hehe2

    public class Queue<T>
    {
        private readonly ConcurrentQueue<T> _queue = new ConcurrentQueue<T>();
        private long _count = 0;
        private readonly Action<T> _action = null;

        public Queue(Action<T> action)
        {
            _action = action;
        }

        public void EnqueueAsync(T item)
        {
            var count = Interlocked.Increment(ref _count);
            _queue.Enqueue(item);
            if (count == 1)
            {
                Task.Run(() => Dequeue());
            }
        }

        private async void Dequeue()
        {
            while (true)
            {
                T item;
                if (_queue.TryDequeue(out item))
                {
                    _action(item);
                    var count = Interlocked.Decrement(ref _count);
                    if (count == 0)
                    {
                        return;
                    }
                }
                else
                {
                    await Task.Yield();
                }
            }
        }
    }