异步套接字错误

本文关键字:错误 套接字 异步 | 更新日期: 2023-09-27 18:25:57

我试图在这个ms示例中进行一些小的更改我想做"聊天服务器"从这个"回声服务器"的例子

所以。。。

我在类服务器中添加了一些块,这很好,但。。。就在两个telnet连接之间,当我添加两个以上的客户端时,我会收到错误"使用此SocketAsyncEventArgs实例已经在进行异步套接字操作。";

你能告诉我哪里出错了吗?非常感谢。

这是我的服务器类:

namespace AsyncSocketSample
{
    /// <summary>
    /// Implements the connection logic for the socket server.  After accepting a connection, all data read
    /// from the client is sent back to the client.  The read and echo back to the client pattern is continued 
    /// until the client disconnects.
    /// </summary>
    class Server
    {
        private int m_numConnections;   // the maximum number of connections the sample is designed to handle simultaneously 
        private int m_receiveBufferSize;// buffer size to use for each socket I/O operation 
        BufferManager m_bufferManager;  // represents a large reusable set of buffers for all socket operations
        const int opsToPreAlloc = 2;    // read, write (don't alloc buffer space for accepts)
        Socket listenSocket;            // the socket used to listen for incoming connection requests
        // pool of reusable SocketAsyncEventArgs objects for write, read and accept socket operations
        SocketAsyncEventArgsPool m_readWritePool;
        int m_totalBytesRead;           // counter of the total # bytes received by the server
        int m_numConnectedSockets;      // the total number of clients connected to the server 
        Semaphore m_maxNumberAcceptedClients;
        //The ClientInfo structure holds the required information about every
        //client connected to the server
        struct ClientInfo
        {
            public Socket socket;   //Socket of the client
            public AsyncUserToken token; // User Token
            //public string strName;  //Name by which the user logged into the chat room
        }
        //The collection of all clients logged into the room (an array of type ClientInfo)
        ArrayList clientList = new ArrayList();
        /// <summary>
        /// Create an uninitialized server instance.  To start the server listening for connection requests
        /// call the Init method followed by Start method 
        /// </summary>
        /// <param name="numConnections">the maximum number of connections the sample is designed to handle simultaneously</param>
        /// <param name="receiveBufferSize">buffer size to use for each socket I/O operation</param>
        public Server(int numConnections, int receiveBufferSize)
        {
            m_totalBytesRead = 0;
            m_numConnectedSockets = 0;
            m_numConnections = numConnections;
            m_receiveBufferSize = receiveBufferSize;
            // allocate buffers such that the maximum number of sockets can have one outstanding read and 
            //write posted to the socket simultaneously  
            m_bufferManager = new BufferManager(receiveBufferSize * numConnections * opsToPreAlloc,
                receiveBufferSize);
            m_readWritePool = new SocketAsyncEventArgsPool(numConnections);
            m_maxNumberAcceptedClients = new Semaphore(numConnections, numConnections); 
        }
        /// <summary>
        /// Initializes the server by preallocating reusable buffers and context objects.  These objects do not 
        /// need to be preallocated or reused, by is done this way to illustrate how the API can easily be used
        /// to create reusable objects to increase server performance.
        /// </summary>
        public void Init()
        {
            // Allocates one large byte buffer which all I/O operations use a piece of.  This gaurds 
            // against memory fragmentation
            m_bufferManager.InitBuffer();
            // preallocate pool of SocketAsyncEventArgs objects
            SocketAsyncEventArgs readWriteEventArg;
            for (int i = 0; i < m_numConnections; i++)
            {
                //Pre-allocate a set of reusable SocketAsyncEventArgs
                readWriteEventArg = new SocketAsyncEventArgs();
                readWriteEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(IO_Completed);
                readWriteEventArg.UserToken = new AsyncUserToken();
                // assign a byte buffer from the buffer pool to the SocketAsyncEventArg object
                m_bufferManager.SetBuffer(readWriteEventArg);
                // add SocketAsyncEventArg to the pool
                m_readWritePool.Push(readWriteEventArg);
            }
        }
        /// <summary>
        /// Starts the server such that it is listening for incoming connection requests.    
        /// </summary>
        /// <param name="localEndPoint">The endpoint which the server will listening for conenction requests on</param>
        public void Start(IPEndPoint localEndPoint)
        {
            // create the socket which listens for incoming connections
            listenSocket = new Socket(localEndPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
            listenSocket.Bind(localEndPoint);
            // start the server with a listen backlog of 100 connections
            listenSocket.Listen(100);
            // post accepts on the listening socket
            StartAccept(null);            
            //Console.WriteLine("{0} connected sockets with one outstanding receive posted to each....press any key", m_outstandingReadCount);
            Console.WriteLine("Press any key to terminate the server process....");
            Console.ReadKey();
        }

        /// <summary>
        /// Begins an operation to accept a connection request from the client 
        /// </summary>
        /// <param name="acceptEventArg">The context object to use when issuing the accept operation on the 
        /// server's listening socket</param>
        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);
        }
        private void ProcessAccept(SocketAsyncEventArgs e)
        {
            Interlocked.Increment(ref m_numConnectedSockets);
            Console.WriteLine("Client connection accepted. There are {0} clients connected to the server",
                m_numConnectedSockets);
            // Get the socket for the accepted client connection and put it into the 
            //ReadEventArg object user token
            SocketAsyncEventArgs readEventArgs = m_readWritePool.Pop();
            ((AsyncUserToken)readEventArgs.UserToken).Socket = e.AcceptSocket;
            // As soon as the client is connected, post a receive to the connection
            bool willRaiseEvent = e.AcceptSocket.ReceiveAsync(readEventArgs);
            if(!willRaiseEvent){
                ProcessReceive(readEventArgs);
            }
            ClientInfo clientInfo = new ClientInfo();
            clientInfo.socket = ((AsyncUserToken)readEventArgs.UserToken).Socket;
            clientInfo.token =  (AsyncUserToken)readEventArgs.UserToken;
            clientList.Add(clientInfo);
            // Accept the next connection request
            StartAccept(e);
        }
        /// <summary>
        /// This method is called whenever a receive or send opreation is completed on a socket 
        /// </summary> 
        /// <param name="e">SocketAsyncEventArg associated with the completed receive operation</param>
        void IO_Completed(object sender, SocketAsyncEventArgs e)
        {
            // determine which type of operation just completed and call the associated handler
            switch (e.LastOperation)
            {
                case SocketAsyncOperation.Receive:
                    ProcessReceive(e);
                    break;
                case SocketAsyncOperation.Send:
                    ProcessSend(e);
                    break;
                default:
                    throw new ArgumentException("The last operation completed on the socket was not a receive or send");
            }       
        }
        /// <summary>
        /// This method is invoked when an asycnhronous receive operation completes. If the 
        /// remote host closed the connection, then the socket is closed.  If data was received then
        /// the data is echoed back to the client.
        /// </summary>
        private void ProcessReceive(SocketAsyncEventArgs e)
        {
            // check if the remote host closed the connection
            AsyncUserToken token = (AsyncUserToken)e.UserToken;
            if (e.BytesTransferred > 0 && e.SocketError == SocketError.Success)
            {
                //increment the count of the total bytes receive by the server
                Interlocked.Add(ref m_totalBytesRead, e.BytesTransferred);
                Console.WriteLine("The server has read a total of {0} bytes", m_totalBytesRead);
                ///////////////////////////////////////////////////////////////////////////////////////////////////

                try
                {
                    foreach (ClientInfo clientInfo in clientList)
                    {
                        if (clientInfo.token != token)
                        {                           
                            //Data received send to the all client but not for sender
                            bool willRaiseEvent = clientInfo.token.Socket.SendAsync(e); // token.Socket.SendAsync(e);
                            if (!willRaiseEvent)
                            {
                                ProcessSend(e);
                            }
                        }
                    }
                }
                catch (Exception x)
                {
                    Console.WriteLine(x.Message.ToString());
                    Console.ReadKey();
                }
                ///////////////////////////////////////////////////////////////////////////////////////////////////

            }
            else
            {
                CloseClientSocket(e);
            }
        }
        /// <summary>
        /// This method is invoked when an asynchronous send operation completes.  The method issues another receive
        /// on the socket to read any additional data sent from the client
        /// </summary>
        /// <param name="e"></param>
        private void ProcessSend(SocketAsyncEventArgs e)
        {
            if (e.SocketError == SocketError.Success)
            {
                // done echoing data back to the client
                AsyncUserToken token = (AsyncUserToken)e.UserToken;
                // read the next block of data send from the client
                bool willRaiseEvent = token.Socket.ReceiveAsync(e);
                if (!willRaiseEvent)
                {
                    ProcessReceive(e);
                }
            }
            else
            {
                CloseClientSocket(e);
            }
        }
        private void CloseClientSocket(SocketAsyncEventArgs e)
        {
            AsyncUserToken token = e.UserToken as AsyncUserToken;
            // close the socket associated with the client
            try
            {
                token.Socket.Shutdown(SocketShutdown.Send);
            }
            // throws if client process has already closed
            catch (Exception) { }
            token.Socket.Close();
            ///////////////////////////////////////////
            // Connection is terminated, either by force or
            // willingly
            int nIndex = 0;
            foreach (ClientInfo client in clientList)
            {
                if (client.token == token)
                {
                    clientList.RemoveAt(nIndex);
                    break;
                }
                ++nIndex;
            }
            ///////////////////////////////////////////
            // decrement the counter keeping track of the total number of clients connected to the server
            Interlocked.Decrement(ref m_numConnectedSockets);
            m_maxNumberAcceptedClients.Release();
            Console.WriteLine("A client has been disconnected from the server. There are {0} clients connected to the server", m_numConnectedSockets);
            // Free the SocketAsyncEventArg so they can be reused by another client
            m_readWritePool.Push(e);
        }
    }

异步套接字错误

最有可能的是:

foreach (ClientInfo clientInfo in clientList)
{
    if (clientInfo.token != token)
    {                           
        //Data received send to the all client but not for sender
        bool willRaiseEvent = clientInfo.token.Socket.SendAsync(e); // token.Socket.SendAsync(e);
        if (!willRaiseEvent)
        {
            ProcessSend(e);
        }
    }
}

您正在使用相同的e向多个客户端发送异步消息。这是注定的。每个操作都需要不同的参数。这个API确实允许池化参数以重用它们,但首先我要说:让它每次都使用一个新的参数。然后进行优化。

还要注意,ProcessReceive可能应该启动下一个异步接收,否则它们只能发送一条消息。你也需要注意,因为你目前已经开始发送接收;如果你向一个正在监听的套接字发送3条消息,事情就会变得非常混乱。就我个人而言,我会让完全独立的接收和发送处理。发送只是发送;receive只是接收。

正如Mark所写,明显的问题在于ProcessReceive方法,该方法试图使用相同的EventArgs向多个客户端发送数据。作为一个最小工作量的解决方案,您可以每次分配EventArgs,但您应该知道这不是编写此类应用程序的方式。对于发送操作,应该有一个数据包队列(在这种情况下,是简单的字节数组)与ReaderWriterLockSlim等同步原语一起使用,或者只是一个ConcurrentQueue。在发送操作回调中,您检查队列,如果它不是空的,则退出下一个数据包的队列并发送它。由于这是一个双工场景,而不是请求/响应,所以接收不应该作为对发送内容的反应开始,相反,接收应该在循环中工作,在循环条件下,您应该检查套接字是否仍然可用。

您所拥有的代码非常适合请求/响应故事。对于你试图解决的问题,我建议你看看更高级的东西,比如这个框架。