Hi,
There's two almost identical pieces of code in LockRelease and LockReleaseAll that do the opposite of GrantLock.
Here's a small patch that replaces those pieces with a static UnGrantLock function.
This is preparation for the two-phase commit patch, since that introduces more calls to UnGrantLock.
- Heikki
Index: lock.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v
retrieving revision 1.145
diff -c -r1.145 lock.c
*** lock.c 31 Dec 2004 22:01:05 -0000 1.145
--- lock.c 2 Feb 2005 19:40:26 -0000
***************
*** 166,171 ****
--- 166,172 ----
ResourceOwner owner);
static void LockCountMyLocks(SHMEM_OFFSET lockOffset, PGPROC *proc,
int *myHolding);
+ static bool UnGrantLock(LOCK *lock, LOCKMODE lockmode, PROCLOCK *proclock,
LockMethod lockMethodTable);
/*
***************
*** 958,963 ****
--- 959,1020 ----
}
/*
+ * 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 was 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);
+ 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("UnGrantLock: updated", proclock);
+
+ return wakeupNeeded;
+ }
+
+ /*
* GrantLockLocal -- update the locallock data structures to show
* the lock request has been granted.
*
***************
*** 1265,1310 ****
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);
/*
* If this was my last hold on this lock, delete my entry in the
--- 1322,1329 ----
RemoveLocalLock(locallock);
return FALSE;
}
! wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
/*
* If this was my last hold on this lock, delete my entry in the
***************
*** 1484,1503 ****
{
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;
}
}
}
--- 1503,1509 ----
{
if (proclock->holdMask & LOCKBIT_ON(i))
{
! wakeupNeeded |= UnGrantLock(lock, i,
proclock, lockMethodTable);
}
}
}
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