Line data Source code
1 : use std::cmp::min;
2 : use std::io::{self, ErrorKind};
3 : use std::sync::Arc;
4 :
5 : use anyhow::{Context, Result, anyhow, bail};
6 : use bytes::Bytes;
7 : use camino::Utf8PathBuf;
8 : use chrono::{DateTime, Utc};
9 : use futures::{SinkExt, StreamExt, TryStreamExt};
10 : use postgres_ffi::{PG_TLI, XLogFileName, XLogSegNo};
11 : use safekeeper_api::Term;
12 : use safekeeper_api::models::{PullTimelineRequest, PullTimelineResponse, TimelineStatus};
13 : use safekeeper_client::mgmt_api;
14 : use safekeeper_client::mgmt_api::Client;
15 : use serde::Deserialize;
16 : use tokio::fs::OpenOptions;
17 : use tokio::io::AsyncWrite;
18 : use tokio::sync::mpsc;
19 : use tokio::task;
20 : use tokio_tar::{Archive, Builder, Header};
21 : use tokio_util::io::{CopyToBytes, SinkWriter};
22 : use tokio_util::sync::PollSender;
23 : use tracing::{error, info, instrument};
24 : use utils::crashsafe::fsync_async_opt;
25 : use utils::id::{NodeId, TenantTimelineId};
26 : use utils::logging::SecretString;
27 : use utils::lsn::Lsn;
28 : use utils::pausable_failpoint;
29 :
30 : use crate::control_file::CONTROL_FILE_NAME;
31 : use crate::state::{EvictionState, TimelinePersistentState};
32 : use crate::timeline::{Timeline, WalResidentTimeline};
33 : use crate::timelines_global_map::{create_temp_timeline_dir, validate_temp_timeline};
34 : use crate::wal_storage::open_wal_file;
35 : use crate::{GlobalTimelines, debug_dump, wal_backup};
36 :
37 : /// Stream tar archive of timeline to tx.
38 : #[instrument(name = "snapshot", skip_all, fields(ttid = %tli.ttid))]
39 : pub async fn stream_snapshot(
40 : tli: Arc<Timeline>,
41 : source: NodeId,
42 : destination: NodeId,
43 : tx: mpsc::Sender<Result<Bytes>>,
44 : ) {
45 : match tli.try_wal_residence_guard().await {
46 : Err(e) => {
47 : tx.send(Err(anyhow!("Error checking residence: {:#}", e)))
48 : .await
49 : .ok();
50 : }
51 : Ok(maybe_resident_tli) => {
52 : if let Err(e) = match maybe_resident_tli {
53 : Some(resident_tli) => {
54 : stream_snapshot_resident_guts(resident_tli, source, destination, tx.clone())
55 : .await
56 : }
57 : None => stream_snapshot_offloaded_guts(tli, source, destination, tx.clone()).await,
58 : } {
59 : // Error type/contents don't matter as they won't can't reach the client
60 : // (hyper likely doesn't do anything with it), but http stream will be
61 : // prematurely terminated. It would be nice to try to send the error in
62 : // trailers though.
63 : tx.send(Err(anyhow!("snapshot failed"))).await.ok();
64 : error!("snapshot failed: {:#}", e);
65 : }
66 : }
67 : }
68 : }
69 :
70 : /// State needed while streaming the snapshot.
71 : pub struct SnapshotContext {
72 : pub from_segno: XLogSegNo, // including
73 : pub upto_segno: XLogSegNo, // including
74 : pub term: Term,
75 : pub last_log_term: Term,
76 : pub flush_lsn: Lsn,
77 : pub wal_seg_size: usize,
78 : // used to remove WAL hold off in Drop.
79 : pub tli: WalResidentTimeline,
80 : }
81 :
82 : impl Drop for SnapshotContext {
83 0 : fn drop(&mut self) {
84 0 : let tli = self.tli.clone();
85 0 : task::spawn(async move {
86 0 : let mut shared_state = tli.write_shared_state().await;
87 0 : shared_state.wal_removal_on_hold = false;
88 0 : });
89 0 : }
90 : }
91 :
92 : /// Build a tokio_tar stream that sends encoded bytes into a Bytes channel.
93 0 : fn prepare_tar_stream(
94 0 : tx: mpsc::Sender<Result<Bytes>>,
95 0 : ) -> tokio_tar::Builder<impl AsyncWrite + Unpin + Send> {
96 0 : // tokio-tar wants Write implementor, but we have mpsc tx <Result<Bytes>>;
97 0 : // use SinkWriter as a Write impl. That is,
98 0 : // - create Sink from the tx. It returns PollSendError if chan is closed.
99 0 : let sink = PollSender::new(tx);
100 0 : // - SinkWriter needs sink error to be io one, map it.
101 0 : let sink_io_err = sink.sink_map_err(|_| io::Error::from(ErrorKind::BrokenPipe));
102 0 : // - SinkWriter wants sink type to be just Bytes, not Result<Bytes>, so map
103 0 : // it with with(). Note that with() accepts async function which we don't
104 0 : // need and allows the map to fail, which we don't need either, but hence
105 0 : // two Oks.
106 0 : let oksink = sink_io_err.with(|b: Bytes| async { io::Result::Ok(Result::Ok(b)) });
107 0 : // - SinkWriter (not surprisingly) wants sink of &[u8], not bytes, so wrap
108 0 : // into CopyToBytes. This is a data copy.
109 0 : let copy_to_bytes = CopyToBytes::new(oksink);
110 0 : let writer = SinkWriter::new(copy_to_bytes);
111 0 : let pinned_writer = Box::pin(writer);
112 0 :
113 0 : // Note that tokio_tar append_* funcs use tokio::io::copy with 8KB buffer
114 0 : // which is also likely suboptimal.
115 0 : Builder::new_non_terminated(pinned_writer)
116 0 : }
117 :
118 : /// Implementation of snapshot for an offloaded timeline, only reads control file
119 0 : pub(crate) async fn stream_snapshot_offloaded_guts(
120 0 : tli: Arc<Timeline>,
121 0 : source: NodeId,
122 0 : destination: NodeId,
123 0 : tx: mpsc::Sender<Result<Bytes>>,
124 0 : ) -> Result<()> {
125 0 : let mut ar = prepare_tar_stream(tx);
126 0 :
127 0 : tli.snapshot_offloaded(&mut ar, source, destination).await?;
128 :
129 0 : ar.finish().await?;
130 :
131 0 : Ok(())
132 0 : }
133 :
134 : /// Implementation of snapshot for a timeline which is resident (includes some segment data)
135 0 : pub async fn stream_snapshot_resident_guts(
136 0 : tli: WalResidentTimeline,
137 0 : source: NodeId,
138 0 : destination: NodeId,
139 0 : tx: mpsc::Sender<Result<Bytes>>,
140 0 : ) -> Result<()> {
141 0 : let mut ar = prepare_tar_stream(tx);
142 :
143 0 : let bctx = tli.start_snapshot(&mut ar, source, destination).await?;
144 0 : pausable_failpoint!("sk-snapshot-after-list-pausable");
145 :
146 0 : let tli_dir = tli.get_timeline_dir();
147 0 : info!(
148 0 : "sending {} segments [{:#X}-{:#X}], term={}, last_log_term={}, flush_lsn={}",
149 0 : bctx.upto_segno - bctx.from_segno + 1,
150 : bctx.from_segno,
151 : bctx.upto_segno,
152 : bctx.term,
153 : bctx.last_log_term,
154 : bctx.flush_lsn,
155 : );
156 0 : for segno in bctx.from_segno..=bctx.upto_segno {
157 0 : let (mut sf, is_partial) = open_wal_file(&tli_dir, segno, bctx.wal_seg_size).await?;
158 0 : let mut wal_file_name = XLogFileName(PG_TLI, segno, bctx.wal_seg_size);
159 0 : if is_partial {
160 0 : wal_file_name.push_str(".partial");
161 0 : }
162 0 : ar.append_file(&wal_file_name, &mut sf).await?;
163 : }
164 :
165 : // Do the term check before ar.finish to make archive corrupted in case of
166 : // term change. Client shouldn't ignore abrupt stream end, but to be sure.
167 0 : tli.finish_snapshot(&bctx).await?;
168 :
169 0 : ar.finish().await?;
170 :
171 0 : Ok(())
172 0 : }
173 :
174 : impl Timeline {
175 : /// Simple snapshot for an offloaded timeline: we will only upload a renamed partial segment and
176 : /// pass a modified control file into the provided tar stream (nothing with data segments on disk, since
177 : /// we are offloaded and there aren't any)
178 0 : async fn snapshot_offloaded<W: AsyncWrite + Unpin + Send>(
179 0 : self: &Arc<Timeline>,
180 0 : ar: &mut tokio_tar::Builder<W>,
181 0 : source: NodeId,
182 0 : destination: NodeId,
183 0 : ) -> Result<()> {
184 : // Take initial copy of control file, then release state lock
185 0 : let mut control_file = {
186 0 : let shared_state = self.write_shared_state().await;
187 :
188 0 : let control_file = TimelinePersistentState::clone(shared_state.sk.state());
189 :
190 : // Rare race: we got unevicted between entering function and reading control file.
191 : // We error out and let API caller retry.
192 0 : if !matches!(control_file.eviction_state, EvictionState::Offloaded(_)) {
193 0 : bail!("Timeline was un-evicted during snapshot, please retry");
194 0 : }
195 0 :
196 0 : control_file
197 : };
198 :
199 : // Modify the partial segment of the in-memory copy for the control file to
200 : // point to the destination safekeeper.
201 0 : let replace = control_file
202 0 : .partial_backup
203 0 : .replace_uploaded_segment(source, destination)?;
204 :
205 0 : let Some(replace) = replace else {
206 : // In Manager:: ready_for_eviction, we do not permit eviction unless the timeline
207 : // has a partial segment. It is unexpected that
208 0 : anyhow::bail!("Timeline has no partial segment, cannot generate snapshot");
209 : };
210 :
211 0 : tracing::info!("Replacing uploaded partial segment in in-mem control file: {replace:?}");
212 :
213 : // Optimistically try to copy the partial segment to the destination's path: this
214 : // can fail if the timeline was un-evicted and modified in the background.
215 0 : let remote_timeline_path = &self.remote_path;
216 0 : wal_backup::copy_partial_segment(
217 0 : &replace.previous.remote_path(remote_timeline_path),
218 0 : &replace.current.remote_path(remote_timeline_path),
219 0 : )
220 0 : .await?;
221 :
222 : // Since the S3 copy succeeded with the path given in our control file snapshot, and
223 : // we are sending that snapshot in our response, we are giving the caller a consistent
224 : // snapshot even if our local Timeline was unevicted or otherwise modified in the meantime.
225 0 : let buf = control_file
226 0 : .write_to_buf()
227 0 : .with_context(|| "failed to serialize control store")?;
228 0 : let mut header = Header::new_gnu();
229 0 : header.set_size(buf.len().try_into().expect("never breaches u64"));
230 0 : ar.append_data(&mut header, CONTROL_FILE_NAME, buf.as_slice())
231 0 : .await
232 0 : .with_context(|| "failed to append to archive")?;
233 :
234 0 : Ok(())
235 0 : }
236 : }
237 :
238 : impl WalResidentTimeline {
239 : /// Start streaming tar archive with timeline:
240 : /// 1) stream control file under lock;
241 : /// 2) hold off WAL removal;
242 : /// 3) collect SnapshotContext to understand which WAL segments should be
243 : /// streamed.
244 : ///
245 : /// Snapshot streams data up to flush_lsn. To make this safe, we must check
246 : /// that term doesn't change during the procedure, or we risk sending mix of
247 : /// WAL from different histories. Term is remembered in the SnapshotContext
248 : /// and checked in finish_snapshot. Note that in the last segment some WAL
249 : /// higher than flush_lsn set here might be streamed; that's fine as long as
250 : /// terms doesn't change.
251 : ///
252 : /// Alternatively we could send only up to commit_lsn to get some valid
253 : /// state which later will be recovered by compute, in this case term check
254 : /// is not needed, but we likely don't want that as there might be no
255 : /// compute which could perform the recovery.
256 : ///
257 : /// When returned SnapshotContext is dropped WAL hold is removed.
258 0 : async fn start_snapshot<W: AsyncWrite + Unpin + Send>(
259 0 : &self,
260 0 : ar: &mut tokio_tar::Builder<W>,
261 0 : source: NodeId,
262 0 : destination: NodeId,
263 0 : ) -> Result<SnapshotContext> {
264 0 : let mut shared_state = self.write_shared_state().await;
265 0 : let wal_seg_size = shared_state.get_wal_seg_size();
266 0 :
267 0 : let mut control_store = TimelinePersistentState::clone(shared_state.sk.state());
268 : // Modify the partial segment of the in-memory copy for the control file to
269 : // point to the destination safekeeper.
270 0 : let replace = control_store
271 0 : .partial_backup
272 0 : .replace_uploaded_segment(source, destination)?;
273 :
274 0 : if let Some(replace) = replace {
275 : // The deserialized control file has an uploaded partial. We upload a copy
276 : // of it to object storage for the destination safekeeper and send an updated
277 : // control file in the snapshot.
278 0 : tracing::info!(
279 0 : "Replacing uploaded partial segment in in-mem control file: {replace:?}"
280 : );
281 :
282 0 : let remote_timeline_path = &self.tli.remote_path;
283 0 : wal_backup::copy_partial_segment(
284 0 : &replace.previous.remote_path(remote_timeline_path),
285 0 : &replace.current.remote_path(remote_timeline_path),
286 0 : )
287 0 : .await?;
288 0 : }
289 :
290 0 : let buf = control_store
291 0 : .write_to_buf()
292 0 : .with_context(|| "failed to serialize control store")?;
293 0 : let mut header = Header::new_gnu();
294 0 : header.set_size(buf.len().try_into().expect("never breaches u64"));
295 0 : ar.append_data(&mut header, CONTROL_FILE_NAME, buf.as_slice())
296 0 : .await
297 0 : .with_context(|| "failed to append to archive")?;
298 :
299 : // We need to stream since the oldest segment someone (s3 or pageserver)
300 : // still needs. This duplicates calc_horizon_lsn logic.
301 : //
302 : // We know that WAL wasn't removed up to this point because it cannot be
303 : // removed further than `backup_lsn`. Since we're holding shared_state
304 : // lock and setting `wal_removal_on_hold` later, it guarantees that WAL
305 : // won't be removed until we're done.
306 0 : let from_lsn = min(
307 0 : shared_state.sk.state().remote_consistent_lsn,
308 0 : shared_state.sk.state().backup_lsn,
309 0 : );
310 0 : if from_lsn == Lsn::INVALID {
311 : // this is possible if snapshot is called before handling first
312 : // elected message
313 0 : bail!("snapshot is called on uninitialized timeline");
314 0 : }
315 0 : let from_segno = from_lsn.segment_number(wal_seg_size);
316 0 : let term = shared_state.sk.state().acceptor_state.term;
317 0 : let last_log_term = shared_state.sk.last_log_term();
318 0 : let flush_lsn = shared_state.sk.flush_lsn();
319 0 : let upto_segno = flush_lsn.segment_number(wal_seg_size);
320 : // have some limit on max number of segments as a sanity check
321 : const MAX_ALLOWED_SEGS: u64 = 1000;
322 0 : let num_segs = upto_segno - from_segno + 1;
323 0 : if num_segs > MAX_ALLOWED_SEGS {
324 0 : bail!(
325 0 : "snapshot is called on timeline with {} segments, but the limit is {}",
326 0 : num_segs,
327 0 : MAX_ALLOWED_SEGS
328 0 : );
329 0 : }
330 0 :
331 0 : // Prevent WAL removal while we're streaming data.
332 0 : //
333 0 : // Since this a flag, not a counter just bail out if already set; we
334 0 : // shouldn't need concurrent snapshotting.
335 0 : if shared_state.wal_removal_on_hold {
336 0 : bail!("wal_removal_on_hold is already true");
337 0 : }
338 0 : shared_state.wal_removal_on_hold = true;
339 0 :
340 0 : // Drop shared_state to release the lock, before calling wal_residence_guard().
341 0 : drop(shared_state);
342 :
343 0 : let tli_copy = self.wal_residence_guard().await?;
344 0 : let bctx = SnapshotContext {
345 0 : from_segno,
346 0 : upto_segno,
347 0 : term,
348 0 : last_log_term,
349 0 : flush_lsn,
350 0 : wal_seg_size,
351 0 : tli: tli_copy,
352 0 : };
353 0 :
354 0 : Ok(bctx)
355 0 : }
356 :
357 : /// Finish snapshotting: check that term(s) hasn't changed.
358 : ///
359 : /// Note that WAL gc hold off is removed in Drop of SnapshotContext to not
360 : /// forget this if snapshotting fails mid the way.
361 0 : pub async fn finish_snapshot(&self, bctx: &SnapshotContext) -> Result<()> {
362 0 : let shared_state = self.read_shared_state().await;
363 0 : let term = shared_state.sk.state().acceptor_state.term;
364 0 : let last_log_term = shared_state.sk.last_log_term();
365 0 : // There are some cases to relax this check (e.g. last_log_term might
366 0 : // change, but as long as older history is strictly part of new that's
367 0 : // fine), but there is no need to do it.
368 0 : if bctx.term != term || bctx.last_log_term != last_log_term {
369 0 : bail!(
370 0 : "term(s) changed during snapshot: were term={}, last_log_term={}, now term={}, last_log_term={}",
371 0 : bctx.term,
372 0 : bctx.last_log_term,
373 0 : term,
374 0 : last_log_term
375 0 : );
376 0 : }
377 0 : Ok(())
378 0 : }
379 : }
380 :
381 : /// Response for debug dump request.
382 0 : #[derive(Debug, Deserialize)]
383 : pub struct DebugDumpResponse {
384 : pub start_time: DateTime<Utc>,
385 : pub finish_time: DateTime<Utc>,
386 : pub timelines: Vec<debug_dump::Timeline>,
387 : pub timelines_count: usize,
388 : pub config: debug_dump::Config,
389 : }
390 :
391 : /// Find the most advanced safekeeper and pull timeline from it.
392 0 : pub async fn handle_request(
393 0 : request: PullTimelineRequest,
394 0 : sk_auth_token: Option<SecretString>,
395 0 : global_timelines: Arc<GlobalTimelines>,
396 0 : ) -> Result<PullTimelineResponse> {
397 0 : let existing_tli = global_timelines.get(TenantTimelineId::new(
398 0 : request.tenant_id,
399 0 : request.timeline_id,
400 0 : ));
401 0 : if existing_tli.is_ok() {
402 0 : bail!("Timeline {} already exists", request.timeline_id);
403 0 : }
404 0 :
405 0 : // TODO(DimasKovas): add ssl root CA certificate when implementing safekeeper's
406 0 : // part of https support (#24836).
407 0 : let http_client = reqwest::Client::new();
408 0 :
409 0 : let http_hosts = request.http_hosts.clone();
410 :
411 : // Figure out statuses of potential donors.
412 0 : let responses: Vec<Result<TimelineStatus, mgmt_api::Error>> =
413 0 : futures::future::join_all(http_hosts.iter().map(|url| async {
414 0 : let cclient = Client::new(http_client.clone(), url.clone(), sk_auth_token.clone());
415 0 : let info = cclient
416 0 : .timeline_status(request.tenant_id, request.timeline_id)
417 0 : .await?;
418 0 : Ok(info)
419 0 : }))
420 0 : .await;
421 :
422 0 : let mut statuses = Vec::new();
423 0 : for (i, response) in responses.into_iter().enumerate() {
424 0 : let status = response.context(format!("fetching status from {}", http_hosts[i]))?;
425 0 : statuses.push((status, i));
426 : }
427 :
428 : // Find the most advanced safekeeper
429 0 : let (status, i) = statuses
430 0 : .into_iter()
431 0 : .max_by_key(|(status, _)| {
432 0 : (
433 0 : status.acceptor_state.epoch,
434 0 : status.flush_lsn,
435 0 : status.commit_lsn,
436 0 : )
437 0 : })
438 0 : .unwrap();
439 0 : let safekeeper_host = http_hosts[i].clone();
440 0 :
441 0 : assert!(status.tenant_id == request.tenant_id);
442 0 : assert!(status.timeline_id == request.timeline_id);
443 :
444 0 : pull_timeline(status, safekeeper_host, sk_auth_token, global_timelines).await
445 0 : }
446 :
447 0 : async fn pull_timeline(
448 0 : status: TimelineStatus,
449 0 : host: String,
450 0 : sk_auth_token: Option<SecretString>,
451 0 : global_timelines: Arc<GlobalTimelines>,
452 0 : ) -> Result<PullTimelineResponse> {
453 0 : let ttid = TenantTimelineId::new(status.tenant_id, status.timeline_id);
454 0 : info!(
455 0 : "pulling timeline {} from safekeeper {}, commit_lsn={}, flush_lsn={}, term={}, epoch={}",
456 : ttid,
457 : host,
458 : status.commit_lsn,
459 : status.flush_lsn,
460 : status.acceptor_state.term,
461 : status.acceptor_state.epoch
462 : );
463 :
464 0 : let conf = &global_timelines.get_global_config();
465 :
466 0 : let (_tmp_dir, tli_dir_path) = create_temp_timeline_dir(conf, ttid).await?;
467 : // TODO(DimasKovas): add ssl root CA certificate when implementing safekeeper's
468 : // part of https support (#24836).
469 0 : let http_client = reqwest::Client::new();
470 0 : let client = Client::new(http_client, host.clone(), sk_auth_token.clone());
471 : // Request stream with basebackup archive.
472 0 : let bb_resp = client
473 0 : .snapshot(status.tenant_id, status.timeline_id, conf.my_id)
474 0 : .await?;
475 :
476 : // Make Stream of Bytes from it...
477 0 : let bb_stream = bb_resp.bytes_stream().map_err(std::io::Error::other);
478 0 : // and turn it into StreamReader implementing AsyncRead.
479 0 : let bb_reader = tokio_util::io::StreamReader::new(bb_stream);
480 :
481 : // Extract it on the fly to the disk. We don't use simple unpack() to fsync
482 : // files.
483 0 : let mut entries = Archive::new(bb_reader).entries()?;
484 0 : while let Some(base_tar_entry) = entries.next().await {
485 0 : let mut entry = base_tar_entry?;
486 0 : let header = entry.header();
487 0 : let file_path = header.path()?.into_owned();
488 0 : match header.entry_type() {
489 : tokio_tar::EntryType::Regular => {
490 0 : let utf8_file_path =
491 0 : Utf8PathBuf::from_path_buf(file_path).expect("non-Unicode path");
492 0 : let dst_path = tli_dir_path.join(utf8_file_path);
493 0 : let mut f = OpenOptions::new()
494 0 : .create(true)
495 0 : .truncate(true)
496 0 : .write(true)
497 0 : .open(&dst_path)
498 0 : .await?;
499 0 : tokio::io::copy(&mut entry, &mut f).await?;
500 : // fsync the file
501 0 : f.sync_all().await?;
502 : }
503 : _ => {
504 0 : bail!(
505 0 : "entry {} in backup tar archive is of unexpected type: {:?}",
506 0 : file_path.display(),
507 0 : header.entry_type()
508 0 : );
509 : }
510 : }
511 : }
512 :
513 : // fsync temp timeline directory to remember its contents.
514 0 : fsync_async_opt(&tli_dir_path, !conf.no_sync).await?;
515 :
516 : // Let's create timeline from temp directory and verify that it's correct
517 0 : let (commit_lsn, flush_lsn) = validate_temp_timeline(conf, ttid, &tli_dir_path).await?;
518 0 : info!(
519 0 : "finished downloading timeline {}, commit_lsn={}, flush_lsn={}",
520 : ttid, commit_lsn, flush_lsn
521 : );
522 0 : assert!(status.commit_lsn <= status.flush_lsn);
523 :
524 : // Finally, load the timeline.
525 0 : let _tli = global_timelines
526 0 : .load_temp_timeline(ttid, &tli_dir_path, false)
527 0 : .await?;
528 :
529 0 : Ok(PullTimelineResponse {
530 0 : safekeeper_host: host,
531 0 : })
532 0 : }
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