Function groupWaitQueuePop

src/backend/utils/resgroup/resgroup.c:2470–2493

* Pop the top proc from the resgroup wait queue and return it. */

 * Pop the top proc from the resgroup wait queue and return it.
 */
static PGPROC *
groupWaitQueuePop(ResGroupData *group)
{
	PROC_QUEUE			*waitQueue;
	PGPROC				*proc;

	Assert(LWLockHeldByMeInMode(ResGroupLock, LW_EXCLUSIVE));
	Assert(!groupWaitQueueIsEmpty(group));

	groupWaitQueueValidate(group);

	waitQueue = &group->waitProcs;

	proc = (PGPROC *) waitQueue->links.next;
	groupWaitProcValidate(proc, waitQueue);
	Assert(groupWaitQueueFind(group, proc));
	Assert(proc->resSlot == NULL);

	SHMQueueDelete(&proc->links);

	waitQueue->size--;

	return proc;
}

/*
 * Erase proc from the resgroup wait queue.