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Release proclock immediately in RemoveFromWaitQueue() if it represents

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no held locks.  This maintains the invariant that proclocks are present
only for procs that are holding or awaiting a lock; when this is not
true, LockRelease will fail.  Per report from Stephen Clouse.
This commit is contained in:
Tom Lane 2005-03-01 21:15:26 +00:00
parent 510f058932
commit 89dcff555f
1 changed files with 23 additions and 10 deletions
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33
src/backend/storage/lmgr/lock.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.128 2003/10/16 20:59:35 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.128.2.1 2005/03/01 21:15:26 tgl Exp $
*
* NOTES
* Outside modules can create a lock table and acquire/release
@ -900,8 +900,7 @@ WaitOnLock(LOCKMETHOD lockmethod, LOCKMODE lockmode,
{
/*
* We failed as a result of a deadlock, see CheckDeadLock(). Quit
* now. Removal of the proclock and lock objects, if no longer
* needed, will happen in xact cleanup (see above for motivation).
* now.
*/
LOCK_PRINT("WaitOnLock: aborting on lock", lock, lockmode);
LWLockRelease(lockMethodTable->masterLock);
@ -927,23 +926,20 @@ WaitOnLock(LOCKMETHOD lockmethod, LOCKMODE lockmode,
* (caller must know it is on one).
*
* Locktable lock must be held by caller.
*
* NB: this does not remove the process' proclock object, nor the lock object,
* even though their counts might now have gone to zero. That will happen
* during a subsequent LockReleaseAll call, which we expect will happen
* during transaction cleanup. (Removal of a proc from its wait queue by
* this routine can only happen if we are aborting the transaction.)
*/
void
RemoveFromWaitQueue(PGPROC *proc)
{
LOCK *waitLock = proc->waitLock;
PROCLOCK *proclock = proc->waitHolder;
LOCKMODE lockmode = proc->waitLockMode;
LOCKMETHOD lockmethod = LOCK_LOCKMETHOD(*waitLock);
/* Make sure proc is waiting */
Assert(proc->links.next != INVALID_OFFSET);
Assert(waitLock);
Assert(waitLock->waitProcs.size > 0);
Assert(lockmethod > 0 && lockmethod < NumLockMethods);
/* Remove proc from lock's wait queue */
SHMQueueDelete(&(proc->links));
@ -963,8 +959,25 @@ RemoveFromWaitQueue(PGPROC *proc)
proc->waitLock = NULL;
proc->waitHolder = NULL;
/*
* Delete the proclock immediately if it represents no already-held locks.
* This must happen now because if the owner of the lock decides to release
* it, and the requested/granted counts then go to zero, LockRelease
* expects there to be no remaining proclocks.
*/
if (proclock->nHolding == 0)
{
SHMQueueDelete(&proclock->lockLink);
SHMQueueDelete(&proclock->procLink);
proclock = (PROCLOCK *) hash_search(LockMethodTable[lockmethod]->proclockHash,
(void *) proclock,
HASH_REMOVE, NULL);
if (!proclock)
elog(WARNING, "proclock table corrupted");
}
/* See if any other waiters for the lock can be woken up now */
ProcLockWakeup(GetLocksMethodTable(waitLock), waitLock);
ProcLockWakeup(LockMethodTable[lockmethod], waitLock);
}
/*