C# SocketAsyncEventArgs 实现异步通信

Server

Program

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

namespace XGCServerSocketAsyncEventArgs
{
    class Program
    {
        static void Main(string[] args)
        {
            string ip = "127.0.0.1";
            int port = 3000;
            IPAddress ipAdress = IPAddress.Parse(ip);
            IPEndPoint ipe = new IPEndPoint(ipAdress, port);

            Server server = new Server(1024, 64);
            server.Init();
            server.Start(ipe);
        }
    }
}

Server

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

/// <summary>
/// https://msdn.microsoft.com/zh-cn/library/system.net.sockets.socketasynceventargs.aspx
/// </summary>
namespace XGCServerSocketAsyncEventArgs
{
    /// <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.
    ///
    /// 实现套接字服务器的连接逻辑。
    /// 接受连接后，从客户端读取的所有数据都将发送回客户端。
    /// 读取和回传到客户端模式将继续，直到客户端断开连接。
    /// </summary>
    class Server
    {
        /// <summary>
        /// the maximum number of connections the sample is designed to handle simultaneously 例子中设计的同时处理的最大连接数
        /// </summary>
        private int m_numConnections;

        /// <summary>
        /// buffer size to use for each socket I/O operation 
        /// 用于每个Socket I/O 操作的缓冲区大小
        /// </summary>
        private int m_receiveBufferSize;

        /// <summary>
        /// represents a large reusable set of buffers for all socket operations    
        /// 表示用于所有套接字操作的大量可重用的缓冲区
        /// </summary>
        private BufferManager m_bufferManager;

        /// <summary>
        /// read, write (don't alloc buffer space for accepts)  
        /// 读，写（不为接受连接分配缓冲区空间）
        /// </summary>
        const int opsToPreAlloc = 2;

        /// <summary>
        /// the socket used to listen for incoming connection requests
        /// </summary>
        Socket listenSocket;

        /// <summary>
        /// pool of reusable SocketAsyncEventArgs objects for write, read and accept socket operations
        /// 可重用SocketAsyncEventArgs对象的池，用于写入，读取和接受套接字操作
        /// </summary>
        SocketAsyncEventArgsPool m_readWritePool;

        /// <summary>
        /// counter of the total # bytes received by the server     
        /// 由服务器接收的总共＃个字节的计数器
        /// </summary>
        private int m_totalBytesRead;

        /// <summary>
        /// the total number of clients connected to the server 
        /// </summary>
        private int m_numConnectedSockets;

        /// <summary>
        /// 信号量
        /// </summary>
        Semaphore m_maxNumberAcceptedClients;

        /// <summary>
        /// Create an uninitialized server instance.  
        /// To start the server listening for connection requests call the Init method followed by Start method 
        /// 创建一个未初始化的服务器实例。
        /// 要开始监听连接请求的服务器，请调用Init方法，然后调用Start方法
        /// </summary>
        /// <param name="numConnections">the maximum number of connections the sample is designed to handle simultaneously</param>
        /// <param name="receivesBufferSize">buffer size to use for each socket I/O operation</param>
        public Server(int numConnections, int receivesBufferSize)
        {
            m_totalBytesRead = 0;
            m_numConnectedSockets = 0;
            m_numConnections = numConnections;
            m_receiveBufferSize = receivesBufferSize;

            // allocate buffers such that the maximum number of sockets can have one outstanding read and write posted to the socket simultaneously
            // 分配缓冲区，使得最大数量的套接字可以同时具有一个未完成的读写
            m_bufferManager = new BufferManager(receivesBufferSize * numConnections * opsToPreAlloc, receivesBufferSize);

            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, 
        /// but it is done this way to illustrate how the API can easily be used to create reusable objects to increase server performance.
        /// 通过预先分配可重用的缓冲区和上下文对象来初始化服务器。
        /// 这些对象不需要预先分配或重用，但是这样做是为了说明如何轻松地使用API来创建可重用的对象来提高服务器性能。
        /// </summary>
        public void Init()
        {
            // Allocates one large byte buffer which all I/O operations use a piece of.  This gaurds against memory fragmentation
            // 分配一个大字节缓冲区, 所有的 I/O 操作都使用一个。 这样对抗内存分裂
            m_bufferManager.InitBuffer();

            // preallocate pool of SocketAsyncEventArgs objects
            // 预先分配SocketAsyncEventArgs对象的池
            SocketAsyncEventArgs readWriteEventArg;

            for (int i = 0; i < m_numConnections; i++)
            {
                // Pre-allocate a set of reusable SocketAsyncEventArgs
                // 预先分配一组可重用的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
                // 给SocketAsyncEventArg对象从缓冲池分配一个字节缓冲区
                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 connection 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 在接收端口上接收
            StartAccept(null);

            //按任意键终止服务器进程....
            Console.WriteLine("Server Started : 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="p">The context object to use when issuing the accept operation on the server's listening socket</param>
        private void StartAccept(SocketAsyncEventArgs acceptEventArg)
        {
            if (acceptEventArg == null)
            {
                acceptEventArg = new SocketAsyncEventArgs();
                acceptEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(AcceptEventArgs_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>
        private void AcceptEventArgs_Completed(object sender, SocketAsyncEventArgs e)
        {
            ProcessAccept(e);
        }

        private void ProcessAccept(SocketAsyncEventArgs e)
        {
            // 为多个线程共享的变量提供原子操作。以原子操作的形式递增指定变量的值并存储结果。
            Interlocked.Increment(ref m_numConnectedSockets);

            string ipClient = e.AcceptSocket.RemoteEndPoint.ToString();
            Console.WriteLine("Server : Client [ {0} ] connected. There are {1} clients connected to server", ipClient, 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).UserSocket = 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);
            }

            // Accept the next connection request
            StartAccept(e);
        }

        /// <summary>
        /// This method is called whenever a receive or send operation is completed on a socket 
        /// </summary>
        /// <param name="e">SocketAsyncEventArg associated with the completed receive operation</param>
        private void IO_Completed(object sender, SocketAsyncEventArgs e)
        {
            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 asynchronous 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>
        /// <param name="e"></param>
        private void ProcessReceive(SocketAsyncEventArgs e)
        {
            AsyncUserToken token = (AsyncUserToken)e.UserToken;
            // e.BytesTransferred获取套接字操作中传输的字节数。 
            if (e.BytesTransferred > 0 && e.SocketError == SocketError.Success)
            {
                // 对两个 32 位整数进行求和并用和替换第一个整数，上述操作作为一个原子操作完成。
                Interlocked.Add(ref m_totalBytesRead, e.BytesTransferred);
                Console.WriteLine("Server : The server has read a total of {0} bytes", m_totalBytesRead);

                //echo the data received back to the client
                e.SetBuffer(e.Offset, e.BytesTransferred);
                bool willRaiseEvent = token.UserSocket.SendAsync(e);
                if (!willRaiseEvent)
                {
                    ProcessSend(e);
                }
            }
            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>
        private void ProcessSend(SocketAsyncEventArgs e)
        {
            if (e.SocketError == SocketError.Success)
            {
                // done echoing data back to the client     完成回传数据回到客户端
                AsyncUserToken token = (AsyncUserToken)e.UserToken;
                // read the next block of data send from the client     读取从客户端发送的下一个数据块
                bool willRaiseEvent = token.UserSocket.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.UserSocket.Shutdown(SocketShutdown.Send);
            }
            // throws if client process has already closed
            catch (Exception) { }

            token.UserSocket.Close();

            // Free the SocketAsyncEventArg so they can be reused by another client
            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);
        }
    }
}

AsyncUserToken

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

namespace XGCServerSocketAsyncEventArgs
{
    public class AsyncUserToken
    {
        public Socket UserSocket { get; set; }
        public String ID { get; set; }
    }
}

BufferManager

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

/// <summary>
/// https://msdn.microsoft.com/zh-cn/library/bb517542.aspx
/// </summary>
namespace XGCServerSocketAsyncEventArgs
{
    /// <summary>
    /// This class creates a single large buffer which can be divided up 
    /// and assigned to SocketAsyncEventArgs objects for use with each 
    /// socket I/O operation.  
    /// This enables bufffers to be easily reused and guards against 
    /// fragmenting heap memory.
    /// The operations exposed on the BufferManager class are not thread safe.
    /// 
    /// 该类创建一个可以分割并分配给SocketAsyncEventArgs对象的单个大型缓冲区，用于每个套接字 I/O 操作。
    /// 这样可以轻松地重用缓冲区，并防止破坏堆内存。
    /// BufferManager类上暴露的操作不是线程安全的。
    /// </summary>
    public class BufferManager
    {
        private int m_numBytes;                 // the total number of bytes controlled by the buffer pool      由缓冲池控制的总字节数
        private byte[] m_buffer;                // the underlying byte array maintained by the Buffer Manager   缓冲区管理器维护的底层字节数组
        private Stack<int> m_freeIndexPool;     // 用来存储每个 释放的SocketAsyncEventArgs对象的数据缓冲区的偏移 的栈结构
        private int m_currentIndex;             // 相当于一个游标，判断缓冲区最后存储字节的位置
        private int m_bufferSize;               // 传入字节的大小

        public BufferManager(int totalBytes, int bufferSize)
        {
            m_numBytes = totalBytes;
            m_currentIndex = 0;
            m_bufferSize = bufferSize;
            m_freeIndexPool = new Stack<int>();
        }

        /// <summary>
        /// Allocates buffer space used by the buffer pool   分配缓冲池使用的缓冲区
        /// </summary>
        public void InitBuffer()
        {
            // create one big large buffer and divide that out to each SocketAsyncEventArg object
            // 创建一个大的大缓冲区，并将其分隔给每个SocketAsyncEventArg对象
            m_buffer = new byte[m_numBytes];
        }


        /// <summary>
        /// Assigns a buffer from the buffer pool to the specified SocketAsyncEventArgs object
        /// <returns>true if the buffer was successfully set, else false</returns>
        /// 将缓冲池的缓冲区分配给指定的SocketAsyncEventArgs对象
        /// 如果缓冲区成功设置，则返回true，否则返回false
        /// </summary>
        public bool SetBuffer(SocketAsyncEventArgs args)
        {
            if (m_freeIndexPool.Count > 0)
            {
                args.SetBuffer(m_buffer, m_freeIndexPool.Pop(), m_bufferSize);
            }
            else
            {
                if ((m_numBytes - m_bufferSize) < m_currentIndex)
                {
                    return false;
                }
                args.SetBuffer(m_buffer, m_currentIndex, m_bufferSize);
                m_currentIndex += m_bufferSize;
            }
            return true;
        }

        /// <summary>
        /// Removes the buffer from a SocketAsyncEventArg object.  
        /// This frees the buffer back to the buffer pool
        /// 从SocketAsyncEventArg对象中删除缓冲区。
        /// 将缓冲区释放回缓冲池
        /// </summary>
        public void FreeBugffer(SocketAsyncEventArgs args)
        {
            m_freeIndexPool.Push(args.Offset);
            args.SetBuffer(null, 0, 0);
        }

    }
}

SocketAsyncEventArgsPool

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

/// <summary>
/// https://msdn.microsoft.com/zh-cn/library/system.net.sockets.socketasynceventargs.socketasynceventargs.aspx
/// </summary>
namespace XGCServerSocketAsyncEventArgs
{
    /// <summary>
    /// Represents a collection of reusable SocketAsyncEventArgs objects.  
    /// 表示可重用的SocketAsyncEventArgs对象的集合。
    /// </summary>
    public class SocketAsyncEventArgsPool
    {
        private Stack<SocketAsyncEventArgs> m_pool;

        public SocketAsyncEventArgsPool(int capacity)
        {
            m_pool = new Stack<SocketAsyncEventArgs>(capacity);
        }

        public void Push(SocketAsyncEventArgs item)
        {
            if (item == null) { throw new ArgumentException("Items added to a SocketAsyncEventArgsPool cannot be null"); }
            lock (m_pool)
            {
                m_pool.Push(item);
            }
        }

        public SocketAsyncEventArgs Pop()
        {
            lock (m_pool)
            {
                return m_pool.Pop();
            }
        }

        public int Count
        {
            get { return m_pool.Count; }
        }
    }
}

---

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Client

Program

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace XGCClientSocketAsyncEventArgs
{
    class Program
    {
        static void Main(string[] args)
        {
            string ip = "127.0.0.1";
            int port = 3000;
            Client m_client = new Client(ip, port);
            m_client.Start();
        }
    }
}

Client

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

namespace XGCClientSocketAsyncEventArgs
{
    class Client
    {
        public Socket m_socket;
        IPEndPoint m_endPoint;
        private SocketAsyncEventArgs m_connectSAEA;
        private SocketAsyncEventArgs m_sendSAEA;

        public Client(string ip, int port)
        {
            m_socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            IPAddress iPAddress = IPAddress.Parse(ip);
            m_endPoint = new IPEndPoint(iPAddress, port);
            m_connectSAEA = new SocketAsyncEventArgs { RemoteEndPoint = m_endPoint };
        }

        public void Start()
        {
            m_connectSAEA.Completed += OnConnectedCompleted;
            m_socket.ConnectAsync(m_connectSAEA);


            Thread.Sleep(5000);
            Send("Hello");

            //按任意键终止服务器进程....
            //Console.WriteLine("Client : Press any key to terminate the server process....");
            Console.ReadKey();
        }

        public void OnConnectedCompleted(object sender, SocketAsyncEventArgs e)
        {
            if (e.SocketError != SocketError.Success) return;
            Socket socket = sender as Socket;
            string iPRemote = socket.RemoteEndPoint.ToString();

            Console.WriteLine("Client : 连接服务器 [ {0} ] 成功",iPRemote);

            SocketAsyncEventArgs receiveSAEA = new SocketAsyncEventArgs();
            byte[] receiveBuffer = new byte[1024 * 4];
            receiveSAEA.SetBuffer(receiveBuffer, 0, receiveBuffer.Length);
            receiveSAEA.Completed += OnReceiveCompleted;
            receiveSAEA.RemoteEndPoint = m_endPoint;
            socket.ReceiveAsync(receiveSAEA);
        }

        private void OnReceiveCompleted(object sender, SocketAsyncEventArgs e)
        {
            if (e.SocketError == SocketError.OperationAborted) return;

            Socket socket = sender as Socket;

            if (e.SocketError == SocketError.Success && e.BytesTransferred > 0)
            {
                string ipAdress = socket.RemoteEndPoint.ToString();
                int lengthBuffer = e.BytesTransferred;
                byte[] receiveBuffer = e.Buffer;
                byte[] buffer = new byte[lengthBuffer];
                Buffer.BlockCopy(receiveBuffer, 0, buffer, 0, lengthBuffer);

                string msg = Encoding.Unicode.GetString(buffer);
                Console.WriteLine("Client : receive message[ {0} ],from Server[ {1} ]", msg, ipAdress);
                socket.ReceiveAsync(e);
            }
            else if (e.SocketError == SocketError.ConnectionReset && e.BytesTransferred == 0)
            {
                Console.WriteLine("Client: 服务器断开连接 ");
            }
            else
            {
                return;
            }
        }

        public void Send(string msg)
        {
            byte[] sendBuffer = Encoding.Unicode.GetBytes(msg);
            if (m_sendSAEA == null)
            {
                m_sendSAEA = new SocketAsyncEventArgs();
                m_sendSAEA.Completed += OnSendCompleted;
            }

            m_sendSAEA.SetBuffer(sendBuffer, 0, sendBuffer.Length);
            if (m_socket != null)
            {
                m_socket.SendAsync(m_sendSAEA);
            }
        }

        private void OnSendCompleted(object sender, SocketAsyncEventArgs e)
        {
            if (e.SocketError != SocketError.Success) return;
            Socket socket = sender as Socket;
            byte[] sendBuffer = e.Buffer;

            string sendMsg = Encoding.Unicode.GetString(sendBuffer);

            Console.WriteLine("Client : Send message [ {0} ] to Serer[ {1} ]", sendMsg, socket.RemoteEndPoint.ToString());
        }

        public void DisConnect()
        {
            if (m_socket != null)
            {
                try
                {
                    m_socket.Shutdown(SocketShutdown.Both);
                }
                catch (SocketException se)
                {
                }
                finally
                {
                    m_socket.Close();
                }
            }
        }
    }
}

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运行

Server

Client

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源码下载：http://download.youkuaiyun.com/download/fuemocheng/10022537