err(GetVectoredError::InvalidLsn(*lsn));
    4366        42216 :                     }
    4367        42216 :                     max_lsn = std::cmp::max(max_lsn, Some(lsn));
    4368              :                 }
    4369              : 
    4370        20384 :                 if let Some(computed) = max_lsn {
    4371        20384 :                     Ok(*computed)
    4372              :                 } else {
    4373            0 :                     Err(GetVectoredError::Other(anyhow!("empty input")))
    4374              :                 }
    4375              :             }
    4376              :         }
    4377       624876 :     }
    4378              : 
    4379              :     /// Returns the total keyspace being queried: the result of projecting
    4380              :     /// everything in the key dimensions onto the key axis.
    4381       323515 :     fn total_keyspace(&self) -> KeySpace {
    4382       323515 :         match self {
    4383       303131 :             Self::Uniform { keyspace, .. } => keyspace.clone(),
    4384        20384 :             Self::Scattered { keyspaces_at_lsn } => keyspaces_at_lsn
    4385        20384 :                 .iter()
    4386        20384 :                 .map(|(_lsn, keyspace)| keyspace)
    4387        42216 :                 .fold(KeySpace::default(), |mut acc, v| {
    4388        42216 :                     acc.merge(v);
    4389        42216 :                     acc
    4390        42216 :                 }),
    4391              :         }
    4392       323515 :     }
    4393              : 
    4394              :     /// Returns LSN for a specific key.
    4395              :     ///
    4396              :     /// Invariant: requested key must be part of [`Self::total_keyspace`]
    4397       395559 :     pub(super) fn map_key_to_lsn(&self, key: &Key) -> Lsn {
    4398       395559 :         match self {
    4399       322367 :             Self::Uniform { lsn, .. } => *lsn,
    4400        73192 :             Self::Scattered { keyspaces_at_lsn } => {
    4401        73192 :                 keyspaces_at_lsn
    4402        73192 :                     .iter()
    4403       419796 :                     .find(|(_lsn, keyspace)| keyspace.contains(key))
    4404        73192 :                     .expect("Returned key was requested")
    4405              :                     .0
    4406              :             }
    4407              :         }
    4408       395559 :     }
    4409              : 
    4410              :     /// Remove any parts of the query (segments) which overlap with the provided
    4411              :     /// key space (also segments).
    4412       968326 :     fn remove_overlapping_with(&mut self, to_remove: &KeySpace) -> KeySpace {
    4413       968326 :         match self {
    4414       947942 :             Self::Uniform { keyspace, .. } => keyspace.remove_overlapping_with(to_remove),
    4415        20384 :             Self::Scattered { keyspaces_at_lsn } => {
    4416        20384 :                 let mut removed_accum = KeySpaceRandomAccum::new();
    4417        42216 :                 keyspaces_at_lsn.iter_mut().for_each(|(_lsn, keyspace)| {
    4418        42216 :                     let removed = keyspace.remove_overlapping_with(to_remove);
    4419        42216 :                     removed_accum.add_keyspace(removed);
    4420        42216 :                 });
    4421              : 
    4422        20384 :                 removed_accum.to_keyspace()
    4423              :             }
    4424              :         }
    4425       968326 :     }
    4426              : 
    4427       739359 :     fn is_empty(&self) -> bool {
    4428       739359 :         match self {
    4429       718975 :             Self::Uniform { keyspace, .. } => keyspace.is_empty(),
    4430        20384 :             Self::Scattered { keyspaces_at_lsn } => keyspaces_at_lsn
    4431        20384 :                 .iter()
    4432        31300 :                 .all(|(_lsn, keyspace)| keyspace.is_empty()),
    4433              :         }
    4434       739359 :     }
    4435              : 
    4436              :     /// "Lower" the query on the LSN dimension
    4437       114484 :     fn lower(&mut self, to: Lsn) {
    4438       114484 :         match self {
    4439       114484 :             Self::Uniform { lsn, .. } => {
    4440       114484 :                 // If the originally requested LSN is smaller than the starting
    4441       114484 :                 // LSN of the ancestor we are descending into, we need to respect that.
    4442       114484 :                 // Hence the min.
    4443       114484 :                 *lsn = std::cmp::min(*lsn, to);
    4444       114484 :             }
    4445            0 :             Self::Scattered { keyspaces_at_lsn } => {
    4446            0 :                 keyspaces_at_lsn.iter_mut().for_each(|(lsn, _keyspace)| {
    4447            0 :                     *lsn = std::cmp::min(*lsn, to);
    4448            0 :                 });
    4449              :             }
    4450              :         }
    4451       114484 :     }
    4452              : }
    4453              : 
    4454              : impl std::fmt::Display for VersionedKeySpaceQuery {
    4455            0 :     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
    4456            0 :         write!(f, "[")?;
    4457              : 
    4458            0 :         match self {
    4459            0 :             VersionedKeySpaceQuery::Uniform { keyspace, lsn } => {
    4460            0 :                 write!(f, "{keyspace} @ {lsn}")?;
    4461              :             }
    4462            0 :             VersionedKeySpaceQuery::Scattered { keyspaces_at_lsn } => {
    4463            0 :                 for (lsn, keyspace) in keyspaces_at_lsn.iter() {
    4464            0 :                     write!(f, "{keyspace} @ {lsn},")?;
    4465              :                 }
    4466              :             }
    4467              :         }
    4468              : 
    4469            0 :         write!(f, "]")
    4470            0 :     }
    4471              : }
    4472              : 
    4473              : impl Timeline {
    4474              :     #[allow(clippy::doc_lazy_continuation)]
    4475              :     /// Get the data needed to reconstruct all keys in the provided keyspace
    4476              :     ///
    4477              :     /// The algorithm is as follows:
    4478              :     /// 1.   While some keys are still not done and there's a timeline to visit:
    4479              :     /// 2.   Visit the timeline (see [`Timeline::get_vectored_reconstruct_data_timeline`]:
    4480              :     /// 2.1: Build the fringe for the current keyspace
    4481              :     /// 2.2  Visit the newest layer from the fringe to collect all values for the range it
    4482              :     ///      intersects
    4483              :     /// 2.3. Pop the timeline from the fringe
    4484              :     /// 2.4. If the fringe is empty, go back to 1
    4485       312438 :     async fn get_vectored_reconstruct_data(
    4486       312438 :         &self,
    4487       312438 :         mut query: VersionedKeySpaceQuery,
    4488       312438 :         reconstruct_state: &mut ValuesReconstructState,
    4489       312438 :         ctx: &RequestContext,
    4490       312438 :     ) -> Result<(), GetVectoredError> {
    4491       312438 :         let original_hwm_lsn = query.high_watermark_lsn().unwrap();
    4492              : 
    4493              :         let mut timeline_owned: Arc<Timeline>;
    4494       312438 :         let mut timeline = self;
    4495              : 
    4496       312437 :         let missing_keyspace = loop {
    4497       426921 :             if self.cancel.is_cancelled() {
    4498            0 :                 return Err(GetVectoredError::Cancelled);
    4499       426921 :             }
    4500              : 
    4501              :             let TimelineVisitOutcome {
    4502       426921 :                 completed_keyspace: completed,
    4503       426921 :                 image_covered_keyspace,
    4504              :             } = {
    4505       426921 :                 let ctx = RequestContextBuilder::from(ctx)
    4506       426921 :                     .perf_span(|crnt_perf_span| {
    4507            0 :                         info_span!(
    4508              :                             target: PERF_TRACE_TARGET,
    4509            0 :                             parent: crnt_perf_span,
    4510              :                             "PLAN_IO_TIMELINE",
    4511              :                             timeline = %timeline.timeline_id,
    4512            0 :                             high_watermark_lsn = %query.high_watermark_lsn().unwrap(),
    4513              :                         )
    4514            0 :                     })
    4515       426921 :                     .attached_child();
    4516              : 
    4517       426921 :                 Self::get_vectored_reconstruct_data_timeline(
    4518       426921 :                     timeline,
    4519       426921 :                     &query,
    4520       426921 :                     reconstruct_state,
    4521       426921 :                     &self.cancel,
    4522       426921 :                     &ctx,
    4523              :                 )
    4524       426921 :                 .maybe_perf_instrument(&ctx, |crnt_perf_span| crnt_perf_span.clone())
    4525       426921 :                 .await?
    4526              :             };
    4527              : 
    4528       426921 :             query.remove_overlapping_with(&completed);
    4529              : 
    4530              :             // Do not descend into the ancestor timeline for aux files.
    4531              :             // We don't return a blanket [`GetVectoredError::MissingKey`] to avoid
    4532              :             // stalling compaction.
    4533       426921 :             query.remove_overlapping_with(&KeySpace {
    4534       426921 :                 ranges: vec![NON_INHERITED_RANGE, Key::sparse_non_inherited_keyspace()],
    4535       426921 :             });
    4536              : 
    4537              :             // Keyspace is fully retrieved
    4538       426921 :             if query.is_empty() {
    4539       312254 :                 break None;
    4540       114667 :             }
    4541              : 
    4542       114667 :             let Some(ancestor_timeline) = timeline.ancestor_timeline.as_ref() else {
    4543              :                 // Not fully retrieved but no ancestor timeline.
    4544          183 :                 break Some(query.total_keyspace());
    4545              :             };
    4546              : 
    4547              :             // Now we see if there are keys covered by the image layer but does not exist in the
    4548              :             // image layer, which means that the key does not exist.
    4549              : 
    4550              :             // The block below will stop the vectored search if any of the keys encountered an image layer
    4551              :             // which did not contain a snapshot for said key. Since we have already removed all completed
    4552              :             // keys from `keyspace`, we expect there to be no overlap between it and the image covered key
    4553              :             // space. If that's not the case, we had at least one key encounter a gap in the image layer
    4554              :             // and stop the search as a result of that.
    4555       114484 :             let mut removed = query.remove_overlapping_with(&image_covered_keyspace);
    4556              :             // Do not fire missing key error and end early for sparse keys. Note that we hava already removed
    4557              :             // non-inherited keyspaces before, so we can safely do a full `SPARSE_RANGE` remove instead of
    4558              :             // figuring out what is the inherited key range and do a fine-grained pruning.
    4559       114484 :             removed.remove_overlapping_with(&KeySpace {
    4560       114484 :                 ranges: vec![SPARSE_RANGE],
    4561       114484 :             });
    4562       114484 :             if !removed.is_empty() {
    4563            0 :                 break Some(removed);
    4564       114484 :             }
    4565              : 
    4566              :             // Each key range in the original query is at some point in the LSN space.
    4567              :             // When descending into the ancestor, lower all ranges in the LSN space
    4568              :             // such that new changes on the parent timeline are not visible.
    4569       114484 :             query.lower(timeline.ancestor_lsn);
    4570              : 
    4571       114484 :             let ctx = RequestContextBuilder::from(ctx)
    4572       114484 :                 .perf_span(|crnt_perf_span| {
    4573            0 :                     info_span!(
    4574              :                         target: PERF_TRACE_TARGET,
    4575            0 :                         parent: crnt_perf_span,
    4576              :                         "GET_ANCESTOR",
    4577              :                         timeline = %timeline.timeline_id,
    4578            0 :                         ancestor = %ancestor_timeline.timeline_id,
    4579              :                         ancestor_lsn = %timeline.ancestor_lsn
    4580              :                     )
    4581            0 :                 })
    4582       114484 :                 .attached_child();
    4583              : 
    4584       114484 :             timeline_owned = timeline
    4585       114484 :                 .get_ready_ancestor_timeline(ancestor_timeline, &ctx)
    4586       114484 :                 .maybe_perf_instrument(&ctx, |crnt_perf_span| crnt_perf_span.clone())
    4587       114484 :                 .await?;
    4588       114483 :             timeline = &*timeline_owned;
    4589              :         };
    4590              : 
    4591              :         // Remove sparse keys from the keyspace so that it doesn't fire errors.
    4592       312437 :         let missing_keyspace = if let Some(missing_keyspace) = missing_keyspace {
    4593          183 :             let mut missing_keyspace = missing_keyspace;
    4594          183 :             missing_keyspace.remove_overlapping_with(&KeySpace {
    4595          183 :                 ranges: vec![SPARSE_RANGE],
    4596          183 :             });
    4597          183 :             if missing_keyspace.is_empty() {
    4598          176 :                 None
    4599              :             } else {
    4600            7 :                 Some(missing_keyspace)
    4601              :             }
    4602              :         } else {
    4603       312254 :             None
    4604              :         };
    4605              : 
    4606       312437 :         if let Some(missing_keyspace) = missing_keyspace {
    4607            7 :             return Err(GetVectoredError::MissingKey(Box::new(MissingKeyError {
    4608            7 :                 keyspace: missing_keyspace, /* better if we can store the full keyspace */
    4609            7 :                 shard: self.shard_identity.number,
    4610            7 :                 original_hwm_lsn,
    4611            7 :                 ancestor_lsn: Some(timeline.ancestor_lsn),
    4612            7 :                 backtrace: None,
    4613            7 :                 read_path: std::mem::take(&mut reconstruct_state.read_path),
    4614            7 :                 query: None,
    4615            7 :             })));
    4616       312430 :         }
    4617              : 
    4618       312430 :         Ok(())
    4619       312438 :     }
    4620              : 
    4621       426921 :     async fn get_vectored_init_fringe(
    4622       426921 :         &self,
    4623       426921 :         query: &VersionedKeySpaceQuery,
    4624       426921 :     ) -> Result<LayerFringe, GetVectoredError> {
    4625       426921 :         let mut fringe = LayerFringe::new();
    4626       426921 :         let guard = self.layers.read(LayerManagerLockHolder::GetPage).await;
    4627              : 
    4628       426921 :         match query {
    4629       416729 :             VersionedKeySpaceQuery::Uniform { keyspace, lsn } => {
    4630              :                 // LSNs requested by the compute or determined by the pageserver
    4631              :                 // are inclusive. Queries to the layer map use exclusive LSNs.
    4632              :                 // Hence, bump the value before the query - same in the other
    4633              :                 // match arm.
    4634       416729 :                 let cont_lsn = Lsn(lsn.0 + 1);
    4635       416729 :                 guard.update_search_fringe(keyspace, cont_lsn, &mut fringe)?;
    4636              :             }
    4637        10192 :             VersionedKeySpaceQuery::Scattered { keyspaces_at_lsn } => {
    4638        21108 :                 for (lsn, keyspace) in keyspaces_at_lsn.iter() {
    4639        21108 :                     let cont_lsn_for_keyspace = Lsn(lsn.0 + 1);
    4640        21108 :                     guard.update_search_fringe(keyspace, cont_lsn_for_keyspace, &mut fringe)?;
    4641              :                 }
    4642              :             }
    4643              :         }
    4644              : 
    4645       426921 :         Ok(fringe)
    4646       426921 :     }
    4647              : 
    4648              :     /// Collect the reconstruct data for a keyspace from the specified timeline.
    4649              :     ///
    4650              :     /// Maintain a fringe [`LayerFringe`] which tracks all the layers that intersect
    4651              :     /// the current keyspace. The current keyspace of the search at any given timeline
    4652              :     /// is the original keyspace minus all the keys that have been completed minus
    4653              :     /// any keys for which we couldn't find an intersecting layer. It's not tracked explicitly,
    4654              :     /// but if you merge all the keyspaces in the fringe, you get the "current keyspace".
    4655              :     ///
    4656              :     /// This is basically a depth-first search visitor implementation where a vertex
    4657              :     /// is the (layer, lsn range, key space) tuple. The fringe acts as the stack.
    4658              :     ///
    4659              :     /// At each iteration pop the top of the fringe (the layer with the highest Lsn)
    4660              :     /// and get all the required reconstruct data from the layer in one go.
    4661              :     ///
    4662              :     /// Returns the completed keyspace and the keyspaces with image coverage. The caller
    4663              :     /// decides how to deal with these two keyspaces.
    4664       426921 :     async fn get_vectored_reconstruct_data_timeline(
    4665       426921 :         timeline: &Timeline,
    4666       426921 :         query: &VersionedKeySpaceQuery,
    4667       426921 :         reconstruct_state: &mut ValuesReconstructState,
    4668       426921 :         cancel: &CancellationToken,
    4669       426921 :         ctx: &RequestContext,
    4670       426921 :     ) -> Result<TimelineVisitOutcome, GetVectoredError> {
    4671              :         // Prevent GC from progressing while visiting the current timeline.
    4672              :         // If we are GC-ing because a new image layer was added while traversing
    4673              :         // the timeline, then it will remove layers that are required for fulfilling
    4674              :         // the current get request (read-path cannot "look back" and notice the new
    4675              :         // image layer).
    4676       426921 :         let _gc_cutoff_holder = timeline.get_applied_gc_cutoff_lsn();
    4677              : 
    4678              :         // See `compaction::compact_with_gc` for why we need this.
    4679       426921 :         let _guard = timeline.gc_compaction_layer_update_lock.read().await;
    4680              : 
    4681              :         // Initialize the fringe
    4682       426921 :         let mut fringe = timeline.get_vectored_init_fringe(query).await?;
    4683              : 
    4684       426921 :         let mut completed_keyspace = KeySpace::default();
    4685       426921 :         let mut image_covered_keyspace = KeySpaceRandomAccum::new();
    4686              : 
    4687       873909 :         while let Some((layer_to_read, keyspace_to_read, lsn_range)) = fringe.next_layer() {
    4688       446988 :             if cancel.is_cancelled() {
    4689            0 :                 return Err(GetVectoredError::Cancelled);
    4690       446988 :             }
    4691              : 
    4692       446988 :             if let Some(ref mut read_path) = reconstruct_state.read_path {
    4693       446988 :                 read_path.record_layer_visit(&layer_to_read, &keyspace_to_read, &lsn_range);
    4694       446988 :             }
    4695              : 
    4696              :             // Visit the layer and plan IOs for it
    4697       446988 :             let next_cont_lsn = lsn_range.start;
    4698       446988 :             layer_to_read
    4699       446988 :                 .get_values_reconstruct_data(
    4700       446988 :                     keyspace_to_read.clone(),
    4701       446988 :                     lsn_range,
    4702       446988 :                     reconstruct_state,
    4703       446988 :                     ctx,
    4704       446988 :                 )
    4705       446988 :                 .await?;
    4706              : 
    4707       446988 :             let mut unmapped_keyspace = keyspace_to_read;
    4708       446988 :             let cont_lsn = next_cont_lsn;
    4709              : 
    4710       446988 :             reconstruct_state.on_layer_visited(&layer_to_read);
    4711              : 
    4712       446988 :             let (keys_done_last_step, keys_with_image_coverage) =
    4713       446988 :                 reconstruct_state.consume_done_keys();
    4714       446988 :             unmapped_keyspace.remove_overlapping_with(&keys_done_last_step);
    4715       446988 :             completed_keyspace.merge(&keys_done_last_step);
    4716       446988 :             if let Some(keys_with_image_coverage) = keys_with_image_coverage {
    4717        14229 :                 unmapped_keyspace
    4718        14229 :                     .remove_overlapping_with(&KeySpace::single(keys_with_image_coverage.clone()));
    4719        14229 :                 image_covered_keyspace.add_range(keys_with_image_coverage);
    4720       432759 :             }
    4721              : 
    4722              :             // Query the layer map for the next layers to read.
    4723              :             //
    4724              :             // Do not descent any further if the last layer we visited
    4725              :             // completed all keys in the keyspace it inspected. This is not
    4726              :             // required for correctness, but avoids visiting extra layers
    4727              :             // which turns out to be a perf bottleneck in some cases.
    4728       446988 :             if !unmapped_keyspace.is_empty() {
    4729       130220 :                 let guard = timeline.layers.read(LayerManagerLockHolder::GetPage).await;
    4730       130220 :                 guard.update_search_fringe(&unmapped_keyspace, cont_lsn, &mut fringe)?;
    4731              : 
    4732              :                 // It's safe to drop the layer map lock after planning the next round of reads.
    4733              :                 // The fringe keeps readable handles for the layers which are safe to read even
    4734              :                 // if layers were compacted or flushed.
    4735              :                 //
    4736              :                 // The more interesting consideration is: "Why is the read algorithm still correct
    4737              :                 // if the layer map changes while it is operating?". Doing a vectored read on a
    4738              :                 // timeline boils down to pushing an imaginary lsn boundary downwards for each range
    4739              :                 // covered by the read. The layer map tells us how to move the lsn downwards for a
    4740              :                 // range at *a particular point in time*. It is fine for the answer to be different
    4741              :                 // at two different time points.
    4742       130220 :                 drop(guard);
    4743       316768 :             }
    4744              :         }
    4745              : 
    4746       426921 :         Ok(TimelineVisitOutcome {
    4747       426921 :             completed_keyspace,
    4748       426921 :             image_covered_keyspace: image_covered_keyspace.consume_keyspace(),
    4749       426921 :         })
    4750       426921 :     }
    4751              : 
    4752       114484 :     async fn get_ready_ancestor_timeline(
    4753       114484 :         &self,
    4754       114484 :         ancestor: &Arc<Timeline>,
    4755       114484 :         ctx: &RequestContext,
    4756       114484 :     ) -> Result<Arc<Timeline>, GetReadyAncestorError> {
    4757              :         // It's possible that the ancestor timeline isn't active yet, or
    4758              :         // is active but hasn't yet caught up to the branch point. Wait
    4759              :         // for it.
    4760              :         //
    4761              :         // This cannot happen while the pageserver is running normally,
    4762              :         // because you cannot create a branch from a point that isn't
    4763              :         // present in the pageserver yet. However, we don't wait for the
    4764              :         // branch point to be uploaded to cloud storage before creating
    4765              :         // a branch. I.e., the branch LSN need not be remote consistent
    4766              :         // for the branching operation to succeed.
    4767              :         //
    4768              :         // Hence, if we try to load a tenant in such a state where
    4769              :         // 1. the existence of the branch was persisted (in IndexPart and/or locally)
    4770              :         // 2. but the ancestor state is behind branch_lsn because it was not yet persisted
    4771              :         // then we will need to wait for the ancestor timeline to
    4772              :         // re-stream WAL up to branch_lsn before we access it.
    4773              :         //
    4774              :         // How can a tenant get in such a state?
    4775              :         // - ungraceful pageserver process exit
    4776              :         // - detach+attach => this is a bug, https://github.com/neondatabase/neon/issues/4219
    4777              :         //
    4778              :         // NB: this could be avoided by requiring
    4779              :         //   branch_lsn >= remote_consistent_lsn
    4780              :         // during branch creation.
    4781       114484 :         match ancestor.wait_to_become_active(ctx).await {
    4782       114483 :             Ok(()) => {}
    4783              :             Err(TimelineState::Stopping) => {
    4784              :                 // If an ancestor is stopping, it means the tenant is stopping: handle this the same as if this timeline was stopping.
    4785            0 :                 return Err(GetReadyAncestorError::Cancelled);
    4786              :             }
    4787            1 :             Err(state) => {
    4788            1 :                 return Err(GetReadyAncestorError::BadState {
    4789            1 :                     timeline_id: ancestor.timeline_id,
    4790            1 :                     state,
    4791            1 :                 });
    4792              :             }
    4793              :         }
    4794       114483 :         ancestor
    4795       114483 :             .wait_lsn(
    4796       114483 :                 self.ancestor_lsn,
    4797       114483 :                 WaitLsnWaiter::Timeline(self),
    4798       114483 :                 WaitLsnTimeout::Default,
    4799       114483 :                 ctx,
    4800       114483 :             )
    4801       114483 :             .await
    4802       114483 :             .map_err(|e| match e {
    4803            0 :                 e @ WaitLsnError::Timeout(_) => GetReadyAncestorError::AncestorLsnTimeout(e),
    4804            0 :                 WaitLsnError::Shutdown => GetReadyAncestorError::Cancelled,
    4805            0 :                 WaitLsnError::BadState(state) => GetReadyAncestorError::BadState {
    4806            0 :                     timeline_id: ancestor.timeline_id,
    4807            0 :                     state,
    4808            0 :                 },
    4809            0 :             })?;
    4810              : 
    4811       114483 :         Ok(ancestor.clone())
    4812       114484 :     }
    4813              : 
    4814       148592 :     pub(crate) fn get_shard_identity(&self) -> &ShardIdentity {
    4815       148592 :         &self.shard_identity
    4816       148592 :     }
    4817              : 
    4818              :     #[inline(always)]
    4819            0 :     pub(crate) fn shard_timeline_id(&self) -> ShardTimelineId {
    4820            0 :         ShardTimelineId {
    4821            0 :             shard_index: ShardIndex {
    4822            0 :                 shard_number: self.shard_identity.number,
    4823            0 :                 shard_count: self.shard_identity.count,
    4824            0 :             },
    4825            0 :             timeline_id: self.timeline_id,
    4826            0 :         }
    4827            0 :     }
    4828              : 
    4829              :     /// Returns a non-frozen open in-memory layer for ingestion.
    4830              :     ///
    4831              :     /// Takes a witness of timeline writer state lock being held, because it makes no sense to call
    4832              :     /// this function without holding the mutex.
    4833          660 :     async fn get_layer_for_write(
    4834          660 :         &self,
    4835          660 :         lsn: Lsn,
    4836          660 :         _guard: &tokio::sync::MutexGuard<'_, Option<TimelineWriterState>>,
    4837          660 :         ctx: &RequestContext,
    4838          660 :     ) -> anyhow::Result<Arc<InMemoryLayer>> {
    4839          660 :         let mut guard = self
    4840          660 :             .layers
    4841          660 :             .write(LayerManagerLockHolder::GetLayerForWrite)
    4842          660 :             .await;
    4843              : 
    4844          660 :         let last_record_lsn = self.get_last_record_lsn();
    4845          660 :         ensure!(
    4846          660 :             lsn > last_record_lsn,
    4847            0 :             "cannot modify relation after advancing last_record_lsn (incoming_lsn={}, last_record_lsn={})",
    4848              :             lsn,
    4849              :             last_record_lsn,
    4850              :         );
    4851              : 
    4852          660 :         let layer = guard
    4853          660 :             .open_mut()?
    4854          660 :             .get_layer_for_write(
    4855          660 :                 lsn,
    4856          660 :                 self.conf,
    4857          660 :                 self.timeline_id,
    4858          660 :                 self.tenant_shard_id,
    4859          660 :                 &self.gate,
    4860          660 :                 &self.cancel,
    4861          660 :                 ctx,
    4862              :             )
    4863          660 :             .await?;
    4864          660 :         Ok(layer)
    4865          660 :     }
    4866              : 
    4867      2639560 :     pub(crate) fn finish_write(&self, new_lsn: Lsn) {
    4868      2639560 :         assert!(new_lsn.is_aligned());
    4869              : 
    4870      2639560 :         self.metrics.last_record_lsn_gauge.set(new_lsn.0 as i64);
    4871      2639560 :         self.last_record_lsn.advance(new_lsn);
    4872      2639560 :     }
    4873              : 
    4874              :     /// Freeze any existing open in-memory layer and unconditionally notify the flush loop.
    4875              :     ///
    4876              :     /// Unconditional flush loop notification is given because in sharded cases we will want to
    4877              :     /// leave an Lsn gap. Unsharded tenants do not have Lsn gaps.
    4878          611 :     async fn freeze_inmem_layer_at(
    4879          611 :         &self,
    4880          611 :         at: Lsn,
    4881          611 :         write_lock: &mut tokio::sync::MutexGuard<'_, Option<TimelineWriterState>>,
    4882          611 :     ) -> Result<u64, FlushLayerError> {
    4883          611 :         let frozen = {
    4884          611 :             let mut guard = self
    4885          611 :                 .layers
    4886          611 :                 .write(LayerManagerLockHolder::TryFreezeLayer)
    4887          611 :                 .await;
    4888          611 :             guard
    4889          611 :                 .open_mut()?
    4890          611 :                 .try_freeze_in_memory_layer(at, &self.last_freeze_at, write_lock, &self.metrics)
    4891          611 :                 .await
    4892              :         };
    4893              : 
    4894          611 :         if frozen {
    4895          597 :             let now = Instant::now();
    4896          597 :             *(self.last_freeze_ts.write().unwrap()) = now;
    4897          597 :         }
    4898              : 
    4899              :         // Increment the flush cycle counter and wake up the flush task.
    4900              :         // Remember the new value, so that when we listen for the flush
    4901              :         // to finish, we know when the flush that we initiated has
    4902              :         // finished, instead of some other flush that was started earlier.
    4903          611 :         let mut my_flush_request = 0;
    4904              : 
    4905          611 :         let flush_loop_state = { *self.flush_loop_state.lock().unwrap() };
    4906          611 :         if !matches!(flush_loop_state, FlushLoopState::Running { .. }) {
    4907            0 :             return Err(FlushLayerError::NotRunning(flush_loop_state));
    4908          611 :         }
    4909              : 
    4910          611 :         self.layer_flush_start_tx.send_modify(|(counter, lsn)| {
    4911          611 :             my_flush_request = *counter + 1;
    4912          611 :             *counter = my_flush_request;
    4913          611 :             *lsn = std::cmp::max(at, *lsn);
    4914          611 :         });
    4915              : 
    4916          611 :         assert_ne!(my_flush_request, 0);
    4917              : 
    4918          611 :         Ok(my_flush_request)
    4919          611 :     }
    4920              : 
    4921              :     /// Layer flusher task's main loop.
    4922          232 :     async fn flush_loop(
    4923          232 :         self: &Arc<Self>,
    4924          232 :         mut layer_flush_start_rx: tokio::sync::watch::Receiver<(u64, Lsn)>,
    4925          232 :         ctx: &RequestContext,
    4926          232 :     ) {
    4927              :         // Always notify waiters about the flush loop exiting since the loop might stop
    4928              :         // when the timeline hasn't been cancelled.
    4929          232 :         let scopeguard_rx = layer_flush_start_rx.clone();
    4930          232 :         scopeguard::defer! {
    4931              :             let (flush_counter, _) = *scopeguard_rx.borrow();
    4932              :             let _ = self
    4933              :                 .layer_flush_done_tx
    4934              :                 .send_replace((flush_counter, Err(FlushLayerError::Cancelled)));
    4935              :         }
    4936              : 
    4937              :         // Subscribe to L0 delta layer updates, for compaction backpressure.
    4938          232 :         let mut watch_l0 = match self
    4939          232 :             .layers
    4940          232 :             .read(LayerManagerLockHolder::FlushLoop)
    4941          232 :             .await
    4942          232 :             .layer_map()
    4943              :         {
    4944          232 :             Ok(lm) => lm.watch_level0_deltas(),
    4945            0 :             Err(Shutdown) => return,
    4946              :         };
    4947              : 
    4948          232 :         info!("started flush loop");
    4949              :         loop {
    4950          833 :             tokio::select! {
    4951          833 :                 _ = self.cancel.cancelled() => {
    4952            5 :                     info!("shutting down layer flush task due to Timeline::cancel");
    4953            5 :                     break;
    4954              :                 },
    4955          833 :                 _ = layer_flush_start_rx.changed() => {}
    4956              :             }
    4957          601 :             trace!("waking up");
    4958          601 :             let (flush_counter, frozen_to_lsn) = *layer_flush_start_rx.borrow();
    4959              : 
    4960              :             // The highest LSN to which we flushed in the loop over frozen layers
    4961          601 :             let mut flushed_to_lsn = Lsn(0);
    4962              : 
    4963          601 :             let result = loop {
    4964         1197 :                 if self.cancel.is_cancelled() {
    4965            0 :                     info!("dropping out of flush loop for timeline shutdown");
    4966            0 :                     return;
    4967         1197 :                 }
    4968              : 
    4969              :                 // Break to notify potential waiters as soon as we've flushed the requested LSN. If
    4970              :                 // more requests have arrived in the meanwhile, we'll resume flushing afterwards.
    4971         1197 :                 if flushed_to_lsn >= frozen_to_lsn {
    4972          586 :                     break Ok(());
    4973          611 :                 }
    4974              : 
    4975              :                 // Fetch the next layer to flush, if any.
    4976          611 :                 let (layer, l0_count, frozen_count, frozen_size, open_layer_size) = {
    4977          611 :                     let layers = self.layers.read(LayerManagerLockHolder::FlushLoop).await;
    4978          611 :                     let Ok(lm) = layers.layer_map() else {
    4979            0 :                         info!("dropping out of flush loop for timeline shutdown");
    4980            0 :                         return;
    4981              :                     };
    4982          611 :                     let l0_count = lm.level0_deltas().len();
    4983          611 :                     let frozen_count = lm.frozen_layers.len();
    4984          611 :                     let frozen_size: u64 = lm
    4985          611 :                         .frozen_layers
    4986          611 :                         .iter()
    4987          611 :                         .map(|l| l.estimated_in_mem_size())
    4988          611 :                         .sum();
    4989          611 :                     let open_layer_size: u64 = lm
    4990          611 :                         .open_layer
    4991          611 :                         .as_ref()
    4992          611 :                         .map(|l| l.estimated_in_mem_size())
    4993          611 :                         .unwrap_or(0);
    4994          611 :                     let layer = lm.frozen_layers.front().cloned();
    4995          611 :                     (layer, l0_count, frozen_count, frozen_size, open_layer_size)
    4996              :                     // drop 'layers' lock
    4997              :                 };
    4998          611 :                 let Some(layer) = layer else {
    4999           14 :                     break Ok(());
    5000              :                 };
    5001              : 
    5002              :                 // Stall flushes to backpressure if compaction can't keep up. This is propagated up
    5003              :                 // to WAL ingestion by having ephemeral layer rolls wait for flushes.
    5004          597 :                 if let Some(stall_threshold) = self.get_l0_flush_stall_threshold() {
    5005            0 :                     if l0_count >= stall_threshold {
    5006            0 :                         warn!(
    5007            0 :                             "stalling layer flushes for compaction backpressure at {l0_count} \
    5008            0 :                             L0 layers ({frozen_count} frozen layers with {frozen_size} bytes, {open_layer_size} bytes in open layer)"
    5009              :                         );
    5010            0 :                         let stall_timer = self
    5011            0 :                             .metrics
    5012            0 :                             .flush_delay_histo
    5013            0 :                             .start_timer()
    5014            0 :                             .record_on_drop();
    5015            0 :                         tokio::select! {
    5016            0 :                             result = watch_l0.wait_for(|l0| *l0 < stall_threshold) => {
    5017            0 :                                 if let Ok(l0) = result.as_deref() {
    5018            0 :                                     let delay = stall_timer.elapsed().as_secs_f64();
    5019            0 :                                     info!("resuming layer flushes at {l0} L0 layers after {delay:.3}s");
    5020            0 :                                 }
    5021              :                             },
    5022            0 :                             _ = self.cancel.cancelled() => {},
    5023              :                         }
    5024            0 :                         continue; // check again
    5025            0 :                     }
    5026          597 :                 }
    5027              : 
    5028              :                 // Flush the layer.
    5029          597 :                 let flush_timer = self.metrics.flush_time_histo.start_timer();
    5030          597 :                 match self.flush_frozen_layer(layer, ctx).await {
    5031          596 :                     Ok(layer_lsn) => flushed_to_lsn = max(flushed_to_lsn, layer_lsn),
    5032              :                     Err(FlushLayerError::Cancelled) => {
    5033            0 :                         info!("dropping out of flush loop for timeline shutdown");
    5034            0 :                         return;
    5035              :                     }
    5036            1 :                     err @ Err(
    5037              :                         FlushLayerError::NotRunning(_)
    5038              :                         | FlushLayerError::Other(_)
    5039              :                         | FlushLayerError::CreateImageLayersError(_),
    5040              :                     ) => {
    5041            1 :                         error!("could not flush frozen layer: {err:?}");
    5042            1 :                         break err.map(|_| ());
    5043              :                     }
    5044              :                 }
    5045          596 :                 let flush_duration = flush_timer.stop_and_record();
    5046              : 
    5047              :                 // Notify the tenant compaction loop if L0 compaction is needed.
    5048          596 :                 let l0_count = *watch_l0.borrow();
    5049          596 :                 if l0_count >= self.get_compaction_threshold() {
    5050          238 :                     self.l0_compaction_trigger.notify_one();
    5051          358 :                 }
    5052              : 
    5053              :                 // Delay the next flush to backpressure if compaction can't keep up. We delay by the
    5054              :                 // flush duration such that the flush takes 2x as long. This is propagated up to WAL
    5055              :                 // ingestion by having ephemeral layer rolls wait for flushes.
    5056          596 :                 if let Some(delay_threshold) = self.get_l0_flush_delay_threshold() {
    5057            4 :                     if l0_count >= delay_threshold {
    5058            0 :                         let delay = flush_duration.as_secs_f64();
    5059            0 :                         info!(
    5060            0 :                             "delaying layer flush by {delay:.3}s for compaction backpressure at \
    5061            0 :                             {l0_count} L0 layers ({frozen_count} frozen layers with {frozen_size} bytes, {open_layer_size} bytes in open layer)"
    5062              :                         );
    5063            0 :                         let _delay_timer = self
    5064            0 :                             .metrics
    5065            0 :                             .flush_delay_histo
    5066            0 :                             .start_timer()
    5067            0 :                             .record_on_drop();
    5068            0 :                         tokio::select! {
    5069            0 :                             _ = tokio::time::sleep(flush_duration) => {},
    5070            0 :                             _ = watch_l0.wait_for(|l0| *l0 < delay_threshold) => {},
    5071            0 :                             _ = self.cancel.cancelled() => {},
    5072              :                         }
    5073            4 :                     }
    5074          592 :                 }
    5075              :             };
    5076              : 
    5077              :             // Unsharded tenants should never advance their LSN beyond the end of the
    5078              :             // highest layer they write: such gaps between layer data and the frozen LSN
    5079              :             // are only legal on sharded tenants.
    5080          601 :             debug_assert!(
    5081          601 :                 self.shard_identity.count.count() > 1
    5082          594 :                     || flushed_to_lsn >= frozen_to_lsn
    5083           14 :                     || !flushed_to_lsn.is_valid()
    5084              :             );
    5085              : 
    5086          601 :             if flushed_to_lsn < frozen_to_lsn
    5087           15 :                 && self.shard_identity.count.count() > 1
    5088            1 :                 && result.is_ok()
    5089              :             {
    5090              :                 // If our layer flushes didn't carry disk_consistent_lsn up to the `to_lsn` advertised
    5091              :                 // to us via layer_flush_start_rx, then advance it here.
    5092              :                 //
    5093              :                 // This path is only taken for tenants with multiple shards: single sharded tenants should
    5094              :                 // never encounter a gap in the wal.
    5095            0 :                 let old_disk_consistent_lsn = self.disk_consistent_lsn.load();
    5096            0 :                 tracing::debug!(
    5097            0 :                     "Advancing disk_consistent_lsn across layer gap {old_disk_consistent_lsn}->{frozen_to_lsn}"
    5098              :                 );
    5099            0 :                 if self.set_disk_consistent_lsn(frozen_to_lsn) {
    5100            0 :                     if let Err(e) = self.schedule_uploads(frozen_to_lsn, vec![]) {
    5101            0 :                         tracing::warn!(
    5102            0 :                             "Failed to schedule metadata upload after updating disk_consistent_lsn: {e}"
    5103              :                         );
    5104            0 :                     }
    5105            0 :                 }
    5106          601 :             }
    5107              : 
    5108              :             // Notify any listeners that we're done
    5109          601 :             let _ = self
    5110          601 :                 .layer_flush_done_tx
    5111          601 :                 .send_replace((flush_counter, result));
    5112              :         }
    5113            5 :     }
    5114              : 
    5115              :     /// Waits any flush request created by [`Self::freeze_inmem_layer_at`] to complete.
    5116          571 :     async fn wait_flush_completion(&self, request: u64) -> Result<(), FlushLayerError> {
    5117          571 :         let mut rx = self.layer_flush_done_tx.subscribe();
    5118              :         loop {
    5119              :             {
    5120         1160 :                 let (last_result_counter, last_result) = &*rx.borrow();
    5121         1160 :                 if *last_result_counter >= request {
    5122          571 :                     if let Err(err) = last_result {
    5123              :                         // We already logged the original error in
    5124              :                         // flush_loop. We cannot propagate it to the caller
    5125              :                         // here, because it might not be Cloneable
    5126            1 :                         return Err(err.clone());
    5127              :                     } else {
    5128          570 :                         return Ok(());
    5129              :                     }
    5130          589 :                 }
    5131              :             }
    5132          589 :             trace!("waiting for flush to complete");
    5133          589 :             tokio::select! {
    5134          589 :                 rx_e = rx.changed() => {
    5135          589 :                     rx_e.map_err(|_| FlushLayerError::NotRunning(*self.flush_loop_state.lock().unwrap()))?;
    5136              :                 },
    5137              :                 // Cancellation safety: we are not leaving an I/O in-flight for the flush, we're just ignoring
    5138              :                 // the notification from [`flush_loop`] that it completed.
    5139          589 :                 _ = self.cancel.cancelled() => {
    5140            0 :                     tracing::info!("Cancelled layer flush due on timeline shutdown");
    5141            0 :                     return Ok(())
    5142              :                 }
    5143              :             };
    5144          589 :             trace!("done")
    5145              :         }
    5146          571 :     }
    5147              : 
    5148              :     /// Flush one frozen in-memory layer to disk, as a new delta layer.
    5149              :     ///
    5150              :     /// Return value is the last lsn (inclusive) of the layer that was frozen.
    5151              :     #[instrument(skip_all, fields(layer=%frozen_layer))]
    5152              :     async fn flush_frozen_layer(
    5153              :         self: &Arc<Self>,
    5154              :         frozen_layer: Arc<InMemoryLayer>,
    5155              :         ctx: &RequestContext,
    5156              :     ) -> Result<Lsn, FlushLayerError> {
    5157              :         debug_assert_current_span_has_tenant_and_timeline_id();
    5158              : 
    5159              :         // As a special case, when we have just imported an image into the repository,
    5160              :         // instead of writing out a L0 delta layer, we directly write out image layer
    5161              :         // files instead. This is possible as long as *all* the data imported into the
    5162              :         // repository have the same LSN.
    5163              :         let lsn_range = frozen_layer.get_lsn_range();
    5164              : 
    5165              :         // Whether to directly create image layers for this flush, or flush them as delta layers
    5166              :         let create_image_layer =
    5167              :             lsn_range.start == self.initdb_lsn && lsn_range.end == Lsn(self.initdb_lsn.0 + 1);
    5168              : 
    5169              :         #[cfg(test)]
    5170              :         {
    5171              :             match &mut *self.flush_loop_state.lock().unwrap() {
    5172              :                 FlushLoopState::NotStarted | FlushLoopState::Exited => {
    5173              :                     panic!("flush loop not running")
    5174              :                 }
    5175              :                 FlushLoopState::Running {
    5176              :                     expect_initdb_optimization,
    5177              :                     initdb_optimization_count,
    5178              :                     ..
    5179              :                 } => {
    5180              :                     if create_image_layer {
    5181              :                         *initdb_optimization_count += 1;
    5182              :                     } else {
    5183              :                         assert!(!*expect_initdb_optimization, "expected initdb optimization");
    5184              :                     }
    5185              :                 }
    5186              :             }
    5187              :         }
    5188              : 
    5189              :         let (layers_to_upload, delta_layer_to_add) = if create_image_layer {
    5190              :             // Note: The 'ctx' in use here has DownloadBehavior::Error. We should not
    5191              :             // require downloading anything during initial import.
    5192              :             let ((rel_partition, metadata_partition), _lsn) = self
    5193              :                 .repartition(
    5194              :                     self.initdb_lsn,
    5195              :                     self.get_compaction_target_size(),
    5196              :                     EnumSet::empty(),
    5197              :                     ctx,
    5198              :                 )
    5199              :                 .await
    5200            0 :                 .map_err(|e| FlushLayerError::from_anyhow(self, e.into_anyhow()))?;
    5201              : 
    5202              :             if self.cancel.is_cancelled() {
    5203              :                 return Err(FlushLayerError::Cancelled);
    5204              :             }
    5205              : 
    5206              :             // Ensure that we have a single call to `create_image_layers` with a combined dense keyspace.
    5207              :             // So that the key ranges don't overlap.
    5208              :             let mut partitions = KeyPartitioning::default();
    5209              :             partitions.parts.extend(rel_partition.parts);
    5210              :             if !metadata_partition.parts.is_empty() {
    5211              :                 assert_eq!(
    5212              :                     metadata_partition.parts.len(),
    5213              :                     1,
    5214              :                     "currently sparse keyspace should only contain a single metadata keyspace"
    5215              :                 );
    5216              :                 // Safety: create_image_layers treat sparse keyspaces differently that it does not scan
    5217              :                 // every single key within the keyspace, and therefore, it's safe to force converting it
    5218              :                 // into a dense keyspace before calling this function.
    5219              :                 partitions
    5220              :                     .parts
    5221              :                     .extend(metadata_partition.into_dense().parts);
    5222              :             }
    5223              : 
    5224              :             let mut layers_to_upload = Vec::new();
    5225              :             let (generated_image_layers, is_complete) = self
    5226              :                 .create_image_layers(
    5227              :                     &partitions,
    5228              :                     self.initdb_lsn,
    5229              :                     None,
    5230              :                     ImageLayerCreationMode::Initial,
    5231              :                     ctx,
    5232              :                     LastImageLayerCreationStatus::Initial,
    5233              :                     false, // don't yield for L0, we're flushing L0
    5234              :                 )
    5235              :                 .instrument(info_span!("create_image_layers", mode = %ImageLayerCreationMode::Initial, partition_mode = "initial", lsn = %self.initdb_lsn))
    5236              :                 .await?;
    5237              :             debug_assert!(
    5238              :                 matches!(is_complete, LastImageLayerCreationStatus::Complete),
    5239              :                 "init image generation mode must fully cover the keyspace"
    5240              :             );
    5241              :             layers_to_upload.extend(generated_image_layers);
    5242              : 
    5243              :             (layers_to_upload, None)
    5244              :         } else {
    5245              :             // Normal case, write out a L0 delta layer file.
    5246              :             // `create_delta_layer` will not modify the layer map.
    5247              :             // We will remove frozen layer and add delta layer in one atomic operation later.
    5248              :             let Some(layer) = self
    5249              :                 .create_delta_layer(&frozen_layer, None, ctx)
    5250              :                 .await
    5251            0 :                 .map_err(|e| FlushLayerError::from_anyhow(self, e))?
    5252              :             else {
    5253              :                 panic!("delta layer cannot be empty if no filter is applied");
    5254              :             };
    5255              :             (
    5256              :                 // FIXME: even though we have a single image and single delta layer assumption
    5257              :                 // we push them to vec
    5258              :                 vec![layer.clone()],
    5259              :                 Some(layer),
    5260              :             )
    5261              :         };
    5262              : 
    5263              :         pausable_failpoint!("flush-layer-cancel-after-writing-layer-out-pausable");
    5264              : 
    5265              :         if self.cancel.is_cancelled() {
    5266              :             return Err(FlushLayerError::Cancelled);
    5267              :         }
    5268              : 
    5269            1 :         fail_point!("flush-layer-before-update-remote-consistent-lsn", |_| {
    5270            1 :             Err(FlushLayerError::Other(anyhow!("failpoint").into()))
    5271            1 :         });
    5272              : 
    5273              :         let disk_consistent_lsn = Lsn(lsn_range.end.0 - 1);
    5274              : 
    5275              :         // The new on-disk layers are now in the layer map. We can remove the
    5276              :         // in-memory layer from the map now. The flushed layer is stored in
    5277              :         // the mapping in `create_delta_layer`.
    5278              :         {
    5279              :             let mut guard = self
    5280              :                 .layers
    5281              :                 .write(LayerManagerLockHolder::FlushFrozenLayer)
    5282              :                 .await;
    5283              : 
    5284              :             guard.open_mut()?.finish_flush_l0_layer(
    5285              :                 delta_layer_to_add.as_ref(),
    5286              :                 &frozen_layer,
    5287              :                 &self.metrics,
    5288              :             );
    5289              : 
    5290              :             if self.set_disk_consistent_lsn(disk_consistent_lsn) {
    5291              :                 // Schedule remote uploads that will reflect our new disk_consistent_lsn
    5292              :                 self.schedule_uploads(disk_consistent_lsn, layers_to_upload)
    5293            0 :                     .map_err(|e| FlushLayerError::from_anyhow(self, e))?;
    5294              :             }
    5295              :             // release lock on 'layers'
    5296              :         };
    5297              : 
    5298              :         // FIXME: between create_delta_layer and the scheduling of the upload in `update_metadata_file`,
    5299              :         // a compaction can delete the file and then it won't be available for uploads any more.
    5300              :         // We still schedule the upload, resulting in an error, but ideally we'd somehow avoid this
    5301              :         // race situation.
    5302              :         // See https://github.com/neondatabase/neon/issues/4526
    5303              :         pausable_failpoint!("flush-frozen-pausable");
    5304              : 
    5305              :         // This failpoint is used by another test case `test_pageserver_recovery`.
    5306              :         fail_point!("flush-frozen-exit");
    5307              : 
    5308              :         Ok(Lsn(lsn_range.end.0 - 1))
    5309              :     }
    5310              : 
    5311              :     /// Return true if the value changed
    5312              :     ///
    5313              :     /// This function must only be used from the layer flush task.
    5314          596 :     fn set_disk_consistent_lsn(&self, new_value: Lsn) -> bool {
    5315          596 :         let old_value = self.disk_consistent_lsn.fetch_max(new_value);
    5316          596 :         assert!(
    5317          596 :             new_value >= old_value,
    5318            0 :             "disk_consistent_lsn must be growing monotonously at runtime; current {old_value}, offered {new_value}"
    5319              :         );
    5320              : 
    5321          596 :         self.metrics
    5322          596 :             .disk_consistent_lsn_gauge
    5323          596 :             .set(new_value.0 as i64);
    5324          596 :         new_value != old_value
    5325          596 :     }
    5326              : 
    5327              :     /// Update metadata file
    5328          623 :     fn schedule_uploads(
    5329          623 :         &self,
    5330          623 :         disk_consistent_lsn: Lsn,
    5331          623 :         layers_to_upload: impl IntoIterator<Item = ResidentLayer>,
    5332          623 :     ) -> anyhow::Result<()> {
    5333              :         // We can only save a valid 'prev_record_lsn' value on disk if we
    5334              :         // flushed *all* in-memory changes to disk. We only track
    5335              :         // 'prev_record_lsn' in memory for the latest processed record, so we
    5336              :         // don't remember what the correct value that corresponds to some old
    5337              :         // LSN is. But if we flush everything, then the value corresponding
    5338              :         // current 'last_record_lsn' is correct and we can store it on disk.
    5339              :         let RecordLsn {
    5340          623 :             last: last_record_lsn,
    5341          623 :             prev: prev_record_lsn,
    5342          623 :         } = self.last_record_lsn.load();
    5343          623 :         let ondisk_prev_record_lsn = if disk_consistent_lsn == last_record_lsn {
    5344          559 :             Some(prev_record_lsn)
    5345              :         } else {
    5346           64 :             None
    5347              :         };
    5348              : 
    5349          623 :         let update = crate::tenant::metadata::MetadataUpdate::new(
    5350          623 :             disk_consistent_lsn,
    5351          623 :             ondisk_prev_record_lsn,
    5352          623 :             *self.applied_gc_cutoff_lsn.read(),
    5353              :         );
    5354              : 
    5355          623 :         fail_point!("checkpoint-before-saving-metadata", |x| bail!(
    5356            0 :             "{}",
    5357            0 :             x.unwrap()
    5358              :         ));
    5359              : 
    5360         1225 :         for layer in layers_to_upload {
    5361          602 :             self.remote_client.schedule_layer_file_upload(layer)?;
    5362              :         }
    5363          623 :         self.remote_client
    5364          623 :             .schedule_index_upload_for_metadata_update(&update)?;
    5365              : 
    5366          623 :         Ok(())
    5367          623 :     }
    5368              : 
    5369            0 :     pub(crate) async fn preserve_initdb_archive(&self) -> anyhow::Result<()> {
    5370            0 :         self.remote_client
    5371            0 :             .preserve_initdb_archive(
    5372            0 :                 &self.tenant_shard_id.tenant_id,
    5373            0 :                 &self.timeline_id,
    5374            0 :                 &self.cancel,
    5375            0 :             )
    5376            0 :             .await
    5377            0 :     }
    5378              : 
    5379              :     // Write out the given frozen in-memory layer as a new L0 delta file. This L0 file will not be tracked
    5380              :     // in layer map immediately. The caller is responsible to put it into the layer map.
    5381          486 :     async fn create_delta_layer(
    5382          486 :         self: &Arc<Self>,
    5383          486 :         frozen_layer: &Arc<InMemoryLayer>,
    5384          486 :         key_range: Option<Range<Key>>,
    5385          486 :         ctx: &RequestContext,
    5386          486 :     ) -> anyhow::Result<Option<ResidentLayer>> {
    5387          486 :         let self_clone = Arc::clone(self);
    5388          486 :         let frozen_layer = Arc::clone(frozen_layer);
    5389          486 :         let ctx = ctx.attached_child();
    5390          486 :         let work = async move {
    5391          486 :             let Some((desc, path)) = frozen_layer
    5392          486 :                 .write_to_disk(
    5393          486 :                     &ctx,
    5394          486 :                     key_range,
    5395          486 :                     self_clone.l0_flush_global_state.inner(),
    5396          486 :                     &self_clone.gate,
    5397          486 :                     self_clone.cancel.clone(),
    5398          486 :                 )
    5399          486 :                 .await?
    5400              :             else {
    5401            0 :                 return Ok(None);
    5402              :             };
    5403          486 :             let new_delta = Layer::finish_creating(self_clone.conf, &self_clone, desc, &path)?;
    5404              : 
    5405              :             // The write_to_disk() above calls writer.finish() which already did the fsync of the inodes.
    5406              :             // We just need to fsync the directory in which these inodes are linked,
    5407              :             // which we know to be the timeline directory.
    5408              :             //
    5409              :             // We use fatal_err() below because the after write_to_disk returns with success,
    5410              :             // the in-memory state of the filesystem already has the layer file in its final place,
    5411              :             // and subsequent pageserver code could think it's durable while it really isn't.
    5412          486 :             let timeline_dir = VirtualFile::open(
    5413          486 :                 &self_clone
    5414          486 :                     .conf
    5415          486 :                     .timeline_path(&self_clone.tenant_shard_id, &self_clone.timeline_id),
    5416          486 :                 &ctx,
    5417          486 :             )
    5418          486 :             .await
    5419          486 :             .fatal_err("VirtualFile::open for timeline dir fsync");
    5420          486 :             timeline_dir
    5421          486 :                 .sync_all()
    5422          486 :                 .await
    5423          486 :                 .fatal_err("VirtualFile::sync_all timeline dir");
    5424          486 :             anyhow::Ok(Some(new_delta))
    5425          486 :         };
    5426              :         // Before tokio-epoll-uring, we ran write_to_disk & the sync_all inside spawn_blocking.
    5427              :         // Preserve that behavior to maintain the same behavior for `virtual_file_io_engine=std-fs`.
    5428              :         use crate::virtual_file::io_engine::IoEngine;
    5429          486 :         match crate::virtual_file::io_engine::get() {
    5430            0 :             IoEngine::NotSet => panic!("io engine not set"),
    5431              :             IoEngine::StdFs => {
    5432            0 :                 let span = tracing::info_span!("blocking");
    5433            0 :                 tokio::task::spawn_blocking({
    5434            0 :                     move || Handle::current().block_on(work.instrument(span))
    5435              :                 })
    5436            0 :                 .await
    5437            0 :                 .context("spawn_blocking")
    5438            0 :                 .and_then(|x| x)
    5439              :             }
    5440              :             #[cfg(target_os = "linux")]
    5441          486 :             IoEngine::TokioEpollUring => work.await,
    5442              :         }
    5443          486 :     }
    5444              : 
    5445          303 :     async fn repartition(
    5446          303 :         &self,
    5447          303 :         lsn: Lsn,
    5448          303 :         partition_size: u64,
    5449          303 :         flags: EnumSet<CompactFlags>,
    5450          303 :         ctx: &RequestContext,
    5451          303 :     ) -> Result<((KeyPartitioning, SparseKeyPartitioning), Lsn), RepartitionError> {
    5452          303 :         let Ok(mut guard) = self.partitioning.try_write_guard() else {
    5453              :             // NB: there are two callers, one is the compaction task, of which there is only one per struct Tenant and hence Timeline.
    5454              :             // The other is the initdb optimization in flush_frozen_layer, used by `boostrap_timeline`, which runs before `.activate()`
    5455              :             // and hence before the compaction task starts.
    5456            0 :             return Err(RepartitionError::Other(anyhow!(
    5457            0 :                 "repartition() called concurrently"
    5458            0 :             )));
    5459              :         };
    5460          303 :         let ((dense_partition, sparse_partition), partition_lsn) = &*guard.read();
    5461          303 :         if lsn < *partition_lsn {
    5462            0 :             return Err(RepartitionError::Other(anyhow!(
    5463            0 :                 "repartition() called with LSN going backwards, this should not happen"
    5464            0 :             )));
    5465          303 :         }
    5466              : 
    5467          303 :         let distance = lsn.0 - partition_lsn.0;
    5468          303 :         if *partition_lsn != Lsn(0)
    5469          141 :             && distance <= self.repartition_threshold
    5470          141 :             && !flags.contains(CompactFlags::ForceRepartition)
    5471              :         {
    5472          134 :             debug!(
    5473              :                 distance,
    5474              :                 threshold = self.repartition_threshold,
    5475            0 :                 "no repartitioning needed"
    5476              :             );
    5477          134 :             return Ok((
    5478          134 :                 (dense_partition.clone(), sparse_partition.clone()),
    5479          134 :                 *partition_lsn,
    5480          134 :             ));
    5481          169 :         }
    5482              : 
    5483          169 :         let (dense_ks, sparse_ks) = self
    5484          169 :             .collect_keyspace(lsn, ctx)
    5485          169 :             .await
    5486          169 :             .map_err(RepartitionError::CollectKeyspace)?;
    5487          169 :         let dense_partitioning = dense_ks.partition(
    5488          169 :             &self.shard_identity,
    5489          169 :             partition_size,
    5490          169 :             postgres_ffi::BLCKSZ as u64,
    5491              :         );
    5492          169 :         let sparse_partitioning = SparseKeyPartitioning {
    5493          169 :             parts: vec![sparse_ks],
    5494          169 :         }; // no partitioning for metadata keys for now
    5495          169 :         let result = ((dense_partitioning, sparse_partitioning), lsn);
    5496          169 :         guard.write(result.clone());
    5497          169 :         Ok(result)
    5498          303 :     }
    5499              : 
    5500              :     // Is it time to create a new image layer for the given partition? True if we want to generate.
    5501           57 :     async fn time_for_new_image_layer(
    5502           57 :         &self,
    5503           57 :         partition: &KeySpace,
    5504           57 :         lsn: Lsn,
    5505           57 :         force_image_creation_lsn: Option<Lsn>,
    5506           57 :     ) -> bool {
    5507           57 :         let threshold = self.get_image_creation_threshold();
    5508              : 
    5509           57 :         let guard = self.layers.read(LayerManagerLockHolder::Compaction).await;
    5510           57 :         let Ok(layers) = guard.layer_map() else {
    5511            0 :             return false;
    5512              :         };
    5513           57 :         let mut min_image_lsn: Lsn = Lsn::MAX;
    5514           57 :         let mut max_deltas = 0;
    5515          364 :         for part_range in &partition.ranges {
    5516          307 :             let image_coverage = layers.image_coverage(part_range, lsn);
    5517          614 :             for (img_range, last_img) in image_coverage {
    5518          307 :                 let img_lsn = if let Some(last_img) = last_img {
    5519            0 :                     last_img.get_lsn_range().end
    5520              :                 } else {
    5521          307 :                     Lsn(0)
    5522              :                 };
    5523              :                 // Let's consider an example:
    5524              :                 //
    5525              :                 // delta layer with LSN range 71-81
    5526              :                 // delta layer with LSN range 81-91
    5527              :                 // delta layer with LSN range 91-101
    5528              :                 // image layer at LSN 100
    5529              :                 //
    5530              :                 // If 'lsn' is still 100, i.e. no new WAL has been processed since the last image layer,
    5531              :                 // there's no need to create a new one. We check this case explicitly, to avoid passing
    5532              :                 // a bogus range to count_deltas below, with start > end. It's even possible that there
    5533              :                 // are some delta layers *later* than current 'lsn', if more WAL was processed and flushed
    5534              :                 // after we read last_record_lsn, which is passed here in the 'lsn' argument.
    5535          307 :                 if img_lsn < lsn {
    5536          307 :                     let num_deltas =
    5537          307 :                         layers.count_deltas(&img_range, &(img_lsn..lsn), Some(threshold));
    5538              : 
    5539          307 :                     max_deltas = max_deltas.max(num_deltas);
    5540          307 :                     if num_deltas >= threshold {
    5541            0 :                         debug!(
    5542            0 :                             "key range {}-{}, has {} deltas on this timeline in LSN range {}..{}",
    5543              :                             img_range.start, img_range.end, num_deltas, img_lsn, lsn
    5544              :                         );
    5545            0 :                         return true;
    5546          307 :                     }
    5547            0 :                 }
    5548          307 :                 min_image_lsn = min(min_image_lsn, img_lsn);
    5549              :             }
    5550              :         }
    5551              : 
    5552              :         // HADRON
    5553              :         // for child timelines, we consider all pages up to ancestor_LSN are redone successfully by the parent timeline
    5554           57 :         min_image_lsn = min_image_lsn.max(self.get_ancestor_lsn());
    5555           57 :         if min_image_lsn < force_image_creation_lsn.unwrap_or(Lsn(0)) && max_deltas > 0 {
    5556            0 :             info!(
    5557            0 :                 "forcing image creation for partitioned range {}-{}. Min image LSN: {}, force image creation LSN: {}, num deltas: {}",
    5558            0 :                 partition.ranges[0].start,
    5559            0 :                 partition.ranges[0].end,
    5560              :                 min_image_lsn,
    5561            0 :                 force_image_creation_lsn.unwrap(),
    5562              :                 max_deltas
    5563              :             );
    5564            0 :             return true;
    5565           57 :         }
    5566              : 
    5567           57 :         debug!(
    5568              :             max_deltas,
    5569            0 :             "none of the partitioned ranges had >= {threshold} deltas"
    5570              :         );
    5571           57 :         false
    5572           57 :     }
    5573              : 
    5574              :     /// Create image layers for Postgres data. Assumes the caller passes a partition that is not too large,
    5575              :     /// so that at most one image layer will be produced from this function.
    5576              :     #[allow(clippy::too_many_arguments)]
    5577          124 :     async fn create_image_layer_for_rel_blocks(
    5578          124 :         self: &Arc<Self>,
    5579          124 :         partition: &KeySpace,
    5580          124 :         mut image_layer_writer: ImageLayerWriter,
    5581          124 :         lsn: Lsn,
    5582          124 :         ctx: &RequestContext,
    5583          124 :         img_range: Range<Key>,
    5584          124 :         io_concurrency: IoConcurrency,
    5585          124 :         progress: Option<(usize, usize)>,
    5586          124 :     ) -> Result<ImageLayerCreationOutcome, CreateImageLayersError> {
    5587          124 :         let mut wrote_keys = false;
    5588              : 
    5589          124 :         let mut key_request_accum = KeySpaceAccum::new();
    5590          824 :         for range in &partition.ranges {
    5591          700 :             let mut key = range.start;
    5592         1517 :             while key < range.end {
    5593              :                 // Decide whether to retain this key: usually we do, but sharded tenants may
    5594              :                 // need to drop keys that don't belong to them.  If we retain the key, add it
    5595              :                 // to `key_request_accum` for later issuing a vectored get
    5596          817 :                 if self.shard_identity.is_key_disposable(&key) {
    5597            0 :                     debug!(
    5598            0 :                         "Dropping key {} during compaction (it belongs on shard {:?})",
    5599              :                         key,
    5600            0 :                         self.shard_identity.get_shard_number(&key)
    5601              :                     );
    5602          817 :                 } else {
    5603          817 :                     key_request_accum.add_key(key);
    5604          817 :                 }
    5605              : 
    5606          817 :                 let last_key_in_range = key.next() == range.end;
    5607          817 :                 key = key.next();
    5608              : 
    5609              :                 // Maybe flush `key_rest_accum`
    5610          817 :                 if key_request_accum.raw_size() >= self.conf.max_get_vectored_keys.get() as u64
    5611          817 :                     || (last_key_in_range && key_request_accum.raw_size() > 0)
    5612              :                 {
    5613          700 :                     let query =
    5614          700 :                         VersionedKeySpaceQuery::uniform(key_request_accum.consume_keyspace(), lsn);
    5615              : 
    5616          700 :                     let results = self
    5617          700 :                         .get_vectored(query, io_concurrency.clone(), ctx)
    5618          700 :                         .await?;
    5619              : 
    5620          700 :                     if self.cancel.is_cancelled() {
    5621            0 :                         return Err(CreateImageLayersError::Cancelled);
    5622          700 :                     }
    5623              : 
    5624         1517 :                     for (img_key, img) in results {
    5625          817 :                         let img = match img {
    5626          817 :                             Ok(img) => img,
    5627            0 :                             Err(err) => {
    5628              :                                 // If we fail to reconstruct a VM or FSM page, we can zero the
    5629              :                                 // page without losing any actual user data. That seems better
    5630              :                                 // than failing repeatedly and getting stuck.
    5631              :                                 //
    5632              :                                 // We had a bug at one point, where we truncated the FSM and VM
    5633              :                                 // in the pageserver, but the Postgres didn't know about that
    5634              :                                 // and continued to generate incremental WAL records for pages
    5635              :                                 // that didn't exist in the pageserver. Trying to replay those
    5636              :                                 // WAL records failed to find the previous image of the page.
    5637              :                                 // This special case allows us to recover from that situation.
    5638              :                                 // See https://github.com/neondatabase/neon/issues/2601.
    5639              :                                 //
    5640              :                                 // Unfortunately we cannot do this for the main fork, or for
    5641              :                                 // any metadata keys, keys, as that would lead to actual data
    5642              :                                 // loss.
    5643            0 :                                 if img_key.is_rel_fsm_block_key() || img_key.is_rel_vm_block_key() {
    5644            0 :                                     warn!(
    5645            0 :                                         "could not reconstruct FSM or VM key {img_key}, filling with zeros: {err:?}"
    5646              :                                     );
    5647            0 :                                     ZERO_PAGE.clone()
    5648              :                                 } else {
    5649            0 :                                     return Err(CreateImageLayersError::from(err));
    5650              :                                 }
    5651              :                             }
    5652              :                         };
    5653              : 
    5654              :                         // Write all the keys we just read into our new image layer.
    5655          817 :                         image_layer_writer.put_image(img_key, img, ctx).await?;
    5656          817 :                         wrote_keys = true;
    5657              :                     }
    5658          117 :                 }
    5659              :             }
    5660              :         }
    5661              : 
    5662          124 :         let progress_report = progress
    5663          124 :             .map(|(idx, total)| format!("({idx}/{total}) "))
    5664          124 :             .unwrap_or_default();
    5665          124 :         if wrote_keys {
    5666              :             // Normal path: we have written some data into the new image layer for this
    5667              :             // partition, so flush it to disk.
    5668          124 :             info!(
    5669            0 :                 "{} produced image layer for rel {}",
    5670              :                 progress_report,
    5671            0 :                 ImageLayerName {
    5672            0 :                     key_range: img_range.clone(),
    5673            0 :                     lsn
    5674            0 :                 },
    5675              :             );
    5676          124 :             Ok(ImageLayerCreationOutcome::Generated {
    5677          124 :                 unfinished_image_layer: image_layer_writer,
    5678          124 :             })
    5679              :         } else {
    5680            0 :             tracing::debug!(
    5681            0 :                 "{} no data in range {}-{}",
    5682              :                 progress_report,
    5683              :                 img_range.start,
    5684              :                 img_range.end
    5685              :             );
    5686            0 :             Ok(ImageLayerCreationOutcome::Empty)
    5687              :         }
    5688          124 :     }
    5689              : 
    5690              :     /// Create an image layer for metadata keys. This function produces one image layer for all metadata
    5691              :     /// keys for now. Because metadata keys cannot exceed basebackup size limit, the image layer for it
    5692              :     /// would not be too large to fit in a single image layer.
    5693              :     ///
    5694              :     /// Creating image layers for metadata keys are different from relational keys. Firstly, instead of
    5695              :     /// iterating each key and get an image for each of them, we do a `vectored_get` scan over the sparse
    5696              :     /// keyspace to get all images in one run. Secondly, we use a different image layer generation metrics
    5697              :     /// for metadata keys than relational keys, which is the number of delta files visited during the scan.
    5698              :     #[allow(clippy::too_many_arguments)]
    5699          169 :     async fn create_image_layer_for_metadata_keys(
    5700          169 :         self: &Arc<Self>,
    5701          169 :         partition: &KeySpace,
    5702          169 :         mut image_layer_writer: ImageLayerWriter,
    5703          169 :         lsn: Lsn,
    5704          169 :         ctx: &RequestContext,
    5705          169 :         img_range: Range<Key>,
    5706          169 :         mode: ImageLayerCreationMode,
    5707          169 :         io_concurrency: IoConcurrency,
    5708          169 :     ) -> Result<ImageLayerCreationOutcome, CreateImageLayersError> {
    5709              :         // Metadata keys image layer creation.
    5710          169 :         let mut reconstruct_state = ValuesReconstructState::new(io_concurrency);
    5711          169 :         let begin = Instant::now();
    5712              :         // Directly use `get_vectored_impl` to skip the max_vectored_read_key limit check. Note that the keyspace should
    5713              :         // not contain too many keys, otherwise this takes a lot of memory.
    5714          169 :         let data = self
    5715          169 :             .get_vectored_impl(
    5716          169 :                 VersionedKeySpaceQuery::uniform(partition.clone(), lsn),
    5717          169 :                 &mut reconstruct_state,
    5718          169 :                 ctx,
    5719          169 :             )
    5720          169 :             .await?;
    5721          169 :         let (data, total_kb_retrieved, total_keys_retrieved) = {
    5722          169 :             let mut new_data = BTreeMap::new();
    5723          169 :             let mut total_kb_retrieved = 0;
    5724          169 :             let mut total_keys_retrieved = 0;
    5725         5175 :             for (k, v) in data {
    5726         5006 :                 let v = v?;
    5727         5006 :                 total_kb_retrieved += KEY_SIZE + v.len();
    5728         5006 :                 total_keys_retrieved += 1;
    5729         5006 :                 new_data.insert(k, v);
    5730              :             }
    5731          169 :             (new_data, total_kb_retrieved / 1024, total_keys_retrieved)
    5732              :         };
    5733          169 :         let delta_files_accessed = reconstruct_state.get_delta_layers_visited();
    5734          169 :         let elapsed = begin.elapsed();
    5735              : 
    5736          169 :         let trigger_generation = delta_files_accessed as usize >= MAX_AUX_FILE_V2_DELTAS;
    5737          169 :         info!(
    5738            0 :             "metadata key compaction: trigger_generation={trigger_generation}, delta_files_accessed={delta_files_accessed}, total_kb_retrieved={total_kb_retrieved}, total_keys_retrieved={total_keys_retrieved}, read_time={}s",
    5739            0 :             elapsed.as_secs_f64()
    5740              :         );
    5741              : 
    5742          169 :         if !trigger_generation && mode == ImageLayerCreationMode::Try {
    5743           16 :             return Ok(ImageLayerCreationOutcome::Skip);
    5744          153 :         }
    5745          153 :         if self.cancel.is_cancelled() {
    5746            0 :             return Err(CreateImageLayersError::Cancelled);
    5747          153 :         }
    5748          153 :         let mut wrote_any_image = false;
    5749         5159 :         for (k, v) in data {
    5750         5006 :             if v.is_empty() {
    5751              :                 // the key has been deleted, it does not need an image
    5752              :                 // in metadata keyspace, an empty image == tombstone
    5753            4 :                 continue;
    5754         5002 :             }
    5755         5002 :             wrote_any_image = true;
    5756              : 
    5757              :             // No need to handle sharding b/c metadata keys are always on the 0-th shard.
    5758              : 
    5759              :             // TODO: split image layers to avoid too large layer files. Too large image files are not handled
    5760              :             // on the normal data path either.
    5761         5002 :             image_layer_writer.put_image(k, v, ctx).await?;
    5762              :         }
    5763              : 
    5764          153 :         if wrote_any_image {
    5765              :             // Normal path: we have written some data into the new image layer for this
    5766              :             // partition, so flush it to disk.
    5767            6 :             info!(
    5768            0 :                 "created image layer for metadata {}",
    5769            0 :                 ImageLayerName {
    5770            0 :                     key_range: img_range.clone(),
    5771            0 :                     lsn
    5772            0 :                 }
    5773              :             );
    5774            6 :             Ok(ImageLayerCreationOutcome::Generated {
    5775            6 :                 unfinished_image_layer: image_layer_writer,
    5776            6 :             })
    5777              :         } else {
    5778          147 :             tracing::debug!("no data in range {}-{}", img_range.start, img_range.end);
    5779          147 :             Ok(ImageLayerCreationOutcome::Empty)
    5780              :         }
    5781          169 :     }
    5782              : 
    5783              :     /// Predicate function which indicates whether we should check if new image layers
    5784              :     /// are required. Since checking if new image layers are required is expensive in
    5785              :     /// terms of CPU, we only do it in the following cases:
    5786              :     /// 1. If the timeline has ingested sufficient WAL to justify the cost or ...
    5787              :     /// 2. If enough time has passed since the last check:
    5788              :     ///     1. For large tenants, we wish to perform the check more often since they
    5789              :     ///        suffer from the lack of image layers. Note that we assume sharded tenants
    5790              :     ///        to be large since non-zero shards do not track the logical size.
    5791              :     ///     2. For small tenants (that can mostly fit in RAM), we use a much longer interval
    5792          191 :     fn should_check_if_image_layers_required(self: &Arc<Timeline>, lsn: Lsn) -> bool {
    5793          191 :         let large_timeline_threshold = self.conf.image_layer_generation_large_timeline_threshold;
    5794              : 
    5795          191 :         let last_checks_at = self.last_image_layer_creation_check_at.load();
    5796          191 :         let distance = lsn
    5797          191 :             .checked_sub(last_checks_at)
    5798          191 :             .expect("Attempt to compact with LSN going backwards");
    5799          191 :         let min_distance =
    5800          191 :             self.get_image_layer_creation_check_threshold() as u64 * self.get_checkpoint_distance();
    5801              : 
    5802          191 :         let distance_based_decision = distance.0 >= min_distance;
    5803              : 
    5804          191 :         let mut last_check_instant = self.last_image_layer_creation_check_instant.lock().unwrap();
    5805          191 :         let check_required_after = (|| {
    5806          191 :             if self.shard_identity.is_unsharded() {
    5807          135 :                 if let CurrentLogicalSize::Exact(logical_size) =
    5808          186 :                     self.current_logical_size.current_size()
    5809              :                 {
    5810          135 :                     if Some(Into::<u64>::into(&logical_size)) < large_timeline_threshold {
    5811          135 :                         return Duration::from_secs(3600 * 48);
    5812            0 :                     }
    5813           51 :                 }
    5814            5 :             }
    5815              : 
    5816           56 :             self.get_checkpoint_timeout()
    5817              :         })();
    5818              : 
    5819          191 :         let time_based_decision = match *last_check_instant {
    5820           29 :             Some(last_check) => {
    5821           29 :                 let elapsed = last_check.elapsed();
    5822           29 :                 elapsed >= check_required_after
    5823              :             }
    5824          162 :             None => true,
    5825              :         };
    5826              : 
    5827              :         // Do the expensive delta layer counting only if this timeline has ingested sufficient
    5828              :         // WAL since the last check or a checkpoint timeout interval has elapsed since the last
    5829              :         // check.
    5830          191 :         let decision = distance_based_decision || time_based_decision;
    5831          191 :         tracing::info!(
    5832            0 :             "Decided to check image layers: {}. Distance-based decision: {}, time-based decision: {}",
    5833              :             decision,
    5834              :             distance_based_decision,
    5835              :             time_based_decision
    5836              :         );
    5837          191 :         if decision {
    5838          162 :             self.last_image_layer_creation_check_at.store(lsn);
    5839          162 :             *last_check_instant = Some(Instant::now());
    5840          162 :         }
    5841              : 
    5842          191 :         decision
    5843          191 :     }
    5844              : 
    5845              :     /// Returns the image layers generated and an enum indicating whether the process is fully completed.
    5846              :     /// true = we have generate all image layers, false = we preempt the process for L0 compaction.
    5847              :     ///
    5848              :     /// `partition_mode` is only for logging purpose and is not used anywhere in this function.
    5849              :     #[allow(clippy::too_many_arguments)]
    5850          191 :     async fn create_image_layers(
    5851          191 :         self: &Arc<Timeline>,
    5852          191 :         partitioning: &KeyPartitioning,
    5853          191 :         lsn: Lsn,
    5854          191 :         force_image_creation_lsn: Option<Lsn>,
    5855          191 :         mode: ImageLayerCreationMode,
    5856          191 :         ctx: &RequestContext,
    5857          191 :         last_status: LastImageLayerCreationStatus,
    5858          191 :         yield_for_l0: bool,
    5859          191 :     ) -> Result<(Vec<ResidentLayer>, LastImageLayerCreationStatus), CreateImageLayersError> {
    5860          191 :         let timer = self.metrics.create_images_time_histo.start_timer();
    5861              : 
    5862          191 :         if partitioning.parts.is_empty() {
    5863            0 :             warn!("no partitions to create image layers for");
    5864            0 :             return Ok((vec![], LastImageLayerCreationStatus::Complete));
    5865          191 :         }
    5866              : 
    5867              :         // We need to avoid holes between generated image layers.
    5868              :         // Otherwise LayerMap::image_layer_exists will return false if key range of some layer is covered by more than one
    5869              :         // image layer with hole between them. In this case such layer can not be utilized by GC.
    5870              :         //
    5871              :         // How such hole between partitions can appear?
    5872              :         // if we have relation with relid=1 and size 100 and relation with relid=2 with size 200 then result of
    5873              :         // KeySpace::partition may contain partitions <100000000..100000099> and <200000000..200000199>.
    5874              :         // If there is delta layer <100000000..300000000> then it never be garbage collected because
    5875              :         // image layers  <100000000..100000099> and <200000000..200000199> are not completely covering it.
    5876          191 :         let mut start = Key::MIN;
    5877              : 
    5878          191 :         let check_for_image_layers =
    5879          191 :             if let LastImageLayerCreationStatus::Incomplete { last_key } = last_status {
    5880            0 :                 info!(
    5881            0 :                     "resuming image layer creation: last_status=incomplete, continue from {}",
    5882              :                     last_key
    5883              :                 );
    5884            0 :                 true
    5885              :             } else {
    5886          191 :                 self.should_check_if_image_layers_required(lsn)
    5887              :             };
    5888              : 
    5889          191 :         let mut batch_image_writer = BatchLayerWriter::new(self.conf);
    5890              : 
    5891          191 :         let mut all_generated = true;
    5892              : 
    5893          191 :         let mut partition_processed = 0;
    5894          191 :         let mut total_partitions = partitioning.parts.len();
    5895          191 :         let mut last_partition_processed = None;
    5896          191 :         let mut partition_parts = partitioning.parts.clone();
    5897              : 
    5898          191 :         if let LastImageLayerCreationStatus::Incomplete { last_key } = last_status {
    5899              :             // We need to skip the partitions that have already been processed.
    5900            0 :             let mut found = false;
    5901            0 :             for (i, partition) in partition_parts.iter().enumerate() {
    5902            0 :                 if last_key <= partition.end().unwrap() {
    5903              :                     // ```plain
    5904              :                     // |------|--------|----------|------|
    5905              :                     //              ^last_key
    5906              :                     //                    ^start from this partition
    5907              :                     // ```
    5908              :                     // Why `i+1` instead of `i`?
    5909              :                     // It is possible that the user did some writes after the previous image layer creation attempt so that
    5910              :                     // a relation grows in size, and the last_key is now in the middle of the partition. In this case, we
    5911              :                     // still want to skip this partition, so that we can make progress and avoid generating image layers over
    5912              :                     // the same partition. Doing a mod to ensure we don't end up with an empty vec.
    5913            0 :                     if i + 1 >= total_partitions {
    5914              :                         // In general, this case should not happen -- if last_key is on the last partition, the previous
    5915              :                         // iteration of image layer creation should return a complete status.
    5916            0 :                         break; // with found=false
    5917            0 :                     }
    5918            0 :                     partition_parts = partition_parts.split_off(i + 1); // Remove the first i + 1 elements
    5919            0 :                     total_partitions = partition_parts.len();
    5920              :                     // Update the start key to the partition start.
    5921            0 :                     start = partition_parts[0].start().unwrap();
    5922            0 :                     found = true;
    5923            0 :                     break;
    5924            0 :                 }
    5925              :             }
    5926            0 :             if !found {
    5927              :                 // Last key is within the last partition, or larger than all partitions.
    5928            0 :                 return Ok((vec![], LastImageLayerCreationStatus::Complete));
    5929            0 :             }
    5930          191 :         }
    5931              : 
    5932          191 :         let total = partition_parts.len();
    5933          394 :         for (idx, partition) in partition_parts.iter().enumerate() {
    5934          394 :             if self.cancel.is_cancelled() {
    5935            0 :                 return Err(CreateImageLayersError::Cancelled);
    5936          394 :             }
    5937          394 :             partition_processed += 1;
    5938          394 :             let img_range = start..partition.ranges.last().unwrap().end;
    5939          394 :             let compact_metadata = partition.overlaps(&Key::metadata_key_range());
    5940          394 :             if compact_metadata {
    5941          764 :                 for range in &partition.ranges {
    5942          573 :                     assert!(
    5943          573 :                         range.start.field1 >= METADATA_KEY_BEGIN_PREFIX
    5944          573 :                             && range.end.field1 <= METADATA_KEY_END_PREFIX,
    5945            0 :                         "metadata keys must be partitioned separately"
    5946              :                     );
    5947              :                 }
    5948          191 :                 if mode == ImageLayerCreationMode::Try && !check_for_image_layers {
    5949              :                     // Skip compaction if there are not enough updates. Metadata compaction will do a scan and
    5950              :                     // might mess up with evictions.
    5951           22 :                     start = img_range.end;
    5952           22 :                     continue;
    5953          169 :                 }
    5954              :                 // For initial and force modes, we always generate image layers for metadata keys.
    5955          203 :             } else if let ImageLayerCreationMode::Try = mode {
    5956              :                 // check_for_image_layers = false -> skip
    5957              :                 // check_for_image_layers = true -> check time_for_new_image_layer -> skip/generate
    5958           79 :                 if !check_for_image_layers
    5959           57 :                     || !self
    5960           57 :                         .time_for_new_image_layer(partition, lsn, force_image_creation_lsn)
    5961           57 :                         .await
    5962              :                 {
    5963           79 :                     start = img_range.end;
    5964           79 :                     continue;
    5965            0 :                 }
    5966          124 :             }
    5967          293 :             if let ImageLayerCreationMode::Force = mode {
    5968              :                 // When forced to create image layers, we might try and create them where they already
    5969              :                 // exist.  This mode is only used in tests/debug.
    5970           14 :                 let layers = self.layers.read(LayerManagerLockHolder::Compaction).await;
    5971           14 :                 if layers.contains_key(&PersistentLayerKey {
    5972           14 :                     key_range: img_range.clone(),
    5973           14 :                     lsn_range: PersistentLayerDesc::image_layer_lsn_range(lsn),
    5974           14 :                     is_delta: false,
    5975           14 :                 }) {
    5976              :                     // TODO: this can be processed with the BatchLayerWriter::finish_with_discard
    5977              :                     // in the future.
    5978            0 :                     tracing::info!(
    5979            0 :                         "Skipping image layer at {lsn} {}..{}, already exists",
    5980              :                         img_range.start,
    5981              :                         img_range.end
    5982              :                     );
    5983            0 :                     start = img_range.end;
    5984            0 :                     continue;
    5985           14 :                 }
    5986          279 :             }
    5987              : 
    5988          293 :             let image_layer_writer = ImageLayerWriter::new(
    5989          293 :                 self.conf,
    5990          293 :                 self.timeline_id,
    5991          293 :                 self.tenant_shard_id,
    5992          293 :                 &img_range,
    5993          293 :                 lsn,
    5994          293 :                 &self.gate,
    5995          293 :                 self.cancel.clone(),
    5996          293 :                 ctx,
    5997          293 :             )
    5998          293 :             .await
    5999          293 :             .map_err(CreateImageLayersError::Other)?;
    6000              : 
    6001          293 :             fail_point!("image-layer-writer-fail-before-finish", |_| {
    6002            0 :                 Err(CreateImageLayersError::Other(anyhow::anyhow!(
    6003            0 :                     "failpoint image-layer-writer-fail-before-finish"
    6004            0 :                 )))
    6005            0 :             });
    6006              : 
    6007          293 :             let io_concurrency = IoConcurrency::spawn_from_conf(
    6008          293 :                 self.conf.get_vectored_concurrent_io,
    6009          293 :                 self.gate
    6010          293 :                     .enter()
    6011          293 :                     .map_err(|_| CreateImageLayersError::Cancelled)?,
    6012              :             );
    6013              : 
    6014          293 :             let outcome = if !compact_metadata {
    6015          124 :                 self.create_image_layer_for_rel_blocks(
    6016          124 :                     partition,
    6017          124 :                     image_layer_writer,
    6018          124 :                     lsn,
    6019          124 :                     ctx,
    6020          124 :                     img_range.clone(),
    6021          124 :                     io_concurrency,
    6022          124 :                     Some((idx, total)),
    6023          124 :                 )
    6024          124 :                 .await?
    6025              :             } else {
    6026          169 :                 self.create_image_layer_for_metadata_keys(
    6027          169 :                     partition,
    6028          169 :                     image_layer_writer,
    6029          169 :                     lsn,
    6030          169 :                     ctx,
    6031          169 :                     img_range.clone(),
    6032          169 :                     mode,
    6033          169 :                     io_concurrency,
    6034          169 :                 )
    6035          169 :                 .await?
    6036              :             };
    6037          293 :             match outcome {
    6038          147 :                 ImageLayerCreationOutcome::Empty => {
    6039          147 :                     // No data in this partition, so we don't need to create an image layer (for now).
    6040          147 :                     // The next image layer should cover this key range, so we don't advance the `start`
    6041          147 :                     // key.
    6042          147 :                 }
    6043              :                 ImageLayerCreationOutcome::Generated {
    6044          130 :                     unfinished_image_layer,
    6045          130 :                 } => {
    6046          130 :                     batch_image_writer.add_unfinished_image_writer(
    6047          130 :                         unfinished_image_layer,
    6048          130 :                         img_range.clone(),
    6049          130 :                         lsn,
    6050          130 :                     );
    6051          130 :                     // The next image layer should be generated right after this one.
    6052          130 :                     start = img_range.end;
    6053          130 :                 }
    6054           16 :                 ImageLayerCreationOutcome::Skip => {
    6055           16 :                     // We don't need to create an image layer for this partition.
    6056           16 :                     // The next image layer should NOT cover this range, otherwise
    6057           16 :                     // the keyspace becomes empty (reads don't go past image layers).
    6058           16 :                     start = img_range.end;
    6059           16 :                 }
    6060              :             }
    6061              : 
    6062          293 :             if let ImageLayerCreationMode::Try = mode {
    6063              :                 // We have at least made some progress
    6064           51 :                 if yield_for_l0 && batch_image_writer.pending_layer_num() >= 1 {
    6065              :                     // The `Try` mode is currently only used on the compaction path. We want to avoid
    6066              :                     // image layer generation taking too long time and blocking L0 compaction. So in this
    6067              :                     // mode, we also inspect the current number of L0 layers and skip image layer generation
    6068              :                     // if there are too many of them.
    6069            0 :                     let image_preempt_threshold = self.get_image_creation_preempt_threshold()
    6070            0 :                         * self.get_compaction_threshold();
    6071              :                     // TODO: currently we do not respect `get_image_creation_preempt_threshold` and always yield
    6072              :                     // when there is a single timeline with more than L0 threshold L0 layers. As long as the
    6073              :                     // `get_image_creation_preempt_threshold` is set to a value greater than 0, we will yield for L0 compaction.
    6074            0 :                     if image_preempt_threshold != 0 {
    6075            0 :                         let should_yield = self
    6076            0 :                             .l0_compaction_trigger
    6077            0 :                             .notified()
    6078            0 :                             .now_or_never()
    6079            0 :                             .is_some();
    6080            0 :                         if should_yield {
    6081            0 :                             tracing::info!(
    6082            0 :                                 "preempt image layer generation at {lsn} when processing partition {}..{}: too many L0 layers",
    6083            0 :                                 partition.start().unwrap(),
    6084            0 :                                 partition.end().unwrap()
    6085              :                             );
    6086            0 :                             last_partition_processed = Some(partition.clone());
    6087            0 :                             all_generated = false;
    6088            0 :                             break;
    6089            0 :                         }
    6090            0 :                     }
    6091           51 :                 }
    6092          242 :             }
    6093              :         }
    6094              : 
    6095          191 :         let image_layers = batch_image_writer
    6096          191 :             .finish(self, ctx)
    6097          191 :             .await
    6098          191 :             .map_err(CreateImageLayersError::Other)?;
    6099              : 
    6100          191 :         let mut guard = self.layers.write(LayerManagerLockHolder::Compaction).await;
    6101              : 
    6102              :         // FIXME: we could add the images to be uploaded *before* returning from here, but right
    6103              :         // now they are being scheduled outside of write lock; current way is inconsistent with
    6104              :         // compaction lock order.
    6105          191 :         guard
    6106          191 :             .open_mut()?
    6107          191 :             .track_new_image_layers(&image_layers, &self.metrics);
    6108          191 :         drop_layer_manager_wlock(guard);
    6109          191 :         let duration = timer.stop_and_record();
    6110              : 
    6111              :         // Creating image layers may have caused some previously visible layers to be covered
    6112          191 :         if !image_layers.is_empty() {
    6113          118 :             self.update_layer_visibility().await?;
    6114           73 :         }
    6115              : 
    6116          191 :         let total_layer_size = image_layers
    6117          191 :             .iter()
    6118          191 :             .map(|l| l.metadata().file_size)
    6119          191 :             .sum::<u64>();
    6120              : 
    6121          191 :         if !image_layers.is_empty() {
    6122          118 :             info!(
    6123            0 :                 "created {} image layers ({} bytes) in {}s, processed {} out of {} partitions",
    6124            0 :                 image_layers.len(),
    6125              :                 total_layer_size,
    6126            0 :                 duration.as_secs_f64(),
    6127              :                 partition_processed,
    6128              :                 total_partitions
    6129              :             );
    6130           73 :         }
    6131              : 
    6132              :         Ok((
    6133          191 :             image_layers,
    6134          191 :             if all_generated {
    6135          191 :                 LastImageLayerCreationStatus::Complete
    6136              :             } else {
    6137              :                 LastImageLayerCreationStatus::Incomplete {
    6138            0 :                     last_key: if let Some(last_partition_processed) = last_partition_processed {
    6139            0 :                         last_partition_processed.end().unwrap_or(Key::MIN)
    6140              :                     } else {
    6141              :                         // This branch should be unreachable, but in case it happens, we can just return the start key.
    6142            0 :                         Key::MIN
    6143              :                     },
    6144              :                 }
    6145              :             },
    6146              :         ))
    6147          191 :     }
    6148              : 
    6149              :     /// Wait until the background initial logical size calculation is complete, or
    6150              :     /// this Timeline is shut down.  Calling this function will cause the initial
    6151              :     /// logical size calculation to skip waiting for the background jobs barrier.
    6152            0 :     pub(crate) async fn await_initial_logical_size(self: Arc<Self>) {
    6153            0 :         if !self.shard_identity.is_shard_zero() {
    6154              :             // We don't populate logical size on shard >0: skip waiting for it.
    6155            0 :             return;
    6156            0 :         }
    6157              : 
    6158            0 :         if self.remote_client.is_deleting() {
    6159              :             // The timeline was created in a deletion-resume state, we don't expect logical size to be populated
    6160            0 :             return;
    6161            0 :         }
    6162              : 
    6163            0 :         if self.current_logical_size.current_size().is_exact() {
    6164              :             // root timelines are initialized with exact count, but never start the background
    6165              :             // calculation
    6166            0 :             return;
    6167            0 :         }
    6168              : 
    6169            0 :         if self.cancel.is_cancelled() {
    6170              :             // We already requested stopping the tenant, so we cannot wait for the logical size
    6171              :             // calculation to complete given the task might have been already cancelled.
    6172            0 :             return;
    6173            0 :         }
    6174              : 
    6175            0 :         if let Some(await_bg_cancel) = self
    6176            0 :             .current_logical_size
    6177            0 :             .cancel_wait_for_background_loop_concurrency_limit_semaphore
    6178            0 :             .get()
    6179            0 :         {
    6180            0 :             await_bg_cancel.cancel();
    6181            0 :         } else {
    6182              :             // We should not wait if we were not able to explicitly instruct
    6183              :             // the logical size cancellation to skip the concurrency limit semaphore.
    6184              :             // TODO: this is an unexpected case.  We should restructure so that it
    6185              :             // can't happen.
    6186            0 :             tracing::warn!(
    6187            0 :                 "await_initial_logical_size: can't get semaphore cancel token, skipping"
    6188              :             );
    6189            0 :             debug_assert!(false);
    6190              :         }
    6191              : 
    6192            0 :         tokio::select!(
    6193            0 :             _ = self.current_logical_size.initialized.acquire() => {},
    6194            0 :             _ = self.cancel.cancelled() => {}
    6195              :         )
    6196            0 :     }
    6197              : 
    6198              :     /// Detach this timeline from its ancestor by copying all of ancestors layers as this
    6199              :     /// Timelines layers up to the ancestor_lsn.
    6200              :     ///
    6201              :     /// Requires a timeline that:
    6202              :     /// - has an ancestor to detach from
    6203              :     /// - the ancestor does not have an ancestor -- follows from the original RFC limitations, not
    6204              :     ///   a technical requirement
    6205              :     ///
    6206              :     /// After the operation has been started, it cannot be canceled. Upon restart it needs to be
    6207              :     /// polled again until completion.
    6208              :     ///
    6209              :     /// During the operation all timelines sharing the data with this timeline will be reparented
    6210              :     /// from our ancestor to be branches of this timeline.
    6211            0 :     pub(crate) async fn prepare_to_detach_from_ancestor(
    6212            0 :         self: &Arc<Timeline>,
    6213            0 :         tenant: &crate::tenant::TenantShard,
    6214            0 :         options: detach_ancestor::Options,
    6215            0 :         behavior: DetachBehavior,
    6216            0 :         ctx: &RequestContext,
    6217            0 :     ) -> Result<detach_ancestor::Progress, detach_ancestor::Error> {
    6218            0 :         detach_ancestor::prepare(self, tenant, behavior, options, ctx).await
    6219            0 :     }
    6220              : 
    6221              :     /// Second step of detach from ancestor; detaches the `self` from it's current ancestor and
    6222              :     /// reparents any reparentable children of previous ancestor.
    6223              :     ///
    6224              :     /// This method is to be called while holding the TenantManager's tenant slot, so during this
    6225              :     /// method we cannot be deleted nor can any timeline be deleted. After this method returns
    6226              :     /// successfully, tenant must be reloaded.
    6227              :     ///
    6228              :     /// Final step will be to [`Self::complete_detaching_timeline_ancestor`] after optionally
    6229              :     /// resetting the tenant.
    6230            0 :     pub(crate) async fn detach_from_ancestor_and_reparent(
    6231            0 :         self: &Arc<Timeline>,
    6232            0 :         tenant: &crate::tenant::TenantShard,
    6233            0 :         prepared: detach_ancestor::PreparedTimelineDetach,
    6234            0 :         ancestor_timeline_id: TimelineId,
    6235            0 :         ancestor_lsn: Lsn,
    6236            0 :         behavior: DetachBehavior,
    6237            0 :         ctx: &RequestContext,
    6238            0 :     ) -> Result<detach_ancestor::DetachingAndReparenting, detach_ancestor::Error> {
    6239            0 :         detach_ancestor::detach_and_reparent(
    6240            0 :             self,
    6241            0 :             tenant,
    6242            0 :             prepared,
    6243            0 :             ancestor_timeline_id,
    6244            0 :             ancestor_lsn,
    6245            0 :             behavior,
    6246            0 :             ctx,
    6247            0 :         )
    6248            0 :         .await
    6249            0 :     }
    6250              : 
    6251              :     /// Final step which unblocks the GC.
    6252              :     ///
    6253              :     /// The tenant must've been reset if ancestry was modified previously (in tenant manager).
    6254            0 :     pub(crate) async fn complete_detaching_timeline_ancestor(
    6255            0 :         self: &Arc<Timeline>,
    6256            0 :         tenant: &crate::tenant::TenantShard,
    6257            0 :         attempt: detach_ancestor::Attempt,
    6258            0 :         ctx: &RequestContext,
    6259            0 :     ) -> Result<(), detach_ancestor::Error> {
    6260            0 :         detach_ancestor::complete(self, tenant, attempt, ctx).await
    6261            0 :     }
    6262              : }
    6263              : 
    6264              : impl Drop for Timeline {
    6265            5 :     fn drop(&mut self) {
    6266            5 :         if let Some(ancestor) = &self.ancestor_timeline {
    6267              :             // This lock should never be poisoned, but in case it is we do a .map() instead of
    6268              :             // an unwrap(), to avoid panicking in a destructor and thereby aborting the process.
    6269            2 :             if let Ok(mut gc_info) = ancestor.gc_info.write() {
    6270            2 :                 if !gc_info.remove_child_not_offloaded(self.timeline_id) {
    6271            0 :                     tracing::error!(tenant_id = %self.tenant_shard_id.tenant_id, shard_id = %self.tenant_shard_id.shard_slug(), timeline_id = %self.timeline_id,
    6272            0 :                         "Couldn't remove retain_lsn entry from timeline's parent on drop: already removed");
    6273            2 :                 }
    6274            0 :             }
    6275            3 :         }
    6276            5 :         info!(
    6277            0 :             "Timeline {} for tenant {} is being dropped",
    6278              :             self.timeline_id, self.tenant_shard_id.tenant_id
    6279              :         );
    6280            5 :     }
    6281              : }
    6282              : 
    6283              : pub(crate) use compaction_error::CompactionError;
    6284              : /// In a private mod to enforce that [`CompactionError::is_cancel`] is used
    6285              : /// instead of `match`ing on [`CompactionError::ShuttingDown`].
    6286              : mod compaction_error {
    6287              :     use utils::sync::gate::GateError;
    6288              : 
    6289              :     use crate::{
    6290              :         pgdatadir_mapping::CollectKeySpaceError,
    6291              :         tenant::{PageReconstructError, blob_io::WriteBlobError, upload_queue::NotInitialized},
    6292              :         virtual_file::owned_buffers_io::write::FlushTaskError,
    6293              :     };
    6294              : 
    6295              :     /// Top-level failure to compact. Use [`Self::is_cancel`].
    6296              :     #[derive(Debug, thiserror::Error)]
    6297              :     pub(crate) enum CompactionError {
    6298              :         /// Use [`Self::is_cancel`] instead of checking for this variant.
    6299              :         #[error("The timeline or pageserver is shutting down")]
    6300              :         #[allow(private_interfaces)]
    6301              :         ShuttingDown(ForbidMatching), // private ForbidMatching enforces use of [`Self::is_cancel`].
    6302              :         #[error(transparent)]
    6303              :         Other(anyhow::Error),
    6304              :     }
    6305              : 
    6306              :     #[derive(Debug)]
    6307              :     struct ForbidMatching;
    6308              : 
    6309              :     impl CompactionError {
    6310            0 :         pub fn new_cancelled() -> Self {
    6311            0 :             Self::ShuttingDown(ForbidMatching)
    6312            0 :         }
    6313              :         /// Errors that can be ignored, i.e., cancel and shutdown.
    6314            0 :         pub fn is_cancel(&self) -> bool {
    6315            0 :             let other = match self {
    6316            0 :                 CompactionError::ShuttingDown(_) => return true,
    6317            0 :                 CompactionError::Other(other) => other,
    6318              :             };
    6319              : 
    6320              :             // The write path of compaction in particular often lacks differentiated
    6321              :             // handling errors stemming from cancellation from other errors.
    6322              :             // So, if requested, we also check the ::Other variant by downcasting.
    6323              :             // The list below has been found empirically from flaky tests and production logs.
    6324              :             // The process is simple: on ::Other(), compaction will print the enclosed
    6325              :             // anyhow::Error in debug mode, i.e., with backtrace. That backtrace contains the
    6326              :             // line where the write path / compaction code does undifferentiated error handling
    6327              :             // from a non-anyhow type to an anyhow type. Add the type to the list of downcasts
    6328              :             // below, following the same is_cancel() pattern.
    6329              : 
    6330            0 :             let root_cause = other.root_cause();
    6331              : 
    6332            0 :             let upload_queue = root_cause
    6333            0 :                 .downcast_ref::<NotInitialized>()
    6334            0 :                 .is_some_and(|e| e.is_stopping());
    6335            0 :             let timeline = root_cause
    6336            0 :                 .downcast_ref::<PageReconstructError>()
    6337            0 :                 .is_some_and(|e| e.is_cancel());
    6338            0 :             let buffered_writer_flush_task_canelled = root_cause
    6339            0 :                 .downcast_ref::<FlushTaskError>()
    6340            0 :                 .is_some_and(|e| e.is_cancel());
    6341            0 :             let write_blob_cancelled = root_cause
    6342            0 :                 .downcast_ref::<WriteBlobError>()
    6343            0 :                 .is_some_and(|e| e.is_cancel());
    6344            0 :             let gate_closed = root_cause
    6345            0 :                 .downcast_ref::<GateError>()
    6346            0 :                 .is_some_and(|e| e.is_cancel());
    6347            0 :             upload_queue
    6348            0 :                 || timeline
    6349            0 :                 || buffered_writer_flush_task_canelled
    6350            0 :                 || write_blob_cancelled
    6351            0 :                 || gate_closed
    6352            0 :         }
    6353            0 :         pub fn into_anyhow(self) -> anyhow::Error {
    6354            0 :             match self {
    6355            0 :                 CompactionError::ShuttingDown(ForbidMatching) => anyhow::Error::new(self),
    6356            0 :                 CompactionError::Other(e) => e,
    6357              :             }
    6358            0 :         }
    6359            0 :         pub fn from_collect_keyspace(err: CollectKeySpaceError) -> Self {
    6360            0 :             if err.is_cancel() {
    6361            0 :                 Self::new_cancelled()
    6362              :             } else {
    6363            0 :                 Self::Other(err.into_anyhow())
    6364              :             }
    6365            0 :         }
    6366              :     }
    6367              : }
    6368              : 
    6369              : impl From<super::upload_queue::NotInitialized> for CompactionError {
    6370            0 :     fn from(value: super::upload_queue::NotInitialized) -> Self {
    6371            0 :         match value {
    6372              :             super::upload_queue::NotInitialized::Uninitialized => {
    6373            0 :                 CompactionError::Other(anyhow::anyhow!(value))
    6374              :             }
    6375              :             super::upload_queue::NotInitialized::ShuttingDown
    6376            0 :             | super::upload_queue::NotInitialized::Stopped => CompactionError::new_cancelled(),
    6377              :         }
    6378            0 :     }
    6379              : }
    6380              : 
    6381              : impl From<super::storage_layer::layer::DownloadError> for CompactionError {
    6382            0 :     fn from(e: super::storage_layer::layer::DownloadError) -> Self {
    6383            0 :         match e {
    6384              :             super::storage_layer::layer::DownloadError::TimelineShutdown
    6385              :             | super::storage_layer::layer::DownloadError::DownloadCancelled => {
    6386            0 :                 CompactionError::new_cancelled()
    6387              :             }
    6388              :             super::storage_layer::layer::DownloadError::ContextAndConfigReallyDeniesDownloads
    6389              :             | super::storage_layer::layer::DownloadError::DownloadRequired
    6390              :             | super::storage_layer::layer::DownloadError::NotFile(_)
    6391              :             | super::storage_layer::layer::DownloadError::DownloadFailed
    6392              :             | super::storage_layer::layer::DownloadError::PreStatFailed(_) => {
    6393            0 :                 CompactionError::Other(anyhow::anyhow!(e))
    6394              :             }
    6395              :             #[cfg(test)]
    6396              :             super::storage_layer::layer::DownloadError::Failpoint(_) => {
    6397            0 :                 CompactionError::Other(anyhow::anyhow!(e))
    6398              :             }
    6399              :         }
    6400            0 :     }
    6401              : }
    6402              : 
    6403              : impl From<layer_manager::Shutdown> for CompactionError {
    6404            0 :     fn from(_: layer_manager::Shutdown) -> Self {
    6405            0 :         CompactionError::new_cancelled()
    6406            0 :     }
    6407              : }
    6408              : 
    6409              : impl From<super::storage_layer::errors::PutError> for CompactionError {
    6410            0 :     fn from(e: super::storage_layer::errors::PutError) -> Self {
    6411            0 :         if e.is_cancel() {
    6412            0 :             CompactionError::new_cancelled()
    6413              :         } else {
    6414            0 :             CompactionError::Other(e.into_anyhow())
    6415              :         }
    6416            0 :     }
    6417              : }
    6418              : 
    6419              : #[serde_as]
    6420              : #[derive(serde::Serialize)]
    6421              : struct RecordedDuration(#[serde_as(as = "serde_with::DurationMicroSeconds")] Duration);
    6422              : 
    6423              : #[derive(Default)]
    6424              : enum DurationRecorder {
    6425              :     #[default]
    6426              :     NotStarted,
    6427              :     Recorded(RecordedDuration, tokio::time::Instant),
    6428              : }
    6429              : 
    6430              : impl DurationRecorder {
    6431          115 :     fn till_now(&self) -> DurationRecorder {
    6432          115 :         match self {
    6433              :             DurationRecorder::NotStarted => {
    6434            0 :                 panic!("must only call on recorded measurements")
    6435              :             }
    6436          115 :             DurationRecorder::Recorded(_, ended) => {
    6437          115 :                 let now = tokio::time::Instant::now();
    6438          115 :                 DurationRecorder::Recorded(RecordedDuration(now - *ended), now)
    6439              :             }
    6440              :         }
    6441          115 :     }
    6442          138 :     fn into_recorded(self) -> Option<RecordedDuration> {
    6443          138 :         match self {
    6444            0 :             DurationRecorder::NotStarted => None,
    6445          138 :             DurationRecorder::Recorded(recorded, _) => Some(recorded),
    6446              :         }
    6447          138 :     }
    6448              : }
    6449              : 
    6450              : /// Descriptor for a delta layer used in testing infra. The start/end key/lsn range of the
    6451              : /// delta layer might be different from the min/max key/lsn in the delta layer. Therefore,
    6452              : /// the layer descriptor requires the user to provide the ranges, which should cover all
    6453              : /// keys specified in the `data` field.
    6454              : #[cfg(test)]
    6455              : #[derive(Clone)]
    6456              : pub struct DeltaLayerTestDesc {
    6457              :     pub lsn_range: Range<Lsn>,
    6458              :     pub key_range: Range<Key>,
    6459              :     pub data: Vec<(Key, Lsn, Value)>,
    6460              : }
    6461              : 
    6462              : #[cfg(test)]
    6463              : #[derive(Clone)]
    6464              : pub struct InMemoryLayerTestDesc {
    6465              :     pub lsn_range: Range<Lsn>,
    6466              :     pub data: Vec<(Key, Lsn, Value)>,
    6467              :     pub is_open: bool,
    6468              : }
    6469              : 
    6470              : #[cfg(test)]
    6471              : impl DeltaLayerTestDesc {
    6472            2 :     pub fn new(lsn_range: Range<Lsn>, key_range: Range<Key>, data: Vec<(Key, Lsn, Value)>) -> Self {
    6473            2 :         Self {
    6474            2 :             lsn_range,
    6475            2 :             key_range,
    6476            2 :             data,
    6477            2 :         }
    6478            2 :     }
    6479              : 
    6480           45 :     pub fn new_with_inferred_key_range(
    6481           45 :         lsn_range: Range<Lsn>,
    6482           45 :         data: Vec<(Key, Lsn, Value)>,
    6483           45 :     ) -> Self {
    6484           45 :         let key_min = data.iter().map(|(key, _, _)| key).min().unwrap();
    6485           45 :         let key_max = data.iter().map(|(key, _, _)| key).max().unwrap();
    6486           45 :         Self {
    6487           45 :             key_range: (*key_min)..(key_max.next()),
    6488           45 :             lsn_range,
    6489           45 :             data,
    6490           45 :         }
    6491           45 :     }
    6492              : 
    6493            5 :     pub(crate) fn layer_name(&self) -> LayerName {
    6494            5 :         LayerName::Delta(super::storage_layer::DeltaLayerName {
    6495            5 :             key_range: self.key_range.clone(),
    6496            5 :             lsn_range: self.lsn_range.clone(),
    6497            5 :         })
    6498            5 :     }
    6499              : }
    6500              : 
    6501              : impl Timeline {
    6502           23 :     async fn finish_compact_batch(
    6503           23 :         self: &Arc<Self>,
    6504           23 :         new_deltas: &[ResidentLayer],
    6505           23 :         new_images: &[ResidentLayer],
    6506           23 :         layers_to_remove: &[Layer],
    6507           23 :     ) -> Result<(), CompactionError> {
    6508           23 :         let mut guard = tokio::select! {
    6509           23 :             guard = self.layers.write(LayerManagerLockHolder::Compaction) => guard,
    6510           23 :             _ = self.cancel.cancelled() => {
    6511            0 :                 return Err(CompactionError::new_cancelled());
    6512              :             }
    6513              :         };
    6514              : 
    6515           23 :         let mut duplicated_layers = HashSet::new();
    6516              : 
    6517           23 :         let mut insert_layers = Vec::with_capacity(new_deltas.len());
    6518              : 
    6519          186 :         for l in new_deltas {
    6520          163 :             if guard.contains(l.as_ref()) {
    6521              :                 // expected in tests
    6522            0 :                 tracing::error!(layer=%l, "duplicated L1 layer");
    6523              : 
    6524              :                 // good ways to cause a duplicate: we repeatedly error after taking the writelock
    6525              :                 // `guard`  on self.layers. as of writing this, there are no error returns except
    6526              :                 // for compact_level0_phase1 creating an L0, which does not happen in practice
    6527              :                 // because we have not implemented L0 => L0 compaction.
    6528            0 :                 duplicated_layers.insert(l.layer_desc().key());
    6529          163 :             } else if LayerMap::is_l0(&l.layer_desc().key_range, l.layer_desc().is_delta) {
    6530            0 :                 return Err(CompactionError::Other(anyhow::anyhow!(
    6531            0 :                     "compaction generates a L0 layer file as output, which will cause infinite compaction."
    6532            0 :                 )));
    6533          163 :             } else {
    6534          163 :                 insert_layers.push(l.clone());
    6535          163 :             }
    6536              :         }
    6537              : 
    6538              :         // only remove those inputs which were not outputs
    6539           23 :         let remove_layers: Vec<Layer> = layers_to_remove
    6540           23 :             .iter()
    6541          201 :             .filter(|l| !duplicated_layers.contains(&l.layer_desc().key()))
    6542           23 :             .cloned()
    6543           23 :             .collect();
    6544              : 
    6545           23 :         if !new_images.is_empty() {
    6546            0 :             guard
    6547            0 :                 .open_mut()?
    6548            0 :                 .track_new_image_layers(new_images, &self.metrics);
    6549           23 :         }
    6550              : 
    6551           23 :         guard
    6552           23 :             .open_mut()?
    6553           23 :             .finish_compact_l0(&remove_layers, &insert_layers, &self.metrics);
    6554              : 
    6555           23 :         self.remote_client
    6556           23 :             .schedule_compaction_update(&remove_layers, new_deltas)?;
    6557              : 
    6558           23 :         drop_layer_manager_wlock(guard);
    6559              : 
    6560           23 :         Ok(())
    6561           23 :     }
    6562              : 
    6563            0 :     async fn rewrite_layers(
    6564            0 :         self: &Arc<Self>,
    6565            0 :         mut replace_layers: Vec<(Layer, ResidentLayer)>,
    6566            0 :         mut drop_layers: Vec<Layer>,
    6567            0 :     ) -> Result<(), CompactionError> {
    6568            0 :         let mut guard = self.layers.write(LayerManagerLockHolder::Compaction).await;
    6569              : 
    6570              :         // Trim our lists in case our caller (compaction) raced with someone else (GC) removing layers: we want
    6571              :         // to avoid double-removing, and avoid rewriting something that was removed.
    6572            0 :         replace_layers.retain(|(l, _)| guard.contains(l));
    6573            0 :         drop_layers.retain(|l| guard.contains(l));
    6574              : 
    6575            0 :         guard
    6576            0 :             .open_mut()?
    6577            0 :             .rewrite_layers(&replace_layers, &drop_layers, &self.metrics);
    6578              : 
    6579            0 :         let upload_layers: Vec<_> = replace_layers.into_iter().map(|r| r.1).collect();
    6580              : 
    6581            0 :         self.remote_client
    6582            0 :             .schedule_compaction_update(&drop_layers, &upload_layers)?;
    6583              : 
    6584            0 :         Ok(())
    6585            0 :     }
    6586              : 
    6587              :     /// Schedules the uploads of the given image layers
    6588           80 :     fn upload_new_image_layers(
    6589           80 :         self: &Arc<Self>,
    6590           80 :         new_images: impl IntoIterator<Item = ResidentLayer>,
    6591           80 :     ) -> Result<(), super::upload_queue::NotInitialized> {
    6592           93 :         for layer in new_images {
    6593           13 :             self.remote_client.schedule_layer_file_upload(layer)?;
    6594              :         }
    6595              :         // should any new image layer been created, not uploading index_part will
    6596              :         // result in a mismatch between remote_physical_size and layermap calculated
    6597              :         // size, which will fail some tests, but should not be an issue otherwise.
    6598           80 :         self.remote_client
    6599           80 :             .schedule_index_upload_for_file_changes()?;
    6600           80 :         Ok(())
    6601           80 :     }
    6602              : 
    6603            0 :     async fn find_gc_time_cutoff(
    6604            0 :         &self,
    6605            0 :         now: SystemTime,
    6606            0 :         pitr: Duration,
    6607            0 :         cancel: &CancellationToken,
    6608            0 :         ctx: &RequestContext,
    6609            0 :     ) -> Result<Option<Lsn>, PageReconstructError> {
    6610            0 :         debug_assert_current_span_has_tenant_and_timeline_id();
    6611            0 :         if self.shard_identity.is_shard_zero() {
    6612              :             // Shard Zero has SLRU data and can calculate the PITR time -> LSN mapping itself
    6613            0 :             let time_range = if pitr == Duration::ZERO {
    6614            0 :                 humantime::parse_duration(DEFAULT_PITR_INTERVAL).expect("constant is invalid")
    6615              :             } else {
    6616            0 :                 pitr
    6617              :             };
    6618              : 
    6619              :             // If PITR is so large or `now` is so small that this underflows, we will retain no history (highly unexpected case)
    6620            0 :             let time_cutoff = now.checked_sub(time_range).unwrap_or(now);
    6621            0 :             let timestamp = to_pg_timestamp(time_cutoff);
    6622              : 
    6623            0 :             let time_cutoff = match self.find_lsn_for_timestamp(timestamp, cancel, ctx).await? {
    6624            0 :                 LsnForTimestamp::Present(lsn) => Some(lsn),
    6625            0 :                 LsnForTimestamp::Future(lsn) => {
    6626              :                     // The timestamp is in the future. That sounds impossible,
    6627              :                     // but what it really means is that there hasn't been
    6628              :                     // any commits since the cutoff timestamp.
    6629              :                     //
    6630              :                     // In this case we should use the LSN of the most recent commit,
    6631              :                     // which is implicitly the last LSN in the log.
    6632            0 :                     debug!("future({})", lsn);
    6633            0 :                     Some(self.get_last_record_lsn())
    6634              :                 }
    6635            0 :                 LsnForTimestamp::Past(lsn) => {
    6636            0 :                     debug!("past({})", lsn);
    6637            0 :                     None
    6638              :                 }
    6639            0 :                 LsnForTimestamp::NoData(lsn) => {
    6640            0 :                     debug!("nodata({})", lsn);
    6641            0 :                     None
    6642              :                 }
    6643              :             };
    6644            0 :             Ok(time_cutoff)
    6645              :         } else {
    6646              :             // Shards other than shard zero cannot do timestamp->lsn lookups, and must instead learn their GC cutoff
    6647              :             // from shard zero's index.  The index doesn't explicitly tell us the time cutoff, but we may assume that
    6648              :             // the point up to which shard zero's last_gc_cutoff has advanced will either be the time cutoff, or a
    6649              :             // space cutoff that we would also have respected ourselves.
    6650            0 :             match self
    6651            0 :                 .remote_client
    6652            0 :                 .download_foreign_index(ShardNumber(0), cancel)
    6653            0 :                 .await
    6654              :             {
    6655            0 :                 Ok((index_part, index_generation, _index_mtime)) => {
    6656            0 :                     tracing::info!(
    6657            0 :                         "GC loaded shard zero metadata (gen {index_generation:?}): latest_gc_cutoff_lsn: {}",
    6658            0 :                         index_part.metadata.latest_gc_cutoff_lsn()
    6659              :                     );
    6660            0 :                     Ok(Some(index_part.metadata.latest_gc_cutoff_lsn()))
    6661              :                 }
    6662              :                 Err(DownloadError::NotFound) => {
    6663              :                     // This is unexpected, because during timeline creations shard zero persists to remote
    6664              :                     // storage before other shards are called, and during timeline deletion non-zeroth shards are
    6665              :                     // deleted before the zeroth one.  However, it should be harmless: if we somehow end up in this
    6666              :                     // state, then shard zero should _eventually_ write an index when it GCs.
    6667            0 :                     tracing::warn!("GC couldn't find shard zero's index for timeline");
    6668            0 :                     Ok(None)
    6669              :                 }
    6670            0 :                 Err(e) => {
    6671              :                     // TODO: this function should return a different error type than page reconstruct error
    6672            0 :                     Err(PageReconstructError::Other(anyhow::anyhow!(e)))
    6673              :                 }
    6674              :             }
    6675              : 
    6676              :             // TODO: after reading shard zero's GC cutoff, we should validate its generation with the storage
    6677              :             // controller.  Otherwise, it is possible that we see the GC cutoff go backwards while shard zero
    6678              :             // is going through a migration if we read the old location's index and it has GC'd ahead of the
    6679              :             // new location.  This is legal in principle, but problematic in practice because it might result
    6680              :             // in a timeline creation succeeding on shard zero ('s new location) but then failing on other shards
    6681              :             // because they have GC'd past the branch point.
    6682              :         }
    6683            0 :     }
    6684              : 
    6685              :     /// Find the Lsns above which layer files need to be retained on
    6686              :     /// garbage collection.
    6687              :     ///
    6688              :     /// We calculate two cutoffs, one based on time and one based on WAL size.  `pitr`
    6689              :     /// controls the time cutoff (or ZERO to disable time-based retention), and `space_cutoff` controls
    6690              :     /// the space-based retention.
    6691              :     ///
    6692              :     /// This function doesn't simply to calculate time & space based retention: it treats time-based
    6693              :     /// retention as authoritative if enabled, and falls back to space-based retention if calculating
    6694              :     /// the LSN for a time point isn't possible.  Therefore the GcCutoffs::horizon in the response might
    6695              :     /// be different to the `space_cutoff` input.  Callers should treat the min() of the two cutoffs
    6696              :     /// in the response as the GC cutoff point for the timeline.
    6697              :     #[instrument(skip_all, fields(timeline_id=%self.timeline_id))]
    6698              :     pub(super) async fn find_gc_cutoffs(
    6699              :         &self,
    6700              :         now: SystemTime,
    6701              :         space_cutoff: Lsn,
    6702              :         pitr: Duration,
    6703              :         cancel: &CancellationToken,
    6704              :         ctx: &RequestContext,
    6705              :     ) -> Result<GcCutoffs, PageReconstructError> {
    6706              :         let _timer = self
    6707              :             .metrics
    6708              :             .find_gc_cutoffs_histo
    6709              :             .start_timer()
    6710              :             .record_on_drop();
    6711              : 
    6712              :         pausable_failpoint!("Timeline::find_gc_cutoffs-pausable");
    6713              : 
    6714              :         if cfg!(test) && pitr == Duration::ZERO {
    6715              :             // Unit tests which specify zero PITR interval expect to avoid doing any I/O for timestamp lookup
    6716              :             return Ok(GcCutoffs {
    6717              :                 time: Some(self.get_last_record_lsn()),
    6718              :                 space: space_cutoff,
    6719              :             });
    6720              :         }
    6721              : 
    6722              :         // Calculate a time-based limit on how much to retain:
    6723              :         // - if PITR interval is set, then this is our cutoff.
    6724              :         // - if PITR interval is not set, then we do a lookup
    6725              :         //   based on DEFAULT_PITR_INTERVAL, so that size-based retention does not result in keeping history around permanently on idle databases.
    6726              :         let time_cutoff = self.find_gc_time_cutoff(now, pitr, cancel, ctx).await?;
    6727              : 
    6728              :         Ok(match (pitr, time_cutoff) {
    6729              :             (Duration::ZERO, Some(time_cutoff)) => {
    6730              :                 // PITR is not set. Retain the size-based limit, or the default time retention,
    6731              :                 // whichever requires less data.
    6732              :                 GcCutoffs {
    6733              :                     time: Some(self.get_last_record_lsn()),
    6734              :                     space: std::cmp::max(time_cutoff, space_cutoff),
    6735              :                 }
    6736              :             }
    6737              :             (Duration::ZERO, None) => {
    6738              :                 // PITR is not set, and time lookup failed
    6739              :                 GcCutoffs {
    6740              :                     time: Some(self.get_last_record_lsn()),
    6741              :                     space: space_cutoff,
    6742              :                 }
    6743              :             }
    6744              :             (_, None) => {
    6745              :                 // PITR interval is set & we didn't look up a timestamp successfully.  Conservatively assume PITR
    6746              :                 // cannot advance beyond what was already GC'd, and respect space-based retention
    6747              :                 GcCutoffs {
    6748              :                     time: Some(*self.get_applied_gc_cutoff_lsn()),
    6749              :                     space: space_cutoff,
    6750              :                 }
    6751              :             }
    6752              :             (_, Some(time_cutoff)) => {
    6753              :                 // PITR interval is set and we looked up timestamp successfully.  Ignore
    6754              :                 // size based retention and make time cutoff authoritative
    6755              :                 GcCutoffs {
    6756              :                     time: Some(time_cutoff),
    6757              :                     space: time_cutoff,
    6758              :                 }
    6759              :             }
    6760              :         })
    6761              :     }
    6762              : 
    6763              :     /// Garbage collect layer files on a timeline that are no longer needed.
    6764              :     ///
    6765              :     /// Currently, we don't make any attempt at removing unneeded page versions
    6766              :     /// within a layer file. We can only remove the whole file if it's fully
    6767              :     /// obsolete.
    6768          377 :     pub(super) async fn gc(&self) -> Result<GcResult, GcError> {
    6769              :         // this is most likely the background tasks, but it might be the spawned task from
    6770              :         // immediate_gc
    6771          377 :         let _g = tokio::select! {
    6772          377 :             guard = self.gc_lock.lock() => guard,
    6773          377 :             _ = self.cancel.cancelled() => return Ok(GcResult::default()),
    6774              :         };
    6775          377 :         let timer = self.metrics.garbage_collect_histo.start_timer();
    6776              : 
    6777          377 :         fail_point!("before-timeline-gc");
    6778              : 
    6779              :         // Is the timeline being deleted?
    6780          377 :         if self.is_stopping() {
    6781            0 :             return Err(GcError::TimelineCancelled);
    6782          377 :         }
    6783              : 
    6784          377 :         let (space_cutoff, time_cutoff, retain_lsns, max_lsn_with_valid_lease) = {
    6785          377 :             let gc_info = self.gc_info.read().unwrap();
    6786              : 
    6787          377 :             let space_cutoff = min(gc_info.cutoffs.space, self.get_disk_consistent_lsn());
    6788          377 :             let time_cutoff = gc_info.cutoffs.time;
    6789          377 :             let retain_lsns = gc_info
    6790          377 :                 .retain_lsns
    6791          377 :                 .iter()
    6792          377 :                 .map(|(lsn, _child_id, _is_offloaded)| *lsn)
    6793          377 :                 .collect();
    6794              : 
    6795              :             // Gets the maximum LSN that holds the valid lease.
    6796              :             //
    6797              :             // Caveat: `refresh_gc_info` is in charged of updating the lease map.
    6798              :             // Here, we do not check for stale leases again.
    6799          377 :             let max_lsn_with_valid_lease = gc_info.leases.last_key_value().map(|(lsn, _)| *lsn);
    6800              : 
    6801          377 :             (
    6802          377 :                 space_cutoff,
    6803          377 :                 time_cutoff,
    6804          377 :                 retain_lsns,
    6805          377 :                 max_lsn_with_valid_lease,
    6806          377 :             )
    6807              :         };
    6808              : 
    6809          377 :         let mut new_gc_cutoff = space_cutoff.min(time_cutoff.unwrap_or_default());
    6810          377 :         let standby_horizon = self.standby_horizon.load();
    6811              :         // Hold GC for the standby, but as a safety guard do it only within some
    6812              :         // reasonable lag.
    6813          377 :         if standby_horizon != Lsn::INVALID {
    6814            0 :             if let Some(standby_lag) = new_gc_cutoff.checked_sub(standby_horizon) {
    6815              :                 const MAX_ALLOWED_STANDBY_LAG: u64 = 10u64 << 30; // 10 GB
    6816            0 :                 if standby_lag.0 < MAX_ALLOWED_STANDBY_LAG {
    6817            0 :                     new_gc_cutoff = Lsn::min(standby_horizon, new_gc_cutoff);
    6818            0 :                     trace!("holding off GC for standby apply LSN {}", standby_horizon);
    6819              :                 } else {
    6820            0 :                     warn!(
    6821            0 :                         "standby is lagging for more than {}MB, not holding gc for it",
    6822            0 :                         MAX_ALLOWED_STANDBY_LAG / 1024 / 1024
    6823              :                     )
    6824              :                 }
    6825            0 :             }
    6826          377 :         }
    6827              : 
    6828              :         // Reset standby horizon to ignore it if it is not updated till next GC.
    6829              :         // It is an easy way to unset it when standby disappears without adding
    6830              :         // more conf options.
    6831          377 :         self.standby_horizon.store(Lsn::INVALID);
    6832          377 :         self.metrics
    6833          377 :             .standby_horizon_gauge
    6834          377 :             .set(Lsn::INVALID.0 as i64);
    6835              : 
    6836          377 :         let res = self
    6837          377 :             .gc_timeline(
    6838          377 :                 space_cutoff,
    6839          377 :                 time_cutoff,
    6840          377 :                 retain_lsns,
    6841          377 :                 max_lsn_with_valid_lease,
    6842          377 :                 new_gc_cutoff,
    6843              :             )
    6844          377 :             .instrument(
    6845          377 :                 info_span!("gc_timeline", timeline_id = %self.timeline_id, cutoff = %new_gc_cutoff),
    6846              :             )
    6847          377 :             .await?;
    6848              : 
    6849              :         // only record successes
    6850          377 :         timer.stop_and_record();
    6851              : 
    6852          377 :         Ok(res)
    6853          377 :     }
    6854              : 
    6855          377 :     async fn gc_timeline(
    6856          377 :         &self,
    6857          377 :         space_cutoff: Lsn,
    6858          377 :         time_cutoff: Option<Lsn>, // None if uninitialized
    6859          377 :         retain_lsns: Vec<Lsn>,
    6860          377 :         max_lsn_with_valid_lease: Option<Lsn>,
    6861          377 :         new_gc_cutoff: Lsn,
    6862          377 :     ) -> Result<GcResult, GcError> {
    6863              :         // FIXME: if there is an ongoing detach_from_ancestor, we should just skip gc
    6864              : 
    6865          377 :         let now = SystemTime::now();
    6866          377 :         let mut result: GcResult = GcResult::default();
    6867              : 
    6868              :         // Nothing to GC. Return early.
    6869          377 :         let latest_gc_cutoff = *self.get_applied_gc_cutoff_lsn();
    6870          377 :         if latest_gc_cutoff >= new_gc_cutoff {
    6871           11 :             info!(
    6872            0 :                 "Nothing to GC: new_gc_cutoff_lsn {new_gc_cutoff}, latest_gc_cutoff_lsn {latest_gc_cutoff}",
    6873              :             );
    6874           11 :             return Ok(result);
    6875          366 :         }
    6876              : 
    6877          366 :         let Some(time_cutoff) = time_cutoff else {
    6878              :             // The GC cutoff should have been computed by now, but let's be defensive.
    6879            0 :             info!("Nothing to GC: time_cutoff not yet computed");
    6880            0 :             return Ok(result);
    6881              :         };
    6882              : 
    6883              :         // We need to ensure that no one tries to read page versions or create
    6884              :         // branches at a point before latest_gc_cutoff_lsn. See branch_timeline()
    6885              :         // for details. This will block until the old value is no longer in use.
    6886              :         //
    6887              :         // The GC cutoff should only ever move forwards.
    6888          366 :         let waitlist = {
    6889          366 :             let write_guard = self.applied_gc_cutoff_lsn.lock_for_write();
    6890          366 :             if *write_guard > new_gc_cutoff {
    6891            0 :                 return Err(GcError::BadLsn {
    6892            0 :                     why: format!(
    6893            0 :                         "Cannot move GC cutoff LSN backwards (was {}, new {})",
    6894            0 :                         *write_guard, new_gc_cutoff
    6895            0 :                     ),
    6896            0 :                 });
    6897          366 :             }
    6898              : 
    6899          366 :             write_guard.store_and_unlock(new_gc_cutoff)
    6900              :         };
    6901          366 :         let waitlist_wait_fut = std::pin::pin!(waitlist.wait());
    6902          366 :         log_slow(
    6903          366 :             "applied_gc_cutoff waitlist wait",
    6904          366 :             Duration::from_secs(30),
    6905          366 :             waitlist_wait_fut,
    6906          366 :         )
    6907          366 :         .await;
    6908              : 
    6909          366 :         info!("GC starting");
    6910              : 
    6911          366 :         debug!("retain_lsns: {:?}", retain_lsns);
    6912              : 
    6913          366 :         let max_retain_lsn = retain_lsns.iter().max();
    6914              : 
    6915              :         // Scan all layers in the timeline (remote or on-disk).
    6916              :         //
    6917              :         // Garbage collect the layer if all conditions are satisfied:
    6918              :         // 1. it is older than cutoff LSN;
    6919              :         // 2. it is older than PITR interval;
    6920              :         // 3. it doesn't need to be retained for 'retain_lsns';
    6921              :         // 4. it does not need to be kept for LSNs holding valid leases.
    6922              :         // 5. newer on-disk image layers cover the layer's whole key range
    6923          366 :         let layers_to_remove = {
    6924          366 :             let mut layers_to_remove = Vec::new();
    6925              : 
    6926          366 :             let guard = self
    6927          366 :                 .layers
    6928          366 :                 .read(LayerManagerLockHolder::GarbageCollection)
    6929          366 :                 .await;
    6930          366 :             let layers = guard.layer_map()?;
    6931         6209 :             'outer: for l in layers.iter_historic_layers() {
    6932         6209 :                 result.layers_total += 1;
    6933              : 
    6934              :                 // 1. Is it newer than GC horizon cutoff point?
    6935         6209 :                 if l.get_lsn_range().end > space_cutoff {
    6936          371 :                     debug!(
    6937            0 :                         "keeping {} because it's newer than space_cutoff {}",
    6938            0 :                         l.layer_name(),
    6939              :                         space_cutoff,
    6940              :                     );
    6941          371 :                     result.layers_needed_by_cutoff += 1;
    6942          371 :                     continue 'outer;
    6943         5838 :                 }
    6944              : 
    6945              :                 // 2. It is newer than PiTR cutoff point?
    6946         5838 :                 if l.get_lsn_range().end > time_cutoff {
    6947            0 :                     debug!(
    6948            0 :                         "keeping {} because it's newer than time_cutoff {}",
    6949            0 :                         l.layer_name(),
    6950              :                         time_cutoff,
    6951              :                     );
    6952            0 :                     result.layers_needed_by_pitr += 1;
    6953            0 :                     continue 'outer;
    6954         5838 :                 }
    6955              : 
    6956              :                 // 3. Is it needed by a child branch?
    6957              :                 // NOTE With that we would keep data that
    6958              :                 // might be referenced by child branches forever.
    6959              :                 // We can track this in child timeline GC and delete parent layers when
    6960              :                 // they are no longer needed. This might be complicated with long inheritance chains.
    6961         5838 :                 if let Some(retain_lsn) = max_retain_lsn {
    6962              :                     // start_lsn is inclusive
    6963            6 :                     if &l.get_lsn_range().start <= retain_lsn {
    6964            6 :                         debug!(
    6965            0 :                             "keeping {} because it's still might be referenced by child branch forked at {} is_dropped: xx is_incremental: {}",
    6966            0 :                             l.layer_name(),
    6967              :                             retain_lsn,
    6968            0 :                             l.is_incremental(),
    6969              :                         );
    6970            6 :                         result.layers_needed_by_branches += 1;
    6971            6 :                         continue 'outer;
    6972            0 :                     }
    6973         5832 :                 }
    6974              : 
    6975              :                 // 4. Is there a valid lease that requires us to keep this layer?
    6976         5832 :                 if let Some(lsn) = &max_lsn_with_valid_lease {
    6977              :                     // keep if layer start <= any of the lease
    6978            9 :                     if &l.get_lsn_range().start <= lsn {
    6979            7 :                         debug!(
    6980            0 :                             "keeping {} because there is a valid lease preventing GC at {}",
    6981            0 :                             l.layer_name(),
    6982              :                             lsn,
    6983              :                         );
    6984            7 :                         result.layers_needed_by_leases += 1;
    6985            7 :                         continue 'outer;
    6986            2 :                     }
    6987         5823 :                 }
    6988              : 
    6989              :                 // 5. Is there a later on-disk layer for this relation?
    6990              :                 //
    6991              :                 // The end-LSN is exclusive, while disk_consistent_lsn is
    6992              :                 // inclusive. For example, if disk_consistent_lsn is 100, it is
    6993              :                 // OK for a delta layer to have end LSN 101, but if the end LSN
    6994              :                 // is 102, then it might not have been fully flushed to disk
    6995              :                 // before crash.
    6996              :                 //
    6997              :                 // For example, imagine that the following layers exist:
    6998              :                 //
    6999              :                 // 1000      - image (A)
    7000              :                 // 1000-2000 - delta (B)
    7001              :                 // 2000      - image (C)
    7002              :                 // 2000-3000 - delta (D)
    7003              :                 // 3000      - image (E)
    7004              :                 //
    7005              :                 // If GC horizon is at 2500, we can remove layers A and B, but
    7006              :                 // we cannot remove C, even though it's older than 2500, because
    7007              :                 // the delta layer 2000-3000 depends on it.
    7008         5825 :                 if !layers
    7009         5825 :                     .image_layer_exists(&l.get_key_range(), &(l.get_lsn_range().end..new_gc_cutoff))
    7010              :                 {
    7011         5821 :                     debug!("keeping {} because it is the latest layer", l.layer_name());
    7012         5821 :                     result.layers_not_updated += 1;
    7013         5821 :                     continue 'outer;
    7014            4 :                 }
    7015              : 
    7016              :                 // We didn't find any reason to keep this file, so remove it.
    7017            4 :                 info!(
    7018            0 :                     "garbage collecting {} is_dropped: xx is_incremental: {}",
    7019            0 :                     l.layer_name(),
    7020            0 :                     l.is_incremental(),
    7021              :                 );
    7022            4 :                 layers_to_remove.push(l);
    7023              :             }
    7024              : 
    7025          366 :             layers_to_remove
    7026              :         };
    7027              : 
    7028          366 :         if !layers_to_remove.is_empty() {
    7029              :             // Persist the new GC cutoff value before we actually remove anything.
    7030              :             // This unconditionally schedules also an index_part.json update, even though, we will
    7031              :             // be doing one a bit later with the unlinked gc'd layers.
    7032            3 :             let disk_consistent_lsn = self.disk_consistent_lsn.load();
    7033            3 :             self.schedule_uploads(disk_consistent_lsn, None)
    7034            3 :                 .map_err(|e| {
    7035            0 :                     if self.cancel.is_cancelled() {
    7036            0 :                         GcError::TimelineCancelled
    7037              :                     } else {
    7038            0 :                         GcError::Remote(e)
    7039              :                     }
    7040            0 :                 })?;
    7041              : 
    7042            3 :             let mut guard = self
    7043            3 :                 .layers
    7044            3 :                 .write(LayerManagerLockHolder::GarbageCollection)
    7045            3 :                 .await;
    7046              : 
    7047            3 :             let gc_layers = layers_to_remove
    7048            3 :                 .iter()
    7049            4 :                 .flat_map(|desc| guard.try_get_from_key(&desc.key()).cloned())
    7050            3 :                 .collect::<Vec<Layer>>();
    7051              : 
    7052            3 :             result.layers_removed = gc_layers.len() as u64;
    7053              : 
    7054            3 :             self.remote_client.schedule_gc_update(&gc_layers)?;
    7055            3 :             guard.open_mut()?.finish_gc_timeline(&gc_layers);
    7056              : 
    7057              :             #[cfg(feature = "testing")]
    7058            3 :             {
    7059            3 :                 result.doomed_layers = gc_layers;
    7060            3 :             }
    7061          363 :         }
    7062              : 
    7063          366 :         info!(
    7064            0 :             "GC completed removing {} layers, cutoff {}",
    7065              :             result.layers_removed, new_gc_cutoff
    7066              :         );
    7067              : 
    7068          366 :         result.elapsed = now.elapsed().unwrap_or(Duration::ZERO);
    7069          366 :         Ok(result)
    7070          377 :     }
    7071              : 
    7072              :     /// Reconstruct a value, using the given base image and WAL records in 'data'.
    7073       364892 :     pub(crate) async fn reconstruct_value(
    7074       364892 :         &self,
    7075       364892 :         key: Key,
    7076       364892 :         request_lsn: Lsn,
    7077       364892 :         mut data: ValueReconstructState,
    7078       364892 :         redo_attempt_type: RedoAttemptType,
    7079       364892 :     ) -> Result<Bytes, PageReconstructError> {
    7080              :         // Perform WAL redo if needed
    7081       364892 :         data.records.reverse();
    7082              : 
    7083       364892 :         let fire_critical_error = match redo_attempt_type {
    7084       363559 :             RedoAttemptType::ReadPage => true,
    7085            0 :             RedoAttemptType::LegacyCompaction => true,
    7086         1333 :             RedoAttemptType::GcCompaction => false,
    7087              :         };
    7088              : 
    7089              :         // If we have a page image, and no WAL, we're all set
    7090       364892 :         if data.records.is_empty() {
    7091       338243 :             if let Some((img_lsn, img)) = &data.img {
    7092       338243 :                 trace!(
    7093            0 :                     "found page image for key {} at {}, no WAL redo required, req LSN {}",
    7094              :                     key, img_lsn, request_lsn,
    7095              :                 );
    7096       338243 :                 Ok(img.clone())
    7097              :             } else {
    7098            0 :                 Err(PageReconstructError::from(anyhow!(
    7099            0 :                     "base image for {key} at {request_lsn} not found"
    7100            0 :                 )))
    7101              :             }
    7102              :         } else {
    7103              :             // We need to do WAL redo.
    7104              :             //
    7105              :             // If we don't have a base image, then the oldest WAL record better initialize
    7106              :             // the page
    7107        26649 :             if data.img.is_none() && !data.records.first().unwrap().1.will_init() {
    7108            0 :                 Err(PageReconstructError::from(anyhow!(
    7109            0 :                     "Base image for {} at {} not found, but got {} WAL records",
    7110            0 :                     key,
    7111            0 :                     request_lsn,
    7112            0 :                     data.records.len()
    7113            0 :                 )))
    7114              :             } else {
    7115        26649 :                 if data.img.is_some() {
    7116        12781 :                     trace!(
    7117            0 :                         "found {} WAL records and a base image for {} at {}, performing WAL redo",
    7118            0 :                         data.records.len(),
    7119              :                         key,
    7120              :                         request_lsn
    7121              :                     );
    7122              :                 } else {
    7123        13868 :                     trace!(
    7124            0 :                         "found {} WAL records that will init the page for {} at {}, performing WAL redo",
    7125            0 :                         data.records.len(),
    7126              :                         key,
    7127              :                         request_lsn
    7128              :                     );
    7129              :                 };
    7130        26649 :                 let res = self
    7131        26649 :                     .walredo_mgr
    7132        26649 :                     .as_ref()
    7133        26649 :                     .context("timeline has no walredo manager")
    7134        26649 :                     .map_err(PageReconstructError::WalRedo)?
    7135        26649 :                     .request_redo(
    7136        26649 :                         key,
    7137        26649 :                         request_lsn,
    7138        26649 :                         data.img,
    7139        26649 :                         data.records,
    7140        26649 :                         self.pg_version,
    7141        26649 :                         redo_attempt_type,
    7142              :                     )
    7143        26649 :                     .await;
    7144        26648 :                 let img = match res {
    7145        26648 :                     Ok(img) => img,
    7146            0 :                     Err(walredo::Error::Cancelled) => return Err(PageReconstructError::Cancelled),
    7147            1 :                     Err(walredo::Error::Other(err)) => {
    7148            1 :                         if fire_critical_error {
    7149            0 :                             critical_timeline!(
    7150            0 :                                 self.tenant_shard_id,
    7151            0 :                                 self.timeline_id,
    7152            0 :                                 "walredo failure during page reconstruction: {err:?}"
    7153              :                             );
    7154            1 :                         }
    7155            1 :                         return Err(PageReconstructError::WalRedo(
    7156            1 :                             err.context("reconstruct a page image"),
    7157            1 :                         ));
    7158              :                     }
    7159              :                 };
    7160        26648 :                 Ok(img)
    7161              :             }
    7162              :         }
    7163       364892 :     }
    7164              : 
    7165            0 :     pub(crate) async fn spawn_download_all_remote_layers(
    7166            0 :         self: Arc<Self>,
    7167            0 :         request: DownloadRemoteLayersTaskSpawnRequest,
    7168            0 :         ctx: &RequestContext,
    7169            0 :     ) -> Result<DownloadRemoteLayersTaskInfo, DownloadRemoteLayersTaskInfo> {
    7170              :         use pageserver_api::models::DownloadRemoteLayersTaskState;
    7171              : 
    7172              :         // this is not really needed anymore; it has tests which really check the return value from
    7173              :         // http api. it would be better not to maintain this anymore.
    7174              : 
    7175            0 :         let mut status_guard = self.download_all_remote_layers_task_info.write().unwrap();
    7176            0 :         if let Some(st) = &*status_guard {
    7177            0 :             match &st.state {
    7178              :                 DownloadRemoteLayersTaskState::Running => {
    7179            0 :                     return Err(st.clone());
    7180              :                 }
    7181              :                 DownloadRemoteLayersTaskState::ShutDown
    7182            0 :                 | DownloadRemoteLayersTaskState::Completed => {
    7183            0 :                     *status_guard = None;
    7184            0 :                 }
    7185              :             }
    7186            0 :         }
    7187              : 
    7188            0 :         let self_clone = Arc::clone(&self);
    7189            0 :         let task_ctx = ctx.detached_child(
    7190            0 :             TaskKind::DownloadAllRemoteLayers,
    7191            0 :             DownloadBehavior::Download,
    7192              :         );
    7193            0 :         let task_id = task_mgr::spawn(
    7194            0 :             task_mgr::BACKGROUND_RUNTIME.handle(),
    7195            0 :             task_mgr::TaskKind::DownloadAllRemoteLayers,
    7196            0 :             self.tenant_shard_id,
    7197            0 :             Some(self.timeline_id),
    7198            0 :             "download all remote layers task",
    7199            0 :             async move {
    7200            0 :                 self_clone.download_all_remote_layers(request, &task_ctx).await;
    7201            0 :                 let mut status_guard = self_clone.download_all_remote_layers_task_info.write().unwrap();
    7202            0 :                  match &mut *status_guard {
    7203              :                     None => {
    7204            0 :                         warn!("tasks status is supposed to be Some(), since we are running");
    7205              :                     }
    7206            0 :                     Some(st) => {
    7207            0 :                         let exp_task_id = format!("{}", task_mgr::current_task_id().unwrap());
    7208            0 :                         if st.task_id != exp_task_id {
    7209            0 :                             warn!("task id changed while we were still running, expecting {} but have {}", exp_task_id, st.task_id);
    7210            0 :                         } else {
    7211            0 :                             st.state = DownloadRemoteLayersTaskState::Completed;
    7212            0 :                         }
    7213              :                     }
    7214              :                 };
    7215            0 :                 Ok(())
    7216            0 :             }
    7217            0 :             .instrument(info_span!(parent: None, "download_all_remote_layers", tenant_id = %self.tenant_shard_id.tenant_id, shard_id = %self.tenant_shard_id.shard_slug(), timeline_id = %self.timeline_id))
    7218              :         );
    7219              : 
    7220            0 :         let initial_info = DownloadRemoteLayersTaskInfo {
    7221            0 :             task_id: format!("{task_id}"),
    7222            0 :             state: DownloadRemoteLayersTaskState::Running,
    7223            0 :             total_layer_count: 0,
    7224            0 :             successful_download_count: 0,
    7225            0 :             failed_download_count: 0,
    7226            0 :         };
    7227            0 :         *status_guard = Some(initial_info.clone());
    7228              : 
    7229            0 :         Ok(initial_info)
    7230            0 :     }
    7231              : 
    7232            0 :     async fn download_all_remote_layers(
    7233            0 :         self: &Arc<Self>,
    7234            0 :         request: DownloadRemoteLayersTaskSpawnRequest,
    7235            0 :         ctx: &RequestContext,
    7236            0 :     ) {
    7237              :         use pageserver_api::models::DownloadRemoteLayersTaskState;
    7238              : 
    7239            0 :         let remaining = {
    7240            0 :             let guard = self
    7241            0 :                 .layers
    7242            0 :                 .read(LayerManagerLockHolder::GetLayerMapInfo)
    7243            0 :                 .await;
    7244            0 :             let Ok(lm) = guard.layer_map() else {
    7245              :                 // technically here we could look into iterating accessible layers, but downloading
    7246              :                 // all layers of a shutdown timeline makes no sense regardless.
    7247            0 :                 tracing::info!("attempted to download all layers of shutdown timeline");
    7248            0 :                 return;
    7249              :             };
    7250            0 :             lm.iter_historic_layers()
    7251            0 :                 .map(|desc| guard.get_from_desc(&desc))
    7252            0 :                 .collect::<Vec<_>>()
    7253              :         };
    7254            0 :         let total_layer_count = remaining.len();
    7255              : 
    7256              :         macro_rules! lock_status {
    7257              :             ($st:ident) => {
    7258              :                 let mut st = self.download_all_remote_layers_task_info.write().unwrap();
    7259              :                 let st = st
    7260              :                     .as_mut()
    7261              :                     .expect("this function is only called after the task has been spawned");
    7262              :                 assert_eq!(
    7263              :                     st.task_id,
    7264              :                     format!(
    7265              :                         "{}",
    7266              :                         task_mgr::current_task_id().expect("we run inside a task_mgr task")
    7267              :                     )
    7268              :                 );
    7269              :                 let $st = st;
    7270              :             };
    7271              :         }
    7272              : 
    7273              :         {
    7274            0 :             lock_status!(st);
    7275            0 :             st.total_layer_count = total_layer_count as u64;
    7276              :         }
    7277              : 
    7278            0 :         let mut remaining = remaining.into_iter();
    7279            0 :         let mut have_remaining = true;
    7280            0 :         let mut js = tokio::task::JoinSet::new();
    7281              : 
    7282            0 :         let cancel = task_mgr::shutdown_token();
    7283              : 
    7284            0 :         let limit = request.max_concurrent_downloads;
    7285              : 
    7286              :         loop {
    7287            0 :             while js.len() < limit.get() && have_remaining && !cancel.is_cancelled() {
    7288            0 :                 let Some(next) = remaining.next() else {
    7289            0 :                     have_remaining = false;
    7290            0 :                     break;
    7291              :                 };
    7292              : 
    7293            0 :                 let span = tracing::info_span!("download", layer = %next);
    7294              : 
    7295            0 :                 let ctx = ctx.attached_child();
    7296            0 :                 js.spawn(
    7297            0 :                     async move {
    7298            0 :                         let res = next.download(&ctx).await;
    7299            0 :                         (next, res)
    7300            0 :                     }
    7301            0 :                     .instrument(span),
    7302              :                 );
    7303              :             }
    7304              : 
    7305            0 :             while let Some(res) = js.join_next().await {
    7306            0 :                 match res {
    7307              :                     Ok((_, Ok(_))) => {
    7308            0 :                         lock_status!(st);
    7309            0 :                         st.successful_download_count += 1;
    7310              :                     }
    7311            0 :                     Ok((layer, Err(e))) => {
    7312            0 :                         tracing::error!(%layer, "download failed: {e:#}");
    7313            0 :                         lock_status!(st);
    7314            0 :                         st.failed_download_count += 1;
    7315              :                     }
    7316            0 :                     Err(je) if je.is_cancelled() => unreachable!("not used here"),
    7317            0 :                     Err(je) if je.is_panic() => {
    7318            0 :                         lock_status!(st);
    7319            0 :                         st.failed_download_count += 1;
    7320              :                     }
    7321            0 :                     Err(je) => tracing::warn!("unknown joinerror: {je:?}"),
    7322              :                 }
    7323              :             }
    7324              : 
    7325            0 :             if js.is_empty() && (!have_remaining || cancel.is_cancelled()) {
    7326            0 :                 break;
    7327            0 :             }
    7328              :         }
    7329              : 
    7330              :         {
    7331            0 :             lock_status!(st);
    7332            0 :             st.state = DownloadRemoteLayersTaskState::Completed;
    7333              :         }
    7334            0 :     }
    7335              : 
    7336            0 :     pub(crate) fn get_download_all_remote_layers_task_info(
    7337            0 :         &self,
    7338            0 :     ) -> Option<DownloadRemoteLayersTaskInfo> {
    7339            0 :         self.download_all_remote_layers_task_info
    7340            0 :             .read()
    7341            0 :             .unwrap()
    7342            0 :             .clone()
    7343            0 :     }
    7344              : 
    7345              :     /* BEGIN_HADRON */
    7346            0 :     pub(crate) async fn compute_image_consistent_lsn(&self) -> anyhow::Result<Lsn> {
    7347            0 :         let guard = self
    7348            0 :             .layers
    7349            0 :             .read(LayerManagerLockHolder::ComputeImageConsistentLsn)
    7350            0 :             .await;
    7351            0 :         let layer_map = guard.layer_map()?;
    7352            0 :         let disk_consistent_lsn = self.get_disk_consistent_lsn();
    7353              : 
    7354            0 :         Ok(layer_map.compute_image_consistent_lsn(disk_consistent_lsn))
    7355            0 :     }
    7356              :     /* END_HADRON */
    7357              : }
    7358              : 
    7359              : impl Timeline {
    7360              :     /// Returns non-remote layers for eviction.
    7361            0 :     pub(crate) async fn get_local_layers_for_disk_usage_eviction(&self) -> DiskUsageEvictionInfo {
    7362            0 :         let guard = self.layers.read(LayerManagerLockHolder::Eviction).await;
    7363            0 :         let mut max_layer_size: Option<u64> = None;
    7364              : 
    7365            0 :         let resident_layers = guard
    7366            0 :             .likely_resident_layers()
    7367            0 :             .map(|layer| {
    7368            0 :                 let file_size = layer.layer_desc().file_size;
    7369            0 :                 max_layer_size = max_layer_size.map_or(Some(file_size), |m| Some(m.max(file_size)));
    7370              : 
    7371            0 :                 let last_activity_ts = layer.latest_activity();
    7372              : 
    7373            0 :                 EvictionCandidate {
    7374            0 :                     layer: layer.to_owned().into(),
    7375            0 :                     last_activity_ts,
    7376            0 :                     relative_last_activity: finite_f32::FiniteF32::ZERO,
    7377            0 :                     visibility: layer.visibility(),
    7378            0 :                 }
    7379            0 :             })
    7380            0 :             .collect();
    7381              : 
    7382            0 :         DiskUsageEvictionInfo {
    7383            0 :             max_layer_size,
    7384            0 :             resident_layers,
    7385            0 :         }
    7386            0 :     }
    7387              : 
    7388          962 :     pub(crate) fn get_shard_index(&self) -> ShardIndex {
    7389          962 :         ShardIndex {
    7390          962 :             shard_number: self.tenant_shard_id.shard_number,
    7391          962 :             shard_count: self.tenant_shard_id.shard_count,
    7392          962 :         }
    7393          962 :     }
    7394              : 
    7395              :     /// Persistently blocks gc for `Manual` reason.
    7396              :     ///
    7397              :     /// Returns true if no such block existed before, false otherwise.
    7398            0 :     pub(crate) async fn block_gc(&self, tenant: &super::TenantShard) -> anyhow::Result<bool> {
    7399              :         use crate::tenant::remote_timeline_client::index::GcBlockingReason;
    7400            0 :         assert_eq!(self.tenant_shard_id, tenant.tenant_shard_id);
    7401            0 :         tenant.gc_block.insert(self, GcBlockingReason::Manual).await
    7402            0 :     }
    7403              : 
    7404              :     /// Persistently unblocks gc for `Manual` reason.
    7405            0 :     pub(crate) async fn unblock_gc(&self, tenant: &super::TenantShard) -> anyhow::Result<()> {
    7406              :         use crate::tenant::remote_timeline_client::index::GcBlockingReason;
    7407            0 :         assert_eq!(self.tenant_shard_id, tenant.tenant_shard_id);
    7408            0 :         tenant.gc_block.remove(self, GcBlockingReason::Manual).await
    7409            0 :     }
    7410              : 
    7411              :     #[cfg(test)]
    7412           31 :     pub(super) fn force_advance_lsn(self: &Arc<Timeline>, new_lsn: Lsn) {
    7413           31 :         self.last_record_lsn.advance(new_lsn);
    7414           31 :     }
    7415              : 
    7416              :     #[cfg(test)]
    7417            2 :     pub(super) fn force_set_disk_consistent_lsn(&self, new_value: Lsn) {
    7418            2 :         self.disk_consistent_lsn.store(new_value);
    7419            2 :     }
    7420              : 
    7421              :     /// Force create an image layer and place it into the layer map.
    7422              :     ///
    7423              :     /// DO NOT use this function directly. Use [`TenantShard::branch_timeline_test_with_layers`]
    7424              :     /// or [`TenantShard::create_test_timeline_with_layers`] to ensure all these layers are
    7425              :     /// placed into the layer map in one run AND be validated.
    7426              :     #[cfg(test)]
    7427           36 :     pub(super) async fn force_create_image_layer(
    7428           36 :         self: &Arc<Timeline>,
    7429           36 :         lsn: Lsn,
    7430           36 :         mut images: Vec<(Key, Bytes)>,
    7431           36 :         check_start_lsn: Option<Lsn>,
    7432           36 :         ctx: &RequestContext,
    7433           36 :     ) -> anyhow::Result<()> {
    7434           36 :         let last_record_lsn = self.get_last_record_lsn();
    7435           36 :         assert!(
    7436           36 :             lsn <= last_record_lsn,
    7437            0 :             "advance last record lsn before inserting a layer, lsn={lsn}, last_record_lsn={last_record_lsn}"
    7438              :         );
    7439           36 :         if let Some(check_start_lsn) = check_start_lsn {
    7440           36 :             assert!(lsn >= check_start_lsn);
    7441            0 :         }
    7442          240 :         images.sort_unstable_by(|(ka, _), (kb, _)| ka.cmp(kb));
    7443           36 :         let min_key = *images.first().map(|(k, _)| k).unwrap();
    7444           36 :         let end_key = images.last().map(|(k, _)| k).unwrap().next();
    7445           36 :         let mut image_layer_writer = ImageLayerWriter::new(
    7446           36 :             self.conf,
    7447           36 :             self.timeline_id,
    7448           36 :             self.tenant_shard_id,
    7449           36 :             &(min_key..end_key),
    7450           36 :             lsn,
    7451           36 :             &self.gate,
    7452           36 :             self.cancel.clone(),
    7453           36 :             ctx,
    7454           36 :         )
    7455           36 :         .await?;
    7456          312 :         for (key, img) in images {
    7457          276 :             image_layer_writer.put_image(key, img, ctx).await?;
    7458              :         }
    7459           36 :         let (desc, path) = image_layer_writer.finish(ctx).await?;
    7460           36 :         let image_layer = Layer::finish_creating(self.conf, self, desc, &path)?;
    7461           36 :         info!("force created image layer {}", image_layer.local_path());
    7462              :         {
    7463           36 :             let mut guard = self.layers.write(LayerManagerLockHolder::Testing).await;
    7464           36 :             guard
    7465           36 :                 .open_mut()
    7466           36 :                 .unwrap()
    7467           36 :                 .force_insert_layer(image_layer.clone());
    7468              :         }
    7469              : 
    7470              :         // Update remote_timeline_client state to reflect existence of this layer
    7471           36 :         self.remote_client
    7472           36 :             .schedule_layer_file_upload(image_layer)
    7473           36 :             .unwrap();
    7474              : 
    7475           36 :         Ok(())
    7476           36 :     }
    7477              : 
    7478              :     /// Force create a delta layer and place it into the layer map.
    7479              :     ///
    7480              :     /// DO NOT use this function directly. Use [`TenantShard::branch_timeline_test_with_layers`]
    7481              :     /// or [`TenantShard::create_test_timeline_with_layers`] to ensure all these layers are
    7482              :     /// placed into the layer map in one run AND be validated.
    7483              :     #[cfg(test)]
    7484           50 :     pub(super) async fn force_create_delta_layer(
    7485           50 :         self: &Arc<Timeline>,
    7486           50 :         mut deltas: DeltaLayerTestDesc,
    7487           50 :         check_start_lsn: Option<Lsn>,
    7488           50 :         ctx: &RequestContext,
    7489           50 :     ) -> anyhow::Result<()> {
    7490           50 :         let last_record_lsn = self.get_last_record_lsn();
    7491           50 :         deltas
    7492           50 :             .data
    7493       124364 :             .sort_unstable_by(|(ka, la, _), (kb, lb, _)| (ka, la).cmp(&(kb, lb)));
    7494           50 :         assert!(deltas.data.first().unwrap().0 >= deltas.key_range.start);
    7495           50 :         assert!(deltas.data.last().unwrap().0 < deltas.key_range.end);
    7496        10464 :         for (_, lsn, _) in &deltas.data {
    7497        10414 :             assert!(deltas.lsn_range.start <= *lsn && *lsn < deltas.lsn_range.end);
    7498              :         }
    7499           50 :         assert!(
    7500           50 :             deltas.lsn_range.end <= last_record_lsn,
    7501            0 :             "advance last record lsn before inserting a layer, end_lsn={}, last_record_lsn={}",
    7502              :             deltas.lsn_range.end,
    7503              :             last_record_lsn
    7504              :         );
    7505           50 :         if let Some(check_start_lsn) = check_start_lsn {
    7506           50 :             assert!(deltas.lsn_range.start >= check_start_lsn);
    7507            0 :         }
    7508           50 :         let mut delta_layer_writer = DeltaLayerWriter::new(
    7509           50 :             self.conf,
    7510           50 :             self.timeline_id,
    7511           50 :             self.tenant_shard_id,
    7512           50 :             deltas.key_range.start,
    7513           50 :             deltas.lsn_range,
    7514           50 :             &self.gate,
    7515           50 :             self.cancel.clone(),
    7516           50 :             ctx,
    7517           50 :         )
    7518           50 :         .await?;
    7519        10464 :         for (key, lsn, val) in deltas.data {
    7520        10414 :             delta_layer_writer.put_value(key, lsn, val, ctx).await?;
    7521              :         }
    7522           50 :         let (desc, path) = delta_layer_writer.finish(deltas.key_range.end, ctx).await?;
    7523           50 :         let delta_layer = Layer::finish_creating(self.conf, self, desc, &path)?;
    7524           50 :         info!("force created delta layer {}", delta_layer.local_path());
    7525              :         {
    7526           50 :             let mut guard = self.layers.write(LayerManagerLockHolder::Testing).await;
    7527           50 :             guard
    7528           50 :                 .open_mut()
    7529           50 :                 .unwrap()
    7530           50 :                 .force_insert_layer(delta_layer.clone());
    7531              :         }
    7532              : 
    7533              :         // Update remote_timeline_client state to reflect existence of this layer
    7534           50 :         self.remote_client
    7535           50 :             .schedule_layer_file_upload(delta_layer)
    7536           50 :             .unwrap();
    7537              : 
    7538           50 :         Ok(())
    7539           50 :     }
    7540              : 
    7541              :     /// Force create an in-memory layer and place them into the layer map.
    7542              :     #[cfg(test)]
    7543            4 :     pub(super) async fn force_create_in_memory_layer(
    7544            4 :         self: &Arc<Timeline>,
    7545            4 :         mut in_memory: InMemoryLayerTestDesc,
    7546            4 :         check_start_lsn: Option<Lsn>,
    7547            4 :         ctx: &RequestContext,
    7548            4 :     ) -> anyhow::Result<()> {
    7549              :         use utils::bin_ser::BeSer;
    7550              : 
    7551              :         // Validate LSNs
    7552            4 :         if let Some(check_start_lsn) = check_start_lsn {
    7553            4 :             assert!(in_memory.lsn_range.start >= check_start_lsn);
    7554            0 :         }
    7555              : 
    7556            4 :         let last_record_lsn = self.get_last_record_lsn();
    7557            4 :         let layer_end_lsn = if in_memory.is_open {
    7558            1 :             in_memory
    7559            1 :                 .data
    7560            1 :                 .iter()
    7561            1 :                 .map(|(_key, lsn, _value)| lsn)
    7562            1 :                 .max()
    7563            1 :                 .cloned()
    7564              :         } else {
    7565            3 :             Some(in_memory.lsn_range.end)
    7566              :         };
    7567              : 
    7568            4 :         if let Some(end) = layer_end_lsn {
    7569            4 :             assert!(
    7570            4 :                 end <= last_record_lsn,
    7571            0 :                 "advance last record lsn before inserting a layer, end_lsn={end}, last_record_lsn={last_record_lsn}",
    7572              :             );
    7573            0 :         }
    7574              : 
    7575        19820 :         in_memory.data.iter().for_each(|(_key, lsn, _value)| {
    7576        19820 :             assert!(*lsn >= in_memory.lsn_range.start);
    7577        19820 :             assert!(*lsn < in_memory.lsn_range.end);
    7578        19820 :         });
    7579              : 
    7580              :         // Build the batch
    7581            4 :         in_memory
    7582            4 :             .data
    7583       273384 :             .sort_unstable_by(|(ka, la, _), (kb, lb, _)| (ka, la).cmp(&(kb, lb)));
    7584              : 
    7585            4 :         let data = in_memory
    7586            4 :             .data
    7587            4 :             .into_iter()
    7588        19820 :             .map(|(key, lsn, value)| {
    7589        19820 :                 let value_size = value.serialized_size().unwrap() as usize;
    7590        19820 :                 (key.to_compact(), lsn, value_size, value)
    7591        19820 :             })
    7592            4 :             .collect::<Vec<_>>();
    7593              : 
    7594            4 :         let batch = SerializedValueBatch::from_values(data);
    7595              : 
    7596              :         // Create the in-memory layer and write the batch into it
    7597            4 :         let layer = InMemoryLayer::create(
    7598            4 :             self.conf,
    7599            4 :             self.timeline_id,
    7600            4 :             self.tenant_shard_id,
    7601            4 :             in_memory.lsn_range.start,
    7602            4 :             &self.gate,
    7603            4 :             // TODO: if we ever use this function in production code, we need to pass the real cancellation token
    7604            4 :             &CancellationToken::new(),
    7605            4 :             ctx,
    7606            4 :         )
    7607            4 :         .await
    7608            4 :         .unwrap();
    7609              : 
    7610            4 :         layer.put_batch(batch, ctx).await.unwrap();
    7611            4 :         if !in_memory.is_open {
    7612            3 :             layer.freeze(in_memory.lsn_range.end).await;
    7613            1 :         }
    7614              : 
    7615            4 :         info!("force created in-memory layer {:?}", in_memory.lsn_range);
    7616              : 
    7617              :         // Link the layer to the layer map
    7618              :         {
    7619            4 :             let mut guard = self.layers.write(LayerManagerLockHolder::Testing).await;
    7620            4 :             let layer_map = guard.open_mut().unwrap();
    7621            4 :             layer_map.force_insert_in_memory_layer(Arc::new(layer));
    7622              :         }
    7623              : 
    7624            4 :         Ok(())
    7625            4 :     }
    7626              : 
    7627              :     /// Return all keys at the LSN in the image layers
    7628              :     #[cfg(test)]
    7629            3 :     pub(crate) async fn inspect_image_layers(
    7630            3 :         self: &Arc<Timeline>,
    7631            3 :         lsn: Lsn,
    7632            3 :         ctx: &RequestContext,
    7633            3 :         io_concurrency: IoConcurrency,
    7634            3 :     ) -> anyhow::Result<Vec<(Key, Bytes)>> {
    7635            3 :         let mut all_data = Vec::new();
    7636            3 :         let guard = self.layers.read(LayerManagerLockHolder::Testing).await;
    7637           17 :         for layer in guard.layer_map()?.iter_historic_layers() {
    7638           17 :             if !layer.is_delta() && layer.image_layer_lsn() == lsn {
    7639            4 :                 let layer = guard.get_from_desc(&layer);
    7640            4 :                 let mut reconstruct_data = ValuesReconstructState::new(io_concurrency.clone());
    7641            4 :                 layer
    7642            4 :                     .get_values_reconstruct_data(
    7643            4 :                         KeySpace::single(Key::MIN..Key::MAX),
    7644            4 :                         lsn..Lsn(lsn.0 + 1),
    7645            4 :                         &mut reconstruct_data,
    7646            4 :                         ctx,
    7647            4 :                     )
    7648            4 :                     .await?;
    7649           33 :                 for (k, v) in std::mem::take(&mut reconstruct_data.keys) {
    7650           33 :                     let v = v.collect_pending_ios().await?;
    7651           33 :                     all_data.push((k, v.img.unwrap().1));
    7652              :                 }
    7653           13 :             }
    7654              :         }
    7655            3 :         all_data.sort();
    7656            3 :         Ok(all_data)
    7657            3 :     }
    7658              : 
    7659              :     /// Get all historic layer descriptors in the layer map
    7660              :     #[cfg(test)]
    7661           12 :     pub(crate) async fn inspect_historic_layers(
    7662           12 :         self: &Arc<Timeline>,
    7663           12 :     ) -> anyhow::Result<Vec<super::storage_layer::PersistentLayerKey>> {
    7664           12 :         let mut layers = Vec::new();
    7665           12 :         let guard = self.layers.read(LayerManagerLockHolder::Testing).await;
    7666           57 :         for layer in guard.layer_map()?.iter_historic_layers() {
    7667           57 :             layers.push(layer.key());
    7668           57 :         }
    7669           12 :         Ok(layers)
    7670           12 :     }
    7671              : 
    7672              :     #[cfg(test)]
    7673            5 :     pub(crate) fn add_extra_test_dense_keyspace(&self, ks: KeySpace) {
    7674            5 :         let mut keyspace = self.extra_test_dense_keyspace.load().as_ref().clone();
    7675            5 :         keyspace.merge(&ks);
    7676            5 :         self.extra_test_dense_keyspace.store(Arc::new(keyspace));
    7677            5 :     }
    7678              : }
    7679              : 
    7680              : /// Tracking writes ingestion does to a particular in-memory layer.
    7681              : ///
    7682              : /// Cleared upon freezing a layer.
    7683              : pub(crate) struct TimelineWriterState {
    7684              :     open_layer: Arc<InMemoryLayer>,
    7685              :     current_size: u64,
    7686              :     // Previous Lsn which passed through
    7687              :     prev_lsn: Option<Lsn>,
    7688              :     // Largest Lsn which passed through the current writer
    7689              :     max_lsn: Option<Lsn>,
    7690              :     // Cached details of the last freeze. Avoids going trough the atomic/lock on every put.
    7691              :     cached_last_freeze_at: Lsn,
    7692              : }
    7693              : 
    7694              : impl TimelineWriterState {
    7695          660 :     fn new(open_layer: Arc<InMemoryLayer>, current_size: u64, last_freeze_at: Lsn) -> Self {
    7696          660 :         Self {
    7697          660 :             open_layer,
    7698          660 :             current_size,
    7699          660 :             prev_lsn: None,
    7700          660 :             max_lsn: None,
    7701          660 :             cached_last_freeze_at: last_freeze_at,
    7702          660 :         }
    7703          660 :     }
    7704              : }
    7705              : 
    7706              : /// Various functions to mutate the timeline.
    7707              : // TODO Currently, Deref is used to allow easy access to read methods from this trait.
    7708              : // This is probably considered a bad practice in Rust and should be fixed eventually,
    7709              : // but will cause large code changes.
    7710              : pub(crate) struct TimelineWriter<'a> {
    7711              :     tl: &'a Timeline,
    7712              :     write_guard: tokio::sync::MutexGuard<'a, Option<TimelineWriterState>>,
    7713              : }
    7714              : 
    7715              : impl Deref for TimelineWriter<'_> {
    7716              :     type Target = Timeline;
    7717              : 
    7718      4949226 :     fn deref(&self) -> &Self::Target {
    7719      4949226 :         self.tl
    7720      4949226 :     }
    7721              : }
    7722              : 
    7723              : #[derive(PartialEq)]
    7724              : enum OpenLayerAction {
    7725              :     Roll,
    7726              :     Open,
    7727              :     None,
    7728              : }
    7729              : 
    7730              : impl TimelineWriter<'_> {
    7731      2402129 :     async fn handle_open_layer_action(
    7732      2402129 :         &mut self,
    7733      2402129 :         at: Lsn,
    7734      2402129 :         action: OpenLayerAction,
    7735      2402129 :         ctx: &RequestContext,
    7736      2402129 :     ) -> anyhow::Result<&Arc<InMemoryLayer>> {
    7737      2402129 :         match action {
    7738              :             OpenLayerAction::Roll => {
    7739           40 :                 let freeze_at = self.write_guard.as_ref().unwrap().max_lsn.unwrap();
    7740           40 :                 self.roll_layer(freeze_at).await?;
    7741           40 :                 self.open_layer(at, ctx).await?;
    7742              :             }
    7743          620 :             OpenLayerAction::Open => self.open_layer(at, ctx).await?,
    7744              :             OpenLayerAction::None => {
    7745      2401469 :                 assert!(self.write_guard.is_some());
    7746              :             }
    7747              :         }
    7748              : 
    7749      2402129 :         Ok(&self.write_guard.as_ref().unwrap().open_layer)
    7750      2402129 :     }
    7751              : 
    7752          660 :     async fn open_layer(&mut self, at: Lsn, ctx: &RequestContext) -> anyhow::Result<()> {
    7753          660 :         let layer = self
    7754          660 :             .tl
    7755          660 :             .get_layer_for_write(at, &self.write_guard, ctx)
    7756          660 :             .await?;
    7757          660 :         let initial_size = layer.len();
    7758              : 
    7759          660 :         let last_freeze_at = self.last_freeze_at.load();
    7760          660 :         self.write_guard.replace(TimelineWriterState::new(
    7761          660 :             layer,
    7762          660 :             initial_size,
    7763          660 :             last_freeze_at,
    7764          660 :         ));
    7765              : 
    7766          660 :         Ok(())
    7767          660 :     }
    7768              : 
    7769           40 :     async fn roll_layer(&mut self, freeze_at: Lsn) -> Result<(), FlushLayerError> {
    7770           40 :         let current_size = self.write_guard.as_ref().unwrap().current_size;
    7771              : 
    7772              :         // If layer flushes are backpressured due to compaction not keeping up, wait for the flush
    7773              :         // to propagate the backpressure up into WAL ingestion.
    7774           40 :         let l0_count = self
    7775           40 :             .tl
    7776           40 :             .layers
    7777           40 :             .read(LayerManagerLockHolder::GetLayerMapInfo)
    7778           40 :             .await
    7779           40 :             .layer_map()?
    7780           40 :             .level0_deltas()
    7781           40 :             .len();
    7782           40 :         let wait_thresholds = [
    7783           40 :             self.get_l0_flush_delay_threshold(),
    7784           40 :             self.get_l0_flush_stall_threshold(),
    7785           40 :         ];
    7786           40 :         let wait_threshold = wait_thresholds.into_iter().flatten().min();
    7787              : 
    7788              :         // self.write_guard will be taken by the freezing
    7789           40 :         let flush_id = self
    7790           40 :             .tl
    7791           40 :             .freeze_inmem_layer_at(freeze_at, &mut self.write_guard)
    7792           40 :             .await?;
    7793              : 
    7794           40 :         assert!(self.write_guard.is_none());
    7795              : 
    7796           40 :         if let Some(wait_threshold) = wait_threshold {
    7797            0 :             if l0_count >= wait_threshold {
    7798            0 :                 debug!(
    7799            0 :                     "layer roll waiting for flush due to compaction backpressure at {l0_count} L0 layers"
    7800              :                 );
    7801            0 :                 self.tl.wait_flush_completion(flush_id).await?;
    7802            0 :             }
    7803           40 :         }
    7804              : 
    7805           40 :         if current_size >= self.get_checkpoint_distance() * 2 {
    7806            0 :             warn!("Flushed oversized open layer with size {}", current_size)
    7807           40 :         }
    7808              : 
    7809           40 :         Ok(())
    7810           40 :     }
    7811              : 
    7812      2402129 :     fn get_open_layer_action(&self, lsn: Lsn, new_value_size: u64) -> OpenLayerAction {
    7813      2402129 :         let state = &*self.write_guard;
    7814      2402129 :         let Some(state) = &state else {
    7815          620 :             return OpenLayerAction::Open;
    7816              :         };
    7817              : 
    7818              :         #[cfg(feature = "testing")]
    7819      2401509 :         if state.cached_last_freeze_at < self.tl.last_freeze_at.load() {
    7820              :             // this check and assertion are not really needed because
    7821              :             // LayerManager::try_freeze_in_memory_layer will always clear out the
    7822              :             // TimelineWriterState if something is frozen. however, we can advance last_freeze_at when there
    7823              :             // is no TimelineWriterState.
    7824            0 :             assert!(
    7825            0 :                 state.open_layer.end_lsn.get().is_some(),
    7826            0 :                 "our open_layer must be outdated"
    7827              :             );
    7828              : 
    7829              :             // this would be a memory leak waiting to happen because the in-memory layer always has
    7830              :             // an index
    7831            0 :             panic!("BUG: TimelineWriterState held on to frozen in-memory layer.");
    7832      2401509 :         }
    7833              : 
    7834      2401509 :         if state.prev_lsn == Some(lsn) {
    7835              :             // Rolling mid LSN is not supported by [downstream code].
    7836              :             // Hence, only roll at LSN boundaries.
    7837              :             //
    7838              :             // [downstream code]: https://github.com/neondatabase/neon/pull/7993#discussion_r1633345422
    7839            3 :             return OpenLayerAction::None;
    7840      2401506 :         }
    7841              : 
    7842      2401506 :         if state.current_size == 0 {
    7843              :             // Don't roll empty layers
    7844            0 :             return OpenLayerAction::None;
    7845      2401506 :         }
    7846              : 
    7847      2401506 :         if self.tl.should_roll(
    7848      2401506 :             state.current_size,
    7849      2401506 :             state.current_size + new_value_size,
    7850      2401506 :             self.get_checkpoint_distance(),
    7851      2401506 :             lsn,
    7852      2401506 :             state.cached_last_freeze_at,
    7853      2401506 :             state.open_layer.get_opened_at(),
    7854              :         ) {
    7855           40 :             OpenLayerAction::Roll
    7856              :         } else {
    7857      2401466 :             OpenLayerAction::None
    7858              :         }
    7859      2402129 :     }
    7860              : 
    7861              :     /// Put a batch of keys at the specified Lsns.
    7862      2402128 :     pub(crate) async fn put_batch(
    7863      2402128 :         &mut self,
    7864      2402128 :         batch: SerializedValueBatch,
    7865      2402128 :         ctx: &RequestContext,
    7866      2402128 :     ) -> anyhow::Result<()> {
    7867      2402128 :         if !batch.has_data() {
    7868            0 :             return Ok(());
    7869      2402128 :         }
    7870              : 
    7871              :         // In debug builds, assert that we don't write any keys that don't belong to this shard.
    7872              :         // We don't assert this in release builds, since key ownership policies may change over
    7873              :         // time. Stray keys will be removed during compaction.
    7874      2402128 :         if cfg!(debug_assertions) {
    7875      4947529 :             for metadata in &batch.metadata {
    7876      2545401 :                 if let ValueMeta::Serialized(metadata) = metadata {
    7877      2545401 :                     let key = Key::from_compact(metadata.key);
    7878      2545401 :                     assert!(
    7879      2545401 :                         self.shard_identity.is_key_local(&key)
    7880           12 :                             || self.shard_identity.is_key_global(&key),
    7881            0 :                         "key {key} does not belong on shard {}",
    7882            0 :                         self.shard_identity.shard_index()
    7883              :                     );
    7884            0 :                 }
    7885              :             }
    7886            0 :         }
    7887              : 
    7888      2402128 :         let batch_max_lsn = batch.max_lsn;
    7889      2402128 :         let buf_size: u64 = batch.buffer_size() as u64;
    7890              : 
    7891      2402128 :         let action = self.get_open_layer_action(batch_max_lsn, buf_size);
    7892      2402128 :         let layer = self
    7893      2402128 :             .handle_open_layer_action(batch_max_lsn, action, ctx)
    7894      2402128 :             .await?;
    7895              : 
    7896      2402128 :         let res = layer.put_batch(batch, ctx).await;
    7897              : 
    7898      2402128 :         if res.is_ok() {
    7899      2402128 :             // Update the current size only when the entire write was ok.
    7900      2402128 :             // In case of failures, we may have had partial writes which
    7901      2402128 :             // render the size tracking out of sync. That's ok because
    7902      2402128 :             // the checkpoint distance should be significantly smaller
    7903      2402128 :             // than the S3 single shot upload limit of 5GiB.
    7904      2402128 :             let state = self.write_guard.as_mut().unwrap();
    7905      2402128 : 
    7906      2402128 :             state.current_size += buf_size;
    7907      2402128 :             state.prev_lsn = Some(batch_max_lsn);
    7908      2402128 :             state.max_lsn = std::cmp::max(state.max_lsn, Some(batch_max_lsn));
    7909      2402128 :         }
    7910              : 
    7911      2402128 :         res
    7912      2402128 :     }
    7913              : 
    7914              :     #[cfg(test)]
    7915              :     /// Test helper, for tests that would like to poke individual values without composing a batch
    7916      2195079 :     pub(crate) async fn put(
    7917      2195079 :         &mut self,
    7918      2195079 :         key: Key,
    7919      2195079 :         lsn: Lsn,
    7920      2195079 :         value: &Value,
    7921      2195079 :         ctx: &RequestContext,
    7922      2195079 :     ) -> anyhow::Result<()> {
    7923              :         use utils::bin_ser::BeSer;
    7924      2195079 :         if !key.is_valid_key_on_write_path() {
    7925            0 :             bail!(
    7926            0 :                 "the request contains data not supported by pageserver at TimelineWriter::put: {}",
    7927              :                 key
    7928              :             );
    7929      2195079 :         }
    7930      2195079 :         let val_ser_size = value.serialized_size().unwrap() as usize;
    7931      2195079 :         let batch = SerializedValueBatch::from_values(vec![(
    7932      2195079 :             key.to_compact(),
    7933      2195079 :             lsn,
    7934      2195079 :             val_ser_size,
    7935      2195079 :             value.clone(),
    7936      2195079 :         )]);
    7937              : 
    7938      2195079 :         self.put_batch(batch, ctx).await
    7939      2195079 :     }
    7940              : 
    7941            1 :     pub(crate) async fn delete_batch(
    7942            1 :         &mut self,
    7943            1 :         batch: &[(Range<Key>, Lsn)],
    7944            1 :         ctx: &RequestContext,
    7945            1 :     ) -> anyhow::Result<()> {
    7946            1 :         if let Some((_, lsn)) = batch.first() {
    7947            1 :             let action = self.get_open_layer_action(*lsn, 0);
    7948            1 :             let layer = self.handle_open_layer_action(*lsn, action, ctx).await?;
    7949            1 :             layer.put_tombstones(batch).await?;
    7950            0 :         }
    7951              : 
    7952            1 :         Ok(())
    7953            1 :     }
    7954              : 
    7955              :     /// Track the end of the latest digested WAL record.
    7956              :     /// Remember the (end of) last valid WAL record remembered in the timeline.
    7957              :     ///
    7958              :     /// Call this after you have finished writing all the WAL up to 'lsn'.
    7959              :     ///
    7960              :     /// 'lsn' must be aligned. This wakes up any wait_lsn() callers waiting for
    7961              :     /// the 'lsn' or anything older. The previous last record LSN is stored alongside
    7962              :     /// the latest and can be read.
    7963      2639560 :     pub(crate) fn finish_write(&self, new_lsn: Lsn) {
    7964      2639560 :         self.tl.finish_write(new_lsn);
    7965      2639560 :     }
    7966              : 
    7967       135285 :     pub(crate) fn update_current_logical_size(&self, delta: i64) {
    7968       135285 :         self.tl.update_current_logical_size(delta)
    7969       135285 :     }
    7970              : }
    7971              : 
    7972              : // We need TimelineWriter to be send in upcoming conversion of
    7973              : // Timeline::layers to tokio::sync::RwLock.
    7974              : #[test]
    7975            1 : fn is_send() {
    7976            1 :     fn _assert_send<T: Send>() {}
    7977            1 :     _assert_send::<TimelineWriter<'_>>();
    7978            1 : }
    7979              : 
    7980              : #[cfg(test)]
    7981              : mod tests {
    7982              :     use std::sync::Arc;
    7983              : 
    7984              :     use pageserver_api::key::Key;
    7985              :     use postgres_ffi::PgMajorVersion;
    7986              :     use std::iter::Iterator;
    7987              :     use tracing::Instrument;
    7988              :     use utils::id::TimelineId;
    7989              :     use utils::lsn::Lsn;
    7990              :     use wal_decoder::models::value::Value;
    7991              : 
    7992              :     use super::HeatMapTimeline;
    7993              :     use crate::context::RequestContextBuilder;
    7994              :     use crate::tenant::harness::{TenantHarness, test_img};
    7995              :     use crate::tenant::layer_map::LayerMap;
    7996              :     use crate::tenant::storage_layer::{Layer, LayerName, LayerVisibilityHint};
    7997              :     use crate::tenant::timeline::layer_manager::LayerManagerLockHolder;
    7998              :     use crate::tenant::timeline::{DeltaLayerTestDesc, EvictionError};
    7999              :     use crate::tenant::{PreviousHeatmap, Timeline};
    8000              : 
    8001            5 :     fn assert_heatmaps_have_same_layers(lhs: &HeatMapTimeline, rhs: &HeatMapTimeline) {
    8002            5 :         assert_eq!(lhs.all_layers().count(), rhs.all_layers().count());
    8003            5 :         let lhs_rhs = lhs.all_layers().zip(rhs.all_layers());
    8004           25 :         for (l, r) in lhs_rhs {
    8005           20 :             assert_eq!(l.name, r.name);
    8006           20 :             assert_eq!(l.metadata, r.metadata);
    8007              :         }
    8008            5 :     }
    8009              : 
    8010              :     #[tokio::test]
    8011            1 :     async fn test_heatmap_generation() {
    8012            1 :         let harness = TenantHarness::create("heatmap_generation").await.unwrap();
    8013              : 
    8014            1 :         let covered_delta = DeltaLayerTestDesc::new_with_inferred_key_range(
    8015            1 :             Lsn(0x10)..Lsn(0x20),
    8016            1 :             vec![(
    8017            1 :                 Key::from_hex("620000000033333333444444445500000000").unwrap(),
    8018            1 :                 Lsn(0x11),
    8019            1 :                 Value::Image(test_img("foo")),
    8020            1 :             )],
    8021              :         );
    8022            1 :         let visible_delta = DeltaLayerTestDesc::new_with_inferred_key_range(
    8023            1 :             Lsn(0x10)..Lsn(0x20),
    8024            1 :             vec![(
    8025            1 :                 Key::from_hex("720000000033333333444444445500000000").unwrap(),
    8026            1 :                 Lsn(0x11),
    8027            1 :                 Value::Image(test_img("foo")),
    8028            1 :             )],
    8029              :         );
    8030            1 :         let l0_delta = DeltaLayerTestDesc::new(
    8031            1 :             Lsn(0x20)..Lsn(0x30),
    8032            1 :             Key::from_hex("000000000000000000000000000000000000").unwrap()
    8033            1 :                 ..Key::from_hex("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF").unwrap(),
    8034            1 :             vec![(
    8035            1 :                 Key::from_hex("720000000033333333444444445500000000").unwrap(),
    8036            1 :                 Lsn(0x25),
    8037            1 :                 Value::Image(test_img("foo")),
    8038            1 :             )],
    8039              :         );
    8040            1 :         let delta_layers = vec![
    8041            1 :             covered_delta.clone(),
    8042            1 :             visible_delta.clone(),
    8043            1 :             l0_delta.clone(),
    8044              :         ];
    8045              : 
    8046            1 :         let image_layer = (
    8047            1 :             Lsn(0x40),
    8048            1 :             vec![(
    8049            1 :                 Key::from_hex("620000000033333333444444445500000000").unwrap(),
    8050            1 :                 test_img("bar"),
    8051            1 :             )],
    8052            1 :         );
    8053            1 :         let image_layers = vec![image_layer];
    8054              : 
    8055            1 :         let (tenant, ctx) = harness.load().await;
    8056            1 :         let timeline = tenant
    8057            1 :             .create_test_timeline_with_layers(
    8058            1 :                 TimelineId::generate(),
    8059            1 :                 Lsn(0x10),
    8060            1 :                 PgMajorVersion::PG14,
    8061            1 :                 &ctx,
    8062            1 :                 Vec::new(), // in-memory layers
    8063            1 :                 delta_layers,
    8064            1 :                 image_layers,
    8065            1 :                 Lsn(0x100),
    8066            1 :             )
    8067            1 :             .await
    8068            1 :             .unwrap();
    8069            1 :         let ctx = &ctx.with_scope_timeline(&timeline);
    8070              : 
    8071              :         // Layer visibility is an input to heatmap generation, so refresh it first
    8072            1 :         timeline.update_layer_visibility().await.unwrap();
    8073              : 
    8074            1 :         let heatmap = timeline
    8075            1 :             .generate_heatmap()
    8076            1 :             .await
    8077            1 :             .expect("Infallible while timeline is not shut down");
    8078              : 
    8079            1 :         assert_eq!(heatmap.timeline_id, timeline.timeline_id);
    8080              : 
    8081              :         // L0 should come last
    8082            1 :         let heatmap_layers = heatmap.all_layers().collect::<Vec<_>>();
    8083            1 :         assert_eq!(heatmap_layers.last().unwrap().name, l0_delta.layer_name());
    8084              : 
    8085            1 :         let mut last_lsn = Lsn::MAX;
    8086            5 :         for layer in heatmap_layers {
    8087              :             // Covered layer should be omitted
    8088            4 :             assert!(layer.name != covered_delta.layer_name());
    8089              : 
    8090            4 :             let layer_lsn = match &layer.name {
    8091            2 :                 LayerName::Delta(d) => d.lsn_range.end,
    8092            2 :                 LayerName::Image(i) => i.lsn,
    8093              :             };
    8094              : 
    8095              :             // Apart from L0s, newest Layers should come first
    8096            4 :             if !LayerMap::is_l0(layer.name.key_range(), layer.name.is_delta()) {
    8097            3 :                 assert!(layer_lsn <= last_lsn);
    8098            3 :                 last_lsn = layer_lsn;
    8099            1 :             }
    8100              :         }
    8101              : 
    8102              :         // Evict all the layers and stash the old heatmap in the timeline.
    8103              :         // This simulates a migration to a cold secondary location.
    8104              : 
    8105            1 :         let guard = timeline.layers.read(LayerManagerLockHolder::Testing).await;
    8106            1 :         let mut all_layers = Vec::new();
    8107            1 :         let forever = std::time::Duration::from_secs(120);
    8108            5 :         for layer in guard.likely_resident_layers() {
    8109            5 :             all_layers.push(layer.clone());
    8110            5 :             layer.evict_and_wait(forever).await.unwrap();
    8111              :         }
    8112            1 :         drop(guard);
    8113              : 
    8114            1 :         timeline
    8115            1 :             .previous_heatmap
    8116            1 :             .store(Some(Arc::new(PreviousHeatmap::Active {
    8117            1 :                 heatmap: heatmap.clone(),
    8118            1 :                 read_at: std::time::Instant::now(),
    8119            1 :                 end_lsn: None,
    8120            1 :             })));
    8121              : 
    8122              :         // Generate a new heatmap and assert that it contains the same layers as the old one.
    8123            1 :         let post_migration_heatmap = timeline.generate_heatmap().await.unwrap();
    8124            1 :         assert_heatmaps_have_same_layers(&heatmap, &post_migration_heatmap);
    8125              : 
    8126              :         // Download each layer one by one. Generate the heatmap at each step and check
    8127              :         // that it's stable.
    8128            6 :         for layer in all_layers {
    8129            5 :             if layer.visibility() == LayerVisibilityHint::Covered {
    8130            1 :                 continue;
    8131            4 :             }
    8132            1 : 
    8133            4 :             eprintln!("Downloading {layer} and re-generating heatmap");
    8134            1 : 
    8135            4 :             let ctx = &RequestContextBuilder::from(ctx)
    8136            4 :                 .download_behavior(crate::context::DownloadBehavior::Download)
    8137            4 :                 .attached_child();
    8138            1 : 
    8139            4 :             let _resident = layer
    8140            4 :                 .download_and_keep_resident(ctx)
    8141            4 :                 .instrument(tracing::info_span!(
    8142            4 :                     parent: None,
    8143            1 :                     "download_layer",
    8144            1 :                     tenant_id = %timeline.tenant_shard_id.tenant_id,
    8145            1 :                     shard_id = %timeline.tenant_shard_id.shard_slug(),
    8146            1 :                     timeline_id = %timeline.timeline_id
    8147            1 :                 ))
    8148            4 :                 .await
    8149            4 :                 .unwrap();
    8150            1 : 
    8151            4 :             let post_download_heatmap = timeline.generate_heatmap().await.unwrap();
    8152            4 :             assert_heatmaps_have_same_layers(&heatmap, &post_download_heatmap);
    8153            1 :         }
    8154            1 : 
    8155            1 :         // Everything from the post-migration heatmap is now resident.
    8156            1 :         // Check that we drop it from memory.
    8157            1 :         assert!(matches!(
    8158            1 :             timeline.previous_heatmap.load().as_deref(),
    8159            1 :             Some(PreviousHeatmap::Obsolete)
    8160            1 :         ));
    8161            1 :     }
    8162              : 
    8163              :     #[tokio::test]
    8164            1 :     async fn test_previous_heatmap_obsoletion() {
    8165            1 :         let harness = TenantHarness::create("heatmap_previous_heatmap_obsoletion")
    8166            1 :             .await
    8167            1 :             .unwrap();
    8168              : 
    8169            1 :         let l0_delta = DeltaLayerTestDesc::new(
    8170            1 :             Lsn(0x20)..Lsn(0x30),
    8171            1 :             Key::from_hex("000000000000000000000000000000000000").unwrap()
    8172            1 :                 ..Key::from_hex("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF").unwrap(),
    8173            1 :             vec![(
    8174            1 :                 Key::from_hex("720000000033333333444444445500000000").unwrap(),
    8175            1 :                 Lsn(0x25),
    8176            1 :                 Value::Image(test_img("foo")),
    8177            1 :             )],
    8178              :         );
    8179              : 
    8180            1 :         let image_layer = (
    8181            1 :             Lsn(0x40),
    8182            1 :             vec![(
    8183            1 :                 Key::from_hex("620000000033333333444444445500000000").unwrap(),
    8184            1 :                 test_img("bar"),
    8185            1 :             )],
    8186            1 :         );
    8187              : 
    8188            1 :         let delta_layers = vec![l0_delta];
    8189            1 :         let image_layers = vec![image_layer];
    8190              : 
    8191            1 :         let (tenant, ctx) = harness.load().await;
    8192            1 :         let timeline = tenant
    8193            1 :             .create_test_timeline_with_layers(
    8194            1 :                 TimelineId::generate(),
    8195            1 :                 Lsn(0x10),
    8196            1 :                 PgMajorVersion::PG14,
    8197            1 :                 &ctx,
    8198            1 :                 Vec::new(), // in-memory layers
    8199            1 :                 delta_layers,
    8200            1 :                 image_layers,
    8201            1 :                 Lsn(0x100),
    8202            1 :             )
    8203            1 :             .await
    8204            1 :             .unwrap();
    8205              : 
    8206              :         // Layer visibility is an input to heatmap generation, so refresh it first
    8207            1 :         timeline.update_layer_visibility().await.unwrap();
    8208              : 
    8209            1 :         let heatmap = timeline
    8210            1 :             .generate_heatmap()
    8211            1 :             .await
    8212            1 :             .expect("Infallible while timeline is not shut down");
    8213              : 
    8214              :         // Both layers should be in the heatmap
    8215            1 :         assert!(heatmap.all_layers().count() > 0);
    8216              : 
    8217              :         // Now simulate a migration.
    8218            1 :         timeline
    8219            1 :             .previous_heatmap
    8220            1 :             .store(Some(Arc::new(PreviousHeatmap::Active {
    8221            1 :                 heatmap: heatmap.clone(),
    8222            1 :                 read_at: std::time::Instant::now(),
    8223            1 :                 end_lsn: None,
    8224            1 :             })));
    8225              : 
    8226              :         // Evict all the layers in the previous heatmap
    8227            1 :         let guard = timeline.layers.read(LayerManagerLockHolder::Testing).await;
    8228            1 :         let forever = std::time::Duration::from_secs(120);
    8229            3 :         for layer in guard.likely_resident_layers() {
    8230            3 :             layer.evict_and_wait(forever).await.unwrap();
    8231              :         }
    8232            1 :         drop(guard);
    8233              : 
    8234              :         // Generate a new heatmap and check that the previous heatmap
    8235              :         // has been marked obsolete.
    8236            1 :         let post_eviction_heatmap = timeline
    8237            1 :             .generate_heatmap()
    8238            1 :             .await
    8239            1 :             .expect("Infallible while timeline is not shut down");
    8240              : 
    8241            1 :         assert_eq!(post_eviction_heatmap.all_layers().count(), 0);
    8242            1 :         assert!(matches!(
    8243            1 :             timeline.previous_heatmap.load().as_deref(),
    8244            1 :             Some(PreviousHeatmap::Obsolete)
    8245            1 :         ));
    8246            1 :     }
    8247              : 
    8248              :     #[tokio::test]
    8249            1 :     async fn two_layer_eviction_attempts_at_the_same_time() {
    8250            1 :         let harness = TenantHarness::create("two_layer_eviction_attempts_at_the_same_time")
    8251            1 :             .await
    8252            1 :             .unwrap();
    8253              : 
    8254            1 :         let (tenant, ctx) = harness.load().await;
    8255            1 :         let timeline = tenant
    8256            1 :             .create_test_timeline(
    8257            1 :                 TimelineId::generate(),
    8258            1 :                 Lsn(0x10),
    8259            1 :                 PgMajorVersion::PG14,
    8260            1 :                 &ctx,
    8261            1 :             )
    8262            1 :             .await
    8263            1 :             .unwrap();
    8264              : 
    8265            1 :         let layer = find_some_layer(&timeline).await;
    8266            1 :         let layer = layer
    8267            1 :             .keep_resident()
    8268            1 :             .await
    8269            1 :             .expect("no download => no downloading errors")
    8270            1 :             .drop_eviction_guard();
    8271              : 
    8272            1 :         let forever = std::time::Duration::from_secs(120);
    8273              : 
    8274            1 :         let first = layer.evict_and_wait(forever);
    8275            1 :         let second = layer.evict_and_wait(forever);
    8276              : 
    8277            1 :         let (first, second) = tokio::join!(first, second);
    8278              : 
    8279            1 :         let res = layer.keep_resident().await;
    8280            1 :         assert!(res.is_none(), "{res:?}");
    8281              : 
    8282            1 :         match (first, second) {
    8283            1 :             (Ok(()), Ok(())) => {
    8284            1 :                 // because there are no more timeline locks being taken on eviction path, we can
    8285            1 :                 // witness all three outcomes here.
    8286            1 :             }
    8287            1 :             (Ok(()), Err(EvictionError::NotFound)) | (Err(EvictionError::NotFound), Ok(())) => {
    8288            0 :                 // if one completes before the other, this is fine just as well.
    8289            0 :             }
    8290            1 :             other => unreachable!("unexpected {:?}", other),
    8291            1 :         }
    8292            1 :     }
    8293              : 
    8294            1 :     async fn find_some_layer(timeline: &Timeline) -> Layer {
    8295            1 :         let layers = timeline
    8296            1 :             .layers
    8297            1 :             .read(LayerManagerLockHolder::GetLayerMapInfo)
    8298            1 :             .await;
    8299            1 :         let desc = layers
    8300            1 :             .layer_map()
    8301            1 :             .unwrap()
    8302            1 :             .iter_historic_layers()
    8303            1 :             .next()
    8304            1 :             .expect("must find one layer to evict");
    8305              : 
    8306            1 :         layers.get_from_desc(&desc)
    8307            1 :     }
    8308              : }
        

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