C#: Asynchronous NamedPipeServerStream The pipe is being closed 异常

Question

我之前关于同一主题的问题:C#: Asynchronous NamedPipeServerStream understanding现在我有下一个:

private void StartListeningPipes()
{
    try
    {
        isPipeWorking = true;
                namedPipeServerStream = new NamedPipeServerStream(PIPENAME, PipeDirection.InOut, 1, PipeTransmissionMode.Byte, PipeOptions.Asynchronous, BUFFERSIZE, BUFFERSIZE);
                Console.Write("Waiting for client connection...");
                while(isPipeWorking)
                {
            IAsyncResult asyncResult = namedPipeServerStream.BeginWaitForConnection(this.WaitForConnectionAsyncCallback, null);
                        Thread.Sleep(3*1000);
                }
        }
        //// Catch the IOException that is raised if the pipe is broken or disconnected.
        catch (IOException e)
        {
        Console.WriteLine("IOException: {0}. Restart pipe server...", e.Message);
                StopListeningPipes();
                StartListeningPipes();
        }
        //// Catch ObjectDisposedException if server was stopped. Then do nothing.
        catch (ObjectDisposedException)
        {
        }
}

private void WaitForConnectionAsyncCallback(IAsyncResult result)
{
    try
    {
        namedPipeServerStream.EndWaitForConnection(result);
        Console.WriteLine("Client connected.");
        namedPipeServerStream.WaitForPipeDrain();
                byte[] buff = new byte[BUFFERSIZE];
                namedPipeServerStream.Read(buff, 0, BUFFERSIZE);
                string recStr = TrimNulls(buff);
                Array.Clear(buff, 0, buff.Length);
                Console.WriteLine();
                Console.WriteLine("'"+recStr+"'");
    }
    catch (Exception e)
    {
        Console.WriteLine("Error: " + e.Message);            
        }
}

但是我得到了

管道正在关闭异常 每次我收到来自客户端的消息

为什么？

我的客户:

 using (NamedPipeClientStream pipeStream = new NamedPipeClientStream(General.PIPENAME))
{
    try
        {
        byte[] bytes = General.Iso88591Encoding.GetBytes(sendingMessage);
                pipeStream.Write(bytes, 0, bytes.Length);
                pipeStream.Flush();
                pipeStream.WaitForPipeDrain();
        }
        catch (TimeoutException)
        {
        Console.WriteLine("Timeout error!");
        }
    catch (Exception e)
        {
        Console.WriteLine(string.Format("Error! ", e.Message));
        }
}

---

目前的最终代码是:

/// <summary>
        /// Create new NamedPipeServerStream for listening to pipe client connection
        /// </summary>
        private void ListenForPipeClients()
        {
            if (!this.isListeningToClients)
                return;

            try
            {
                PipeSecurity ps = new PipeSecurity();
                PipeAccessRule par = new PipeAccessRule("Everyone", PipeAccessRights.ReadWrite, System.Security.AccessControl.AccessControlType.Allow);
                ps.AddAccessRule(par);
                pipeClientConnection = new NamedPipeServerStream(General.PIPENAME, PipeDirection.InOut, 1, PipeTransmissionMode.Byte, PipeOptions.Asynchronous, General.BUFFERSIZE, General.BUFFERSIZE, ps);
                Console.Write("Waiting for client connection...");
                /*namedPipeServerStream.WaitForConnection();
                OnPipeConnected(namedPipeServerStream);*/
                IAsyncResult result = pipeClientConnection.BeginWaitForConnection(OnPipeConnected, pipeClientConnection);
            }
            catch (ObjectDisposedException)
            {
                //// Catch ObjectDisposedException if server was stopped. Then do nothing.
            }
            catch (Exception e)
            {
                Console.WriteLine("Error occures: {0}. Restart pipe server...", e.Message);
                this.logger.Add(LogLevel.Warning, string.Format("Error occures: {0}. Restart pipe server...", e.Message));
                ListenForPipeClients();
            }
        }

        /// <summary>
        /// Async callback on client connected action
        /// </summary>
        /// <param name="asyncResult">Async result</param>
        private void OnPipeConnected(IAsyncResult asyncResult)
        {
            using (var conn = (NamedPipeServerStream)asyncResult.AsyncState)
            {
                try
                {
                    conn.EndWaitForConnection(asyncResult);
                    Console.WriteLine("Client connected.");
                    PipeClientConnection clientConnection = new PipeClientConnection(conn, notifierSenderCache, defaultStorageTime);
                }
                catch (Exception e)
                {
                    Console.WriteLine(e.Message);
                    this.logger.Add(LogLevel.Warning, e.Message);
                }
            }

            ListenForPipeClients();
        }

Answer 1

您似乎需要为每个客户端使用单独的 NamedPipeServerStream。 (请注意，我不是发现这一点的人，请参阅其他答案。)我想象工作服务器端看起来像这样(代码草案):

while(this.isServerRunning)
{
     var pipeClientConnection = new NamedPipeServerStream(...);

     try
     {
         pipeClientConnection.WaitForConnection();
     }
     catch(...)
     {
         ...
         continue;
     }

     ThreadPool.QueueUserWorkItem(state =>
          {
               // we need a separate variable here, so as not to make the lambda capture the pipeClientConnection variable, which is not recommended in multi-threaded scenarios
               using(var pipeClientConn = (NamedPipeServerStream)state)
               {
                    // do stuff
                    ...
               }
          }, pipeClientConnection);
}

作为旁注，正如在对您的问题的评论中指出的那样，通过在循环中调用 BeginWaitForConnection 每 3 秒启动一次新的异步调用是在浪费内存(唯一这不会浪费内存的情况是在小于 3 秒的时间间隔内建立新连接，但我怀疑你能肯定地知道这一点)。您会看到，基本上每 3 秒您就会启动一个新的异步调用，而不管最后一个调用是否仍在等待或已完成。此外，它再次没有考虑到您需要为每个客户端使用单独的 NamedPipeServerStream。

要解决此问题，您需要消除循环，并使用回调方法“链接”BeginWaitForConnection 调用。这是您在使用 .NET 时经常在异步 I/O 中看到的类似模式。代码草稿:

private void StartListeningPipes()
{
    if(!this.isServerRunning)
    {
        return;
    }

    var pipeClientConnection = new NamedPipeServerStream(...);

    try
    {
        pipeClientConnection.BeginWaitForConnection(asyncResult =>
            {
                // note that the body of the lambda is not part of the outer try... catch block!
                using(var conn = (NamedPipeServerStream)asyncResult.AsyncState)
                {
                    try
                    {
                        conn.EndWaitForConnection(asyncResult);
                    }
                    catch(...)
                    {
                        ...
                    }

                    // we have a connection established, time to wait for new ones while this thread does its business with the client
                    // this may look like a recursive call, but it is not: remember, we're in a lambda expression
                    // if this bothers you, just export the lambda into a named private method, like you did in your question
                    StartListeningPipes();

                    // do business with the client
                    conn.WaitForPipeDrain();
                    ...
                }
            }, pipeClientConnection);
    }
    catch(...)
    {
        ...
    }
}

控制流程是这样的:

• [主线程] StartListeningPipes():创建了NamedPipeServerStream，启动了BeginWaitForConnection()
• [线程池线程 1] 客户端 #1 连接，BeginWaitForConnection() 回调:EndWaitForConnection() 然后 StartListeningPipes()
• [线程池线程 1] StartListeningPipes():创建了新的 NamedPipeServerStream，BeginWaitForConnection() 调用
• [线程池线程 1] 回到 BeginWaitForConnection() 回调:开始处理连接的客户端(#1)
• [线程池线程 2] 客户端 #2 连接，BeginWaitForConnection() 回调:...
• ...

我认为这比使用阻塞 I/O 困难得多 - 事实上，我不太确定我做对了，如果你看到任何错误请指出 - 而且它也更令人困惑.

要在任一示例中暂停服务器，您显然需要将 this.isServerRunning 标志设置为 false。