diff options
Diffstat (limited to 'src/backend/storage/ipc/sinval.c')
| -rw-r--r-- | src/backend/storage/ipc/sinval.c | 65 |
1 files changed, 38 insertions, 27 deletions
diff --git a/src/backend/storage/ipc/sinval.c b/src/backend/storage/ipc/sinval.c index 1d43b1ead4..24506b9729 100644 --- a/src/backend/storage/ipc/sinval.c +++ b/src/backend/storage/ipc/sinval.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.40 2001/08/26 16:56:00 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.41 2001/09/29 04:02:24 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -23,8 +23,6 @@ #include "miscadmin.h" -SPINLOCK SInvalLock = (SPINLOCK) NULL; - /****************************************************************************/ /* CreateSharedInvalidationState() Initialize SI buffer */ /* */ @@ -33,7 +31,7 @@ SPINLOCK SInvalLock = (SPINLOCK) NULL; void CreateSharedInvalidationState(int maxBackends) { - /* SInvalLock must be initialized already, during spinlock init */ + /* SInvalLock must be initialized already, during LWLock init */ SIBufferInit(maxBackends); } @@ -46,9 +44,9 @@ InitBackendSharedInvalidationState(void) { int flag; - SpinAcquire(SInvalLock); + LWLockAcquire(SInvalLock, LW_EXCLUSIVE); flag = SIBackendInit(shmInvalBuffer); - SpinRelease(SInvalLock); + LWLockRelease(SInvalLock); if (flag < 0) /* unexpected problem */ elog(FATAL, "Backend cache invalidation initialization failed"); if (flag == 0) /* expected problem: MaxBackends exceeded */ @@ -64,9 +62,9 @@ SendSharedInvalidMessage(SharedInvalidationMessage *msg) { bool insertOK; - SpinAcquire(SInvalLock); + LWLockAcquire(SInvalLock, LW_EXCLUSIVE); insertOK = SIInsertDataEntry(shmInvalBuffer, msg); - SpinRelease(SInvalLock); + LWLockRelease(SInvalLock); if (!insertOK) elog(DEBUG, "SendSharedInvalidMessage: SI buffer overflow"); } @@ -86,9 +84,25 @@ ReceiveSharedInvalidMessages( for (;;) { - SpinAcquire(SInvalLock); + /* + * We can run SIGetDataEntry in parallel with other backends running + * SIGetDataEntry for themselves, since each instance will modify + * only fields of its own backend's ProcState, and no instance will + * look at fields of other backends' ProcStates. We express this + * by grabbing SInvalLock in shared mode. Note that this is not + * exactly the normal (read-only) interpretation of a shared lock! + * Look closely at the interactions before allowing SInvalLock to + * be grabbed in shared mode for any other reason! + * + * The routines later in this file that use shared mode are okay + * with this, because they aren't looking at the ProcState fields + * associated with SI message transfer; they only use the ProcState + * array as an easy way to find all the PROC structures. + */ + LWLockAcquire(SInvalLock, LW_SHARED); getResult = SIGetDataEntry(shmInvalBuffer, MyBackendId, &data); - SpinRelease(SInvalLock); + LWLockRelease(SInvalLock); + if (getResult == 0) break; /* nothing more to do */ if (getResult < 0) @@ -108,9 +122,9 @@ ReceiveSharedInvalidMessages( /* If we got any messages, try to release dead messages */ if (gotMessage) { - SpinAcquire(SInvalLock); + LWLockAcquire(SInvalLock, LW_EXCLUSIVE); SIDelExpiredDataEntries(shmInvalBuffer); - SpinRelease(SInvalLock); + LWLockRelease(SInvalLock); } } @@ -149,7 +163,7 @@ DatabaseHasActiveBackends(Oid databaseId, bool ignoreMyself) ProcState *stateP = segP->procState; int index; - SpinAcquire(SInvalLock); + LWLockAcquire(SInvalLock, LW_SHARED); for (index = 0; index < segP->lastBackend; index++) { @@ -170,7 +184,7 @@ DatabaseHasActiveBackends(Oid databaseId, bool ignoreMyself) } } - SpinRelease(SInvalLock); + LWLockRelease(SInvalLock); return result; } @@ -186,7 +200,7 @@ TransactionIdIsInProgress(TransactionId xid) ProcState *stateP = segP->procState; int index; - SpinAcquire(SInvalLock); + LWLockAcquire(SInvalLock, LW_SHARED); for (index = 0; index < segP->lastBackend; index++) { @@ -206,7 +220,7 @@ TransactionIdIsInProgress(TransactionId xid) } } - SpinRelease(SInvalLock); + LWLockRelease(SInvalLock); return result; } @@ -237,7 +251,7 @@ GetOldestXmin(bool allDbs) result = GetCurrentTransactionId(); - SpinAcquire(SInvalLock); + LWLockAcquire(SInvalLock, LW_SHARED); for (index = 0; index < segP->lastBackend; index++) { @@ -265,7 +279,7 @@ GetOldestXmin(bool allDbs) } } - SpinRelease(SInvalLock); + LWLockRelease(SInvalLock); return result; } @@ -298,7 +312,7 @@ GetSnapshotData(bool serializable) snapshot->xmin = GetCurrentTransactionId(); - SpinAcquire(SInvalLock); + LWLockAcquire(SInvalLock, LW_SHARED); /* * There can be no more than lastBackend active transactions, so this @@ -307,15 +321,12 @@ GetSnapshotData(bool serializable) snapshot->xip = (TransactionId *) malloc(segP->lastBackend * sizeof(TransactionId)); if (snapshot->xip == NULL) - { - SpinRelease(SInvalLock); elog(ERROR, "Memory exhausted in GetSnapshotData"); - } /*-------------------- * Unfortunately, we have to call ReadNewTransactionId() after acquiring * SInvalLock above. It's not good because ReadNewTransactionId() does - * SpinAcquire(XidGenLockId), but *necessary*. We need to be sure that + * LWLockAcquire(XidGenLock), but *necessary*. We need to be sure that * no transactions exit the set of currently-running transactions * between the time we fetch xmax and the time we finish building our * snapshot. Otherwise we could have a situation like this: @@ -373,7 +384,7 @@ GetSnapshotData(bool serializable) if (serializable) MyProc->xmin = snapshot->xmin; - SpinRelease(SInvalLock); + LWLockRelease(SInvalLock); /* Serializable snapshot must be computed before any other... */ Assert(TransactionIdIsValid(MyProc->xmin)); @@ -439,7 +450,7 @@ GetUndoRecPtr(void) XLogRecPtr tempr; int index; - SpinAcquire(SInvalLock); + LWLockAcquire(SInvalLock, LW_SHARED); for (index = 0; index < segP->lastBackend; index++) { @@ -458,7 +469,7 @@ GetUndoRecPtr(void) } } - SpinRelease(SInvalLock); + LWLockRelease(SInvalLock); return (urec); } @@ -470,7 +481,7 @@ GetUndoRecPtr(void) * knows that the backend isn't going to go away, so we do not bother with * locking. */ -struct proc * +struct PROC * BackendIdGetProc(BackendId procId) { SISeg *segP = shmInvalBuffer; |