ResourceOwner owner);
static void LockCountMyLocks(SHMEM_OFFSET lockOffset, PGPROC *proc,
int *myHolding);
+static bool UnGrantLock(LOCK *lock, LOCKMODE lockmode,
+ PROCLOCK *proclock, LockMethod lockMethodTable);
/*
Assert(lock->nGranted <= lock->nRequested);
}
+/*
+ * UnGrantLock -- opposite of GrantLock.
+ *
+ * Updates the lock and proclock data structures to show that the lock
+ * is no longer held nor requested by the current holder.
+ *
+ * Returns true if there were any waiters waiting on the lock that
+ * should now be woken up with ProcLockWakeup.
+ */
+static bool
+UnGrantLock(LOCK *lock, LOCKMODE lockmode,
+ PROCLOCK *proclock, LockMethod lockMethodTable)
+{
+ bool wakeupNeeded = false;
+
+ Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
+ Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
+ Assert(lock->nGranted <= lock->nRequested);
+
+ /*
+ * fix the general lock stats
+ */
+ lock->nRequested--;
+ lock->requested[lockmode]--;
+ lock->nGranted--;
+ lock->granted[lockmode]--;
+
+ if (lock->granted[lockmode] == 0)
+ {
+ /* change the conflict mask. No more of this lock type. */
+ lock->grantMask &= LOCKBIT_OFF(lockmode);
+ }
+
+ LOCK_PRINT("UnGrantLock: updated", lock, lockmode);
+
+ /*
+ * We need only run ProcLockWakeup if the released lock conflicts with
+ * at least one of the lock types requested by waiter(s). Otherwise
+ * whatever conflict made them wait must still exist. NOTE: before
+ * MVCC, we could skip wakeup if lock->granted[lockmode] was still
+ * positive. But that's not true anymore, because the remaining
+ * granted locks might belong to some waiter, who could now be
+ * awakened because he doesn't conflict with his own locks.
+ */
+ if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
+ wakeupNeeded = true;
+
+ /*
+ * Now fix the per-proclock state.
+ */
+ proclock->holdMask &= LOCKBIT_OFF(lockmode);
+ PROCLOCK_PRINT("UnGrantLock: updated", proclock);
+
+ return wakeupNeeded;
+}
+
/*
* GrantLockLocal -- update the locallock data structures to show
* the lock request has been granted.
ResourceOwner owner)
{
LockMethod lockMethodTable = LockMethods[lockmethodid];
- char *new_status,
- *old_status;
+ const char *old_status;
+ char *new_status;
+ int len;
Assert(lockmethodid < NumLockMethods);
LOCK_PRINT("WaitOnLock: sleeping on lock",
locallock->lock, locallock->tag.mode);
- old_status = pstrdup(get_ps_display());
- new_status = (char *) palloc(strlen(old_status) + 10);
- strcpy(new_status, old_status);
- strcat(new_status, " waiting");
+ old_status = get_ps_display(&len);
+ new_status = (char *) palloc(len + 8 + 1);
+ memcpy(new_status, old_status, len);
+ strcpy(new_status + len, " waiting");
set_ps_display(new_status);
+ new_status[len] = '\0'; /* truncate off " waiting" */
awaitedLock = locallock;
awaitedOwner = owner;
{
/*
* 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",
awaitedLock = NULL;
- set_ps_display(old_status);
- pfree(old_status);
+ set_ps_display(new_status);
pfree(new_status);
LOCK_PRINT("WaitOnLock: wakeup on lock",
*
* 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));
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);
}
/*
PROCLOCK *proclock;
LWLockId masterLock;
LockMethod lockMethodTable;
- bool wakeupNeeded = false;
+ bool wakeupNeeded;
#ifdef LOCK_DEBUG
if (lockmethodid == USER_LOCKMETHOD && Trace_userlocks)
RemoveLocalLock(locallock);
return FALSE;
}
- Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
- Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
- Assert(lock->nGranted <= lock->nRequested);
- /*
- * fix the general lock stats
- */
- lock->nRequested--;
- lock->requested[lockmode]--;
- lock->nGranted--;
- lock->granted[lockmode]--;
-
- if (lock->granted[lockmode] == 0)
- {
- /* change the conflict mask. No more of this lock type. */
- lock->grantMask &= LOCKBIT_OFF(lockmode);
- }
-
- LOCK_PRINT("LockRelease: 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
- * at least one of the lock types requested by waiter(s). Otherwise
- * whatever conflict made them wait must still exist. NOTE: before
- * MVCC, we could skip wakeup if lock->granted[lockmode] was still
- * positive. But that's not true anymore, because the remaining
- * granted locks might belong to some waiter, who could now be
- * awakened because he doesn't conflict with his own locks.
- */
- if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
- wakeupNeeded = true;
-
- /*
- * Now fix the per-proclock state.
- */
- proclock->holdMask &= LOCKBIT_OFF(lockmode);
- PROCLOCK_PRINT("LockRelease: updated", proclock);
+ wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
/*
* If this was my last hold on this lock, delete my entry in the
*/
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],
* 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),
for (i = 1; i <= numLockModes; i++)
{
if (proclock->holdMask & LOCKBIT_ON(i))
- {
- lock->requested[i]--;
- lock->granted[i]--;
- Assert(lock->requested[i] >= 0 && lock->granted[i] >= 0);
- if (lock->granted[i] == 0)
- lock->grantMask &= LOCKBIT_OFF(i);
- lock->nRequested--;
- lock->nGranted--;
-
- /*
- * Read comments in LockRelease
- */
- if (!wakeupNeeded &&
- lockMethodTable->conflictTab[i] & lock->waitMask)
- wakeupNeeded = true;
- }
+ wakeupNeeded |= UnGrantLock(lock, i, proclock,
+ lockMethodTable);
}
}
Assert((lock->nRequested >= 0) && (lock->nGranted >= 0));
projects / users / bernd / postgres.git / commitdiff