public override IFetchedJob FetchNextJob(string[] queueNames, CancellationToken cancellationToken)
{
using (var ready = new SemaphoreSlim(0, queueNames.Length))
{
var waitNode = new InMemoryQueueWaitNode(ready);
var waitAdded = false;
while (!cancellationToken.IsCancellationRequested)
{
// TODO: Ensure duplicate queue names do not fail everything
var entries = _dispatcher.GetOrAddQueues(queueNames);
foreach (var entry in entries)
{
if (entry.Value.Queue.TryDequeue(out var jobId))
{
_dispatcher.SignalOneQueueWaitNode(entry.Value);
return(new InMemoryFetchedJob(_dispatcher, entry.Key, jobId));
}
}
if (!waitAdded && ready.CurrentCount == 0)
{
foreach (var entry in entries)
{
_dispatcher.AddQueueWaitNode(entry.Value, waitNode);
}
waitAdded = true;
continue;
}
ready.Wait(cancellationToken);
waitAdded = false;
}
}
cancellationToken.ThrowIfCancellationRequested();
return(null);
}
public override IFetchedJob FetchNextJob([NotNull] 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));
}
using (var cancellationEvent = cancellationToken.GetCancellationEvent())
{
var entries = _dispatcher.GetOrAddQueues(queues).ToArray();
var readyEvents = new WaitHandle[entries.Length + 1];
var waitAdded = new bool[entries.Length];
try
{
for (var i = 0; i < entries.Length; i++)
{
readyEvents[i] = new AutoResetEvent(false);
}
readyEvents[entries.Length] = cancellationEvent.WaitHandle;
while (!cancellationToken.IsCancellationRequested)
{
foreach (var entry in entries)
{
if (entry.Value.Queue.TryDequeue(out var jobId))
{
_dispatcher.SignalOneQueueWaitNode(entry.Value);
return(new InMemoryFetchedJob(_dispatcher, entry.Key, jobId));
}
}
for (var i = 0; i < entries.Length; i++)
{
if (!waitAdded[i])
{
_dispatcher.AddQueueWaitNode(entries[i].Value, new InMemoryQueueWaitNode((AutoResetEvent)readyEvents[i]));
waitAdded[i] = true;
}
}
var ready = WaitHandle.WaitAny(readyEvents, TimeSpan.FromSeconds(1));
if (ready != WaitHandle.WaitTimeout && ready < entries.Length)
{
waitAdded[ready] = false;
}
}
cancellationToken.ThrowIfCancellationRequested();
return(null);
}
finally
{
for (var i = 0; i < entries.Length; i++)
{
readyEvents[i]?.Dispose();
}
}
}
}
