C＃套接字和多线程

Question

我正在尝试了解有关C＃中的套接字和线程的更多信息。 我在网上遇到了很多很好的资源，可以帮助我入门。 到目前为止，我编写的程序是一个简单的“中间人”应用程序。 它的设计如下：客户端<-> [应用程序] <->服务器

给定以下代码，如何防止该线程在100％CPU上运行？ 当客户端/服务器空闲时，如何让线程等待并阻止数据并且不退出？

while (true)
       {
            lock (ClientState)
            {
                checkConnectionStatus(client, server);
            }

            if (clientStream.CanRead && clientStream.DataAvailable)
            {
                Byte[] bytes = new Byte[(client.ReceiveBufferSize)];

                IAsyncResult result = clientStream.BeginRead(bytes, 0, client.ReceiveBufferSize, null, null);
                int size = clientStream.EndRead(result);

                sendData(bytes, serverStream, size);
            }
            if (serverStream.CanRead && serverStream.DataAvailable)
            {
                Byte[] bytes = new byte[(server.ReceiveBufferSize)];

                IAsyncResult result = serverStream.BeginRead(bytes, 0, server.ReceiveBufferSize, null, null);
                int size = serverStream.EndRead(result);

                sendData(bytes, clientStream, size);
            }
        }

编辑：决定为有兴趣的人发布整个“ Connection.cs”类。 我是一名初学者，所以我知道这里有一些不良的编码做法。 基本上，整个类都在另一个线程中运行，并且（与客户端套接字或服务器套接字的连接）连接断开时，它们应该死亡。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
using System.Threading;
using System.Net;

namespace TCPRelay
{
public class Connection
{
    public delegate void delThreadSafeHandleException(System.Exception ex);
    public delegate void ConnectionDelegate(Connection conn);
    public int DataGridIndex;

    Main pMain;

    public TcpClient client { get; set; }
    public TcpClient server { get; set; }
    public String ClientState { get; set; }

    public string ListenPort { get; set; }
    public string remotePort { get; set; }

    public string listenAddress { get; set; }
    public string remoteAddress { get; set; }

    private TcpListener service { get; set; }

    private Main Form
    {
        get
        {
            return pMain;
        }
    }
    private NetworkStream clientStream { get; set; }
    private NetworkStream serverStream { get; set; }


    public Connection(TcpClient client, TcpClient server)
    {
        clientStream = client.GetStream();
        serverStream = server.GetStream();
    }

    public Connection(String srcAddress, int srcPort, String dstAddress, int dstPort, Main caller)
    {
        try
        {
            pMain = caller;
            TcpListener _service = new TcpListener((IPAddress.Parse(srcAddress)), srcPort);

            //Start the client service and add to connection property
            _service.Start();
            service = _service;


            //Set other useful parameters
            listenAddress = srcAddress;
            ListenPort = srcPort.ToString();

            remoteAddress = dstAddress;
            remotePort = dstPort.ToString();

            this.ClientState = "Listening";
        }
        catch (Exception ex)
        {
            pMain.HandleException(ex);
            Thread.CurrentThread.Abort();
        }

    }

    private TcpClient getServerConnection(String address, int port)
    {
        TcpClient client = new TcpClient(address, port);
        if (client.Connected)
        {
            return client;
        }
        else
        {
            throw new Exception(
                String.Format("Unable to connect to {0} on port {0}",
                address,
                port)
                );
        }
    }
    private void sendData(Byte[] databuf, NetworkStream stream, int size)
    {
        bool waiting = true;
        while (waiting)
        {
            if (stream.CanWrite)
            {
                waiting = false;
                stream.Write(databuf, 0, size);
            }
            else { throw new Exception("Unable to write to network stream"); }
        }
    }

    //Main Looping and data processing goes here
    public void ProcessClientRequest()
    {
        try
        {
            //Wait for a connection to the client
            TcpClient client = service.AcceptTcpClient();

            //Get the streams and set the peer endpoints
            this.clientStream = client.GetStream();
            this.client = client;

            //Now that we have a client, lets connect to our server endpoint
            TcpClient server = getServerConnection(remoteAddress, int.Parse(remotePort));

            //Set some useful parameters
            this.server = server;
            this.serverStream = server.GetStream();
        }
        catch (Exception ex)
        {
            lock (ClientState)
            {
                this.ClientState = ex.Message;    
            }

            CloseConnection();
            Thread.CurrentThread.Abort();
        }
        while (true)
       {
            lock (ClientState)
            {
                checkConnectionStatus(client, server);
            }

            if (clientStream.CanRead && clientStream.DataAvailable)
            {
                Byte[] bytes = new Byte[(client.ReceiveBufferSize)];

                IAsyncResult result = clientStream.BeginRead(bytes, 0, client.ReceiveBufferSize, null, null);
                int size = clientStream.EndRead(result);

                sendData(bytes, serverStream, size);
            }
            if (serverStream.CanRead && serverStream.DataAvailable)
            {
                Byte[] bytes = new byte[(server.ReceiveBufferSize)];

                IAsyncResult result = serverStream.BeginRead(bytes, 0, server.ReceiveBufferSize, null, null);
                int size = serverStream.EndRead(result);

                sendData(bytes, clientStream, size);
            }
        }
    }

    private void checkConnectionStatus(TcpClient _client, TcpClient _server)
    {
        try
        {
            if (_client.Client.Poll(0, SelectMode.SelectRead))
            {
                byte[] buff = new byte[1];
                if (_client.Client.Receive(buff, SocketFlags.Peek) == 0)
                {
                    this.ClientState = "Closed";
                    CloseConnection();
                    Thread.CurrentThread.Abort();
                }
            }
            else if (_server.Client.Poll(0, SelectMode.SelectRead))
            {
                byte[] buff = new byte[1];
                if (_server.Client.Receive(buff, SocketFlags.Peek) == 0)
                {
                    this.ClientState = "Closed";
                    CloseConnection();
                    Thread.CurrentThread.Abort();
                }
            }
            else { this.ClientState = "Connected"; }
        }
        catch (System.Net.Sockets.SocketException ex)
        {
            this.ClientState = ex.SocketErrorCode.ToString();
            CloseConnection();
            Thread.CurrentThread.Abort();
        }
    }

    public void CloseConnection()
    {
        if (clientStream != null)
        {
            clientStream.Close();
            clientStream.Dispose();
        }

        if (client != null)
        {
            client.Close();
        }

        if (serverStream != null)
        {
            serverStream.Close();
            serverStream.Dispose();
        }

        if (server != null)
        {
            server.Close();
        }

        if (service != null)
        {
            service.Stop();
        }
    }       
}

}

我也有一个“ Main”窗体和一个“ ConnectionManager”类，我正在玩。

Answer 1

处理此问题的最有效方法是在每个流上通过回调发出读取。

发出两次读取后，请在要用来发出线程应停止其工作信号的对象上永远等待（ManualResetEvent是传统上使用的对象-可用于一次发出多个线程信号）。

收到数据后，操作系统将调用您的回调函数，您将在其中进行处理，然后（重要地）将另一个读取排队。

这意味着您的线程永远是空闲的，正在等待一个信号对象，该对象告诉它该离开了（以一种“唤醒-死亡的时间”之类的方式），并且只有在OS告诉它时才做有数据要处理。

为真正友好起见，您还可以异步进行写操作，以使一个连接不能耗尽另一个连接的处理时间（在当前实现中，如果一个写阻塞，则另一个流永远不会得到服务）。

最后，要获得超好效果，您可以将此行为封装在一个对象中，该对象将要使用的流作为参数，然后简单地实例化它们中的两个，而不是拥有两个流并在主代码中进行两次操作。

Answer 2

在接受中间人的套接字后，我执行以下操作：

 private void WaitForData()
    {
        try
        {
            if (socketReadCallBack == null)
            {
                socketReadCallBack = new AsyncCallback(OnDataReceived);
            }

            ReceiveState rState = new ReceiveState();
            rState.Client = mySocket;

            mySocket.BeginReceive(rState.Buffer, 0, rState.Buffer.Length, SocketFlags.None,
                new AsyncCallback(socketReadCallBack), rState);

        }
        catch (SocketException excpt)
        {
            // Process Exception
        }

    }

接收状态为：

public class ReceiveState
  {
    public byte[] Buffer = new byte[1024]; //buffer for network i/o
    public int DataSize = 0; //data size to be received by the server
    public bool DataSizeReceived = false; //whether prefix was received
    public MemoryStream Data = new MemoryStream(); //place where data is stored
    public Socket Client;   //client socket
   }

接收到数据后，我的例程“ OnDataReceived”将对其进行处理。 我没有遇到任何CPU问题。

客户端和中间人使用相同的代码。