private bool TryLeaseUnsynchronized(int permitCount, [NotNullWhen(true)] out RateLimitLease?lease)
{
// if permitCount is 0 we want to queue it if there are no available permits
if (_permitCount >= permitCount && _permitCount != 0)
{
if (permitCount == 0)
{
// Edge case where the check before the lock showed 0 available permits but when we got the lock some permits were now available
lease = SuccessfulLease;
return(true);
}
// a. if there are no items queued we can lease
// b. if there are items queued but the processing order is newest first, then we can lease the incoming request since it is the newest
if (_queueCount == 0 || (_queueCount > 0 && _options.QueueProcessingOrder == QueueProcessingOrder.NewestFirst))
{
_permitCount -= permitCount;
Debug.Assert(_permitCount >= 0);
lease = new ConcurrencyLease(true, this, permitCount);
return(true);
}
}
lease = null;
return(false);
}
private void Release(int releaseCount)
{
lock (Lock)
{
_permitCount += releaseCount;
Debug.Assert(_permitCount <= _options.PermitLimit);
while (_queue.Count > 0)
{
RequestRegistration nextPendingRequest =
_options.QueueProcessingOrder == QueueProcessingOrder.OldestFirst
? _queue.PeekHead()
: _queue.PeekTail();
if (_permitCount >= nextPendingRequest.Count)
{
nextPendingRequest =
_options.QueueProcessingOrder == QueueProcessingOrder.OldestFirst
? _queue.DequeueHead()
: _queue.DequeueTail();
_permitCount -= nextPendingRequest.Count;
_queueCount -= nextPendingRequest.Count;
Debug.Assert(_queueCount >= 0);
Debug.Assert(_permitCount >= 0);
ConcurrencyLease lease = nextPendingRequest.Count == 0 ? SuccessfulLease : new ConcurrencyLease(true, this, nextPendingRequest.Count);
// Check if request was canceled
if (!nextPendingRequest.Tcs.TrySetResult(lease))
{
// Queued item was canceled so add count back
_permitCount += nextPendingRequest.Count;
}
nextPendingRequest.CancellationTokenRegistration.Dispose();
}
else
{
break;
}
}
}
}
