SaeQueuePool

 internal class SaeQueuePool {
        /// <summary>
        /// SocketAsyncEventArgs可复用队列
        /// </summary>
        private readonly ConcurrentQueue<SocketAsyncEventArgs> _saeQueue;

        /// <summary>
        /// 获取队列中的数量
        /// </summary>
        public int Count => _saeQueue.Count;

        /// <summary>
        /// 构造函数
        /// </summary>
        public SaeQueuePool(int count) {
            _saeQueue = new ConcurrentQueue<SocketAsyncEventArgs>();
            for (var i = 0; i < count; i++) { 
                _saeQueue.Enqueue(new SocketAsyncEventArgs()); 
            }
        }

        /// <summary>
        /// 取出项
        /// </summary>
        public Task<SocketAsyncEventArgs> Dequeue() {
            return Task.Run(() =>
             {
                 try
                 {
                     var success = _saeQueue.TryDequeue(out var item);
                     if (!success)
                         item = new SocketAsyncEventArgs();

                     item.Completed += Item_Completed;
                     return item; 
                 }
                 catch (System.Exception)
                 {
                     return null;

                 }
             });
        }

        /// <summary>
        /// 
        /// </summary>
        private void Item_Completed(object sender, SocketAsyncEventArgs e) {
            e.Completed -= Item_Completed;
            _saeQueue.Enqueue(e);
        }

        /// <summary>
        /// 退回项到池中
        /// </summary>
        public void Enqueue(SocketAsyncEventArgs sae) {
            sae.Completed -= Item_Completed;
            _saeQueue.Enqueue(sae);
        }
    }