LCOV - code coverage report
Current view: top level - safekeeper/src - wal_backup.rs (source / functions) Coverage Total Hit
Test: f081ec316c96fa98335efd15ef501745aa4f015d.info Lines: 0.0 % 427 0
Test Date: 2024-06-25 15:11:17 Functions: 0.0 % 55 0

            Line data    Source code
       1              : use anyhow::{Context, Result};
       2              : 
       3              : use camino::{Utf8Path, Utf8PathBuf};
       4              : use futures::stream::FuturesOrdered;
       5              : use futures::StreamExt;
       6              : use tokio::task::JoinHandle;
       7              : use tokio_util::sync::CancellationToken;
       8              : use utils::backoff;
       9              : use utils::id::NodeId;
      10              : 
      11              : use std::cmp::min;
      12              : use std::collections::HashSet;
      13              : use std::num::NonZeroU32;
      14              : use std::pin::Pin;
      15              : use std::sync::Arc;
      16              : use std::time::Duration;
      17              : 
      18              : use postgres_ffi::v14::xlog_utils::XLogSegNoOffsetToRecPtr;
      19              : use postgres_ffi::XLogFileName;
      20              : use postgres_ffi::{XLogSegNo, PG_TLI};
      21              : use remote_storage::{GenericRemoteStorage, ListingMode, RemotePath, StorageMetadata};
      22              : use tokio::fs::File;
      23              : 
      24              : use tokio::select;
      25              : use tokio::sync::mpsc::{self, Receiver, Sender};
      26              : use tokio::sync::watch;
      27              : use tokio::time::sleep;
      28              : use tracing::*;
      29              : 
      30              : use utils::{id::TenantTimelineId, lsn::Lsn};
      31              : 
      32              : use crate::metrics::{BACKED_UP_SEGMENTS, BACKUP_ERRORS, WAL_BACKUP_TASKS};
      33              : use crate::timeline::{FullAccessTimeline, PeerInfo, Timeline};
      34              : use crate::timeline_manager::StateSnapshot;
      35              : use crate::{SafeKeeperConf, WAL_BACKUP_RUNTIME};
      36              : 
      37              : use once_cell::sync::OnceCell;
      38              : 
      39              : const UPLOAD_FAILURE_RETRY_MIN_MS: u64 = 10;
      40              : const UPLOAD_FAILURE_RETRY_MAX_MS: u64 = 5000;
      41              : 
      42              : /// Default buffer size when interfacing with [`tokio::fs::File`].
      43              : const BUFFER_SIZE: usize = 32 * 1024;
      44              : 
      45              : pub struct WalBackupTaskHandle {
      46              :     shutdown_tx: Sender<()>,
      47              :     handle: JoinHandle<()>,
      48              : }
      49              : 
      50              : /// Do we have anything to upload to S3, i.e. should safekeepers run backup activity?
      51            0 : pub fn is_wal_backup_required(
      52            0 :     wal_seg_size: usize,
      53            0 :     num_computes: usize,
      54            0 :     state: &StateSnapshot,
      55            0 : ) -> bool {
      56            0 :     num_computes > 0 ||
      57              :     // Currently only the whole segment is offloaded, so compare segment numbers.
      58            0 :     (state.commit_lsn.segment_number(wal_seg_size) > state.backup_lsn.segment_number(wal_seg_size))
      59            0 : }
      60              : 
      61              : /// Based on peer information determine which safekeeper should offload; if it
      62              : /// is me, run (per timeline) task, if not yet. OTOH, if it is not me and task
      63              : /// is running, kill it.
      64            0 : pub async fn update_task(
      65            0 :     conf: &SafeKeeperConf,
      66            0 :     tli: &Arc<Timeline>,
      67            0 :     need_backup: bool,
      68            0 :     state: &StateSnapshot,
      69            0 :     entry: &mut Option<WalBackupTaskHandle>,
      70            0 : ) {
      71            0 :     let (offloader, election_dbg_str) =
      72            0 :         determine_offloader(&state.peers, state.backup_lsn, tli.ttid, conf);
      73            0 :     let elected_me = Some(conf.my_id) == offloader;
      74              : 
      75            0 :     let should_task_run = need_backup && elected_me;
      76              : 
      77              :     // start or stop the task
      78            0 :     if should_task_run != (entry.is_some()) {
      79            0 :         if should_task_run {
      80            0 :             info!("elected for backup: {}", election_dbg_str);
      81              : 
      82            0 :             let (shutdown_tx, shutdown_rx) = mpsc::channel(1);
      83            0 : 
      84            0 :             let async_task = backup_task_main(tli.clone(), conf.backup_parallel_jobs, shutdown_rx);
      85              : 
      86            0 :             let handle = if conf.current_thread_runtime {
      87            0 :                 tokio::spawn(async_task)
      88              :             } else {
      89            0 :                 WAL_BACKUP_RUNTIME.spawn(async_task)
      90              :             };
      91              : 
      92            0 :             *entry = Some(WalBackupTaskHandle {
      93            0 :                 shutdown_tx,
      94            0 :                 handle,
      95            0 :             });
      96              :         } else {
      97            0 :             if !need_backup {
      98              :                 // don't need backup at all
      99            0 :                 info!("stepping down from backup, need_backup={}", need_backup);
     100              :             } else {
     101              :                 // someone else has been elected
     102            0 :                 info!("stepping down from backup: {}", election_dbg_str);
     103              :             }
     104            0 :             shut_down_task(entry).await;
     105              :         }
     106            0 :     }
     107            0 : }
     108              : 
     109            0 : async fn shut_down_task(entry: &mut Option<WalBackupTaskHandle>) {
     110            0 :     if let Some(wb_handle) = entry.take() {
     111              :         // Tell the task to shutdown. Error means task exited earlier, that's ok.
     112            0 :         let _ = wb_handle.shutdown_tx.send(()).await;
     113              :         // Await the task itself. TODO: restart panicked tasks earlier.
     114            0 :         if let Err(e) = wb_handle.handle.await {
     115            0 :             warn!("WAL backup task panicked: {}", e);
     116            0 :         }
     117            0 :     }
     118            0 : }
     119              : 
     120              : /// The goal is to ensure that normally only one safekeepers offloads. However,
     121              : /// it is fine (and inevitable, as s3 doesn't provide CAS) that for some short
     122              : /// time we have several ones as they PUT the same files. Also,
     123              : /// - frequently changing the offloader would be bad;
     124              : /// - electing seriously lagging safekeeper is undesirable;
     125              : /// So we deterministically choose among the reasonably caught up candidates.
     126              : /// TODO: take into account failed attempts to deal with hypothetical situation
     127              : /// where s3 is unreachable only for some sks.
     128            0 : fn determine_offloader(
     129            0 :     alive_peers: &[PeerInfo],
     130            0 :     wal_backup_lsn: Lsn,
     131            0 :     ttid: TenantTimelineId,
     132            0 :     conf: &SafeKeeperConf,
     133            0 : ) -> (Option<NodeId>, String) {
     134            0 :     // TODO: remove this once we fill newly joined safekeepers since backup_lsn.
     135            0 :     let capable_peers = alive_peers
     136            0 :         .iter()
     137            0 :         .filter(|p| p.local_start_lsn <= wal_backup_lsn);
     138            0 :     match capable_peers.clone().map(|p| p.commit_lsn).max() {
     139            0 :         None => (None, "no connected peers to elect from".to_string()),
     140            0 :         Some(max_commit_lsn) => {
     141            0 :             let threshold = max_commit_lsn
     142            0 :                 .checked_sub(conf.max_offloader_lag_bytes)
     143            0 :                 .unwrap_or(Lsn(0));
     144            0 :             let mut caughtup_peers = capable_peers
     145            0 :                 .clone()
     146            0 :                 .filter(|p| p.commit_lsn >= threshold)
     147            0 :                 .collect::<Vec<_>>();
     148            0 :             caughtup_peers.sort_by(|p1, p2| p1.sk_id.cmp(&p2.sk_id));
     149            0 : 
     150            0 :             // To distribute the load, shift by timeline_id.
     151            0 :             let offloader = caughtup_peers
     152            0 :                 [(u128::from(ttid.timeline_id) % caughtup_peers.len() as u128) as usize]
     153            0 :                 .sk_id;
     154            0 : 
     155            0 :             let mut capable_peers_dbg = capable_peers
     156            0 :                 .map(|p| (p.sk_id, p.commit_lsn))
     157            0 :                 .collect::<Vec<_>>();
     158            0 :             capable_peers_dbg.sort_by(|p1, p2| p1.0.cmp(&p2.0));
     159            0 :             (
     160            0 :                 Some(offloader),
     161            0 :                 format!(
     162            0 :                     "elected {} among {:?} peers, with {} of them being caughtup",
     163            0 :                     offloader,
     164            0 :                     capable_peers_dbg,
     165            0 :                     caughtup_peers.len()
     166            0 :                 ),
     167            0 :             )
     168              :         }
     169              :     }
     170            0 : }
     171              : 
     172              : static REMOTE_STORAGE: OnceCell<Option<GenericRemoteStorage>> = OnceCell::new();
     173              : 
     174              : // Storage must be configured and initialized when this is called.
     175            0 : fn get_configured_remote_storage() -> &'static GenericRemoteStorage {
     176            0 :     REMOTE_STORAGE
     177            0 :         .get()
     178            0 :         .expect("failed to get remote storage")
     179            0 :         .as_ref()
     180            0 :         .unwrap()
     181            0 : }
     182              : 
     183            0 : pub fn init_remote_storage(conf: &SafeKeeperConf) {
     184            0 :     // TODO: refactor REMOTE_STORAGE to avoid using global variables, and provide
     185            0 :     // dependencies to all tasks instead.
     186            0 :     REMOTE_STORAGE.get_or_init(|| {
     187            0 :         conf.remote_storage
     188            0 :             .as_ref()
     189            0 :             .map(|c| GenericRemoteStorage::from_config(c).expect("failed to create remote storage"))
     190            0 :     });
     191            0 : }
     192              : 
     193              : struct WalBackupTask {
     194              :     timeline: FullAccessTimeline,
     195              :     timeline_dir: Utf8PathBuf,
     196              :     wal_seg_size: usize,
     197              :     parallel_jobs: usize,
     198              :     commit_lsn_watch_rx: watch::Receiver<Lsn>,
     199              : }
     200              : 
     201              : /// Offload single timeline.
     202            0 : #[instrument(name = "WAL backup", skip_all, fields(ttid = %tli.ttid))]
     203              : async fn backup_task_main(tli: Arc<Timeline>, parallel_jobs: usize, mut shutdown_rx: Receiver<()>) {
     204              :     let _guard = WAL_BACKUP_TASKS.guard();
     205              : 
     206              :     let tli = match tli.full_access_guard().await {
     207              :         Ok(tli) => tli,
     208              :         Err(e) => {
     209              :             error!("backup error: {}", e);
     210              :             return;
     211              :         }
     212              :     };
     213              :     info!("started");
     214              : 
     215              :     let mut wb = WalBackupTask {
     216              :         wal_seg_size: tli.get_wal_seg_size().await,
     217              :         commit_lsn_watch_rx: tli.get_commit_lsn_watch_rx(),
     218              :         timeline_dir: tli.get_timeline_dir(),
     219              :         timeline: tli,
     220              :         parallel_jobs,
     221              :     };
     222              : 
     223              :     // task is spinned up only when wal_seg_size already initialized
     224              :     assert!(wb.wal_seg_size > 0);
     225              : 
     226              :     let mut canceled = false;
     227              :     select! {
     228              :         _ = wb.run() => {}
     229              :         _ = shutdown_rx.recv() => {
     230              :             canceled = true;
     231              :         }
     232              :     }
     233              :     info!("task {}", if canceled { "canceled" } else { "terminated" });
     234              : }
     235              : 
     236              : impl WalBackupTask {
     237            0 :     async fn run(&mut self) {
     238            0 :         let mut backup_lsn = Lsn(0);
     239            0 : 
     240            0 :         let mut retry_attempt = 0u32;
     241              :         // offload loop
     242            0 :         loop {
     243            0 :             if retry_attempt == 0 {
     244              :                 // wait for new WAL to arrive
     245            0 :                 if let Err(e) = self.commit_lsn_watch_rx.changed().await {
     246              :                     // should never happen, as we hold Arc to timeline.
     247            0 :                     error!("commit_lsn watch shut down: {:?}", e);
     248            0 :                     return;
     249            0 :                 }
     250              :             } else {
     251              :                 // or just sleep if we errored previously
     252            0 :                 let mut retry_delay = UPLOAD_FAILURE_RETRY_MAX_MS;
     253            0 :                 if let Some(backoff_delay) = UPLOAD_FAILURE_RETRY_MIN_MS.checked_shl(retry_attempt)
     254            0 :                 {
     255            0 :                     retry_delay = min(retry_delay, backoff_delay);
     256            0 :                 }
     257            0 :                 sleep(Duration::from_millis(retry_delay)).await;
     258              :             }
     259              : 
     260            0 :             let commit_lsn = *self.commit_lsn_watch_rx.borrow();
     261            0 : 
     262            0 :             // Note that backup_lsn can be higher than commit_lsn if we
     263            0 :             // don't have much local WAL and others already uploaded
     264            0 :             // segments we don't even have.
     265            0 :             if backup_lsn.segment_number(self.wal_seg_size)
     266            0 :                 >= commit_lsn.segment_number(self.wal_seg_size)
     267              :             {
     268            0 :                 retry_attempt = 0;
     269            0 :                 continue; /* nothing to do, common case as we wake up on every commit_lsn bump */
     270            0 :             }
     271            0 :             // Perhaps peers advanced the position, check shmem value.
     272            0 :             backup_lsn = self.timeline.get_wal_backup_lsn().await;
     273            0 :             if backup_lsn.segment_number(self.wal_seg_size)
     274            0 :                 >= commit_lsn.segment_number(self.wal_seg_size)
     275              :             {
     276            0 :                 retry_attempt = 0;
     277            0 :                 continue;
     278            0 :             }
     279            0 : 
     280            0 :             match backup_lsn_range(
     281            0 :                 &self.timeline,
     282            0 :                 &mut backup_lsn,
     283            0 :                 commit_lsn,
     284            0 :                 self.wal_seg_size,
     285            0 :                 &self.timeline_dir,
     286            0 :                 self.parallel_jobs,
     287            0 :             )
     288            0 :             .await
     289              :             {
     290            0 :                 Ok(()) => {
     291            0 :                     retry_attempt = 0;
     292            0 :                 }
     293            0 :                 Err(e) => {
     294            0 :                     error!(
     295            0 :                         "failed while offloading range {}-{}: {:?}",
     296              :                         backup_lsn, commit_lsn, e
     297              :                     );
     298              : 
     299            0 :                     retry_attempt = retry_attempt.saturating_add(1);
     300              :                 }
     301              :             }
     302              :         }
     303            0 :     }
     304              : }
     305              : 
     306            0 : async fn backup_lsn_range(
     307            0 :     timeline: &FullAccessTimeline,
     308            0 :     backup_lsn: &mut Lsn,
     309            0 :     end_lsn: Lsn,
     310            0 :     wal_seg_size: usize,
     311            0 :     timeline_dir: &Utf8Path,
     312            0 :     parallel_jobs: usize,
     313            0 : ) -> Result<()> {
     314            0 :     if parallel_jobs < 1 {
     315            0 :         anyhow::bail!("parallel_jobs must be >= 1");
     316            0 :     }
     317              : 
     318            0 :     let remote_timeline_path = remote_timeline_path(&timeline.ttid)?;
     319            0 :     let start_lsn = *backup_lsn;
     320            0 :     let segments = get_segments(start_lsn, end_lsn, wal_seg_size);
     321            0 : 
     322            0 :     // Pool of concurrent upload tasks. We use `FuturesOrdered` to
     323            0 :     // preserve order of uploads, and update `backup_lsn` only after
     324            0 :     // all previous uploads are finished.
     325            0 :     let mut uploads = FuturesOrdered::new();
     326            0 :     let mut iter = segments.iter();
     327              : 
     328              :     loop {
     329            0 :         let added_task = match iter.next() {
     330            0 :             Some(s) => {
     331            0 :                 uploads.push_back(backup_single_segment(
     332            0 :                     s,
     333            0 :                     timeline_dir,
     334            0 :                     &remote_timeline_path,
     335            0 :                 ));
     336            0 :                 true
     337              :             }
     338            0 :             None => false,
     339              :         };
     340              : 
     341              :         // Wait for the next segment to upload if we don't have any more segments,
     342              :         // or if we have too many concurrent uploads.
     343            0 :         if !added_task || uploads.len() >= parallel_jobs {
     344            0 :             let next = uploads.next().await;
     345            0 :             if let Some(res) = next {
     346              :                 // next segment uploaded
     347            0 :                 let segment = res?;
     348            0 :                 let new_backup_lsn = segment.end_lsn;
     349            0 :                 timeline
     350            0 :                     .set_wal_backup_lsn(new_backup_lsn)
     351            0 :                     .await
     352            0 :                     .context("setting wal_backup_lsn")?;
     353            0 :                 *backup_lsn = new_backup_lsn;
     354              :             } else {
     355              :                 // no more segments to upload
     356            0 :                 break;
     357              :             }
     358            0 :         }
     359              :     }
     360              : 
     361            0 :     info!(
     362            0 :         "offloaded segnos {:?} up to {}, previous backup_lsn {}",
     363            0 :         segments.iter().map(|&s| s.seg_no).collect::<Vec<_>>(),
     364              :         end_lsn,
     365              :         start_lsn,
     366              :     );
     367            0 :     Ok(())
     368            0 : }
     369              : 
     370            0 : async fn backup_single_segment(
     371            0 :     seg: &Segment,
     372            0 :     timeline_dir: &Utf8Path,
     373            0 :     remote_timeline_path: &RemotePath,
     374            0 : ) -> Result<Segment> {
     375            0 :     let segment_file_path = seg.file_path(timeline_dir)?;
     376            0 :     let remote_segment_path = seg.remote_path(remote_timeline_path);
     377              : 
     378            0 :     let res = backup_object(&segment_file_path, &remote_segment_path, seg.size()).await;
     379            0 :     if res.is_ok() {
     380            0 :         BACKED_UP_SEGMENTS.inc();
     381            0 :     } else {
     382            0 :         BACKUP_ERRORS.inc();
     383            0 :     }
     384            0 :     res?;
     385            0 :     debug!("Backup of {} done", segment_file_path);
     386              : 
     387            0 :     Ok(*seg)
     388            0 : }
     389              : 
     390              : #[derive(Debug, Copy, Clone)]
     391              : pub struct Segment {
     392              :     seg_no: XLogSegNo,
     393              :     start_lsn: Lsn,
     394              :     end_lsn: Lsn,
     395              : }
     396              : 
     397              : impl Segment {
     398            0 :     pub fn new(seg_no: u64, start_lsn: Lsn, end_lsn: Lsn) -> Self {
     399            0 :         Self {
     400            0 :             seg_no,
     401            0 :             start_lsn,
     402            0 :             end_lsn,
     403            0 :         }
     404            0 :     }
     405              : 
     406            0 :     pub fn object_name(self) -> String {
     407            0 :         XLogFileName(PG_TLI, self.seg_no, self.size())
     408            0 :     }
     409              : 
     410            0 :     pub fn file_path(self, timeline_dir: &Utf8Path) -> Result<Utf8PathBuf> {
     411            0 :         Ok(timeline_dir.join(self.object_name()))
     412            0 :     }
     413              : 
     414            0 :     pub fn remote_path(self, remote_timeline_path: &RemotePath) -> RemotePath {
     415            0 :         remote_timeline_path.join(self.object_name())
     416            0 :     }
     417              : 
     418            0 :     pub fn size(self) -> usize {
     419            0 :         (u64::from(self.end_lsn) - u64::from(self.start_lsn)) as usize
     420            0 :     }
     421              : }
     422              : 
     423            0 : fn get_segments(start: Lsn, end: Lsn, seg_size: usize) -> Vec<Segment> {
     424            0 :     let first_seg = start.segment_number(seg_size);
     425            0 :     let last_seg = end.segment_number(seg_size);
     426            0 : 
     427            0 :     let res: Vec<Segment> = (first_seg..last_seg)
     428            0 :         .map(|s| {
     429            0 :             let start_lsn = XLogSegNoOffsetToRecPtr(s, 0, seg_size);
     430            0 :             let end_lsn = XLogSegNoOffsetToRecPtr(s + 1, 0, seg_size);
     431            0 :             Segment::new(s, Lsn::from(start_lsn), Lsn::from(end_lsn))
     432            0 :         })
     433            0 :         .collect();
     434            0 :     res
     435            0 : }
     436              : 
     437            0 : async fn backup_object(
     438            0 :     source_file: &Utf8Path,
     439            0 :     target_file: &RemotePath,
     440            0 :     size: usize,
     441            0 : ) -> Result<()> {
     442            0 :     let storage = get_configured_remote_storage();
     443              : 
     444            0 :     let file = File::open(&source_file)
     445            0 :         .await
     446            0 :         .with_context(|| format!("Failed to open file {source_file:?} for wal backup"))?;
     447              : 
     448            0 :     let file = tokio_util::io::ReaderStream::with_capacity(file, BUFFER_SIZE);
     449            0 : 
     450            0 :     let cancel = CancellationToken::new();
     451            0 : 
     452            0 :     storage
     453            0 :         .upload_storage_object(file, size, target_file, &cancel)
     454            0 :         .await
     455            0 : }
     456              : 
     457            0 : pub(crate) async fn backup_partial_segment(
     458            0 :     source_file: &Utf8Path,
     459            0 :     target_file: &RemotePath,
     460            0 :     size: usize,
     461            0 : ) -> Result<()> {
     462            0 :     let storage = get_configured_remote_storage();
     463              : 
     464            0 :     let file = File::open(&source_file)
     465            0 :         .await
     466            0 :         .with_context(|| format!("Failed to open file {source_file:?} for wal backup"))?;
     467              : 
     468              :     // limiting the file to read only the first `size` bytes
     469            0 :     let limited_file = tokio::io::AsyncReadExt::take(file, size as u64);
     470            0 : 
     471            0 :     let file = tokio_util::io::ReaderStream::with_capacity(limited_file, BUFFER_SIZE);
     472            0 : 
     473            0 :     let cancel = CancellationToken::new();
     474            0 : 
     475            0 :     storage
     476            0 :         .upload(
     477            0 :             file,
     478            0 :             size,
     479            0 :             target_file,
     480            0 :             Some(StorageMetadata::from([("sk_type", "partial_segment")])),
     481            0 :             &cancel,
     482            0 :         )
     483            0 :         .await
     484            0 : }
     485              : 
     486            0 : pub async fn read_object(
     487            0 :     file_path: &RemotePath,
     488            0 :     offset: u64,
     489            0 : ) -> anyhow::Result<Pin<Box<dyn tokio::io::AsyncRead + Send + Sync>>> {
     490            0 :     let storage = REMOTE_STORAGE
     491            0 :         .get()
     492            0 :         .context("Failed to get remote storage")?
     493            0 :         .as_ref()
     494            0 :         .context("No remote storage configured")?;
     495              : 
     496            0 :     info!("segment download about to start from remote path {file_path:?} at offset {offset}");
     497              : 
     498            0 :     let cancel = CancellationToken::new();
     499              : 
     500            0 :     let download = storage
     501            0 :         .download_storage_object(Some((offset, None)), file_path, &cancel)
     502            0 :         .await
     503            0 :         .with_context(|| {
     504            0 :             format!("Failed to open WAL segment download stream for remote path {file_path:?}")
     505            0 :         })?;
     506              : 
     507            0 :     let reader = tokio_util::io::StreamReader::new(download.download_stream);
     508            0 : 
     509            0 :     let reader = tokio::io::BufReader::with_capacity(BUFFER_SIZE, reader);
     510            0 : 
     511            0 :     Ok(Box::pin(reader))
     512            0 : }
     513              : 
     514              : /// Delete WAL files for the given timeline. Remote storage must be configured
     515              : /// when called.
     516            0 : pub async fn delete_timeline(ttid: &TenantTimelineId) -> Result<()> {
     517            0 :     let storage = get_configured_remote_storage();
     518            0 :     let remote_path = remote_timeline_path(ttid)?;
     519              : 
     520              :     // see DEFAULT_MAX_KEYS_PER_LIST_RESPONSE
     521              :     // const Option unwrap is not stable, otherwise it would be const.
     522            0 :     let batch_size: NonZeroU32 = NonZeroU32::new(1000).unwrap();
     523            0 : 
     524            0 :     // A backoff::retry is used here for two reasons:
     525            0 :     // - To provide a backoff rather than busy-polling the API on errors
     526            0 :     // - To absorb transient 429/503 conditions without hitting our error
     527            0 :     //   logging path for issues deleting objects.
     528            0 :     //
     529            0 :     // Note: listing segments might take a long time if there are many of them.
     530            0 :     // We don't currently have http requests timeout cancellation, but if/once
     531            0 :     // we have listing should get streaming interface to make progress.
     532            0 : 
     533            0 :     let cancel = CancellationToken::new(); // not really used
     534            0 :     backoff::retry(
     535            0 :         || async {
     536            0 :             // Do list-delete in batch_size batches to make progress even if there a lot of files.
     537            0 :             // Alternatively we could make remote storage list return iterator, but it is more complicated and
     538            0 :             // I'm not sure deleting while iterating is expected in s3.
     539            0 :             loop {
     540            0 :                 let files = storage
     541            0 :                     .list(
     542            0 :                         Some(&remote_path),
     543            0 :                         ListingMode::NoDelimiter,
     544            0 :                         Some(batch_size),
     545            0 :                         &cancel,
     546            0 :                     )
     547            0 :                     .await?
     548            0 :                     .keys;
     549            0 :                 if files.is_empty() {
     550            0 :                     return Ok(()); // done
     551            0 :                 }
     552            0 :                 // (at least) s3 results are sorted, so can log min/max:
     553            0 :                 // "List results are always returned in UTF-8 binary order."
     554            0 :                 info!(
     555            0 :                     "deleting batch of {} WAL segments [{}-{}]",
     556            0 :                     files.len(),
     557            0 :                     files.first().unwrap().object_name().unwrap_or(""),
     558            0 :                     files.last().unwrap().object_name().unwrap_or("")
     559            0 :                 );
     560            0 :                 storage.delete_objects(&files, &cancel).await?;
     561            0 :             }
     562            0 :         },
     563            0 :         // consider TimeoutOrCancel::caused_by_cancel when using cancellation
     564            0 :         |_| false,
     565            0 :         3,
     566            0 :         10,
     567            0 :         "executing WAL segments deletion batch",
     568            0 :         &cancel,
     569            0 :     )
     570            0 :     .await
     571            0 :     .ok_or_else(|| anyhow::anyhow!("canceled"))
     572            0 :     .and_then(|x| x)?;
     573              : 
     574            0 :     Ok(())
     575            0 : }
     576              : 
     577              : /// Used by wal_backup_partial.
     578            0 : pub async fn delete_objects(paths: &[RemotePath]) -> Result<()> {
     579            0 :     let cancel = CancellationToken::new(); // not really used
     580            0 :     let storage = get_configured_remote_storage();
     581            0 :     storage.delete_objects(paths, &cancel).await
     582            0 : }
     583              : 
     584              : /// Copy segments from one timeline to another. Used in copy_timeline.
     585            0 : pub async fn copy_s3_segments(
     586            0 :     wal_seg_size: usize,
     587            0 :     src_ttid: &TenantTimelineId,
     588            0 :     dst_ttid: &TenantTimelineId,
     589            0 :     from_segment: XLogSegNo,
     590            0 :     to_segment: XLogSegNo,
     591            0 : ) -> Result<()> {
     592            0 :     const SEGMENTS_PROGRESS_REPORT_INTERVAL: u64 = 1024;
     593            0 : 
     594            0 :     let storage = REMOTE_STORAGE
     595            0 :         .get()
     596            0 :         .expect("failed to get remote storage")
     597            0 :         .as_ref()
     598            0 :         .unwrap();
     599              : 
     600            0 :     let remote_dst_path = remote_timeline_path(dst_ttid)?;
     601              : 
     602            0 :     let cancel = CancellationToken::new();
     603              : 
     604            0 :     let files = storage
     605            0 :         .list(
     606            0 :             Some(&remote_dst_path),
     607            0 :             ListingMode::NoDelimiter,
     608            0 :             None,
     609            0 :             &cancel,
     610            0 :         )
     611            0 :         .await?
     612              :         .keys;
     613              : 
     614            0 :     let uploaded_segments = &files
     615            0 :         .iter()
     616            0 :         .filter_map(|file| file.object_name().map(ToOwned::to_owned))
     617            0 :         .collect::<HashSet<_>>();
     618            0 : 
     619            0 :     debug!(
     620            0 :         "these segments have already been uploaded: {:?}",
     621              :         uploaded_segments
     622              :     );
     623              : 
     624            0 :     for segno in from_segment..to_segment {
     625            0 :         if segno % SEGMENTS_PROGRESS_REPORT_INTERVAL == 0 {
     626            0 :             info!("copied all segments from {} until {}", from_segment, segno);
     627            0 :         }
     628              : 
     629            0 :         let segment_name = XLogFileName(PG_TLI, segno, wal_seg_size);
     630            0 :         if uploaded_segments.contains(&segment_name) {
     631            0 :             continue;
     632            0 :         }
     633            0 :         debug!("copying segment {}", segment_name);
     634              : 
     635            0 :         let from = remote_timeline_path(src_ttid)?.join(&segment_name);
     636            0 :         let to = remote_dst_path.join(&segment_name);
     637            0 : 
     638            0 :         storage.copy_object(&from, &to, &cancel).await?;
     639              :     }
     640              : 
     641            0 :     info!(
     642            0 :         "finished copying segments from {} until {}",
     643              :         from_segment, to_segment
     644              :     );
     645            0 :     Ok(())
     646            0 : }
     647              : 
     648              : /// Get S3 (remote_storage) prefix path used for timeline files.
     649            0 : pub fn remote_timeline_path(ttid: &TenantTimelineId) -> Result<RemotePath> {
     650            0 :     RemotePath::new(&Utf8Path::new(&ttid.tenant_id.to_string()).join(ttid.timeline_id.to_string()))
     651            0 : }
        

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