From 11635c3f6fe1961dddc1155dfc4de145fa007c88 Mon Sep 17 00:00:00 2001
From: Neil Conway <neilc@samurai.com>
Date: Fri, 4 Feb 2005 02:04:53 +0000
Subject: [PATCH] Refactor some duplicated code in lock.c: create
UnGrantLock(), move code from LockRelease() and LockReleaseAll() into it.
From Heikki Linnakangas.
---
src/backend/storage/lmgr/lock.c | 121 +++++++++++++++++---------------
1 file changed, 65 insertions(+), 56 deletions(-)
diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
index 7bb89e5a103..76b2ff9b480 100644
--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.145 2004/12/31 22:01:05 pgsql Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.146 2005/02/04 02:04:53 neilc Exp $
*
* NOTES
* Outside modules can create a lock table and acquire/release
@@ -166,6 +166,8 @@ static int WaitOnLock(LOCKMETHODID lockmethodid, LOCALLOCK *locallock,
ResourceOwner owner);
static void LockCountMyLocks(SHMEM_OFFSET lockOffset, PGPROC *proc,
int *myHolding);
+static bool UnGrantLock(LOCK *lock, LOCKMODE lockmode,
+ PROCLOCK *proclock, LockMethod lockMethodTable);
/*
@@ -957,6 +959,65 @@ GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode)
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);
+ 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.
@@ -1265,46 +1326,8 @@ LockRelease(LOCKMETHODID lockmethodid, LOCKTAG *locktag,
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
@@ -1483,22 +1506,8 @@ LockReleaseAll(LOCKMETHODID lockmethodid, bool allxids)
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));
--
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