/**
* Gets the next waiter index. The index is zero for the first waiter.
* If waiter was not the first, the index if the highest active index + 1.
* The highest active index is determined by checking the last entries
* in both exclusive and shared lists. Must be called under synchronization
*/
STATIC int RWLOCK_GetNextWaiterIndex(RWLock * lock)
{
int i = 0;
RWLockWaiter * lastWaiter;
QEntry * e = QUEUE_Last(&lock->shareWaiters);
if (e) {
lastWaiter = QCAST(e,RWLockWaiter,entry);
i = lastWaiter->index + 1;
}
e = QUEUE_Last(&lock->exclusiveWaiters);
if (e) {
lastWaiter = QCAST(e,RWLockWaiter,entry);
i = MAX(i,lastWaiter->index + 1);
}
return i;
}
/**
* Removes the last entry from the queue.
* Returns NULL if queue is empty
*/
QEntry * QUEUE_RemoveTail(Queue * q)
{
QEntry * e = QUEUE_Last(q);
if (e) {
_RemoveEntry(e);
_InvalidateEntry(e);
q->size--;
}
return e;
}
