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[Issue #115]: minor improvements
This commit is contained in:
Grigory Smolkin
parent
a98ff6154a
commit
64b05d9597
17
src/backup.c
17
src/backup.c
@ -1528,14 +1528,14 @@ wait_wal_lsn(XLogRecPtr target_lsn, bool is_start_lsn, TimeLineID tli,
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* If we failed to get target LSN in a reasonable time, try
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* to get LSN of last valid record prior to the target LSN. But only
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* in case of a backup from a replica.
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* Note, that with NullOffset target_lsn we do not wait
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* Note, that with NullXRecOff target_lsn we do not wait
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* for 'timeout / 2' seconds before going for previous record,
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* because such LSN cannot be delivered at all.
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*
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* There are two cases for this:
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* 1. Replica returned readpoint LSN which just do not exists. We want to look
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* for previous record in the same(!) WAL segment which endpoint points to this LSN.
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* 2. Replica returened endpoint LSN with 0 offset. We want to look
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* 2. Replica returened endpoint LSN with NullXRecOff. We want to look
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* for previous record which endpoint points greater or equal LSN in previous WAL segment.
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*/
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if (current.from_replica &&
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@ -1543,7 +1543,7 @@ wait_wal_lsn(XLogRecPtr target_lsn, bool is_start_lsn, TimeLineID tli,
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{
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XLogRecPtr res;
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res = get_last_wal_lsn(wal_segment_dir, current.start_lsn, target_lsn, tli,
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res = get_prior_record_lsn(wal_segment_dir, current.start_lsn, target_lsn, tli,
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in_prev_segment, instance_config.xlog_seg_size);
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if (!XLogRecPtrIsInvalid(res))
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@ -1803,7 +1803,7 @@ pg_stop_backup(pgBackup *backup, PGconn *pg_startbackup_conn,
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if (!XRecOffIsValid(stop_backup_lsn_tmp))
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{
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/* It is ok for replica to return STOP LSN with null offset */
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/* It is ok for replica to return STOP LSN with NullXRecOff */
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if (backup->from_replica && XRecOffIsNull(stop_backup_lsn_tmp))
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{
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char *xlog_path,
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@ -1820,7 +1820,7 @@ pg_stop_backup(pgBackup *backup, PGconn *pg_startbackup_conn,
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/*
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* Note: even with gdb it is very hard to produce automated tests for
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* contrecord + null_offset STOP_LSN, so emulate it for manual testing.
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* contrecord + NullXRecOff, so emulate it for manual testing.
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*/
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//stop_backup_lsn_tmp = stop_backup_lsn_tmp - XLOG_SEG_SIZE;
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//elog(WARNING, "New Invalid stop_backup_lsn value %X/%X",
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@ -1841,7 +1841,7 @@ pg_stop_backup(pgBackup *backup, PGconn *pg_startbackup_conn,
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/*
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* Note, that there is no guarantee that corresponding WAL file even exists.
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* Replica may return LSN from future and keep staying in present.
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* Or it can return LSN with invalid XRecOff.
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* Or it can return LSN with NullXRecOff.
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*
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* That's bad, since we want to get real LSN to save it in backup label file
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* and to use it in WAL validation.
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@ -1851,9 +1851,8 @@ pg_stop_backup(pgBackup *backup, PGconn *pg_startbackup_conn,
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* look for the first valid record in it.
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* It solves the problem of occasional invalid XRecOff on write-busy system.
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* 2. Failing that, look for record in previous segment with endpoint
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* equal or greater than stop_lsn. It may(!) solve the problem of 0 offset
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* equal or greater than stop_lsn. It may(!) solve the problem of NullXRecOff
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* on write-idle system. If that fails too, error out.
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* //TODO what kind of record that refers to?
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*/
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/* Wait for segment with current stop_lsn, it is ok for it to never arrive */
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@ -1861,7 +1860,7 @@ pg_stop_backup(pgBackup *backup, PGconn *pg_startbackup_conn,
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false, true, WARNING, stream_wal);
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/* Get the first record in segment with current stop_lsn */
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lsn_tmp = get_first_wal_lsn(xlog_path, segno, backup->tli,
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lsn_tmp = get_first_record_lsn(xlog_path, segno, backup->tli,
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instance_config.xlog_seg_size);
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/* Check that returned LSN is valid and greater than stop_lsn */
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@ -529,13 +529,10 @@ wal_contains_lsn(const char *archivedir, XLogRecPtr target_lsn,
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}
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/*
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* Get LSN of first record within the WAL segment with number 'segno'.
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*
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* Returns LSN which points to end+1 of the last WAL record if seek_prev_segment
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* is true. Otherwise returns LSN of the record prior to stop_lsn.
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* Get LSN of a first record within the WAL segment with number 'segno'.
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*/
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XLogRecPtr
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get_first_wal_lsn(const char *archivedir, XLogSegNo segno,
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get_first_record_lsn(const char *archivedir, XLogSegNo segno,
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TimeLineID tli, uint32 wal_seg_size)
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{
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XLogReaderState *xlogreader;
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@ -574,20 +571,18 @@ get_first_wal_lsn(const char *archivedir, XLogSegNo segno,
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}
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/*
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* Get LSN of last or prior record within the WAL segment with number 'segno'.
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* If 'start_lsn'
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* is in the segment with number 'segno' then start from 'start_lsn', otherwise
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* start from offset 0 within the segment.
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* Get LSN of a record prior to target_lsn.
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* If 'start_lsn' is in the segment with number 'segno' then start from 'start_lsn',
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* otherwise start from offset 0 within the segment.
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*
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* Returns LSN which points to end+1 of the last WAL record if seek_prev_segment
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* is true. Otherwise returns LSN of the record prior to stop_lsn.
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* Returns LSN of a record which EndRecPtr is greater or equal to target_lsn.
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* If 'seek_prev_segment' is true, then look for prior record in prior WAL segment.
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*
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* TODO Let's think of better function name.
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* it's unclear that "last" in "last_wal_lsn" refers to the
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* "closest to stop_lsn backward or forward, depending on seek_prev_segment setting".
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*/
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XLogRecPtr
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get_last_wal_lsn(const char *archivedir, XLogRecPtr start_lsn,
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get_prior_record_lsn(const char *archivedir, XLogRecPtr start_lsn,
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XLogRecPtr stop_lsn, TimeLineID tli, bool seek_prev_segment,
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uint32 wal_seg_size)
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{
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@ -711,11 +711,11 @@ extern bool read_recovery_info(const char *archivedir, TimeLineID tli,
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TransactionId *recovery_xid);
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extern bool wal_contains_lsn(const char *archivedir, XLogRecPtr target_lsn,
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TimeLineID target_tli, uint32 seg_size);
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extern XLogRecPtr get_last_wal_lsn(const char *archivedir, XLogRecPtr start_lsn,
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extern XLogRecPtr get_prior_record_lsn(const char *archivedir, XLogRecPtr start_lsn,
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XLogRecPtr stop_lsn, TimeLineID tli,
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bool seek_prev_segment, uint32 seg_size);
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extern XLogRecPtr get_first_wal_lsn(const char *archivedir, XLogRecPtr start_lsn,
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extern XLogRecPtr get_first_record_lsn(const char *archivedir, XLogRecPtr start_lsn,
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TimeLineID tli, uint32 wal_seg_size);
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/* in util.c */
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