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Start compute node without generation of new WAL segment

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This commit is contained in:
Konstantin Knizhnik
2021-06-17 18:10:57 +03:00
parent 0d9805a505
commit 14a0ae5456
11 changed files with 37 additions and 56 deletions
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16
pageserver/src/basebackup.rs
View File

@@ -220,23 +220,23 @@ impl<'a> Basebackup<'a> {
let mut pg_control = ControlFileData::decode(&pg_control_bytes)?;
let mut checkpoint = CheckPoint::decode(&checkpoint_bytes)?;
// Here starts pg_resetwal inspired magic
// Generate new pg_control and WAL needed for bootstrap
let new_segno = self.lsn.segment_number(pg_constants::WAL_SEGMENT_SIZE) + 1;
let new_lsn = XLogSegNoOffsetToRecPtr(
new_segno,
let checkpoint_segno = self.lsn.segment_number(pg_constants::WAL_SEGMENT_SIZE);
let checkpoint_lsn = XLogSegNoOffsetToRecPtr(
checkpoint_segno,
XLOG_SIZE_OF_XLOG_LONG_PHD as u32,
pg_constants::WAL_SEGMENT_SIZE,
);
checkpoint.redo = new_lsn;
checkpoint.redo = self.lsn.0 + self.lsn.calc_padding(8u32);
//reset some fields we don't want to preserve
checkpoint.oldestActiveXid = 0;
//save new values in pg_control
pg_control.checkPoint = new_lsn;
pg_control.checkPoint = checkpoint_lsn;
pg_control.checkPointCopy = checkpoint;
info!("pg_control.state = {}", pg_control.state);
pg_control.state = pg_constants::DB_SHUTDOWNED;
//send pg_control
let pg_control_bytes = pg_control.encode();
@@ -246,7 +246,7 @@ impl<'a> Basebackup<'a> {
//send wal segment
let wal_file_name = XLogFileName(
1, // FIXME: always use Postgres timeline 1
new_segno,
checkpoint_segno,
pg_constants::WAL_SEGMENT_SIZE,
);
let wal_file_path = format!("pg_wal/{}", wal_file_name);

25
pageserver/src/object_repository.rs
View File

@@ -478,7 +478,10 @@ impl Timeline for ObjectTimeline {
let val = ObjectValue::RelationSize(new_nblocks);
trace!(
"Extended relation {} from {} to {} blocks at {}",
tag.rel, old_nblocks, new_nblocks, lsn
tag.rel,
old_nblocks,
new_nblocks,
lsn
);
self.obj_store.put(&key, lsn, &ObjectValue::ser(&val)?)?;
@@ -556,16 +559,16 @@ impl Timeline for ObjectTimeline {
fn advance_last_record_lsn(&self, lsn: Lsn) {
// Can't move backwards.
let old = self.last_record_lsn.fetch_max(lsn);
if old <= lsn {
// Also advance last_valid_lsn
let old = self.last_valid_lsn.advance(lsn);
// Can't move backwards.
if lsn < old {
warn!(
"attempted to move last record LSN backwards (was {}, new {})",
old, lsn
);
}
assert!(old <= lsn);
// Also advance last_valid_lsn
let old = self.last_valid_lsn.advance(lsn);
// Can't move backwards.
if lsn < old {
warn!(
"attempted to move last record LSN backwards (was {}, new {})",
old, lsn
);
}
}
fn get_last_record_lsn(&self) -> Lsn {

1
pageserver/src/restore_local_repo.rs
View File

@@ -334,7 +334,6 @@ pub fn import_timeline_wal(walpath: &Path, timeline: &dyn Timeline, startpoint:
// Assume that an error means we've reached the end of
// a partial WAL record. So that's ok.
trace!("WAL decoder error {:?}", rec);
waldecoder.set_position(Lsn((segno + 1) * pg_constants::WAL_SEGMENT_SIZE as u64));
break;
}
if let Some((lsn, recdata)) = rec.unwrap() {

17
pageserver/src/waldecoder.rs
View File

@@ -65,13 +65,6 @@ impl WalStreamDecoder {
}
}
pub fn set_position(&mut self, lsn: Lsn) {
self.lsn = lsn;
self.contlen = 0;
self.padlen = 0;
self.inputbuf.clear();
}
pub fn feed_bytes(&mut self, buf: &[u8]) {
self.inputbuf.extend_from_slice(buf);
}
@@ -97,12 +90,10 @@ impl WalStreamDecoder {
let hdr = XLogLongPageHeaderData::from_bytes(&mut self.inputbuf);
if hdr.std.xlp_pageaddr != self.lsn.0 {
info!(
"Receive page with LSN {} instead of expected {}",
Lsn(hdr.std.xlp_pageaddr),
self.lsn
);
self.lsn = Lsn(hdr.std.xlp_pageaddr);
return Err(WalDecodeError {
msg: "invalid xlog segment header".into(),
lsn: self.lsn,
});
}
// TODO: verify the remaining fields in the header

12
pageserver/src/walreceiver.rs
View File

@@ -150,12 +150,12 @@ fn walreceiver_main(
error!("No previous WAL position");
}
// FIXME: We have to do it to handle new segment generated by pg_resetwal at compute node startup.
// This hack is needed only when pageserver is connected directly to compute node, not through walkeeper.
startpoint = Lsn::max(startpoint, end_of_wal);
// Always start from the beginning of segment
startpoint = Lsn(startpoint.0 & !(pg_constants::WAL_SEGMENT_SIZE as u64 - 1));
// There might be some padding after the last full record, skip it.
//
// FIXME: It probably would be better to always start streaming from the beginning
// of the page, or the segment, so that we could check the page/segment headers
// too. Just for the sake of paranoia.
startpoint += startpoint.calc_padding(8u32);
debug!(
"last_record_lsn {} starting replication from {} for timeline {}, server is at {}...",

1
postgres_ffi/src/pg_constants.rs
View File

@@ -87,6 +87,7 @@ pub const XACT_XINFO_HAS_TWOPHASE: u32 = 1u32 << 4;
pub const XLOG_NEXTOID: u8 = 0x30;
pub const XLOG_SWITCH: u8 = 0x40;
pub const XLOG_SMGR_TRUNCATE: u8 = 0x20;
pub const DB_SHUTDOWNED: u32 = 1;
// From multixact.h
pub const FIRST_MULTIXACT_ID: u32 = 1;

2
postgres_ffi/src/xlog_utils.rs
View File

@@ -399,7 +399,7 @@ pub fn generate_wal_segment(pg_control: &ControlFileData) -> Bytes {
xlp_magic: XLOG_PAGE_MAGIC as u16,
xlp_info: pg_constants::XLP_LONG_HEADER,
xlp_tli: 1, // FIXME: always use Postgres timeline 1
xlp_pageaddr: pg_control.checkPointCopy.redo - XLOG_SIZE_OF_XLOG_LONG_PHD as u64,
xlp_pageaddr: pg_control.checkPoint - XLOG_SIZE_OF_XLOG_LONG_PHD as u64,
xlp_rem_len: 0,
}
},

2
test_runner/batch_others/test_restart_compute.py
View File

@@ -19,7 +19,7 @@ def test_restart_compute(zenith_cli, pageserver, postgres, pg_bin):
cur.execute("INSERT INTO foo VALUES ('bar')")
# Stop and restart the Postgres instance
pg.stop().start()
pg.stop_and_destroy().create_start('test_restart_compute')
with closing(pg.connect()) as conn:
with conn.cursor() as cur:

2
vendor/postgres vendored

Submodule vendor/postgres updated: 928beb4241...044647e499

10
walkeeper/src/receive_wal.rs
View File

@@ -247,16 +247,6 @@ impl ReceiveWalConn {
/* Calculate WAL end based on local data */
let (flush_lsn, timeline) = self.timeline.find_end_of_wal(&self.conf.data_dir, true);
my_info.flush_lsn = flush_lsn;
// FIXME: Yet another trick to handle creation of new WAL segment at
// compute node startup (a-la pg_resetwal).
// If restart_lsn was not adjusted then walproposer will try to perform recovery
// because restart_lsn != flush_lsn and fail because first WAL segment is missed.
// May be it is better to handle it by wal proposer, but it will contradict with wal_proposer
// usage in other branches.
// This adjustment is needed only for first segment.
let min_lsn = Lsn((server_info.wal_seg_size as u64) * 2);
my_info.restart_lsn = Lsn::max(my_info.restart_lsn, min_lsn);
my_info.server.timeline = timeline;
/* Report my identifier to proposer */

5
walkeeper/src/timeline.rs
View File

@@ -234,10 +234,7 @@ impl TimelineTools for Option<Arc<Timeline>> {
let seg_size = self.get().get_info().server.wal_seg_size as usize;
assert!(seg_size > 0);
let (lsn, timeline) = find_end_of_wal(data_dir, seg_size, precise);
// FIXME: because of generation of new segment at compute node start we just do not have first WAL segment
let wal_start = Lsn((seg_size * 2) as u64);
let lsn = Lsn::max(Lsn(lsn), wal_start);
(lsn, timeline)
(Lsn(lsn), timeline)
}
}