Function ResLockAcquire

src/backend/utils/resscheduler/resqueue.c:167–613

* ResLockAcquire -- acquire a resource lock. * * Notes and critisms: * * Returns LOCKACQUIRE_OK if we get the lock, * LOCKACQUIRE_NOT_AVAIL if we don't want to take the lock after all. * * Analogous to LockAcquire, but the lockmode and session boolean are not * required in the function prototype as we are *always* lockmode ExclusiveLock * and have no session locks. * * The semantics o

 *
 */
LockAcquireResult
ResLockAcquire(LOCKTAG *locktag, ResPortalIncrement *incrementSet)
{
	LOCKMODE	lockmode = ExclusiveLock;
	LOCK	   *lock;
	PROCLOCK   *proclock;
	PROCLOCKTAG proclocktag;
	LOCALLOCKTAG localtag;
	LOCALLOCK  *locallock;
	uint32		hashcode;
	uint32		proclock_hashcode;
	int			partition;
	LWLockId	partitionLock;
	bool		found;
	ResourceOwner owner;
	ResQueue	queue;
	int			status;
	ResIncrementAddStatus addStatus;

	if (resLockAcquireStatus != RQA_NOT_STARTED_OR_DONE)
	{
		elog(LOG,
			 "Resource queue %d: previous ResLockAcquire() interrupted, "
			 " status = %d, portal id = %u",
			 locktag->locktag_field1,
			 resLockAcquireStatus,
			 incrementSet->portalId);
	}

	resLockAcquireStatus = RQA_STARTED;

	/* Setup the lock method bits. */
	Assert(locktag->locktag_lockmethodid == RESOURCE_LOCKMETHOD);

	/* Provide a resource owner. */
	owner = CurrentResourceOwner;

	/*
	 * Find or create a LOCALLOCK entry for this lock and lockmode
	 */
	MemSet(&localtag, 0, sizeof(localtag));		/* must clear padding */
	localtag.lock = *locktag;
	localtag.mode = lockmode;

	locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
										  (void *) &localtag,
										  HASH_ENTER, &found);

	/*
	 * if it's a new locallock object, initialize it, if it already exists
	 * then that is enough for the resource locks.
	 */
	if (!found)
	{
		locallock->lock = NULL;
		locallock->proclock = NULL;
		locallock->hashcode = LockTagHashCode(&(localtag.lock));