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Refactor some duplicated code in lock.c: create UnGrantLock(), move code 

from LockRelease() and LockReleaseAll() into it. From Heikki Linnakangas.
This commit is contained in:
Neil Conway 2005-02-04 02:04:53 +00:00
parent ee467c3530
commit 11635c3f6f
1 changed files with 65 additions and 56 deletions
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121
src/backend/storage/lmgr/lock.c
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@ -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));