c# - NamedPipeServerStream.EndWaitForConnection()仅在使用时挂起

我正在尝试第一次使用命名管道。在MS文档中找到here，它指出:



因此，我试图成为一名优秀的小程序员并遵循文档，但是当我使用EndWaitForConnection()时，它会无限期地挂起。

因此，我将代码精简到最低限度，以查看是否可以隔离问题，但没有骰子。我从编写的类中拉出了以下代码。我已经对其进行了修改，以便它开始等待管道连接，然后立即尝试停止等待该管道连接:

private void WaitForConnectionCallBack(IAsyncResult result)
{

}

public void Start()
{
    var tempPipe = new NamedPipeServerStream("TempPipe",
                                             PipeDirection.In,
                                             254,
                                             PipeTransmissionMode.Message,
                                             PipeOptions.Asynchronous);

    IAsyncResult result = tempPipe.BeginWaitForConnection(
                                    new AsyncCallback(WaitForConnectionCallBack), this);

    tempPipe.EndWaitForConnection(result);  // <----- Hangs on this line right here
}

1)为什么卡在EndWaitForConnection()上？如果要在收到连接之前关闭服务器，该如何从本质上取消此BeginWaitForConnection()回调？

2)假设我没有上述问题。如果2个客户端尝试非常快速地连接到我的命名管道，会发生什么？

我是否对每个请求都进行了回调调用，还是必须等待接收第一个连接通知，然后快速先调用EndWaitForConnection()，然后再次调用WaitForConnectionCallBack()，才能再次开始监听下一个客户端？

在我看来，后者似乎是一个竞争条件，因为我可能没有足够快地设置连接监听器。

最佳答案

因此，对我有用的解决方案的基本框架如下:

private void WaitForConnectionCallBack(IAsyncResult result)
{
    try
    {
        PipeServer.EndWaitForConnection(result);

        /// ...
        /// Some arbitrary code
        /// ...
    }
    catch
    {
        // If the pipe is closed before a client ever connects,
        // EndWaitForConnection() will throw an exception.

        // If we are in here that is probably the case so just return.
        return;
    }
}

这是服务器代码。

public void Start()
{
    var server= new NamedPipeServerStream("TempPipe",
                                          PipeDirection.In,
                                          254,
                                          PipeTransmissionMode.Message,
                                          PipeOptions.Asynchronous);

    // If nothing ever connects, the callback will never be called.
    server.BeginWaitForConnection(new AsyncCallback(WaitForConnectionCallBack), this);

    // ... arbitrary code

// EndWaitForConnection() was not the right answer here, it would just wait indefinitely
// if you called it.  As Hans Passant mention, its meant to be used in the callback.
// Which it now is. Instead, we are going to close the pipe.  This will trigger
// the callback to get called.

// However, the EndWaitForConnection() that will excecute in the callback will fail
// with an exception since the pipe is closed by time it gets invoked,
// thus you must capture it with a try/catch

    server.Close(); // <--- effectively closes our pipe and gets our
                        //       BeginWaitForConnection() moving, even though any future
                        //       operations on the pipe will fail.
}