diff options
| -rw-r--r-- | src/backend/storage/ipc/sinvaladt.c | 28 |
1 files changed, 17 insertions, 11 deletions
diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 8aa4ec836b5..b7933a05c42 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.73 2008/07/01 02:09:34 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.74 2008/07/18 14:45:48 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -296,8 +296,6 @@ SharedInvalBackendInit(void) MyBackendId = (stateP - &segP->procState[0]) + 1; - elog(DEBUG4, "my backend id is %d", MyBackendId); - /* Advertise assigned backend ID in MyProc */ MyProc->backendId = MyBackendId; @@ -314,6 +312,8 @@ SharedInvalBackendInit(void) /* register exit routine to mark my entry inactive at exit */ on_shmem_exit(CleanupInvalidationState, PointerGetDatum(segP)); + + elog(DEBUG4, "my backend id is %d", MyBackendId); } /* @@ -416,16 +416,18 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) * If the buffer is full, we *must* acquire some space. Clean the * queue and reset anyone who is preventing space from being freed. * Otherwise, clean the queue only when it's exceeded the next - * fullness threshold. + * fullness threshold. We have to loop and recheck the buffer state + * after any call of SICleanupQueue. */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; - if (numMsgs + nthistime > MAXNUMMESSAGES) + for (;;) { - SICleanupQueue(true, nthistime); - Assert((segP->maxMsgNum - segP->minMsgNum + nthistime) <= MAXNUMMESSAGES); + numMsgs = segP->maxMsgNum - segP->minMsgNum; + if (numMsgs + nthistime > MAXNUMMESSAGES || + numMsgs >= segP->nextThreshold) + SICleanupQueue(true, nthistime); + else + break; } - else if (numMsgs >= segP->nextThreshold) - SICleanupQueue(true, 0); /* * Insert new message(s) into proper slot of circular buffer @@ -546,12 +548,16 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) * Remove messages that have been consumed by all active backends * * callerHasWriteLock is TRUE if caller is holding SInvalWriteLock. - * minFree is the minimum number of free message slots required at completion. + * minFree is the minimum number of message slots to make free. * * Possible side effects of this routine include marking one or more * backends as "reset" in the array, and sending a catchup interrupt (SIGUSR1) * to some backend that seems to be getting too far behind. We signal at * most one backend at a time, for reasons explained at the top of the file. + * + * Caution: because we transiently release write lock when we have to signal + * some other backend, it is NOT guaranteed that there are still minFree + * free message slots at exit. Caller must recheck and perhaps retry. */ void SICleanupQueue(bool callerHasWriteLock, int minFree) |