public virtual IFetchedJob FetchNextJob(string[] queues, CancellationToken cancellationToken)
{
if (queues == null)
{
throw new ArgumentNullException(nameof(queues));
}
if (queues.Length == 0)
{
throw new ArgumentException("Queue array must be non-empty.", nameof(queues));
}
MongoFetchedJob fetchedJob = null;
var tryAllQueues = true;
while (fetchedJob == null)
{
cancellationToken.ThrowIfCancellationRequested();
if (tryAllQueues)
{
fetchedJob = TryAllQueues(queues, cancellationToken);
}
if (fetchedJob != null)
{
// make sure to try to decrement semaphore if we succeed in getting a job from the queue
_semaphore.WaitNonBlock(fetchedJob.Queue);
return(fetchedJob);
}
if (_semaphore.WaitAny(queues, cancellationToken, _storageOptions.QueuePollInterval, out var queue, out var timedOut))
{
fetchedJob = TryGetEnqueuedJob(queue, cancellationToken);
}
// at this point only try all queues if semaphore timed out
tryAllQueues = timedOut;
}
return(fetchedJob);
}