fast mailbox

gistfile1.cs

public class Mailbox
{
    private static class MailboxStatus
    {
        public const int Idle = 0;
        public const int Busy = 1;
    }

    private readonly ConcurrentQueue<Envelope> _queue = new ConcurrentQueue<Envelope>();
    private volatile bool _hasUnScheduledMessages;
    private int _status;

    public void Run(object state)
    {
        Envelope envelope;
        while (_queue.TryDequeue(out envelope))
        {
            //insert code here
        }

        Interlocked.Exchange(ref _status, MailboxStatus.Idle);            

        if (_hasUnScheduledMessages)
        {
            _hasUnScheduledMessages = false;
            Schedule();
        }
    }

    public void Post(Envelope envelope)
    {
        _hasUnScheduledMessages = true;
        _queue.Enqueue(envelope);
        Schedule();
    }

    private void Schedule()
    {
        //only schedule if we idle
        if (Interlocked.Exchange(ref _status, MailboxStatus.Busy) == MailboxStatus.Idle)
        {
            ThreadPool.QueueUserWorkItem(Run);
        }
    }
}