From 54b36ff6e82f1a01b42fdb059b9c6db842534fc3 Mon Sep 17 00:00:00 2001 From: Alexander Korotkov Date: Thu, 19 Sep 2024 14:48:44 +0300 Subject: [PATCH v3 2/3] Refactor WaitForLSNReplay() to return the result of waiting Currently WaitForLSNReplay() immediatly 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 for new procedure pg_wal_replay_wait_status(), which will expose the waiting result to the user instead of throwing an error. --- src/backend/access/transam/xlogfuncs.c | 31 +++++++++++++++++++++++- src/backend/commands/waitlsn.c | 33 +++++++++----------------- src/include/commands/waitlsn.h | 12 +++++++++- 3 files changed, 52 insertions(+), 24 deletions(-) diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c index 3e3d2bb6189..4c79c264e13 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/commands/waitlsn.c b/src/backend/commands/waitlsn.c index 7f3cd62e2a2..237351316a8 100644 --- a/src/backend/commands/waitlsn.c +++ b/src/backend/commands/waitlsn.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/commands/waitlsn.h b/src/include/commands/waitlsn.h index bb5ac858dcc..edf4a793e63 100644 --- a/src/include/commands/waitlsn.h +++ b/src/include/commands/waitlsn.h @@ -70,12 +70,22 @@ 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 occured */ + 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 /* WAIT_LSN_H */ -- 2.39.5 (Apple Git-154)