Release proclock immediately in RemoveFromWaitQueue() if it represents

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.

Author: tglsfdc

src/backend/storage/lmgr/lock.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.146 2005/02/04 02:04:53 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.147 2005/03/01 21:14:59 tgl Exp $
  *
  * NOTES
  *	  Outside modules can create a lock table and acquire/release
@@ -993,9 +993,6 @@ UnGrantLock(LOCK *lock, LOCKMODE lockmode,
 	}
 
 	LOCK_PRINT("UnGrantLock: updated", lock, lockmode);
-	Assert((lock->nRequested >= 0) && (lock->requested[lockmode] >= 0));
-	Assert((lock->nGranted >= 0) && (lock->granted[lockmode] >= 0));
-	Assert(lock->nGranted <= lock->nRequested);
 
 	/*
 	 * We need only run ProcLockWakeup if the released lock conflicts with
@@ -1115,8 +1112,7 @@ WaitOnLock(LOCKMETHODID lockmethodid, LOCALLOCK *locallock,
 	{
 		/*
 		 * 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.
 		 */
 		awaitedLock = NULL;
 		LOCK_PRINT("WaitOnLock: aborting on lock",
@@ -1148,22 +1144,21 @@ WaitOnLock(LOCKMETHODID lockmethodid, LOCALLOCK *locallock,
  *
  * 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.)
+ * NB: this does not clean up any locallock object that may exist for the lock.
  */
 void
 RemoveFromWaitQueue(PGPROC *proc)
 {
 	LOCK	   *waitLock = proc->waitLock;
+	PROCLOCK   *proclock = proc->waitProcLock;
 	LOCKMODE	lockmode = proc->waitLockMode;
+	LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*waitLock);
 
 	/* Make sure proc is waiting */
 	Assert(proc->links.next != INVALID_OFFSET);
 	Assert(waitLock);
 	Assert(waitLock->waitProcs.size > 0);
+	Assert(0 < lockmethodid && lockmethodid < NumLockMethods);
 
 	/* Remove proc from lock's wait queue */
 	SHMQueueDelete(&(proc->links));
@@ -1183,8 +1178,32 @@ RemoveFromWaitQueue(PGPROC *proc)
 	proc->waitLock = NULL;
 	proc->waitProcLock = 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->holdMask == 0)
+	{
+		PROCLOCK_PRINT("RemoveFromWaitQueue: deleting proclock", proclock);
+		SHMQueueDelete(&proclock->lockLink);
+		SHMQueueDelete(&proclock->procLink);
+		proclock = (PROCLOCK *) hash_search(LockMethodProcLockHash[lockmethodid],
+											(void *) &(proclock->tag),
+											HASH_REMOVE, NULL);
+		if (!proclock)
+			elog(WARNING, "proclock table corrupted");
+	}
+
+	/*
+	 * There should still be some requests for the lock ... else what were
+	 * we waiting for?  Therefore no need to delete the lock object.
+	 */
+	Assert(waitLock->nRequested > 0);
+
 	/* See if any other waiters for the lock can be woken up now */
-	ProcLockWakeup(GetLocksMethodTable(waitLock), waitLock);
+	ProcLockWakeup(LockMethods[lockmethodid], waitLock);
 }
 
 /*
@@ -1207,7 +1226,7 @@ LockRelease(LOCKMETHODID lockmethodid, LOCKTAG *locktag,
 	PROCLOCK   *proclock;
 	LWLockId	masterLock;
 	LockMethod	lockMethodTable;
-	bool		wakeupNeeded = false;
+	bool		wakeupNeeded;
 
 #ifdef LOCK_DEBUG
 	if (lockmethodid == USER_LOCKMETHOD && Trace_userlocks)
@@ -1335,7 +1354,7 @@ LockRelease(LOCKMETHODID lockmethodid, LOCKTAG *locktag,
 	 */
 	if (proclock->holdMask == 0)
 	{
-		PROCLOCK_PRINT("LockRelease: deleting", proclock);
+		PROCLOCK_PRINT("LockRelease: deleting proclock", proclock);
 		SHMQueueDelete(&proclock->lockLink);
 		SHMQueueDelete(&proclock->procLink);
 		proclock = (PROCLOCK *) hash_search(LockMethodProcLockHash[lockmethodid],
@@ -1356,6 +1375,7 @@ LockRelease(LOCKMETHODID lockmethodid, LOCKTAG *locktag,
 		 * We've just released the last lock, so garbage-collect the lock
 		 * object.
 		 */
+		LOCK_PRINT("LockRelease: deleting lock", lock, lockmode);
 		Assert(SHMQueueEmpty(&(lock->procLocks)));
 		lock = (LOCK *) hash_search(LockMethodLockHash[lockmethodid],
 									(void *) &(lock->tag),