Dequeueing objects from a ConcurrentQueue in C#

Question

Hey, I\'m trying to implement a ConcurrentQueue in C# for an asynchronous server. Items are being queued as soon as a complete message is received. To dequeue messages, I\

Answer 1

You could use a static locking object for the threads to wait on and then pulse it when something is ready to be processed.

static readonly object queueLock = new object();

// Threads that enqueue an object
void QueueMessage() {
  lock (queueLock) {
    queue.Enqueue(obj);
    Monitor.Pulse(queueLock);
  }
}
// Thread dequeuer
private void startParsingMessages() {
  QueueContainer dequeued = null;
  Console.WriteLine("Trying");
  while (true) {
    lock(queueLock) {
      if (!queue.TryDequeue(out dequeued)) {
        Console.WriteLine("No object to dequeue, waiting...");
        // Threads will wait here and only one will be released when .Pulse()d
        Monitor.Wait(queueLock);
        dequeued = queue.Dequeue();
      }
      if (dequeued != null) {
        Console.WriteLine("processing queue");
        ProcessMessage(dequeued.socket, dequeued.message);
      }
    }
  }
}

Keep in mind that this can get quite complicated with the more branches you have, but the gist of it is, you lock on a common object and call Monitor.Wait to wait on an object to be Pulsed. When this happens only one thread that was waiting on it will be released. If you enqueue a lot of objects and want them all to go, you can call Monitor.PulseAll which will release all threads that were waiting on the object.