From: Alexander Korotkov Date: Thu, 24 Oct 2024 11:38:27 +0000 (+0300) Subject: Refactor WaitForLSNReplay() to return the result of waiting X-Git-Tag: REL_18_BETA1~1642 X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=73da6b8d1b3e8b7541961c3534e584243cb0470e;p=postgresql.git Refactor WaitForLSNReplay() to return the result of waiting Currently, WaitForLSNReplay() immediately throws an error if waiting for LSN replay is not successful. This commit teaches WaitForLSNReplay() to return the result of waiting, while making pg_wal_replay_wait() responsible for throwing an appropriate error. This is preparation to adding 'no_error' argument to pg_wal_replay_wait() and new function pg_wal_replay_wait_status(), which returns the last wait result status. Additionally, we stop distinguishing situations when we find our instance to be not in a recovery state before entering the waiting loop and inside the waiting loop. Standby promotion may happen at any moment, even between issuing a procedure call statement and pg_wal_replay_wait() doing a first check of recovery status. Thus, there is no pointing distinguishing these situations. Also, since we may exit the waiting loop and see our instance not in recovery without throwing an error, we need to deleteLSNWaiter() in that case. We do this unconditionally for the sake of simplicity, even if standby was already promoted after reaching the target LSN, the startup process surely already deleted us. Reported-by: Michael Paquier Discussion: https://postgr.es/m/ZtUF17gF0pNpwZDI%40paquier.xyz Reviewed-by: Michael Paquier, Pavel Borisov --- diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c index cbf84ef7d8f..ddca78d3717 100644 --- a/src/backend/access/transam/xlogfuncs.c +++ b/src/backend/access/transam/xlogfuncs.c @@ -759,6 +759,7 @@ pg_wal_replay_wait(PG_FUNCTION_ARGS) { XLogRecPtr target_lsn = PG_GETARG_LSN(0); int64 timeout = PG_GETARG_INT64(1); + WaitLSNResult result; if (timeout < 0) ereport(ERROR, @@ -799,7 +800,35 @@ pg_wal_replay_wait(PG_FUNCTION_ARGS) */ Assert(MyProc->xmin == InvalidTransactionId); - (void) WaitForLSNReplay(target_lsn, timeout); + result = WaitForLSNReplay(target_lsn, timeout); + + /* + * Process the result of WaitForLSNReplay(). Throw appropriate error if + * needed. + */ + switch (result) + { + case WAIT_LSN_RESULT_SUCCESS: + /* Nothing to do on success */ + break; + + case WAIT_LSN_RESULT_TIMEOUT: + ereport(ERROR, + (errcode(ERRCODE_QUERY_CANCELED), + errmsg("timed out while waiting for target LSN %X/%X to be replayed; current replay LSN %X/%X", + LSN_FORMAT_ARGS(target_lsn), + LSN_FORMAT_ARGS(GetXLogReplayRecPtr(NULL))))); + break; + + case WAIT_LSN_RESULT_NOT_IN_RECOVERY: + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("recovery is not in progress"), + errdetail("Recovery ended before replaying target LSN %X/%X; last replay LSN %X/%X.", + LSN_FORMAT_ARGS(target_lsn), + LSN_FORMAT_ARGS(GetXLogReplayRecPtr(NULL))))); + break; + } PG_RETURN_VOID(); } diff --git a/src/backend/access/transam/xlogwait.c b/src/backend/access/transam/xlogwait.c index 353b7854dc8..58fb10aa5a8 100644 --- a/src/backend/access/transam/xlogwait.c +++ b/src/backend/access/transam/xlogwait.c @@ -217,7 +217,7 @@ WaitLSNCleanup(void) * Wait using MyLatch till the given LSN is replayed, the postmaster dies or * timeout happens. */ -void +WaitLSNResult WaitForLSNReplay(XLogRecPtr targetLSN, int64 timeout) { XLogRecPtr currentLSN; @@ -240,17 +240,14 @@ WaitForLSNReplay(XLogRecPtr targetLSN, int64 timeout) * check the last replay LSN before reporting an error. */ if (targetLSN <= GetXLogReplayRecPtr(NULL)) - return; - ereport(ERROR, - (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), - errmsg("recovery is not in progress"), - errhint("Waiting for LSN can only be executed during recovery."))); + return WAIT_LSN_RESULT_SUCCESS; + return WAIT_LSN_RESULT_NOT_IN_RECOVERY; } else { /* If target LSN is already replayed, exit immediately */ if (targetLSN <= GetXLogReplayRecPtr(NULL)) - return; + return WAIT_LSN_RESULT_SUCCESS; } if (timeout > 0) @@ -276,17 +273,13 @@ WaitForLSNReplay(XLogRecPtr targetLSN, int64 timeout) { /* * Recovery was ended, but recheck if target LSN was already - * replayed. + * replayed. See the comment regarding deleteLSNWaiter() below. */ + deleteLSNWaiter(); currentLSN = GetXLogReplayRecPtr(NULL); if (targetLSN <= currentLSN) - return; - ereport(ERROR, - (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), - errmsg("recovery is not in progress"), - errdetail("Recovery ended before replaying target LSN %X/%X; last replay LSN %X/%X.", - LSN_FORMAT_ARGS(targetLSN), - LSN_FORMAT_ARGS(currentLSN)))); + return WAIT_LSN_RESULT_SUCCESS; + return WAIT_LSN_RESULT_NOT_IN_RECOVERY; } else { @@ -338,11 +331,7 @@ WaitForLSNReplay(XLogRecPtr targetLSN, int64 timeout) * If we didn't reach the target LSN, we must be exited by timeout. */ if (targetLSN > currentLSN) - { - ereport(ERROR, - (errcode(ERRCODE_QUERY_CANCELED), - errmsg("timed out while waiting for target LSN %X/%X to be replayed; current replay LSN %X/%X", - LSN_FORMAT_ARGS(targetLSN), - LSN_FORMAT_ARGS(currentLSN)))); - } + return WAIT_LSN_RESULT_TIMEOUT; + + return WAIT_LSN_RESULT_SUCCESS; } diff --git a/src/include/access/xlogwait.h b/src/include/access/xlogwait.h index 31e208cb7ad..eb2260aa2ec 100644 --- a/src/include/access/xlogwait.h +++ b/src/include/access/xlogwait.h @@ -70,12 +70,23 @@ typedef struct WaitLSNState WaitLSNProcInfo procInfos[FLEXIBLE_ARRAY_MEMBER]; } WaitLSNState; +/* + * Result statuses for WaitForLSNReplay(). + */ +typedef enum +{ + WAIT_LSN_RESULT_SUCCESS, /* Target LSN is reached */ + WAIT_LSN_RESULT_TIMEOUT, /* Timeout occurred */ + WAIT_LSN_RESULT_NOT_IN_RECOVERY, /* Recovery ended before or during our + * wait */ +} WaitLSNResult; + extern PGDLLIMPORT WaitLSNState *waitLSNState; extern Size WaitLSNShmemSize(void); extern void WaitLSNShmemInit(void); extern void WaitLSNSetLatches(XLogRecPtr currentLSN); extern void WaitLSNCleanup(void); -extern void WaitForLSNReplay(XLogRecPtr targetLSN, int64 timeout); +extern WaitLSNResult WaitForLSNReplay(XLogRecPtr targetLSN, int64 timeout); #endif /* XLOG_WAIT_H */ diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 4b8139c4b47..110089695e1 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -3126,6 +3126,7 @@ WaitEventIPC WaitEventSet WaitEventTimeout WaitLSNProcInfo +WaitLSNResult WaitLSNState WaitPMResult WalCloseMethod