.net - 异步套接字-处理错误的socket.AcceptAsync值

Question

Socket类具有方法.AcceptAsync，该方法返回true或false。

我本以为错误的返回值是一个错误情况，但是在Microsoft提供的Async套接字示例中，它们在检查失败后同步调用了回调函数，如下所示:

public void StartAccept(SocketAsyncEventArgs acceptEventArg)
    {
        if (acceptEventArg == null)
        {
            acceptEventArg = new SocketAsyncEventArgs();
            acceptEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(AcceptEventArg_Completed);
        }
        else
        {
            // socket must be cleared since the context object is being reused
            acceptEventArg.AcceptSocket = null;
        }

        m_maxNumberAcceptedClients.WaitOne();
        bool willRaiseEvent = listenSocket.AcceptAsync(acceptEventArg);
        if (!willRaiseEvent)
        {
            ProcessAccept(acceptEventArg);
        }
    }

    /// <summary>
    /// This method is the callback method associated with Socket.AcceptAsync operations and is invoked
    /// when an accept operation is complete
    /// </summary>
    void AcceptEventArg_Completed(object sender, SocketAsyncEventArgs e)
    {
        ProcessAccept(e);
    }

他们为什么这样做呢？它违反了异步套接字的目的，并阻止了该方法的返回。

Answer 1

根据AcceptAsync规范:

Returns false if the I/O operation completed synchronously. The SocketAsyncEventArgs.Completed event on the e parameter will not be raised and the e object passed as a parameter may be examined immediately after the method call returns to retrieve the result of the operation.

当它返回false时，您应该立即处理新接受的套接字。