public void AddQueueWaitNode(QueueEntry entry, InMemoryQueueWaitNode node)
{
var headNext = node.Next = null;
var spinWait = new SpinWait();
while (true)
{
var newNext = Interlocked.CompareExchange(ref entry.WaitHead.Next, node, headNext);
if (newNext == headNext)
{
break;
}
headNext = node.Next = newNext;
spinWait.SpinOnce();
}
}
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);
}
