Function SHMQueueEmpty

src/backend/storage/ipc/shmqueue.c:179–190

* SHMQueueEmpty -- true if queue head is only element, false otherwise */

 * SHMQueueEmpty -- true if queue head is only element, false otherwise
 */
bool
SHMQueueEmpty(const SHM_QUEUE *queue)
{
	Assert(ShmemAddrIsValid(queue));

	if (queue->prev == queue)
	{
		Assert(queue->next == queue);
		return true;
	}
	return false;
}