LCOV - code coverage report
Current view: top level - pageserver/src/tenant/storage_layer - delta_layer.rs (source / functions) Coverage Total Hit
Test: 20b6afc7b7f34578dcaab2b3acdaecfe91cd8bf1.info Lines: 85.1 % 1642 1397
Test Date: 2024-11-25 17:48:16 Functions: 69.6 % 168 117

            Line data    Source code
       1              : //! A DeltaLayer represents a collection of WAL records or page images in a range of
       2              : //! LSNs, and in a range of Keys. It is stored on a file on disk.
       3              : //!
       4              : //! Usually a delta layer only contains differences, in the form of WAL records
       5              : //! against a base LSN. However, if a relation extended or a whole new relation
       6              : //! is created, there would be no base for the new pages. The entries for them
       7              : //! must be page images or WAL records with the 'will_init' flag set, so that
       8              : //! they can be replayed without referring to an older page version.
       9              : //!
      10              : //! The delta files are stored in `timelines/<timeline_id>` directory.  Currently,
      11              : //! there are no subdirectories, and each delta file is named like this:
      12              : //!
      13              : //! ```text
      14              : //!    <key start>-<key end>__<start LSN>-<end LSN>
      15              : //! ```
      16              : //!
      17              : //! For example:
      18              : //!
      19              : //! ```text
      20              : //!    000000067F000032BE0000400000000020B6-000000067F000032BE0000400000000030B6__000000578C6B29-0000000057A50051
      21              : //! ```
      22              : //!
      23              : //! Every delta file consists of three parts: "summary", "values", and
      24              : //! "index". The summary is a fixed size header at the beginning of the file,
      25              : //! and it contains basic information about the layer, and offsets to the other
      26              : //! parts. The "index" is a B-tree, mapping from Key and LSN to an offset in the
      27              : //! "values" part.  The actual page images and WAL records are stored in the
      28              : //! "values" part.
      29              : //!
      30              : use crate::config::PageServerConf;
      31              : use crate::context::{PageContentKind, RequestContext, RequestContextBuilder};
      32              : use crate::page_cache::{self, FileId, PAGE_SZ};
      33              : use crate::tenant::blob_io::BlobWriter;
      34              : use crate::tenant::block_io::{BlockBuf, BlockCursor, BlockLease, BlockReader, FileBlockReader};
      35              : use crate::tenant::disk_btree::{
      36              :     DiskBtreeBuilder, DiskBtreeIterator, DiskBtreeReader, VisitDirection,
      37              : };
      38              : use crate::tenant::storage_layer::layer::S3_UPLOAD_LIMIT;
      39              : use crate::tenant::timeline::GetVectoredError;
      40              : use crate::tenant::vectored_blob_io::{
      41              :     BlobFlag, BufView, StreamingVectoredReadPlanner, VectoredBlobReader, VectoredRead,
      42              :     VectoredReadPlanner,
      43              : };
      44              : use crate::tenant::PageReconstructError;
      45              : use crate::virtual_file::owned_buffers_io::io_buf_ext::{FullSlice, IoBufExt};
      46              : use crate::virtual_file::IoBufferMut;
      47              : use crate::virtual_file::{self, MaybeFatalIo, VirtualFile};
      48              : use crate::TEMP_FILE_SUFFIX;
      49              : use crate::{DELTA_FILE_MAGIC, STORAGE_FORMAT_VERSION};
      50              : use anyhow::{anyhow, bail, ensure, Context, Result};
      51              : use camino::{Utf8Path, Utf8PathBuf};
      52              : use futures::StreamExt;
      53              : use itertools::Itertools;
      54              : use pageserver_api::config::MaxVectoredReadBytes;
      55              : use pageserver_api::key::DBDIR_KEY;
      56              : use pageserver_api::key::{Key, KEY_SIZE};
      57              : use pageserver_api::keyspace::KeySpace;
      58              : use pageserver_api::models::ImageCompressionAlgorithm;
      59              : use pageserver_api::shard::TenantShardId;
      60              : use pageserver_api::value::Value;
      61              : use rand::{distributions::Alphanumeric, Rng};
      62              : use serde::{Deserialize, Serialize};
      63              : use std::collections::VecDeque;
      64              : use std::fs::File;
      65              : use std::io::SeekFrom;
      66              : use std::ops::Range;
      67              : use std::os::unix::fs::FileExt;
      68              : use std::str::FromStr;
      69              : use std::sync::Arc;
      70              : use tokio::sync::OnceCell;
      71              : use tokio_epoll_uring::IoBuf;
      72              : use tracing::*;
      73              : 
      74              : use utils::{
      75              :     bin_ser::BeSer,
      76              :     id::{TenantId, TimelineId},
      77              :     lsn::Lsn,
      78              : };
      79              : 
      80              : use super::{AsLayerDesc, LayerName, PersistentLayerDesc, ValuesReconstructState};
      81              : 
      82              : ///
      83              : /// Header stored in the beginning of the file
      84              : ///
      85              : /// After this comes the 'values' part, starting on block 1. After that,
      86              : /// the 'index' starts at the block indicated by 'index_start_blk'
      87              : ///
      88         1068 : #[derive(Debug, Serialize, Deserialize, PartialEq, Eq)]
      89              : pub struct Summary {
      90              :     /// Magic value to identify this as a neon delta file. Always DELTA_FILE_MAGIC.
      91              :     pub magic: u16,
      92              :     pub format_version: u16,
      93              : 
      94              :     pub tenant_id: TenantId,
      95              :     pub timeline_id: TimelineId,
      96              :     pub key_range: Range<Key>,
      97              :     pub lsn_range: Range<Lsn>,
      98              : 
      99              :     /// Block number where the 'index' part of the file begins.
     100              :     pub index_start_blk: u32,
     101              :     /// Block within the 'index', where the B-tree root page is stored
     102              :     pub index_root_blk: u32,
     103              : }
     104              : 
     105              : impl From<&DeltaLayer> for Summary {
     106            0 :     fn from(layer: &DeltaLayer) -> Self {
     107            0 :         Self::expected(
     108            0 :             layer.desc.tenant_shard_id.tenant_id,
     109            0 :             layer.desc.timeline_id,
     110            0 :             layer.desc.key_range.clone(),
     111            0 :             layer.desc.lsn_range.clone(),
     112            0 :         )
     113            0 :     }
     114              : }
     115              : 
     116              : impl Summary {
     117         1068 :     pub(super) fn expected(
     118         1068 :         tenant_id: TenantId,
     119         1068 :         timeline_id: TimelineId,
     120         1068 :         keys: Range<Key>,
     121         1068 :         lsns: Range<Lsn>,
     122         1068 :     ) -> Self {
     123         1068 :         Self {
     124         1068 :             magic: DELTA_FILE_MAGIC,
     125         1068 :             format_version: STORAGE_FORMAT_VERSION,
     126         1068 : 
     127         1068 :             tenant_id,
     128         1068 :             timeline_id,
     129         1068 :             key_range: keys,
     130         1068 :             lsn_range: lsns,
     131         1068 : 
     132         1068 :             index_start_blk: 0,
     133         1068 :             index_root_blk: 0,
     134         1068 :         }
     135         1068 :     }
     136              : }
     137              : 
     138              : // Flag indicating that this version initialize the page
     139              : const WILL_INIT: u64 = 1;
     140              : 
     141              : /// Struct representing reference to BLOB in layers.
     142              : ///
     143              : /// Reference contains BLOB offset, and for WAL records it also contains
     144              : /// `will_init` flag. The flag helps to determine the range of records
     145              : /// that needs to be applied, without reading/deserializing records themselves.
     146            0 : #[derive(Debug, Serialize, Deserialize, Copy, Clone)]
     147              : pub struct BlobRef(pub u64);
     148              : 
     149              : impl BlobRef {
     150       520670 :     pub fn will_init(&self) -> bool {
     151       520670 :         (self.0 & WILL_INIT) != 0
     152       520670 :     }
     153              : 
     154      4789544 :     pub fn pos(&self) -> u64 {
     155      4789544 :         self.0 >> 1
     156      4789544 :     }
     157              : 
     158      6471388 :     pub fn new(pos: u64, will_init: bool) -> BlobRef {
     159      6471388 :         let mut blob_ref = pos << 1;
     160      6471388 :         if will_init {
     161      6469916 :             blob_ref |= WILL_INIT;
     162      6469916 :         }
     163      6471388 :         BlobRef(blob_ref)
     164      6471388 :     }
     165              : }
     166              : 
     167              : pub const DELTA_KEY_SIZE: usize = KEY_SIZE + 8;
     168              : struct DeltaKey([u8; DELTA_KEY_SIZE]);
     169              : 
     170              : /// This is the key of the B-tree index stored in the delta layer. It consists
     171              : /// of the serialized representation of a Key and LSN.
     172              : impl DeltaKey {
     173      2064198 :     fn from_slice(buf: &[u8]) -> Self {
     174      2064198 :         let mut bytes: [u8; DELTA_KEY_SIZE] = [0u8; DELTA_KEY_SIZE];
     175      2064198 :         bytes.copy_from_slice(buf);
     176      2064198 :         DeltaKey(bytes)
     177      2064198 :     }
     178              : 
     179      6689011 :     fn from_key_lsn(key: &Key, lsn: Lsn) -> Self {
     180      6689011 :         let mut bytes: [u8; DELTA_KEY_SIZE] = [0u8; DELTA_KEY_SIZE];
     181      6689011 :         key.write_to_byte_slice(&mut bytes[0..KEY_SIZE]);
     182      6689011 :         bytes[KEY_SIZE..].copy_from_slice(&u64::to_be_bytes(lsn.0));
     183      6689011 :         DeltaKey(bytes)
     184      6689011 :     }
     185              : 
     186      2064198 :     fn key(&self) -> Key {
     187      2064198 :         Key::from_slice(&self.0)
     188      2064198 :     }
     189              : 
     190      2064198 :     fn lsn(&self) -> Lsn {
     191      2064198 :         Lsn(u64::from_be_bytes(self.0[KEY_SIZE..].try_into().unwrap()))
     192      2064198 :     }
     193              : 
     194      2725286 :     fn extract_lsn_from_buf(buf: &[u8]) -> Lsn {
     195      2725286 :         let mut lsn_buf = [0u8; 8];
     196      2725286 :         lsn_buf.copy_from_slice(&buf[KEY_SIZE..]);
     197      2725286 :         Lsn(u64::from_be_bytes(lsn_buf))
     198      2725286 :     }
     199              : }
     200              : 
     201              : /// This is used only from `pagectl`. Within pageserver, all layers are
     202              : /// [`crate::tenant::storage_layer::Layer`], which can hold a [`DeltaLayerInner`].
     203              : pub struct DeltaLayer {
     204              :     path: Utf8PathBuf,
     205              :     pub desc: PersistentLayerDesc,
     206              :     inner: OnceCell<Arc<DeltaLayerInner>>,
     207              : }
     208              : 
     209              : impl std::fmt::Debug for DeltaLayer {
     210            0 :     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
     211              :         use super::RangeDisplayDebug;
     212              : 
     213            0 :         f.debug_struct("DeltaLayer")
     214            0 :             .field("key_range", &RangeDisplayDebug(&self.desc.key_range))
     215            0 :             .field("lsn_range", &self.desc.lsn_range)
     216            0 :             .field("file_size", &self.desc.file_size)
     217            0 :             .field("inner", &self.inner)
     218            0 :             .finish()
     219            0 :     }
     220              : }
     221              : 
     222              : /// `DeltaLayerInner` is the in-memory data structure associated with an on-disk delta
     223              : /// file.
     224              : pub struct DeltaLayerInner {
     225              :     // values copied from summary
     226              :     index_start_blk: u32,
     227              :     index_root_blk: u32,
     228              : 
     229              :     file: VirtualFile,
     230              :     file_id: FileId,
     231              : 
     232              :     layer_key_range: Range<Key>,
     233              :     layer_lsn_range: Range<Lsn>,
     234              : 
     235              :     max_vectored_read_bytes: Option<MaxVectoredReadBytes>,
     236              : }
     237              : 
     238              : impl DeltaLayerInner {
     239            0 :     pub(crate) fn layer_dbg_info(&self) -> String {
     240            0 :         format!(
     241            0 :             "delta {}..{} {}..{}",
     242            0 :             self.key_range().start,
     243            0 :             self.key_range().end,
     244            0 :             self.lsn_range().start,
     245            0 :             self.lsn_range().end
     246            0 :         )
     247            0 :     }
     248              : }
     249              : 
     250              : impl std::fmt::Debug for DeltaLayerInner {
     251            0 :     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
     252            0 :         f.debug_struct("DeltaLayerInner")
     253            0 :             .field("index_start_blk", &self.index_start_blk)
     254            0 :             .field("index_root_blk", &self.index_root_blk)
     255            0 :             .finish()
     256            0 :     }
     257              : }
     258              : 
     259              : /// Boilerplate to implement the Layer trait, always use layer_desc for persistent layers.
     260              : impl std::fmt::Display for DeltaLayer {
     261            0 :     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
     262            0 :         write!(f, "{}", self.layer_desc().short_id())
     263            0 :     }
     264              : }
     265              : 
     266              : impl AsLayerDesc for DeltaLayer {
     267            0 :     fn layer_desc(&self) -> &PersistentLayerDesc {
     268            0 :         &self.desc
     269            0 :     }
     270              : }
     271              : 
     272              : impl DeltaLayer {
     273            0 :     pub async fn dump(&self, verbose: bool, ctx: &RequestContext) -> Result<()> {
     274            0 :         self.desc.dump();
     275            0 : 
     276            0 :         if !verbose {
     277            0 :             return Ok(());
     278            0 :         }
     279              : 
     280            0 :         let inner = self.load(ctx).await?;
     281              : 
     282            0 :         inner.dump(ctx).await
     283            0 :     }
     284              : 
     285         1438 :     fn temp_path_for(
     286         1438 :         conf: &PageServerConf,
     287         1438 :         tenant_shard_id: &TenantShardId,
     288         1438 :         timeline_id: &TimelineId,
     289         1438 :         key_start: Key,
     290         1438 :         lsn_range: &Range<Lsn>,
     291         1438 :     ) -> Utf8PathBuf {
     292         1438 :         let rand_string: String = rand::thread_rng()
     293         1438 :             .sample_iter(&Alphanumeric)
     294         1438 :             .take(8)
     295         1438 :             .map(char::from)
     296         1438 :             .collect();
     297         1438 : 
     298         1438 :         conf.timeline_path(tenant_shard_id, timeline_id)
     299         1438 :             .join(format!(
     300         1438 :                 "{}-XXX__{:016X}-{:016X}.{}.{}",
     301         1438 :                 key_start,
     302         1438 :                 u64::from(lsn_range.start),
     303         1438 :                 u64::from(lsn_range.end),
     304         1438 :                 rand_string,
     305         1438 :                 TEMP_FILE_SUFFIX,
     306         1438 :             ))
     307         1438 :     }
     308              : 
     309              :     ///
     310              :     /// Open the underlying file and read the metadata into memory, if it's
     311              :     /// not loaded already.
     312              :     ///
     313            0 :     async fn load(&self, ctx: &RequestContext) -> Result<&Arc<DeltaLayerInner>> {
     314            0 :         // Quick exit if already loaded
     315            0 :         self.inner
     316            0 :             .get_or_try_init(|| self.load_inner(ctx))
     317            0 :             .await
     318            0 :             .with_context(|| format!("Failed to load delta layer {}", self.path()))
     319            0 :     }
     320              : 
     321            0 :     async fn load_inner(&self, ctx: &RequestContext) -> anyhow::Result<Arc<DeltaLayerInner>> {
     322            0 :         let path = self.path();
     323              : 
     324            0 :         let loaded = DeltaLayerInner::load(&path, None, None, ctx).await?;
     325              : 
     326              :         // not production code
     327            0 :         let actual_layer_name = LayerName::from_str(path.file_name().unwrap()).unwrap();
     328            0 :         let expected_layer_name = self.layer_desc().layer_name();
     329            0 : 
     330            0 :         if actual_layer_name != expected_layer_name {
     331            0 :             println!("warning: filename does not match what is expected from in-file summary");
     332            0 :             println!("actual: {:?}", actual_layer_name.to_string());
     333            0 :             println!("expected: {:?}", expected_layer_name.to_string());
     334            0 :         }
     335              : 
     336            0 :         Ok(Arc::new(loaded))
     337            0 :     }
     338              : 
     339              :     /// Create a DeltaLayer struct representing an existing file on disk.
     340              :     ///
     341              :     /// This variant is only used for debugging purposes, by the 'pagectl' binary.
     342            0 :     pub fn new_for_path(path: &Utf8Path, file: File) -> Result<Self> {
     343            0 :         let mut summary_buf = vec![0; PAGE_SZ];
     344            0 :         file.read_exact_at(&mut summary_buf, 0)?;
     345            0 :         let summary = Summary::des_prefix(&summary_buf)?;
     346              : 
     347            0 :         let metadata = file
     348            0 :             .metadata()
     349            0 :             .context("get file metadata to determine size")?;
     350              : 
     351              :         // This function is never used for constructing layers in a running pageserver,
     352              :         // so it does not need an accurate TenantShardId.
     353            0 :         let tenant_shard_id = TenantShardId::unsharded(summary.tenant_id);
     354            0 : 
     355            0 :         Ok(DeltaLayer {
     356            0 :             path: path.to_path_buf(),
     357            0 :             desc: PersistentLayerDesc::new_delta(
     358            0 :                 tenant_shard_id,
     359            0 :                 summary.timeline_id,
     360            0 :                 summary.key_range,
     361            0 :                 summary.lsn_range,
     362            0 :                 metadata.len(),
     363            0 :             ),
     364            0 :             inner: OnceCell::new(),
     365            0 :         })
     366            0 :     }
     367              : 
     368              :     /// Path to the layer file in pageserver workdir.
     369            0 :     fn path(&self) -> Utf8PathBuf {
     370            0 :         self.path.clone()
     371            0 :     }
     372              : }
     373              : 
     374              : /// A builder object for constructing a new delta layer.
     375              : ///
     376              : /// Usage:
     377              : ///
     378              : /// 1. Create the DeltaLayerWriter by calling DeltaLayerWriter::new(...)
     379              : ///
     380              : /// 2. Write the contents by calling `put_value` for every page
     381              : ///    version to store in the layer.
     382              : ///
     383              : /// 3. Call `finish`.
     384              : ///
     385              : struct DeltaLayerWriterInner {
     386              :     pub path: Utf8PathBuf,
     387              :     timeline_id: TimelineId,
     388              :     tenant_shard_id: TenantShardId,
     389              : 
     390              :     key_start: Key,
     391              :     lsn_range: Range<Lsn>,
     392              : 
     393              :     tree: DiskBtreeBuilder<BlockBuf, DELTA_KEY_SIZE>,
     394              : 
     395              :     blob_writer: BlobWriter<true>,
     396              : 
     397              :     // Number of key-lsns in the layer.
     398              :     num_keys: usize,
     399              : }
     400              : 
     401              : impl DeltaLayerWriterInner {
     402              :     ///
     403              :     /// Start building a new delta layer.
     404              :     ///
     405         1438 :     async fn new(
     406         1438 :         conf: &'static PageServerConf,
     407         1438 :         timeline_id: TimelineId,
     408         1438 :         tenant_shard_id: TenantShardId,
     409         1438 :         key_start: Key,
     410         1438 :         lsn_range: Range<Lsn>,
     411         1438 :         ctx: &RequestContext,
     412         1438 :     ) -> anyhow::Result<Self> {
     413         1438 :         // Create the file initially with a temporary filename. We don't know
     414         1438 :         // the end key yet, so we cannot form the final filename yet. We will
     415         1438 :         // rename it when we're done.
     416         1438 :         //
     417         1438 :         // Note: This overwrites any existing file. There shouldn't be any.
     418         1438 :         // FIXME: throw an error instead?
     419         1438 :         let path =
     420         1438 :             DeltaLayer::temp_path_for(conf, &tenant_shard_id, &timeline_id, key_start, &lsn_range);
     421              : 
     422         1438 :         let mut file = VirtualFile::create(&path, ctx).await?;
     423              :         // make room for the header block
     424         1438 :         file.seek(SeekFrom::Start(PAGE_SZ as u64)).await?;
     425         1438 :         let blob_writer = BlobWriter::new(file, PAGE_SZ as u64);
     426         1438 : 
     427         1438 :         // Initialize the b-tree index builder
     428         1438 :         let block_buf = BlockBuf::new();
     429         1438 :         let tree_builder = DiskBtreeBuilder::new(block_buf);
     430         1438 : 
     431         1438 :         Ok(Self {
     432         1438 :             path,
     433         1438 :             timeline_id,
     434         1438 :             tenant_shard_id,
     435         1438 :             key_start,
     436         1438 :             lsn_range,
     437         1438 :             tree: tree_builder,
     438         1438 :             blob_writer,
     439         1438 :             num_keys: 0,
     440         1438 :         })
     441         1438 :     }
     442              : 
     443              :     ///
     444              :     /// Append a key-value pair to the file.
     445              :     ///
     446              :     /// The values must be appended in key, lsn order.
     447              :     ///
     448      2084624 :     async fn put_value(
     449      2084624 :         &mut self,
     450      2084624 :         key: Key,
     451      2084624 :         lsn: Lsn,
     452      2084624 :         val: Value,
     453      2084624 :         ctx: &RequestContext,
     454      2084624 :     ) -> anyhow::Result<()> {
     455      2084624 :         let (_, res) = self
     456      2084624 :             .put_value_bytes(
     457      2084624 :                 key,
     458      2084624 :                 lsn,
     459      2084624 :                 Value::ser(&val)?.slice_len(),
     460      2084624 :                 val.will_init(),
     461      2084624 :                 ctx,
     462              :             )
     463         1982 :             .await;
     464      2084624 :         res
     465      2084624 :     }
     466              : 
     467      6471284 :     async fn put_value_bytes<Buf>(
     468      6471284 :         &mut self,
     469      6471284 :         key: Key,
     470      6471284 :         lsn: Lsn,
     471      6471284 :         val: FullSlice<Buf>,
     472      6471284 :         will_init: bool,
     473      6471284 :         ctx: &RequestContext,
     474      6471284 :     ) -> (FullSlice<Buf>, anyhow::Result<()>)
     475      6471284 :     where
     476      6471284 :         Buf: IoBuf + Send,
     477      6471284 :     {
     478      6471284 :         assert!(
     479      6471284 :             self.lsn_range.start <= lsn,
     480            0 :             "lsn_start={}, lsn={}",
     481              :             self.lsn_range.start,
     482              :             lsn
     483              :         );
     484              :         // We don't want to use compression in delta layer creation
     485      6471284 :         let compression = ImageCompressionAlgorithm::Disabled;
     486      6471284 :         let (val, res) = self
     487      6471284 :             .blob_writer
     488      6471284 :             .write_blob_maybe_compressed(val, ctx, compression)
     489         4930 :             .await;
     490      6471284 :         let off = match res {
     491      6471284 :             Ok((off, _)) => off,
     492            0 :             Err(e) => return (val, Err(anyhow::anyhow!(e))),
     493              :         };
     494              : 
     495      6471284 :         let blob_ref = BlobRef::new(off, will_init);
     496      6471284 : 
     497      6471284 :         let delta_key = DeltaKey::from_key_lsn(&key, lsn);
     498      6471284 :         let res = self.tree.append(&delta_key.0, blob_ref.0);
     499      6471284 : 
     500      6471284 :         self.num_keys += 1;
     501      6471284 : 
     502      6471284 :         (val, res.map_err(|e| anyhow::anyhow!(e)))
     503      6471284 :     }
     504              : 
     505      2023972 :     fn size(&self) -> u64 {
     506      2023972 :         self.blob_writer.size() + self.tree.borrow_writer().size()
     507      2023972 :     }
     508              : 
     509              :     ///
     510              :     /// Finish writing the delta layer.
     511              :     ///
     512         1414 :     async fn finish(
     513         1414 :         self,
     514         1414 :         key_end: Key,
     515         1414 :         ctx: &RequestContext,
     516         1414 :     ) -> anyhow::Result<(PersistentLayerDesc, Utf8PathBuf)> {
     517         1414 :         let temp_path = self.path.clone();
     518         9694 :         let result = self.finish0(key_end, ctx).await;
     519         1414 :         if let Err(ref e) = result {
     520            0 :             tracing::info!(%temp_path, "cleaning up temporary file after error during writing: {e}");
     521            0 :             if let Err(e) = std::fs::remove_file(&temp_path) {
     522            0 :                 tracing::warn!(error=%e, %temp_path, "error cleaning up temporary layer file after error during writing");
     523            0 :             }
     524         1414 :         }
     525         1414 :         result
     526         1414 :     }
     527              : 
     528         1414 :     async fn finish0(
     529         1414 :         self,
     530         1414 :         key_end: Key,
     531         1414 :         ctx: &RequestContext,
     532         1414 :     ) -> anyhow::Result<(PersistentLayerDesc, Utf8PathBuf)> {
     533         1414 :         let index_start_blk = self.blob_writer.size().div_ceil(PAGE_SZ as u64) as u32;
     534              : 
     535         1414 :         let mut file = self.blob_writer.into_inner(ctx).await?;
     536              : 
     537              :         // Write out the index
     538         1414 :         let (index_root_blk, block_buf) = self.tree.finish()?;
     539         1414 :         file.seek(SeekFrom::Start(index_start_blk as u64 * PAGE_SZ as u64))
     540            0 :             .await?;
     541        15056 :         for buf in block_buf.blocks {
     542        13642 :             let (_buf, res) = file.write_all(buf.slice_len(), ctx).await;
     543        13642 :             res?;
     544              :         }
     545         1414 :         assert!(self.lsn_range.start < self.lsn_range.end);
     546              :         // Fill in the summary on blk 0
     547         1414 :         let summary = Summary {
     548         1414 :             magic: DELTA_FILE_MAGIC,
     549         1414 :             format_version: STORAGE_FORMAT_VERSION,
     550         1414 :             tenant_id: self.tenant_shard_id.tenant_id,
     551         1414 :             timeline_id: self.timeline_id,
     552         1414 :             key_range: self.key_start..key_end,
     553         1414 :             lsn_range: self.lsn_range.clone(),
     554         1414 :             index_start_blk,
     555         1414 :             index_root_blk,
     556         1414 :         };
     557         1414 : 
     558         1414 :         let mut buf = Vec::with_capacity(PAGE_SZ);
     559         1414 :         // TODO: could use smallvec here but it's a pain with Slice<T>
     560         1414 :         Summary::ser_into(&summary, &mut buf)?;
     561         1414 :         file.seek(SeekFrom::Start(0)).await?;
     562         1414 :         let (_buf, res) = file.write_all(buf.slice_len(), ctx).await;
     563         1414 :         res?;
     564              : 
     565         1414 :         let metadata = file
     566         1414 :             .metadata()
     567          710 :             .await
     568         1414 :             .context("get file metadata to determine size")?;
     569              : 
     570              :         // 5GB limit for objects without multipart upload (which we don't want to use)
     571              :         // Make it a little bit below to account for differing GB units
     572              :         // https://docs.aws.amazon.com/AmazonS3/latest/userguide/upload-objects.html
     573         1414 :         ensure!(
     574         1414 :             metadata.len() <= S3_UPLOAD_LIMIT,
     575            0 :             "Created delta layer file at {} of size {} above limit {S3_UPLOAD_LIMIT}!",
     576            0 :             file.path(),
     577            0 :             metadata.len()
     578              :         );
     579              : 
     580              :         // Note: Because we opened the file in write-only mode, we cannot
     581              :         // reuse the same VirtualFile for reading later. That's why we don't
     582              :         // set inner.file here. The first read will have to re-open it.
     583              : 
     584         1414 :         let desc = PersistentLayerDesc::new_delta(
     585         1414 :             self.tenant_shard_id,
     586         1414 :             self.timeline_id,
     587         1414 :             self.key_start..key_end,
     588         1414 :             self.lsn_range.clone(),
     589         1414 :             metadata.len(),
     590         1414 :         );
     591         1414 : 
     592         1414 :         // fsync the file
     593         1414 :         file.sync_all()
     594          710 :             .await
     595         1414 :             .maybe_fatal_err("delta_layer sync_all")?;
     596              : 
     597         1414 :         trace!("created delta layer {}", self.path);
     598              : 
     599         1414 :         Ok((desc, self.path))
     600         1414 :     }
     601              : }
     602              : 
     603              : /// A builder object for constructing a new delta layer.
     604              : ///
     605              : /// Usage:
     606              : ///
     607              : /// 1. Create the DeltaLayerWriter by calling DeltaLayerWriter::new(...)
     608              : ///
     609              : /// 2. Write the contents by calling `put_value` for every page
     610              : ///    version to store in the layer.
     611              : ///
     612              : /// 3. Call `finish`.
     613              : ///
     614              : /// # Note
     615              : ///
     616              : /// As described in <https://github.com/neondatabase/neon/issues/2650>, it's
     617              : /// possible for the writer to drop before `finish` is actually called. So this
     618              : /// could lead to odd temporary files in the directory, exhausting file system.
     619              : /// This structure wraps `DeltaLayerWriterInner` and also contains `Drop`
     620              : /// implementation that cleans up the temporary file in failure. It's not
     621              : /// possible to do this directly in `DeltaLayerWriterInner` since `finish` moves
     622              : /// out some fields, making it impossible to implement `Drop`.
     623              : ///
     624              : #[must_use]
     625              : pub struct DeltaLayerWriter {
     626              :     inner: Option<DeltaLayerWriterInner>,
     627              : }
     628              : 
     629              : impl DeltaLayerWriter {
     630              :     ///
     631              :     /// Start building a new delta layer.
     632              :     ///
     633         1438 :     pub async fn new(
     634         1438 :         conf: &'static PageServerConf,
     635         1438 :         timeline_id: TimelineId,
     636         1438 :         tenant_shard_id: TenantShardId,
     637         1438 :         key_start: Key,
     638         1438 :         lsn_range: Range<Lsn>,
     639         1438 :         ctx: &RequestContext,
     640         1438 :     ) -> anyhow::Result<Self> {
     641         1438 :         Ok(Self {
     642         1438 :             inner: Some(
     643         1438 :                 DeltaLayerWriterInner::new(
     644         1438 :                     conf,
     645         1438 :                     timeline_id,
     646         1438 :                     tenant_shard_id,
     647         1438 :                     key_start,
     648         1438 :                     lsn_range,
     649         1438 :                     ctx,
     650         1438 :                 )
     651          726 :                 .await?,
     652              :             ),
     653              :         })
     654         1438 :     }
     655              : 
     656            0 :     pub fn is_empty(&self) -> bool {
     657            0 :         self.inner.as_ref().unwrap().num_keys == 0
     658            0 :     }
     659              : 
     660              :     ///
     661              :     /// Append a key-value pair to the file.
     662              :     ///
     663              :     /// The values must be appended in key, lsn order.
     664              :     ///
     665      2084624 :     pub async fn put_value(
     666      2084624 :         &mut self,
     667      2084624 :         key: Key,
     668      2084624 :         lsn: Lsn,
     669      2084624 :         val: Value,
     670      2084624 :         ctx: &RequestContext,
     671      2084624 :     ) -> anyhow::Result<()> {
     672      2084624 :         self.inner
     673      2084624 :             .as_mut()
     674      2084624 :             .unwrap()
     675      2084624 :             .put_value(key, lsn, val, ctx)
     676         1982 :             .await
     677      2084624 :     }
     678              : 
     679      4386660 :     pub async fn put_value_bytes<Buf>(
     680      4386660 :         &mut self,
     681      4386660 :         key: Key,
     682      4386660 :         lsn: Lsn,
     683      4386660 :         val: FullSlice<Buf>,
     684      4386660 :         will_init: bool,
     685      4386660 :         ctx: &RequestContext,
     686      4386660 :     ) -> (FullSlice<Buf>, anyhow::Result<()>)
     687      4386660 :     where
     688      4386660 :         Buf: IoBuf + Send,
     689      4386660 :     {
     690      4386660 :         self.inner
     691      4386660 :             .as_mut()
     692      4386660 :             .unwrap()
     693      4386660 :             .put_value_bytes(key, lsn, val, will_init, ctx)
     694         2948 :             .await
     695      4386660 :     }
     696              : 
     697      2023972 :     pub fn size(&self) -> u64 {
     698      2023972 :         self.inner.as_ref().unwrap().size()
     699      2023972 :     }
     700              : 
     701              :     ///
     702              :     /// Finish writing the delta layer.
     703              :     ///
     704         1414 :     pub(crate) async fn finish(
     705         1414 :         mut self,
     706         1414 :         key_end: Key,
     707         1414 :         ctx: &RequestContext,
     708         1414 :     ) -> anyhow::Result<(PersistentLayerDesc, Utf8PathBuf)> {
     709         9694 :         self.inner.take().unwrap().finish(key_end, ctx).await
     710         1414 :     }
     711              : 
     712        12178 :     pub(crate) fn num_keys(&self) -> usize {
     713        12178 :         self.inner.as_ref().unwrap().num_keys
     714        12178 :     }
     715              : 
     716        15088 :     pub(crate) fn estimated_size(&self) -> u64 {
     717        15088 :         let inner = self.inner.as_ref().unwrap();
     718        15088 :         inner.blob_writer.size() + inner.tree.borrow_writer().size() + PAGE_SZ as u64
     719        15088 :     }
     720              : }
     721              : 
     722              : impl Drop for DeltaLayerWriter {
     723         1438 :     fn drop(&mut self) {
     724         1438 :         if let Some(inner) = self.inner.take() {
     725           24 :             // We want to remove the virtual file here, so it's fine to not
     726           24 :             // having completely flushed unwritten data.
     727           24 :             let vfile = inner.blob_writer.into_inner_no_flush();
     728           24 :             vfile.remove();
     729         1414 :         }
     730         1438 :     }
     731              : }
     732              : 
     733            0 : #[derive(thiserror::Error, Debug)]
     734              : pub enum RewriteSummaryError {
     735              :     #[error("magic mismatch")]
     736              :     MagicMismatch,
     737              :     #[error(transparent)]
     738              :     Other(#[from] anyhow::Error),
     739              : }
     740              : 
     741              : impl From<std::io::Error> for RewriteSummaryError {
     742            0 :     fn from(e: std::io::Error) -> Self {
     743            0 :         Self::Other(anyhow::anyhow!(e))
     744            0 :     }
     745              : }
     746              : 
     747              : impl DeltaLayer {
     748            0 :     pub async fn rewrite_summary<F>(
     749            0 :         path: &Utf8Path,
     750            0 :         rewrite: F,
     751            0 :         ctx: &RequestContext,
     752            0 :     ) -> Result<(), RewriteSummaryError>
     753            0 :     where
     754            0 :         F: Fn(Summary) -> Summary,
     755            0 :     {
     756            0 :         let mut file = VirtualFile::open_with_options(
     757            0 :             path,
     758            0 :             virtual_file::OpenOptions::new().read(true).write(true),
     759            0 :             ctx,
     760            0 :         )
     761            0 :         .await
     762            0 :         .with_context(|| format!("Failed to open file '{}'", path))?;
     763            0 :         let file_id = page_cache::next_file_id();
     764            0 :         let block_reader = FileBlockReader::new(&file, file_id);
     765            0 :         let summary_blk = block_reader.read_blk(0, ctx).await?;
     766            0 :         let actual_summary = Summary::des_prefix(summary_blk.as_ref()).context("deserialize")?;
     767            0 :         if actual_summary.magic != DELTA_FILE_MAGIC {
     768            0 :             return Err(RewriteSummaryError::MagicMismatch);
     769            0 :         }
     770            0 : 
     771            0 :         let new_summary = rewrite(actual_summary);
     772            0 : 
     773            0 :         let mut buf = Vec::with_capacity(PAGE_SZ);
     774            0 :         // TODO: could use smallvec here, but it's a pain with Slice<T>
     775            0 :         Summary::ser_into(&new_summary, &mut buf).context("serialize")?;
     776            0 :         file.seek(SeekFrom::Start(0)).await?;
     777            0 :         let (_buf, res) = file.write_all(buf.slice_len(), ctx).await;
     778            0 :         res?;
     779            0 :         Ok(())
     780            0 :     }
     781              : }
     782              : 
     783              : impl DeltaLayerInner {
     784          988 :     pub(crate) fn key_range(&self) -> &Range<Key> {
     785          988 :         &self.layer_key_range
     786          988 :     }
     787              : 
     788          988 :     pub(crate) fn lsn_range(&self) -> &Range<Lsn> {
     789          988 :         &self.layer_lsn_range
     790          988 :     }
     791              : 
     792         1068 :     pub(super) async fn load(
     793         1068 :         path: &Utf8Path,
     794         1068 :         summary: Option<Summary>,
     795         1068 :         max_vectored_read_bytes: Option<MaxVectoredReadBytes>,
     796         1068 :         ctx: &RequestContext,
     797         1068 :     ) -> anyhow::Result<Self> {
     798         1068 :         let file = VirtualFile::open_v2(path, ctx)
     799          534 :             .await
     800         1068 :             .context("open layer file")?;
     801              : 
     802         1068 :         let file_id = page_cache::next_file_id();
     803         1068 : 
     804         1068 :         let block_reader = FileBlockReader::new(&file, file_id);
     805              : 
     806         1068 :         let summary_blk = block_reader
     807         1068 :             .read_blk(0, ctx)
     808          537 :             .await
     809         1068 :             .context("read first block")?;
     810              : 
     811              :         // TODO: this should be an assertion instead; see ImageLayerInner::load
     812         1068 :         let actual_summary =
     813         1068 :             Summary::des_prefix(summary_blk.as_ref()).context("deserialize first block")?;
     814              : 
     815         1068 :         if let Some(mut expected_summary) = summary {
     816              :             // production code path
     817         1068 :             expected_summary.index_start_blk = actual_summary.index_start_blk;
     818         1068 :             expected_summary.index_root_blk = actual_summary.index_root_blk;
     819         1068 :             // mask out the timeline_id, but still require the layers to be from the same tenant
     820         1068 :             expected_summary.timeline_id = actual_summary.timeline_id;
     821         1068 : 
     822         1068 :             if actual_summary != expected_summary {
     823            0 :                 bail!(
     824            0 :                     "in-file summary does not match expected summary. actual = {:?} expected = {:?}",
     825            0 :                     actual_summary,
     826            0 :                     expected_summary
     827            0 :                 );
     828         1068 :             }
     829            0 :         }
     830              : 
     831         1068 :         Ok(DeltaLayerInner {
     832         1068 :             file,
     833         1068 :             file_id,
     834         1068 :             index_start_blk: actual_summary.index_start_blk,
     835         1068 :             index_root_blk: actual_summary.index_root_blk,
     836         1068 :             max_vectored_read_bytes,
     837         1068 :             layer_key_range: actual_summary.key_range,
     838         1068 :             layer_lsn_range: actual_summary.lsn_range,
     839         1068 :         })
     840         1068 :     }
     841              : 
     842              :     // Look up the keys in the provided keyspace and update
     843              :     // the reconstruct state with whatever is found.
     844              :     //
     845              :     // If the key is cached, go no further than the cached Lsn.
     846              :     //
     847              :     // Currently, the index is visited for each range, but this
     848              :     // can be further optimised to visit the index only once.
     849       217289 :     pub(super) async fn get_values_reconstruct_data(
     850       217289 :         &self,
     851       217289 :         keyspace: KeySpace,
     852       217289 :         lsn_range: Range<Lsn>,
     853       217289 :         reconstruct_state: &mut ValuesReconstructState,
     854       217289 :         ctx: &RequestContext,
     855       217289 :     ) -> Result<(), GetVectoredError> {
     856       217289 :         let block_reader = FileBlockReader::new(&self.file, self.file_id);
     857       217289 :         let index_reader = DiskBtreeReader::<_, DELTA_KEY_SIZE>::new(
     858       217289 :             self.index_start_blk,
     859       217289 :             self.index_root_blk,
     860       217289 :             block_reader,
     861       217289 :         );
     862       217289 : 
     863       217289 :         let planner = VectoredReadPlanner::new(
     864       217289 :             self.max_vectored_read_bytes
     865       217289 :                 .expect("Layer is loaded with max vectored bytes config")
     866       217289 :                 .0
     867       217289 :                 .into(),
     868       217289 :         );
     869       217289 : 
     870       217289 :         let data_end_offset = self.index_start_offset();
     871              : 
     872       217289 :         let reads = Self::plan_reads(
     873       217289 :             &keyspace,
     874       217289 :             lsn_range.clone(),
     875       217289 :             data_end_offset,
     876       217289 :             index_reader,
     877       217289 :             planner,
     878       217289 :             reconstruct_state,
     879       217289 :             ctx,
     880       217289 :         )
     881        19507 :         .await
     882       217289 :         .map_err(GetVectoredError::Other)?;
     883              : 
     884       217289 :         self.do_reads_and_update_state(reads, reconstruct_state, ctx)
     885        63762 :             .await;
     886              : 
     887       217289 :         reconstruct_state.on_lsn_advanced(&keyspace, lsn_range.start);
     888       217289 : 
     889       217289 :         Ok(())
     890       217289 :     }
     891              : 
     892       217491 :     async fn plan_reads<Reader>(
     893       217491 :         keyspace: &KeySpace,
     894       217491 :         lsn_range: Range<Lsn>,
     895       217491 :         data_end_offset: u64,
     896       217491 :         index_reader: DiskBtreeReader<Reader, DELTA_KEY_SIZE>,
     897       217491 :         mut planner: VectoredReadPlanner,
     898       217491 :         reconstruct_state: &mut ValuesReconstructState,
     899       217491 :         ctx: &RequestContext,
     900       217491 :     ) -> anyhow::Result<Vec<VectoredRead>>
     901       217491 :     where
     902       217491 :         Reader: BlockReader + Clone,
     903       217491 :     {
     904       217491 :         let ctx = RequestContextBuilder::extend(ctx)
     905       217491 :             .page_content_kind(PageContentKind::DeltaLayerBtreeNode)
     906       217491 :             .build();
     907              : 
     908       217693 :         for range in keyspace.ranges.iter() {
     909       217693 :             let mut range_end_handled = false;
     910       217693 : 
     911       217693 :             let start_key = DeltaKey::from_key_lsn(&range.start, lsn_range.start);
     912       217693 :             let index_stream = index_reader.clone().into_stream(&start_key.0, &ctx);
     913       217693 :             let mut index_stream = std::pin::pin!(index_stream);
     914              : 
     915       634971 :             while let Some(index_entry) = index_stream.next().await {
     916       626274 :                 let (raw_key, value) = index_entry?;
     917       626274 :                 let key = Key::from_slice(&raw_key[..KEY_SIZE]);
     918       626274 :                 let lsn = DeltaKey::extract_lsn_from_buf(&raw_key);
     919       626274 :                 let blob_ref = BlobRef(value);
     920       626274 : 
     921       626274 :                 // Lsns are not monotonically increasing across keys, so we don't assert on them.
     922       626274 :                 assert!(key >= range.start);
     923              : 
     924       626274 :                 let outside_lsn_range = !lsn_range.contains(&lsn);
     925       626274 :                 let below_cached_lsn = reconstruct_state.get_cached_lsn(&key) >= Some(lsn);
     926              : 
     927       626274 :                 let flag = {
     928       626274 :                     if outside_lsn_range || below_cached_lsn {
     929       105604 :                         BlobFlag::Ignore
     930       520670 :                     } else if blob_ref.will_init() {
     931       462328 :                         BlobFlag::ReplaceAll
     932              :                     } else {
     933              :                         // Usual path: add blob to the read
     934        58342 :                         BlobFlag::None
     935              :                     }
     936              :                 };
     937              : 
     938       626274 :                 if key >= range.end || (key.next() == range.end && lsn >= lsn_range.end) {
     939       208996 :                     planner.handle_range_end(blob_ref.pos());
     940       208996 :                     range_end_handled = true;
     941       208996 :                     break;
     942       417278 :                 } else {
     943       417278 :                     planner.handle(key, lsn, blob_ref.pos(), flag);
     944       417278 :                 }
     945              :             }
     946              : 
     947       217693 :             if !range_end_handled {
     948         8697 :                 tracing::debug!("Handling range end fallback at {}", data_end_offset);
     949         8697 :                 planner.handle_range_end(data_end_offset);
     950       208996 :             }
     951              :         }
     952              : 
     953       217491 :         Ok(planner.finish())
     954       217491 :     }
     955              : 
     956       217489 :     fn get_min_read_buffer_size(
     957       217489 :         planned_reads: &[VectoredRead],
     958       217489 :         read_size_soft_max: usize,
     959       217489 :     ) -> usize {
     960       217489 :         let Some(largest_read) = planned_reads.iter().max_by_key(|read| read.size()) else {
     961        95518 :             return read_size_soft_max;
     962              :         };
     963              : 
     964       121971 :         let largest_read_size = largest_read.size();
     965       121971 :         if largest_read_size > read_size_soft_max {
     966              :             // If the read is oversized, it should only contain one key.
     967          200 :             let offenders = largest_read
     968          200 :                 .blobs_at
     969          200 :                 .as_slice()
     970          200 :                 .iter()
     971          200 :                 .filter_map(|(_, blob_meta)| {
     972          200 :                     if blob_meta.key.is_rel_dir_key() || blob_meta.key == DBDIR_KEY {
     973              :                         // The size of values for these keys is unbounded and can
     974              :                         // grow very large in pathological cases.
     975            0 :                         None
     976              :                     } else {
     977          200 :                         Some(format!("{}@{}", blob_meta.key, blob_meta.lsn))
     978              :                     }
     979          200 :                 })
     980          200 :                 .join(", ");
     981          200 : 
     982          200 :             if !offenders.is_empty() {
     983          200 :                 tracing::warn!(
     984            0 :                     "Oversized vectored read ({} > {}) for keys {}",
     985              :                     largest_read_size,
     986              :                     read_size_soft_max,
     987              :                     offenders
     988              :                 );
     989            0 :             }
     990       121771 :         }
     991              : 
     992       121971 :         largest_read_size
     993       217489 :     }
     994              : 
     995       217289 :     async fn do_reads_and_update_state(
     996       217289 :         &self,
     997       217289 :         reads: Vec<VectoredRead>,
     998       217289 :         reconstruct_state: &mut ValuesReconstructState,
     999       217289 :         ctx: &RequestContext,
    1000       217289 :     ) {
    1001       217289 :         let vectored_blob_reader = VectoredBlobReader::new(&self.file);
    1002       217289 :         let mut ignore_key_with_err = None;
    1003       217289 : 
    1004       217289 :         let max_vectored_read_bytes = self
    1005       217289 :             .max_vectored_read_bytes
    1006       217289 :             .expect("Layer is loaded with max vectored bytes config")
    1007       217289 :             .0
    1008       217289 :             .into();
    1009       217289 :         let buf_size = Self::get_min_read_buffer_size(&reads, max_vectored_read_bytes);
    1010       217289 :         let mut buf = Some(IoBufferMut::with_capacity(buf_size));
    1011              : 
    1012              :         // Note that reads are processed in reverse order (from highest key+lsn).
    1013              :         // This is the order that `ReconstructState` requires such that it can
    1014              :         // track when a key is done.
    1015       217289 :         for read in reads.into_iter().rev() {
    1016       125464 :             let res = vectored_blob_reader
    1017       125464 :                 .read_blobs(&read, buf.take().expect("Should have a buffer"), ctx)
    1018        63762 :                 .await;
    1019              : 
    1020       125464 :             let blobs_buf = match res {
    1021       125464 :                 Ok(blobs_buf) => blobs_buf,
    1022            0 :                 Err(err) => {
    1023            0 :                     let kind = err.kind();
    1024            0 :                     for (_, blob_meta) in read.blobs_at.as_slice() {
    1025            0 :                         reconstruct_state.on_key_error(
    1026            0 :                             blob_meta.key,
    1027            0 :                             PageReconstructError::Other(anyhow!(
    1028            0 :                                 "Failed to read blobs from virtual file {}: {}",
    1029            0 :                                 self.file.path(),
    1030            0 :                                 kind
    1031            0 :                             )),
    1032            0 :                         );
    1033            0 :                     }
    1034              : 
    1035              :                     // We have "lost" the buffer since the lower level IO api
    1036              :                     // doesn't return the buffer on error. Allocate a new one.
    1037            0 :                     buf = Some(IoBufferMut::with_capacity(buf_size));
    1038            0 : 
    1039            0 :                     continue;
    1040              :                 }
    1041              :             };
    1042       125464 :             let view = BufView::new_slice(&blobs_buf.buf);
    1043       149739 :             for meta in blobs_buf.blobs.iter().rev() {
    1044       149739 :                 if Some(meta.meta.key) == ignore_key_with_err {
    1045            0 :                     continue;
    1046       149739 :                 }
    1047       149739 :                 let blob_read = meta.read(&view).await;
    1048       149739 :                 let blob_read = match blob_read {
    1049       149739 :                     Ok(buf) => buf,
    1050            0 :                     Err(e) => {
    1051            0 :                         reconstruct_state.on_key_error(
    1052            0 :                             meta.meta.key,
    1053            0 :                             PageReconstructError::Other(anyhow!(e).context(format!(
    1054            0 :                                 "Failed to decompress blob from virtual file {}",
    1055            0 :                                 self.file.path(),
    1056            0 :                             ))),
    1057            0 :                         );
    1058            0 : 
    1059            0 :                         ignore_key_with_err = Some(meta.meta.key);
    1060            0 :                         continue;
    1061              :                     }
    1062              :                 };
    1063              : 
    1064       149739 :                 let value = Value::des(&blob_read);
    1065              : 
    1066       149739 :                 let value = match value {
    1067       149739 :                     Ok(v) => v,
    1068            0 :                     Err(e) => {
    1069            0 :                         reconstruct_state.on_key_error(
    1070            0 :                             meta.meta.key,
    1071            0 :                             PageReconstructError::Other(anyhow!(e).context(format!(
    1072            0 :                                 "Failed to deserialize blob from virtual file {}",
    1073            0 :                                 self.file.path(),
    1074            0 :                             ))),
    1075            0 :                         );
    1076            0 : 
    1077            0 :                         ignore_key_with_err = Some(meta.meta.key);
    1078            0 :                         continue;
    1079              :                     }
    1080              :                 };
    1081              : 
    1082              :                 // Invariant: once a key reaches [`ValueReconstructSituation::Complete`]
    1083              :                 // state, no further updates shall be made to it. The call below will
    1084              :                 // panic if the invariant is violated.
    1085       149739 :                 reconstruct_state.update_key(&meta.meta.key, meta.meta.lsn, value);
    1086              :             }
    1087              : 
    1088       125464 :             buf = Some(blobs_buf.buf);
    1089              :         }
    1090       217289 :     }
    1091              : 
    1092          406 :     pub(crate) async fn index_entries<'a>(
    1093          406 :         &'a self,
    1094          406 :         ctx: &RequestContext,
    1095          406 :     ) -> Result<Vec<DeltaEntry<'a>>> {
    1096          406 :         let block_reader = FileBlockReader::new(&self.file, self.file_id);
    1097          406 :         let tree_reader = DiskBtreeReader::<_, DELTA_KEY_SIZE>::new(
    1098          406 :             self.index_start_blk,
    1099          406 :             self.index_root_blk,
    1100          406 :             block_reader,
    1101          406 :         );
    1102          406 : 
    1103          406 :         let mut all_keys: Vec<DeltaEntry<'_>> = Vec::new();
    1104          406 : 
    1105          406 :         tree_reader
    1106          406 :             .visit(
    1107          406 :                 &[0u8; DELTA_KEY_SIZE],
    1108          406 :                 VisitDirection::Forwards,
    1109      2064046 :                 |key, value| {
    1110      2064046 :                     let delta_key = DeltaKey::from_slice(key);
    1111      2064046 :                     let val_ref = ValueRef {
    1112      2064046 :                         blob_ref: BlobRef(value),
    1113      2064046 :                         layer: self,
    1114      2064046 :                     };
    1115      2064046 :                     let pos = BlobRef(value).pos();
    1116      2064046 :                     if let Some(last) = all_keys.last_mut() {
    1117      2063640 :                         // subtract offset of the current and last entries to get the size
    1118      2063640 :                         // of the value associated with this (key, lsn) tuple
    1119      2063640 :                         let first_pos = last.size;
    1120      2063640 :                         last.size = pos - first_pos;
    1121      2063640 :                     }
    1122      2064046 :                     let entry = DeltaEntry {
    1123      2064046 :                         key: delta_key.key(),
    1124      2064046 :                         lsn: delta_key.lsn(),
    1125      2064046 :                         size: pos,
    1126      2064046 :                         val: val_ref,
    1127      2064046 :                     };
    1128      2064046 :                     all_keys.push(entry);
    1129      2064046 :                     true
    1130      2064046 :                 },
    1131          406 :                 &RequestContextBuilder::extend(ctx)
    1132          406 :                     .page_content_kind(PageContentKind::DeltaLayerBtreeNode)
    1133          406 :                     .build(),
    1134          406 :             )
    1135         2124 :             .await?;
    1136          406 :         if let Some(last) = all_keys.last_mut() {
    1137          406 :             // Last key occupies all space till end of value storage,
    1138          406 :             // which corresponds to beginning of the index
    1139          406 :             last.size = self.index_start_offset() - last.size;
    1140          406 :         }
    1141          406 :         Ok(all_keys)
    1142          406 :     }
    1143              : 
    1144              :     /// Using the given writer, write out a version which has the earlier Lsns than `until`.
    1145              :     ///
    1146              :     /// Return the amount of key value records pushed to the writer.
    1147           10 :     pub(super) async fn copy_prefix(
    1148           10 :         &self,
    1149           10 :         writer: &mut DeltaLayerWriter,
    1150           10 :         until: Lsn,
    1151           10 :         ctx: &RequestContext,
    1152           10 :     ) -> anyhow::Result<usize> {
    1153              :         use crate::tenant::vectored_blob_io::{
    1154              :             BlobMeta, ChunkedVectoredReadBuilder, VectoredReadExtended,
    1155              :         };
    1156              :         use futures::stream::TryStreamExt;
    1157              : 
    1158              :         #[derive(Debug)]
    1159              :         enum Item {
    1160              :             Actual(Key, Lsn, BlobRef),
    1161              :             Sentinel,
    1162              :         }
    1163              : 
    1164              :         impl From<Item> for Option<(Key, Lsn, BlobRef)> {
    1165           70 :             fn from(value: Item) -> Self {
    1166           70 :                 match value {
    1167           60 :                     Item::Actual(key, lsn, blob) => Some((key, lsn, blob)),
    1168           10 :                     Item::Sentinel => None,
    1169              :                 }
    1170           70 :             }
    1171              :         }
    1172              : 
    1173              :         impl Item {
    1174           70 :             fn offset(&self) -> Option<BlobRef> {
    1175           70 :                 match self {
    1176           60 :                     Item::Actual(_, _, blob) => Some(*blob),
    1177           10 :                     Item::Sentinel => None,
    1178              :                 }
    1179           70 :             }
    1180              : 
    1181           70 :             fn is_last(&self) -> bool {
    1182           70 :                 matches!(self, Item::Sentinel)
    1183           70 :             }
    1184              :         }
    1185              : 
    1186           10 :         let block_reader = FileBlockReader::new(&self.file, self.file_id);
    1187           10 :         let tree_reader = DiskBtreeReader::<_, DELTA_KEY_SIZE>::new(
    1188           10 :             self.index_start_blk,
    1189           10 :             self.index_root_blk,
    1190           10 :             block_reader,
    1191           10 :         );
    1192           10 : 
    1193           10 :         let stream = self.stream_index_forwards(tree_reader, &[0u8; DELTA_KEY_SIZE], ctx);
    1194           60 :         let stream = stream.map_ok(|(key, lsn, pos)| Item::Actual(key, lsn, pos));
    1195           10 :         // put in a sentinel value for getting the end offset for last item, and not having to
    1196           10 :         // repeat the whole read part
    1197           10 :         let stream = stream.chain(futures::stream::once(futures::future::ready(Ok(
    1198           10 :             Item::Sentinel,
    1199           10 :         ))));
    1200           10 :         let mut stream = std::pin::pin!(stream);
    1201           10 : 
    1202           10 :         let mut prev: Option<(Key, Lsn, BlobRef)> = None;
    1203           10 : 
    1204           10 :         let mut read_builder: Option<ChunkedVectoredReadBuilder> = None;
    1205           10 : 
    1206           10 :         let max_read_size = self
    1207           10 :             .max_vectored_read_bytes
    1208           10 :             .map(|x| x.0.get())
    1209           10 :             .unwrap_or(8192);
    1210           10 : 
    1211           10 :         let mut buffer = Some(IoBufferMut::with_capacity(max_read_size));
    1212           10 : 
    1213           10 :         // FIXME: buffering of DeltaLayerWriter
    1214           10 :         let mut per_blob_copy = Vec::new();
    1215           10 : 
    1216           10 :         let mut records = 0;
    1217              : 
    1218           80 :         while let Some(item) = stream.try_next().await? {
    1219           70 :             tracing::debug!(?item, "popped");
    1220           70 :             let offset = item
    1221           70 :                 .offset()
    1222           70 :                 .unwrap_or(BlobRef::new(self.index_start_offset(), false));
    1223              : 
    1224           70 :             let actionable = if let Some((key, lsn, start_offset)) = prev.take() {
    1225           60 :                 let end_offset = offset;
    1226           60 : 
    1227           60 :                 Some((BlobMeta { key, lsn }, start_offset..end_offset))
    1228              :             } else {
    1229           10 :                 None
    1230              :             };
    1231              : 
    1232           70 :             let is_last = item.is_last();
    1233           70 : 
    1234           70 :             prev = Option::from(item);
    1235           70 : 
    1236           70 :             let actionable = actionable.filter(|x| x.0.lsn < until);
    1237              : 
    1238           70 :             let builder = if let Some((meta, offsets)) = actionable {
    1239              :                 // extend or create a new builder
    1240           32 :                 if read_builder
    1241           32 :                     .as_mut()
    1242           32 :                     .map(|x| x.extend(offsets.start.pos(), offsets.end.pos(), meta))
    1243           32 :                     .unwrap_or(VectoredReadExtended::No)
    1244           32 :                     == VectoredReadExtended::Yes
    1245              :                 {
    1246           16 :                     None
    1247              :                 } else {
    1248           16 :                     read_builder.replace(ChunkedVectoredReadBuilder::new(
    1249           16 :                         offsets.start.pos(),
    1250           16 :                         offsets.end.pos(),
    1251           16 :                         meta,
    1252           16 :                         max_read_size,
    1253           16 :                     ))
    1254              :                 }
    1255              :             } else {
    1256              :                 // nothing to do, except perhaps flush any existing for the last element
    1257           38 :                 None
    1258              :             };
    1259              : 
    1260              :             // flush the possible older builder and also the new one if the item was the last one
    1261           70 :             let builders = builder.into_iter();
    1262           70 :             let builders = if is_last {
    1263           10 :                 builders.chain(read_builder.take())
    1264              :             } else {
    1265           60 :                 builders.chain(None)
    1266              :             };
    1267              : 
    1268           86 :             for builder in builders {
    1269           16 :                 let read = builder.build();
    1270           16 : 
    1271           16 :                 let reader = VectoredBlobReader::new(&self.file);
    1272           16 : 
    1273           16 :                 let mut buf = buffer.take().unwrap();
    1274           16 : 
    1275           16 :                 buf.clear();
    1276           16 :                 buf.reserve(read.size());
    1277           16 :                 let res = reader.read_blobs(&read, buf, ctx).await?;
    1278              : 
    1279           16 :                 let view = BufView::new_slice(&res.buf);
    1280              : 
    1281           48 :                 for blob in res.blobs {
    1282           32 :                     let key = blob.meta.key;
    1283           32 :                     let lsn = blob.meta.lsn;
    1284              : 
    1285           32 :                     let data = blob.read(&view).await?;
    1286              : 
    1287              :                     #[cfg(debug_assertions)]
    1288           32 :                     Value::des(&data)
    1289           32 :                         .with_context(|| {
    1290            0 :                             format!(
    1291            0 :                                 "blob failed to deserialize for {}: {:?}",
    1292            0 :                                 blob,
    1293            0 :                                 utils::Hex(&data)
    1294            0 :                             )
    1295           32 :                         })
    1296           32 :                         .unwrap();
    1297           32 : 
    1298           32 :                     // is it an image or will_init walrecord?
    1299           32 :                     // FIXME: this could be handled by threading the BlobRef to the
    1300           32 :                     // VectoredReadBuilder
    1301           32 :                     let will_init = pageserver_api::value::ValueBytes::will_init(&data)
    1302           32 :                         .inspect_err(|_e| {
    1303            0 :                             #[cfg(feature = "testing")]
    1304            0 :                             tracing::error!(data=?utils::Hex(&data), err=?_e, %key, %lsn, "failed to parse will_init out of serialized value");
    1305           32 :                         })
    1306           32 :                         .unwrap_or(false);
    1307           32 : 
    1308           32 :                     per_blob_copy.clear();
    1309           32 :                     per_blob_copy.extend_from_slice(&data);
    1310              : 
    1311           32 :                     let (tmp, res) = writer
    1312           32 :                         .put_value_bytes(
    1313           32 :                             key,
    1314           32 :                             lsn,
    1315           32 :                             std::mem::take(&mut per_blob_copy).slice_len(),
    1316           32 :                             will_init,
    1317           32 :                             ctx,
    1318           32 :                         )
    1319            4 :                         .await;
    1320           32 :                     per_blob_copy = tmp.into_raw_slice().into_inner();
    1321           32 : 
    1322           32 :                     res?;
    1323              : 
    1324           32 :                     records += 1;
    1325              :                 }
    1326              : 
    1327           16 :                 buffer = Some(res.buf);
    1328              :             }
    1329              :         }
    1330              : 
    1331           10 :         assert!(
    1332           10 :             read_builder.is_none(),
    1333            0 :             "with the sentinel above loop should had handled all"
    1334              :         );
    1335              : 
    1336           10 :         Ok(records)
    1337           10 :     }
    1338              : 
    1339            4 :     pub(super) async fn dump(&self, ctx: &RequestContext) -> anyhow::Result<()> {
    1340            4 :         println!(
    1341            4 :             "index_start_blk: {}, root {}",
    1342            4 :             self.index_start_blk, self.index_root_blk
    1343            4 :         );
    1344            4 : 
    1345            4 :         let block_reader = FileBlockReader::new(&self.file, self.file_id);
    1346            4 :         let tree_reader = DiskBtreeReader::<_, DELTA_KEY_SIZE>::new(
    1347            4 :             self.index_start_blk,
    1348            4 :             self.index_root_blk,
    1349            4 :             block_reader,
    1350            4 :         );
    1351            4 : 
    1352            4 :         tree_reader.dump().await?;
    1353              : 
    1354            4 :         let keys = self.index_entries(ctx).await?;
    1355              : 
    1356            8 :         async fn dump_blob(val: &ValueRef<'_>, ctx: &RequestContext) -> anyhow::Result<String> {
    1357            8 :             let buf = val.load_raw(ctx).await?;
    1358            8 :             let val = Value::des(&buf)?;
    1359            8 :             let desc = match val {
    1360            8 :                 Value::Image(img) => {
    1361            8 :                     format!(" img {} bytes", img.len())
    1362              :                 }
    1363            0 :                 Value::WalRecord(rec) => {
    1364            0 :                     let wal_desc = pageserver_api::record::describe_wal_record(&rec)?;
    1365            0 :                     format!(
    1366            0 :                         " rec {} bytes will_init: {} {}",
    1367            0 :                         buf.len(),
    1368            0 :                         rec.will_init(),
    1369            0 :                         wal_desc
    1370            0 :                     )
    1371              :                 }
    1372              :             };
    1373            8 :             Ok(desc)
    1374            8 :         }
    1375              : 
    1376           12 :         for entry in keys {
    1377            8 :             let DeltaEntry { key, lsn, val, .. } = entry;
    1378            8 :             let desc = match dump_blob(&val, ctx).await {
    1379            8 :                 Ok(desc) => desc,
    1380            0 :                 Err(err) => {
    1381            0 :                     format!("ERROR: {err}")
    1382              :                 }
    1383              :             };
    1384            8 :             println!("  key {key} at {lsn}: {desc}");
    1385              : 
    1386              :             // Print more details about CHECKPOINT records. Would be nice to print details
    1387              :             // of many other record types too, but these are particularly interesting, as
    1388              :             // have a lot of special processing for them in walingest.rs.
    1389            4 :             use pageserver_api::key::CHECKPOINT_KEY;
    1390            4 :             use postgres_ffi::CheckPoint;
    1391            8 :             if key == CHECKPOINT_KEY {
    1392            0 :                 let val = val.load(ctx).await?;
    1393            0 :                 match val {
    1394            0 :                     Value::Image(img) => {
    1395            0 :                         let checkpoint = CheckPoint::decode(&img)?;
    1396            0 :                         println!("   CHECKPOINT: {:?}", checkpoint);
    1397              :                     }
    1398            0 :                     Value::WalRecord(_rec) => {
    1399            0 :                         println!("   unexpected walrecord value for checkpoint key");
    1400            0 :                     }
    1401              :                 }
    1402            8 :             }
    1403              :         }
    1404              : 
    1405            4 :         Ok(())
    1406            4 :     }
    1407              : 
    1408           30 :     fn stream_index_forwards<'a, R>(
    1409           30 :         &'a self,
    1410           30 :         reader: DiskBtreeReader<R, DELTA_KEY_SIZE>,
    1411           30 :         start: &'a [u8; DELTA_KEY_SIZE],
    1412           30 :         ctx: &'a RequestContext,
    1413           30 :     ) -> impl futures::stream::Stream<
    1414           30 :         Item = Result<(Key, Lsn, BlobRef), crate::tenant::disk_btree::DiskBtreeError>,
    1415           30 :     > + 'a
    1416           30 :     where
    1417           30 :         R: BlockReader + 'a,
    1418           30 :     {
    1419              :         use futures::stream::TryStreamExt;
    1420           30 :         let stream = reader.into_stream(start, ctx);
    1421          152 :         stream.map_ok(|(key, value)| {
    1422          152 :             let key = DeltaKey::from_slice(&key);
    1423          152 :             let (key, lsn) = (key.key(), key.lsn());
    1424          152 :             let offset = BlobRef(value);
    1425          152 : 
    1426          152 :             (key, lsn, offset)
    1427          152 :         })
    1428           30 :     }
    1429              : 
    1430              :     /// The file offset to the first block of index.
    1431              :     ///
    1432              :     /// The file structure is summary, values, and index. We often need this for the size of last blob.
    1433       218287 :     fn index_start_offset(&self) -> u64 {
    1434       218287 :         let offset = self.index_start_blk as u64 * PAGE_SZ as u64;
    1435       218287 :         let bref = BlobRef(offset);
    1436       218287 :         tracing::debug!(
    1437              :             index_start_blk = self.index_start_blk,
    1438              :             offset,
    1439            0 :             pos = bref.pos(),
    1440            0 :             "index_start_offset"
    1441              :         );
    1442       218287 :         offset
    1443       218287 :     }
    1444              : 
    1445          550 :     pub fn iter<'a>(&'a self, ctx: &'a RequestContext) -> DeltaLayerIterator<'a> {
    1446          550 :         let block_reader = FileBlockReader::new(&self.file, self.file_id);
    1447          550 :         let tree_reader =
    1448          550 :             DiskBtreeReader::new(self.index_start_blk, self.index_root_blk, block_reader);
    1449          550 :         DeltaLayerIterator {
    1450          550 :             delta_layer: self,
    1451          550 :             ctx,
    1452          550 :             index_iter: tree_reader.iter(&[0; DELTA_KEY_SIZE], ctx),
    1453          550 :             key_values_batch: std::collections::VecDeque::new(),
    1454          550 :             is_end: false,
    1455          550 :             planner: StreamingVectoredReadPlanner::new(
    1456          550 :                 1024 * 8192, // The default value. Unit tests might use a different value. 1024 * 8K = 8MB buffer.
    1457          550 :                 1024,        // The default value. Unit tests might use a different value
    1458          550 :             ),
    1459          550 :         }
    1460          550 :     }
    1461              : 
    1462              :     /// NB: not super efficient, but not terrible either. Should prob be an iterator.
    1463              :     //
    1464              :     // We're reusing the index traversal logical in plan_reads; would be nice to
    1465              :     // factor that out.
    1466            0 :     pub(crate) async fn load_keys(&self, ctx: &RequestContext) -> anyhow::Result<Vec<Key>> {
    1467            0 :         self.index_entries(ctx)
    1468            0 :             .await
    1469            0 :             .map(|entries| entries.into_iter().map(|entry| entry.key).collect())
    1470            0 :     }
    1471              : }
    1472              : 
    1473              : /// A set of data associated with a delta layer key and its value
    1474              : pub struct DeltaEntry<'a> {
    1475              :     pub key: Key,
    1476              :     pub lsn: Lsn,
    1477              :     /// Size of the stored value
    1478              :     pub size: u64,
    1479              :     /// Reference to the on-disk value
    1480              :     pub val: ValueRef<'a>,
    1481              : }
    1482              : 
    1483              : /// Reference to an on-disk value
    1484              : pub struct ValueRef<'a> {
    1485              :     blob_ref: BlobRef,
    1486              :     layer: &'a DeltaLayerInner,
    1487              : }
    1488              : 
    1489              : impl<'a> ValueRef<'a> {
    1490              :     /// Loads the value from disk
    1491            0 :     pub async fn load(&self, ctx: &RequestContext) -> Result<Value> {
    1492            0 :         let buf = self.load_raw(ctx).await?;
    1493            0 :         let val = Value::des(&buf)?;
    1494            0 :         Ok(val)
    1495            0 :     }
    1496              : 
    1497            8 :     async fn load_raw(&self, ctx: &RequestContext) -> Result<Vec<u8>> {
    1498            8 :         let reader = BlockCursor::new(crate::tenant::block_io::BlockReaderRef::Adapter(Adapter(
    1499            8 :             self.layer,
    1500            8 :         )));
    1501            8 :         let buf = reader.read_blob(self.blob_ref.pos(), ctx).await?;
    1502            8 :         Ok(buf)
    1503            8 :     }
    1504              : }
    1505              : 
    1506              : pub(crate) struct Adapter<T>(T);
    1507              : 
    1508              : impl<T: AsRef<DeltaLayerInner>> Adapter<T> {
    1509            8 :     pub(crate) async fn read_blk(
    1510            8 :         &self,
    1511            8 :         blknum: u32,
    1512            8 :         ctx: &RequestContext,
    1513            8 :     ) -> Result<BlockLease, std::io::Error> {
    1514            8 :         let block_reader = FileBlockReader::new(&self.0.as_ref().file, self.0.as_ref().file_id);
    1515            8 :         block_reader.read_blk(blknum, ctx).await
    1516            8 :     }
    1517              : }
    1518              : 
    1519              : impl AsRef<DeltaLayerInner> for DeltaLayerInner {
    1520           16 :     fn as_ref(&self) -> &DeltaLayerInner {
    1521           16 :         self
    1522           16 :     }
    1523              : }
    1524              : 
    1525              : impl<'a> pageserver_compaction::interface::CompactionDeltaEntry<'a, Key> for DeltaEntry<'a> {
    1526            0 :     fn key(&self) -> Key {
    1527            0 :         self.key
    1528            0 :     }
    1529            0 :     fn lsn(&self) -> Lsn {
    1530            0 :         self.lsn
    1531            0 :     }
    1532            0 :     fn size(&self) -> u64 {
    1533            0 :         self.size
    1534            0 :     }
    1535              : }
    1536              : 
    1537              : pub struct DeltaLayerIterator<'a> {
    1538              :     delta_layer: &'a DeltaLayerInner,
    1539              :     ctx: &'a RequestContext,
    1540              :     planner: StreamingVectoredReadPlanner,
    1541              :     index_iter: DiskBtreeIterator<'a>,
    1542              :     key_values_batch: VecDeque<(Key, Lsn, Value)>,
    1543              :     is_end: bool,
    1544              : }
    1545              : 
    1546              : impl<'a> DeltaLayerIterator<'a> {
    1547            0 :     pub(crate) fn layer_dbg_info(&self) -> String {
    1548            0 :         self.delta_layer.layer_dbg_info()
    1549            0 :     }
    1550              : 
    1551              :     /// Retrieve a batch of key-value pairs into the iterator buffer.
    1552        21380 :     async fn next_batch(&mut self) -> anyhow::Result<()> {
    1553        21380 :         assert!(self.key_values_batch.is_empty());
    1554        21380 :         assert!(!self.is_end);
    1555              : 
    1556        21380 :         let plan = loop {
    1557      2099534 :             if let Some(res) = self.index_iter.next().await {
    1558      2099012 :                 let (raw_key, value) = res?;
    1559      2099012 :                 let key = Key::from_slice(&raw_key[..KEY_SIZE]);
    1560      2099012 :                 let lsn = DeltaKey::extract_lsn_from_buf(&raw_key);
    1561      2099012 :                 let blob_ref = BlobRef(value);
    1562      2099012 :                 let offset = blob_ref.pos();
    1563      2099012 :                 if let Some(batch_plan) = self.planner.handle(key, lsn, offset) {
    1564        20858 :                     break batch_plan;
    1565      2078154 :                 }
    1566              :             } else {
    1567          522 :                 self.is_end = true;
    1568          522 :                 let data_end_offset = self.delta_layer.index_start_offset();
    1569          522 :                 if let Some(item) = self.planner.handle_range_end(data_end_offset) {
    1570          522 :                     break item;
    1571              :                 } else {
    1572            0 :                     return Ok(()); // TODO: test empty iterator
    1573              :                 }
    1574              :             }
    1575              :         };
    1576        21380 :         let vectored_blob_reader = VectoredBlobReader::new(&self.delta_layer.file);
    1577        21380 :         let mut next_batch = std::collections::VecDeque::new();
    1578        21380 :         let buf_size = plan.size();
    1579        21380 :         let buf = IoBufferMut::with_capacity(buf_size);
    1580        21380 :         let blobs_buf = vectored_blob_reader
    1581        21380 :             .read_blobs(&plan, buf, self.ctx)
    1582        10916 :             .await?;
    1583        21380 :         let view = BufView::new_slice(&blobs_buf.buf);
    1584      2098984 :         for meta in blobs_buf.blobs.iter() {
    1585      2098984 :             let blob_read = meta.read(&view).await?;
    1586      2098984 :             let value = Value::des(&blob_read)?;
    1587              : 
    1588      2098984 :             next_batch.push_back((meta.meta.key, meta.meta.lsn, value));
    1589              :         }
    1590        21380 :         self.key_values_batch = next_batch;
    1591        21380 :         Ok(())
    1592        21380 :     }
    1593              : 
    1594      2099722 :     pub async fn next(&mut self) -> anyhow::Result<Option<(Key, Lsn, Value)>> {
    1595      2099722 :         if self.key_values_batch.is_empty() {
    1596        22308 :             if self.is_end {
    1597         1012 :                 return Ok(None);
    1598        21296 :             }
    1599        21296 :             self.next_batch().await?;
    1600      2077414 :         }
    1601      2098710 :         Ok(Some(
    1602      2098710 :             self.key_values_batch
    1603      2098710 :                 .pop_front()
    1604      2098710 :                 .expect("should not be empty"),
    1605      2098710 :         ))
    1606      2099722 :     }
    1607              : }
    1608              : 
    1609              : #[cfg(test)]
    1610              : pub(crate) mod test {
    1611              :     use std::collections::BTreeMap;
    1612              : 
    1613              :     use itertools::MinMaxResult;
    1614              :     use rand::prelude::{SeedableRng, SliceRandom, StdRng};
    1615              :     use rand::RngCore;
    1616              : 
    1617              :     use super::*;
    1618              :     use crate::tenant::harness::TIMELINE_ID;
    1619              :     use crate::tenant::storage_layer::{Layer, ResidentLayer};
    1620              :     use crate::tenant::vectored_blob_io::StreamingVectoredReadPlanner;
    1621              :     use crate::tenant::{Tenant, Timeline};
    1622              :     use crate::{
    1623              :         context::DownloadBehavior,
    1624              :         task_mgr::TaskKind,
    1625              :         tenant::{disk_btree::tests::TestDisk, harness::TenantHarness},
    1626              :         DEFAULT_PG_VERSION,
    1627              :     };
    1628              :     use bytes::Bytes;
    1629              :     use pageserver_api::value::Value;
    1630              : 
    1631              :     /// Construct an index for a fictional delta layer and and then
    1632              :     /// traverse in order to plan vectored reads for a query. Finally,
    1633              :     /// verify that the traversal fed the right index key and value
    1634              :     /// pairs into the planner.
    1635              :     #[tokio::test]
    1636            2 :     async fn test_delta_layer_index_traversal() {
    1637            2 :         let base_key = Key {
    1638            2 :             field1: 0,
    1639            2 :             field2: 1663,
    1640            2 :             field3: 12972,
    1641            2 :             field4: 16396,
    1642            2 :             field5: 0,
    1643            2 :             field6: 246080,
    1644            2 :         };
    1645            2 : 
    1646            2 :         // Populate the index with some entries
    1647            2 :         let entries: BTreeMap<Key, Vec<Lsn>> = BTreeMap::from([
    1648            2 :             (base_key, vec![Lsn(1), Lsn(5), Lsn(25), Lsn(26), Lsn(28)]),
    1649            2 :             (base_key.add(1), vec![Lsn(2), Lsn(5), Lsn(10), Lsn(50)]),
    1650            2 :             (base_key.add(2), vec![Lsn(2), Lsn(5), Lsn(10), Lsn(50)]),
    1651            2 :             (base_key.add(5), vec![Lsn(10), Lsn(15), Lsn(16), Lsn(20)]),
    1652            2 :         ]);
    1653            2 : 
    1654            2 :         let mut disk = TestDisk::default();
    1655            2 :         let mut writer = DiskBtreeBuilder::<_, DELTA_KEY_SIZE>::new(&mut disk);
    1656            2 : 
    1657            2 :         let mut disk_offset = 0;
    1658           10 :         for (key, lsns) in &entries {
    1659           42 :             for lsn in lsns {
    1660           34 :                 let index_key = DeltaKey::from_key_lsn(key, *lsn);
    1661           34 :                 let blob_ref = BlobRef::new(disk_offset, false);
    1662           34 :                 writer
    1663           34 :                     .append(&index_key.0, blob_ref.0)
    1664           34 :                     .expect("In memory disk append should never fail");
    1665           34 : 
    1666           34 :                 disk_offset += 1;
    1667           34 :             }
    1668            2 :         }
    1669            2 : 
    1670            2 :         // Prepare all the arguments for the call into `plan_reads` below
    1671            2 :         let (root_offset, _writer) = writer
    1672            2 :             .finish()
    1673            2 :             .expect("In memory disk finish should never fail");
    1674            2 :         let reader = DiskBtreeReader::<_, DELTA_KEY_SIZE>::new(0, root_offset, disk);
    1675            2 :         let planner = VectoredReadPlanner::new(100);
    1676            2 :         let mut reconstruct_state = ValuesReconstructState::new();
    1677            2 :         let ctx = RequestContext::new(TaskKind::UnitTest, DownloadBehavior::Error);
    1678            2 : 
    1679            2 :         let keyspace = KeySpace {
    1680            2 :             ranges: vec![
    1681            2 :                 base_key..base_key.add(3),
    1682            2 :                 base_key.add(3)..base_key.add(100),
    1683            2 :             ],
    1684            2 :         };
    1685            2 :         let lsn_range = Lsn(2)..Lsn(40);
    1686            2 : 
    1687            2 :         // Plan and validate
    1688            2 :         let vectored_reads = DeltaLayerInner::plan_reads(
    1689            2 :             &keyspace,
    1690            2 :             lsn_range.clone(),
    1691            2 :             disk_offset,
    1692            2 :             reader,
    1693            2 :             planner,
    1694            2 :             &mut reconstruct_state,
    1695            2 :             &ctx,
    1696            2 :         )
    1697            2 :         .await
    1698            2 :         .expect("Read planning should not fail");
    1699            2 : 
    1700            2 :         validate(keyspace, lsn_range, vectored_reads, entries);
    1701            2 :     }
    1702              : 
    1703            2 :     fn validate(
    1704            2 :         keyspace: KeySpace,
    1705            2 :         lsn_range: Range<Lsn>,
    1706            2 :         vectored_reads: Vec<VectoredRead>,
    1707            2 :         index_entries: BTreeMap<Key, Vec<Lsn>>,
    1708            2 :     ) {
    1709              :         #[derive(Debug, PartialEq, Eq)]
    1710              :         struct BlobSpec {
    1711              :             key: Key,
    1712              :             lsn: Lsn,
    1713              :             at: u64,
    1714              :         }
    1715              : 
    1716            2 :         let mut planned_blobs = Vec::new();
    1717           30 :         for read in vectored_reads {
    1718           28 :             for (at, meta) in read.blobs_at.as_slice() {
    1719           28 :                 planned_blobs.push(BlobSpec {
    1720           28 :                     key: meta.key,
    1721           28 :                     lsn: meta.lsn,
    1722           28 :                     at: *at,
    1723           28 :                 });
    1724           28 :             }
    1725              :         }
    1726              : 
    1727            2 :         let mut expected_blobs = Vec::new();
    1728            2 :         let mut disk_offset = 0;
    1729           10 :         for (key, lsns) in index_entries {
    1730           42 :             for lsn in lsns {
    1731           42 :                 let key_included = keyspace.ranges.iter().any(|range| range.contains(&key));
    1732           34 :                 let lsn_included = lsn_range.contains(&lsn);
    1733           34 : 
    1734           34 :                 if key_included && lsn_included {
    1735           28 :                     expected_blobs.push(BlobSpec {
    1736           28 :                         key,
    1737           28 :                         lsn,
    1738           28 :                         at: disk_offset,
    1739           28 :                     });
    1740           28 :                 }
    1741              : 
    1742           34 :                 disk_offset += 1;
    1743              :             }
    1744              :         }
    1745              : 
    1746            2 :         assert_eq!(planned_blobs, expected_blobs);
    1747            2 :     }
    1748              : 
    1749              :     mod constants {
    1750              :         use utils::lsn::Lsn;
    1751              : 
    1752              :         /// Offset used by all lsns in this test
    1753              :         pub(super) const LSN_OFFSET: Lsn = Lsn(0x08);
    1754              :         /// Number of unique keys including in the test data
    1755              :         pub(super) const KEY_COUNT: u8 = 60;
    1756              :         /// Max number of different lsns for each key
    1757              :         pub(super) const MAX_ENTRIES_PER_KEY: u8 = 20;
    1758              :         /// Possible value sizes for each key along with a probability weight
    1759              :         pub(super) const VALUE_SIZES: [(usize, u8); 3] = [(100, 2), (1024, 2), (1024 * 1024, 1)];
    1760              :         /// Probability that there will be a gap between the current key and the next one (33.3%)
    1761              :         pub(super) const KEY_GAP_CHANGES: [(bool, u8); 2] = [(true, 1), (false, 2)];
    1762              :         /// The minimum size of a key range in all the generated reads
    1763              :         pub(super) const MIN_RANGE_SIZE: i128 = 10;
    1764              :         /// The number of ranges included in each vectored read
    1765              :         pub(super) const RANGES_COUNT: u8 = 2;
    1766              :         /// The number of vectored reads performed
    1767              :         pub(super) const READS_COUNT: u8 = 100;
    1768              :         /// Soft max size of a vectored read. Will be violated if we have to read keys
    1769              :         /// with values larger than the limit
    1770              :         pub(super) const MAX_VECTORED_READ_BYTES: usize = 64 * 1024;
    1771              :     }
    1772              : 
    1773              :     struct Entry {
    1774              :         key: Key,
    1775              :         lsn: Lsn,
    1776              :         value: Vec<u8>,
    1777              :     }
    1778              : 
    1779            2 :     fn generate_entries(rng: &mut StdRng) -> Vec<Entry> {
    1780            2 :         let mut current_key = Key::MIN;
    1781            2 : 
    1782            2 :         let mut entries = Vec::new();
    1783          122 :         for _ in 0..constants::KEY_COUNT {
    1784          120 :             let count = rng.gen_range(1..constants::MAX_ENTRIES_PER_KEY);
    1785          120 :             let mut lsns_iter =
    1786         2260 :                 std::iter::successors(Some(Lsn(constants::LSN_OFFSET.0 + 0x08)), |lsn| {
    1787         2260 :                     Some(Lsn(lsn.0 + 0x08))
    1788         2260 :                 });
    1789          120 :             let mut lsns = Vec::new();
    1790         2380 :             while lsns.len() < count as usize {
    1791         2260 :                 let take = rng.gen_bool(0.5);
    1792         2260 :                 let lsn = lsns_iter.next().unwrap();
    1793         2260 :                 if take {
    1794         1112 :                     lsns.push(lsn);
    1795         1148 :                 }
    1796              :             }
    1797              : 
    1798         1232 :             for lsn in lsns {
    1799         1112 :                 let size = constants::VALUE_SIZES
    1800         3336 :                     .choose_weighted(rng, |item| item.1)
    1801         1112 :                     .unwrap()
    1802         1112 :                     .0;
    1803         1112 :                 let mut buf = vec![0; size];
    1804         1112 :                 rng.fill_bytes(&mut buf);
    1805         1112 : 
    1806         1112 :                 entries.push(Entry {
    1807         1112 :                     key: current_key,
    1808         1112 :                     lsn,
    1809         1112 :                     value: buf,
    1810         1112 :                 })
    1811              :             }
    1812              : 
    1813          120 :             let gap = constants::KEY_GAP_CHANGES
    1814          240 :                 .choose_weighted(rng, |item| item.1)
    1815          120 :                 .unwrap()
    1816          120 :                 .0;
    1817          120 :             if gap {
    1818           38 :                 current_key = current_key.add(2);
    1819           82 :             } else {
    1820           82 :                 current_key = current_key.add(1);
    1821           82 :             }
    1822              :         }
    1823              : 
    1824            2 :         entries
    1825            2 :     }
    1826              : 
    1827              :     struct EntriesMeta {
    1828              :         key_range: Range<Key>,
    1829              :         lsn_range: Range<Lsn>,
    1830              :         index: BTreeMap<(Key, Lsn), Vec<u8>>,
    1831              :     }
    1832              : 
    1833            2 :     fn get_entries_meta(entries: &[Entry]) -> EntriesMeta {
    1834         1112 :         let key_range = match entries.iter().minmax_by_key(|e| e.key) {
    1835            2 :             MinMaxResult::MinMax(min, max) => min.key..max.key.next(),
    1836            0 :             _ => panic!("More than one entry is always expected"),
    1837              :         };
    1838              : 
    1839         1112 :         let lsn_range = match entries.iter().minmax_by_key(|e| e.lsn) {
    1840            2 :             MinMaxResult::MinMax(min, max) => min.lsn..Lsn(max.lsn.0 + 1),
    1841            0 :             _ => panic!("More than one entry is always expected"),
    1842              :         };
    1843              : 
    1844            2 :         let mut index = BTreeMap::new();
    1845         1112 :         for entry in entries.iter() {
    1846         1112 :             index.insert((entry.key, entry.lsn), entry.value.clone());
    1847         1112 :         }
    1848              : 
    1849            2 :         EntriesMeta {
    1850            2 :             key_range,
    1851            2 :             lsn_range,
    1852            2 :             index,
    1853            2 :         }
    1854            2 :     }
    1855              : 
    1856          200 :     fn pick_random_keyspace(rng: &mut StdRng, key_range: &Range<Key>) -> KeySpace {
    1857          200 :         let start = key_range.start.to_i128();
    1858          200 :         let end = key_range.end.to_i128();
    1859          200 : 
    1860          200 :         let mut keyspace = KeySpace::default();
    1861              : 
    1862          600 :         for _ in 0..constants::RANGES_COUNT {
    1863          400 :             let mut range: Option<Range<Key>> = Option::default();
    1864         1244 :             while range.is_none() || keyspace.overlaps(range.as_ref().unwrap()) {
    1865          844 :                 let range_start = rng.gen_range(start..end);
    1866          844 :                 let range_end_offset = range_start + constants::MIN_RANGE_SIZE;
    1867          844 :                 if range_end_offset >= end {
    1868          100 :                     range = Some(Key::from_i128(range_start)..Key::from_i128(end));
    1869          744 :                 } else {
    1870          744 :                     let range_end = rng.gen_range((range_start + constants::MIN_RANGE_SIZE)..end);
    1871          744 :                     range = Some(Key::from_i128(range_start)..Key::from_i128(range_end));
    1872          744 :                 }
    1873              :             }
    1874          400 :             keyspace.ranges.push(range.unwrap());
    1875              :         }
    1876              : 
    1877          200 :         keyspace
    1878          200 :     }
    1879              : 
    1880              :     #[tokio::test]
    1881            2 :     async fn test_delta_layer_vectored_read_end_to_end() -> anyhow::Result<()> {
    1882            2 :         let harness = TenantHarness::create("test_delta_layer_oversized_vectored_read").await?;
    1883           15 :         let (tenant, ctx) = harness.load().await;
    1884            2 : 
    1885            2 :         let timeline_id = TimelineId::generate();
    1886            2 :         let timeline = tenant
    1887            2 :             .create_test_timeline(timeline_id, constants::LSN_OFFSET, DEFAULT_PG_VERSION, &ctx)
    1888            6 :             .await?;
    1889            2 : 
    1890            2 :         tracing::info!("Generating test data ...");
    1891            2 : 
    1892            2 :         let rng = &mut StdRng::seed_from_u64(0);
    1893            2 :         let entries = generate_entries(rng);
    1894            2 :         let entries_meta = get_entries_meta(&entries);
    1895            2 : 
    1896            2 :         tracing::info!("Done generating {} entries", entries.len());
    1897            2 : 
    1898            2 :         tracing::info!("Writing test data to delta layer ...");
    1899            2 :         let mut writer = DeltaLayerWriter::new(
    1900            2 :             harness.conf,
    1901            2 :             timeline_id,
    1902            2 :             harness.tenant_shard_id,
    1903            2 :             entries_meta.key_range.start,
    1904            2 :             entries_meta.lsn_range.clone(),
    1905            2 :             &ctx,
    1906            2 :         )
    1907            2 :         .await?;
    1908            2 : 
    1909         1114 :         for entry in entries {
    1910         1112 :             let (_, res) = writer
    1911         1112 :                 .put_value_bytes(entry.key, entry.lsn, entry.value.slice_len(), false, &ctx)
    1912          215 :                 .await;
    1913         1112 :             res?;
    1914            2 :         }
    1915            2 : 
    1916            5 :         let (desc, path) = writer.finish(entries_meta.key_range.end, &ctx).await?;
    1917            2 :         let resident = Layer::finish_creating(harness.conf, &timeline, desc, &path)?;
    1918            2 : 
    1919            2 :         let inner = resident.get_as_delta(&ctx).await?;
    1920            2 : 
    1921            2 :         let file_size = inner.file.metadata().await?.len();
    1922            2 :         tracing::info!(
    1923            2 :             "Done writing test data to delta layer. Resulting file size is: {}",
    1924            2 :             file_size
    1925            2 :         );
    1926            2 : 
    1927          202 :         for i in 0..constants::READS_COUNT {
    1928          200 :             tracing::info!("Doing vectored read {}/{}", i + 1, constants::READS_COUNT);
    1929            2 : 
    1930          200 :             let block_reader = FileBlockReader::new(&inner.file, inner.file_id);
    1931          200 :             let index_reader = DiskBtreeReader::<_, DELTA_KEY_SIZE>::new(
    1932          200 :                 inner.index_start_blk,
    1933          200 :                 inner.index_root_blk,
    1934          200 :                 block_reader,
    1935          200 :             );
    1936          200 : 
    1937          200 :             let planner = VectoredReadPlanner::new(constants::MAX_VECTORED_READ_BYTES);
    1938          200 :             let mut reconstruct_state = ValuesReconstructState::new();
    1939          200 :             let keyspace = pick_random_keyspace(rng, &entries_meta.key_range);
    1940          200 :             let data_end_offset = inner.index_start_blk as u64 * PAGE_SZ as u64;
    1941            2 : 
    1942          200 :             let vectored_reads = DeltaLayerInner::plan_reads(
    1943          200 :                 &keyspace,
    1944          200 :                 entries_meta.lsn_range.clone(),
    1945          200 :                 data_end_offset,
    1946          200 :                 index_reader,
    1947          200 :                 planner,
    1948          200 :                 &mut reconstruct_state,
    1949          200 :                 &ctx,
    1950          200 :             )
    1951            4 :             .await?;
    1952            2 : 
    1953          200 :             let vectored_blob_reader = VectoredBlobReader::new(&inner.file);
    1954          200 :             let buf_size = DeltaLayerInner::get_min_read_buffer_size(
    1955          200 :                 &vectored_reads,
    1956          200 :                 constants::MAX_VECTORED_READ_BYTES,
    1957          200 :             );
    1958          200 :             let mut buf = Some(IoBufferMut::with_capacity(buf_size));
    1959            2 : 
    1960        19924 :             for read in vectored_reads {
    1961        19724 :                 let blobs_buf = vectored_blob_reader
    1962        19724 :                     .read_blobs(&read, buf.take().expect("Should have a buffer"), &ctx)
    1963        10016 :                     .await?;
    1964        19724 :                 let view = BufView::new_slice(&blobs_buf.buf);
    1965        57304 :                 for meta in blobs_buf.blobs.iter() {
    1966        57304 :                     let value = meta.read(&view).await?;
    1967        57304 :                     assert_eq!(
    1968        57304 :                         &value[..],
    1969        57304 :                         &entries_meta.index[&(meta.meta.key, meta.meta.lsn)]
    1970        57304 :                     );
    1971            2 :                 }
    1972            2 : 
    1973        19724 :                 buf = Some(blobs_buf.buf);
    1974            2 :             }
    1975            2 :         }
    1976            2 : 
    1977            2 :         Ok(())
    1978            2 :     }
    1979              : 
    1980              :     #[tokio::test]
    1981            2 :     async fn copy_delta_prefix_smoke() {
    1982            2 :         use bytes::Bytes;
    1983            2 :         use pageserver_api::record::NeonWalRecord;
    1984            2 : 
    1985            2 :         let h = crate::tenant::harness::TenantHarness::create("truncate_delta_smoke")
    1986            2 :             .await
    1987            2 :             .unwrap();
    1988           20 :         let (tenant, ctx) = h.load().await;
    1989            2 :         let ctx = &ctx;
    1990            2 :         let timeline = tenant
    1991            2 :             .create_test_timeline(TimelineId::generate(), Lsn(0x10), 14, ctx)
    1992            6 :             .await
    1993            2 :             .unwrap();
    1994            2 : 
    1995            2 :         let initdb_layer = timeline
    1996            2 :             .layers
    1997            2 :             .read()
    1998            2 :             .await
    1999            2 :             .likely_resident_layers()
    2000            2 :             .next()
    2001            2 :             .cloned()
    2002            2 :             .unwrap();
    2003            2 : 
    2004            2 :         {
    2005            2 :             let mut writer = timeline.writer().await;
    2006            2 : 
    2007            2 :             let data = [
    2008            2 :                 (0x20, 12, Value::Image(Bytes::from_static(b"foobar"))),
    2009            2 :                 (
    2010            2 :                     0x30,
    2011            2 :                     12,
    2012            2 :                     Value::WalRecord(NeonWalRecord::Postgres {
    2013            2 :                         will_init: false,
    2014            2 :                         rec: Bytes::from_static(b"1"),
    2015            2 :                     }),
    2016            2 :                 ),
    2017            2 :                 (
    2018            2 :                     0x40,
    2019            2 :                     12,
    2020            2 :                     Value::WalRecord(NeonWalRecord::Postgres {
    2021            2 :                         will_init: true,
    2022            2 :                         rec: Bytes::from_static(b"2"),
    2023            2 :                     }),
    2024            2 :                 ),
    2025            2 :                 // build an oversized value so we cannot extend and existing read over
    2026            2 :                 // this
    2027            2 :                 (
    2028            2 :                     0x50,
    2029            2 :                     12,
    2030            2 :                     Value::WalRecord(NeonWalRecord::Postgres {
    2031            2 :                         will_init: true,
    2032            2 :                         rec: {
    2033            2 :                             let mut buf =
    2034            2 :                                 vec![0u8; tenant.conf.max_vectored_read_bytes.0.get() + 1024];
    2035            2 :                             buf.iter_mut()
    2036            2 :                                 .enumerate()
    2037       268288 :                                 .for_each(|(i, slot)| *slot = (i % 256) as u8);
    2038            2 :                             Bytes::from(buf)
    2039            2 :                         },
    2040            2 :                     }),
    2041            2 :                 ),
    2042            2 :                 // because the oversized read cannot be extended further, we are sure to exercise the
    2043            2 :                 // builder created on the last round with this:
    2044            2 :                 (
    2045            2 :                     0x60,
    2046            2 :                     12,
    2047            2 :                     Value::WalRecord(NeonWalRecord::Postgres {
    2048            2 :                         will_init: true,
    2049            2 :                         rec: Bytes::from_static(b"3"),
    2050            2 :                     }),
    2051            2 :                 ),
    2052            2 :                 (
    2053            2 :                     0x60,
    2054            2 :                     9,
    2055            2 :                     Value::Image(Bytes::from_static(b"something for a different key")),
    2056            2 :                 ),
    2057            2 :             ];
    2058            2 : 
    2059            2 :             let mut last_lsn = None;
    2060            2 : 
    2061           14 :             for (lsn, key, value) in data {
    2062           12 :                 let key = Key::from_i128(key);
    2063           12 :                 writer.put(key, Lsn(lsn), &value, ctx).await.unwrap();
    2064           12 :                 last_lsn = Some(lsn);
    2065            2 :             }
    2066            2 : 
    2067            2 :             writer.finish_write(Lsn(last_lsn.unwrap()));
    2068            2 :         }
    2069            2 :         timeline.freeze_and_flush().await.unwrap();
    2070            2 : 
    2071            2 :         let new_layer = timeline
    2072            2 :             .layers
    2073            2 :             .read()
    2074            2 :             .await
    2075            2 :             .likely_resident_layers()
    2076            3 :             .find(|&x| x != &initdb_layer)
    2077            2 :             .cloned()
    2078            2 :             .unwrap();
    2079            2 : 
    2080            2 :         // create a copy for the timeline, so we don't overwrite the file
    2081            2 :         let branch = tenant
    2082            2 :             .branch_timeline_test(&timeline, TimelineId::generate(), None, ctx)
    2083            2 :             .await
    2084            2 :             .unwrap();
    2085            2 : 
    2086            2 :         assert_eq!(branch.get_ancestor_lsn(), Lsn(0x60));
    2087            2 : 
    2088            2 :         // truncating at 0x61 gives us a full copy, otherwise just go backwards until there's just
    2089            2 :         // a single key
    2090            2 : 
    2091           12 :         for truncate_at in [0x61, 0x51, 0x41, 0x31, 0x21] {
    2092           10 :             let truncate_at = Lsn(truncate_at);
    2093            2 : 
    2094           10 :             let mut writer = DeltaLayerWriter::new(
    2095           10 :                 tenant.conf,
    2096           10 :                 branch.timeline_id,
    2097           10 :                 tenant.tenant_shard_id,
    2098           10 :                 Key::MIN,
    2099           10 :                 Lsn(0x11)..truncate_at,
    2100           10 :                 ctx,
    2101           10 :             )
    2102            5 :             .await
    2103           10 :             .unwrap();
    2104            2 : 
    2105           10 :             let new_layer = new_layer.download_and_keep_resident().await.unwrap();
    2106           10 : 
    2107           10 :             new_layer
    2108           10 :                 .copy_delta_prefix(&mut writer, truncate_at, ctx)
    2109           15 :                 .await
    2110           10 :                 .unwrap();
    2111            2 : 
    2112           24 :             let (desc, path) = writer.finish(Key::MAX, ctx).await.unwrap();
    2113           10 :             let copied_layer = Layer::finish_creating(tenant.conf, &branch, desc, &path).unwrap();
    2114           10 : 
    2115           10 :             copied_layer.get_as_delta(ctx).await.unwrap();
    2116           10 : 
    2117           10 :             assert_keys_and_values_eq(
    2118           10 :                 new_layer.get_as_delta(ctx).await.unwrap(),
    2119           10 :                 copied_layer.get_as_delta(ctx).await.unwrap(),
    2120           10 :                 truncate_at,
    2121           10 :                 ctx,
    2122            2 :             )
    2123           44 :             .await;
    2124            2 :         }
    2125            2 :     }
    2126              : 
    2127           10 :     async fn assert_keys_and_values_eq(
    2128           10 :         source: &DeltaLayerInner,
    2129           10 :         truncated: &DeltaLayerInner,
    2130           10 :         truncated_at: Lsn,
    2131           10 :         ctx: &RequestContext,
    2132           10 :     ) {
    2133              :         use futures::future::ready;
    2134              :         use futures::stream::TryStreamExt;
    2135              : 
    2136           10 :         let start_key = [0u8; DELTA_KEY_SIZE];
    2137           10 : 
    2138           10 :         let source_reader = FileBlockReader::new(&source.file, source.file_id);
    2139           10 :         let source_tree = DiskBtreeReader::<_, DELTA_KEY_SIZE>::new(
    2140           10 :             source.index_start_blk,
    2141           10 :             source.index_root_blk,
    2142           10 :             &source_reader,
    2143           10 :         );
    2144           10 :         let source_stream = source.stream_index_forwards(source_tree, &start_key, ctx);
    2145           60 :         let source_stream = source_stream.filter(|res| match res {
    2146           60 :             Ok((_, lsn, _)) => ready(lsn < &truncated_at),
    2147            0 :             _ => ready(true),
    2148           60 :         });
    2149           10 :         let mut source_stream = std::pin::pin!(source_stream);
    2150           10 : 
    2151           10 :         let truncated_reader = FileBlockReader::new(&truncated.file, truncated.file_id);
    2152           10 :         let truncated_tree = DiskBtreeReader::<_, DELTA_KEY_SIZE>::new(
    2153           10 :             truncated.index_start_blk,
    2154           10 :             truncated.index_root_blk,
    2155           10 :             &truncated_reader,
    2156           10 :         );
    2157           10 :         let truncated_stream = truncated.stream_index_forwards(truncated_tree, &start_key, ctx);
    2158           10 :         let mut truncated_stream = std::pin::pin!(truncated_stream);
    2159           10 : 
    2160           10 :         let mut scratch_left = Vec::new();
    2161           10 :         let mut scratch_right = Vec::new();
    2162              : 
    2163              :         loop {
    2164           42 :             let (src, truncated) = (source_stream.try_next(), truncated_stream.try_next());
    2165           42 :             let (src, truncated) = tokio::try_join!(src, truncated).unwrap();
    2166           42 : 
    2167           42 :             if src.is_none() {
    2168           10 :                 assert!(truncated.is_none());
    2169           10 :                 break;
    2170           32 :             }
    2171           32 : 
    2172           32 :             let (src, truncated) = (src.unwrap(), truncated.unwrap());
    2173           32 : 
    2174           32 :             // because we've filtered the source with Lsn, we should always have the same keys from both.
    2175           32 :             assert_eq!(src.0, truncated.0);
    2176           32 :             assert_eq!(src.1, truncated.1);
    2177              : 
    2178              :             // if this is needed for something else, just drop this assert.
    2179           32 :             assert!(
    2180           32 :                 src.2.pos() >= truncated.2.pos(),
    2181            0 :                 "value position should not go backwards {} vs. {}",
    2182            0 :                 src.2.pos(),
    2183            0 :                 truncated.2.pos()
    2184              :             );
    2185              : 
    2186           32 :             scratch_left.clear();
    2187           32 :             let src_cursor = source_reader.block_cursor();
    2188           32 :             let left = src_cursor.read_blob_into_buf(src.2.pos(), &mut scratch_left, ctx);
    2189           32 :             scratch_right.clear();
    2190           32 :             let trunc_cursor = truncated_reader.block_cursor();
    2191           32 :             let right = trunc_cursor.read_blob_into_buf(truncated.2.pos(), &mut scratch_right, ctx);
    2192           32 : 
    2193           32 :             tokio::try_join!(left, right).unwrap();
    2194           32 : 
    2195           32 :             assert_eq!(utils::Hex(&scratch_left), utils::Hex(&scratch_right));
    2196              :         }
    2197           10 :     }
    2198              : 
    2199        18224 :     pub(crate) fn sort_delta(
    2200        18224 :         (k1, l1, _): &(Key, Lsn, Value),
    2201        18224 :         (k2, l2, _): &(Key, Lsn, Value),
    2202        18224 :     ) -> std::cmp::Ordering {
    2203        18224 :         (k1, l1).cmp(&(k2, l2))
    2204        18224 :     }
    2205              : 
    2206              :     #[cfg(feature = "testing")]
    2207           94 :     pub(crate) fn sort_delta_value(
    2208           94 :         (k1, l1, v1): &(Key, Lsn, Value),
    2209           94 :         (k2, l2, v2): &(Key, Lsn, Value),
    2210           94 :     ) -> std::cmp::Ordering {
    2211           94 :         let order_1 = if v1.is_image() { 0 } else { 1 };
    2212           94 :         let order_2 = if v2.is_image() { 0 } else { 1 };
    2213           94 :         (k1, l1, order_1).cmp(&(k2, l2, order_2))
    2214           94 :     }
    2215              : 
    2216           22 :     pub(crate) async fn produce_delta_layer(
    2217           22 :         tenant: &Tenant,
    2218           22 :         tline: &Arc<Timeline>,
    2219           22 :         mut deltas: Vec<(Key, Lsn, Value)>,
    2220           22 :         ctx: &RequestContext,
    2221           22 :     ) -> anyhow::Result<ResidentLayer> {
    2222           22 :         deltas.sort_by(sort_delta);
    2223           22 :         let (key_start, _, _) = deltas.first().unwrap();
    2224           22 :         let (key_max, _, _) = deltas.last().unwrap();
    2225         8240 :         let lsn_min = deltas.iter().map(|(_, lsn, _)| lsn).min().unwrap();
    2226         8240 :         let lsn_max = deltas.iter().map(|(_, lsn, _)| lsn).max().unwrap();
    2227           22 :         let lsn_end = Lsn(lsn_max.0 + 1);
    2228           22 :         let mut writer = DeltaLayerWriter::new(
    2229           22 :             tenant.conf,
    2230           22 :             tline.timeline_id,
    2231           22 :             tenant.tenant_shard_id,
    2232           22 :             *key_start,
    2233           22 :             (*lsn_min)..lsn_end,
    2234           22 :             ctx,
    2235           22 :         )
    2236           11 :         .await?;
    2237           22 :         let key_end = key_max.next();
    2238              : 
    2239         8262 :         for (key, lsn, value) in deltas {
    2240         8240 :             writer.put_value(key, lsn, value, ctx).await?;
    2241              :         }
    2242              : 
    2243           63 :         let (desc, path) = writer.finish(key_end, ctx).await?;
    2244           22 :         let delta_layer = Layer::finish_creating(tenant.conf, tline, desc, &path)?;
    2245              : 
    2246           22 :         Ok::<_, anyhow::Error>(delta_layer)
    2247           22 :     }
    2248              : 
    2249           28 :     async fn assert_delta_iter_equal(
    2250           28 :         delta_iter: &mut DeltaLayerIterator<'_>,
    2251           28 :         expect: &[(Key, Lsn, Value)],
    2252           28 :     ) {
    2253           28 :         let mut expect_iter = expect.iter();
    2254              :         loop {
    2255        28028 :             let o1 = delta_iter.next().await.unwrap();
    2256        28028 :             let o2 = expect_iter.next();
    2257        28028 :             assert_eq!(o1.is_some(), o2.is_some());
    2258        28028 :             if o1.is_none() && o2.is_none() {
    2259           28 :                 break;
    2260        28000 :             }
    2261        28000 :             let (k1, l1, v1) = o1.unwrap();
    2262        28000 :             let (k2, l2, v2) = o2.unwrap();
    2263        28000 :             assert_eq!(&k1, k2);
    2264        28000 :             assert_eq!(l1, *l2);
    2265        28000 :             assert_eq!(&v1, v2);
    2266              :         }
    2267           28 :     }
    2268              : 
    2269              :     #[tokio::test]
    2270            2 :     async fn delta_layer_iterator() {
    2271            2 :         let harness = TenantHarness::create("delta_layer_iterator").await.unwrap();
    2272           20 :         let (tenant, ctx) = harness.load().await;
    2273            2 : 
    2274            2 :         let tline = tenant
    2275            2 :             .create_test_timeline(TIMELINE_ID, Lsn(0x10), DEFAULT_PG_VERSION, &ctx)
    2276            6 :             .await
    2277            2 :             .unwrap();
    2278            2 : 
    2279         2000 :         fn get_key(id: u32) -> Key {
    2280         2000 :             let mut key = Key::from_hex("000000000033333333444444445500000000").unwrap();
    2281         2000 :             key.field6 = id;
    2282         2000 :             key
    2283         2000 :         }
    2284            2 :         const N: usize = 1000;
    2285            2 :         let test_deltas = (0..N)
    2286         2000 :             .map(|idx| {
    2287         2000 :                 (
    2288         2000 :                     get_key(idx as u32 / 10),
    2289         2000 :                     Lsn(0x10 * ((idx as u64) % 10 + 1)),
    2290         2000 :                     Value::Image(Bytes::from(format!("img{idx:05}"))),
    2291         2000 :                 )
    2292         2000 :             })
    2293            2 :             .collect_vec();
    2294            2 :         let resident_layer = produce_delta_layer(&tenant, &tline, test_deltas.clone(), &ctx)
    2295            8 :             .await
    2296            2 :             .unwrap();
    2297            2 :         let delta_layer = resident_layer.get_as_delta(&ctx).await.unwrap();
    2298            6 :         for max_read_size in [1, 1024] {
    2299           32 :             for batch_size in [1, 2, 4, 8, 3, 7, 13] {
    2300           28 :                 println!("running with batch_size={batch_size} max_read_size={max_read_size}");
    2301           28 :                 // Test if the batch size is correctly determined
    2302           28 :                 let mut iter = delta_layer.iter(&ctx);
    2303           28 :                 iter.planner = StreamingVectoredReadPlanner::new(max_read_size, batch_size);
    2304           28 :                 let mut num_items = 0;
    2305          112 :                 for _ in 0..3 {
    2306           84 :                     iter.next_batch().await.unwrap();
    2307           84 :                     num_items += iter.key_values_batch.len();
    2308           84 :                     if max_read_size == 1 {
    2309            2 :                         // every key should be a batch b/c the value is larger than max_read_size
    2310           42 :                         assert_eq!(iter.key_values_batch.len(), 1);
    2311            2 :                     } else {
    2312           42 :                         assert!(iter.key_values_batch.len() <= batch_size);
    2313            2 :                     }
    2314           84 :                     if num_items >= N {
    2315            2 :                         break;
    2316           84 :                     }
    2317           84 :                     iter.key_values_batch.clear();
    2318            2 :                 }
    2319            2 :                 // Test if the result is correct
    2320           28 :                 let mut iter = delta_layer.iter(&ctx);
    2321           28 :                 iter.planner = StreamingVectoredReadPlanner::new(max_read_size, batch_size);
    2322         9649 :                 assert_delta_iter_equal(&mut iter, &test_deltas).await;
    2323            2 :             }
    2324            2 :         }
    2325            2 :     }
    2326              : }
        

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