C#编写高性能网络服务器（源码）

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最近有项目要做一个高性能网络服务器，决定下功夫搞定完成端口（IOCP），最终花了一个星期终于把它弄清楚了，并用C++写了一个版本，效率很不错。

但，从项目的总体需求来考虑，最终决定上.net平台，因此又花了一天一夜弄出了一个C#版，在这与大家分享。

一些心得体会：

1、在C#中，不用去面对完成端口的操作系统内核对象，Microsoft已经为我们提供了SocketAsyncEventArgs类，它封装了IOCP的使用。请参考：http://msdn.microsoft.com/zh-cn/library/system.net.sockets.socketasynceventargs.aspx?cs-save-lang=1&cs-lang=cpp#code-snippet-1。

2、我的SocketAsyncEventArgsPool类使用List对象来存储对客户端来通信的SocketAsyncEventArgs对象，它相当于直接使用内核对象时的IoContext。我这样设计比用堆栈来实现的好处理是，我可以在SocketAsyncEventArgsPool池中找到任何一个与服务器连接的客户，主动向它发信息。而用堆栈来实现的话，要主动给客户发信息，则还要设计一个结构来存储已连接上服务器的客户。

3、对每一个客户端不管还发送还是接收，我使用同一个SocketAsyncEventArgs对象，对每一个客户端来说，通信是同步进行的，也就是说服务器高度保证同一个客户连接上要么在投递发送请求，并等待；或者是在投递接收请求，等待中。本例只做echo服务器，还未考虑由服务器主动向客户发送信息。

4、SocketAsyncEventArgs的UserToken被直接设定为被接受的客户端Socket。

5、没有使用BufferManager 类，因为我在初始化时给每一个SocketAsyncEventArgsPool中的对象分配一个缓冲区，发送时使用Arrary.Copy来进行字符拷贝，不去改变缓冲区的位置，只改变使用的长度，因此在下次投递接收请求时恢复缓冲区长度就可以了！如果要主动给客户发信息的话，可以new一个SocketAsyncEventArgs对象，或者在初始化中建立几个来专门用于主动发送信息，因为这种需求一般是进行信息群发，建立一个对象可以用于很多次信息发送，总体来看，这种花销不大，还减去了字符拷贝和消耗。

6、测试结果：（在我的笔记本上时行的，我的本本是T420 I7 8G内存）

100客户 100，000（十万次）不间断的发送接收数据（发送和接收之间没有Sleep，就一个一循环，不断的发送与接收）
耗时3004.6325 秒完成
总共 10,000,000 一千万次访问
平均每分完成 199,691.6 次发送与接收
平均每秒完成 3,328.2 次发送与接收

整个运行过程中，内存消耗在开始两三分种后就保持稳定不再增涨。

看了一下对每个客户端的延迟最多不超过2毫秒，CPU占用在8%左右。

7、下载地址：http://download.csdn.net/detail/ztk12/4928644

8、源码

IoServer.cs
using System;
using System.Collections.Generic;
using System.Text;
using System.Net.Sockets;
using System.Threading;
using System.Net;

namespace IocpServer
{
/// <summary>
/// 基于SocketAsyncEventArgs 实现 IOCP 服务器
/// </summary>
internal sealed class IoServer
{
/// <summary>
/// 监听Socket，用于接受客户端的连接请求
/// </summary>
private Socket listenSocket;

/// <summary>
/// 用于服务器执行的互斥同步对象
/// </summary>
private static Mutex mutex = new Mutex();

/// <summary>
/// 用于每个I/O Socket操作的缓冲区大小
/// </summary>
private Int32 bufferSize;

/// <summary>
/// 服务器上连接的客户端总数
/// </summary>
private Int32 numConnectedSockets;

/// <summary>
/// 服务器能接受的最大连接数量
/// </summary>
private Int32 numConnections;

/// <summary>
/// 完成端口上进行投递所用的IoContext对象池
/// </summary>
private IoContextPool ioContextPool;

public MainForm mainForm;

/// <summary>
/// 构造函数，建立一个未初始化的服务器实例
/// </summary>
/// <param name="numConnections">服务器的最大连接数据</param>
/// <param name="bufferSize"></param>
internal IoServer(Int32 numConnections, Int32 bufferSize)
{
this.numConnectedSockets = 0;
this.numConnections = numConnections;
this.bufferSize = bufferSize;

this.ioContextPool = new IoContextPool(numConnections);

// 为IoContextPool预分配SocketAsyncEventArgs对象
for (Int32 i = 0; i < this.numConnections; i++)
{
SocketAsyncEventArgs ioContext = new SocketAsyncEventArgs();
ioContext.Completed += new EventHandler<SocketAsyncEventArgs>(OnIOCompleted);
ioContext.SetBuffer(new Byte[this.bufferSize], 0, this.bufferSize);

// 将预分配的对象加入SocketAsyncEventArgs对象池中
this.ioContextPool.Add(ioContext);
}
}

/// <summary>
/// 当Socket上的发送或接收请求被完成时，调用此函数
/// </summary>
/// <param name="sender">激发事件的对象</param>
/// <param name="e">与发送或接收完成操作相关联的SocketAsyncEventArg对象</param>
private void OnIOCompleted(object sender, SocketAsyncEventArgs e)
{
// Determine which type of operation just completed and call the associated handler.
switch (e.LastOperation)
{
case SocketAsyncOperation.Receive:
this.ProcessReceive(e);
break;
case SocketAsyncOperation.Send:
this.ProcessSend(e);
break;
default:
throw new ArgumentException("The last operation completed on the socket was not a receive or send");
}
}

/// <summary>
///接收完成时处理函数
/// </summary>
/// <param name="e">与接收完成操作相关联的SocketAsyncEventArg对象</param>
private void ProcessReceive(SocketAsyncEventArgs e)
{
// 检查远程主机是否关闭连接
if (e.BytesTransferred > 0)
{
if (e.SocketError == SocketError.Success)
{
Socket s = (Socket)e.UserToken;
//判断所有需接收的数据是否已经完成
if (s.Available == 0)
{
// 设置发送数据
Array.Copy(e.Buffer, 0, e.Buffer, e.BytesTransferred, e.BytesTransferred);
e.SetBuffer(e.Offset, e.BytesTransferred * 2);
if (!s.SendAsync(e))        //投递发送请求，这个函数有可能同步发送出去，这时返回false，并且不会引发SocketAsyncEventArgs.Completed事件
{
// 同步发送时处理发送完成事件
this.ProcessSend(e);
}
}
else if (!s.ReceiveAsync(e))    //为接收下一段数据，投递接收请求，这个函数有可能同步完成，这时返回false，并且不会引发SocketAsyncEventArgs.Completed事件
{
// 同步接收时处理接收完成事件
this.ProcessReceive(e);
}
}
else
{
this.ProcessError(e);
}
}
else
{
this.CloseClientSocket(e);
}
}

/// <summary>
/// 发送完成时处理函数
/// </summary>
/// <param name="e">与发送完成操作相关联的SocketAsyncEventArg对象</param>
private void ProcessSend(SocketAsyncEventArgs e)
{
if (e.SocketError == SocketError.Success)
{
Socket s = (Socket)e.UserToken;

//接收时根据接收的字节数收缩了缓冲区的大小，因此投递接收请求时，恢复缓冲区大小
e.SetBuffer(0, bufferSize);
if (!s.ReceiveAsync(e))     //投递接收请求
{
// 同步接收时处理接收完成事件
this.ProcessReceive(e);
}
}
else
{
this.ProcessError(e);
}
}

/// <summary>
/// 处理socket错误
/// </summary>
/// <param name="e"></param>
private void ProcessError(SocketAsyncEventArgs e)
{
Socket s = e.UserToken as Socket;
IPEndPoint localEp = s.LocalEndPoint as IPEndPoint;

this.CloseClientSocket(s, e);

string outStr = String.Format("套接字错误 {0}, IP {1}, 操作 {2}。", (Int32)e.SocketError, localEp, e.LastOperation);
mainForm.Invoke(mainForm.setlistboxcallback, outStr);
//Console.WriteLine("Socket error {0} on endpoint {1} during {2}.", (Int32)e.SocketError, localEp, e.LastOperation);
}

/// <summary>
/// 关闭socket连接
/// </summary>
/// <param name="e">SocketAsyncEventArg associated with the completed send/receive operation.</param>
private void CloseClientSocket(SocketAsyncEventArgs e)
{
Socket s = e.UserToken as Socket;
this.CloseClientSocket(s, e);
}

private void CloseClientSocket(Socket s, SocketAsyncEventArgs e)
{
Interlocked.Decrement(ref this.numConnectedSockets);

// SocketAsyncEventArg 对象被释放，压入可重用队列。
this.ioContextPool.Push(e);
string outStr = String.Format("客户 {0} 断开, 共有 {1} 个连接。", s.RemoteEndPoint.ToString(), this.numConnectedSockets);
mainForm.Invoke(mainForm.setlistboxcallback, outStr);
//Console.WriteLine("A client has been disconnected from the server. There are {0} clients connected to the server", this.numConnectedSockets);
try
{
s.Shutdown(SocketShutdown.Send);
}
catch (Exception)
{
// Throw if client has closed, so it is not necessary to catch.
}
finally
{
s.Close();
}
}

/// <summary>
/// accept 操作完成时回调函数
/// </summary>
/// <param name="sender">Object who raised the event.</param>
/// <param name="e">SocketAsyncEventArg associated with the completed accept operation.</param>
private void OnAcceptCompleted(object sender, SocketAsyncEventArgs e)
{
this.ProcessAccept(e);
}

/// <summary>
/// 监听Socket接受处理
/// </summary>
/// <param name="e">SocketAsyncEventArg associated with the completed accept operation.</param>
private void ProcessAccept(SocketAsyncEventArgs e)
{
Socket s = e.AcceptSocket;
if (s.Connected)
{
try
{
SocketAsyncEventArgs ioContext = this.ioContextPool.Pop();
if (ioContext != null)
{
// 从接受的客户端连接中取数据配置ioContext

ioContext.UserToken = s;

Interlocked.Increment(ref this.numConnectedSockets);
string outStr = String.Format("客户 {0} 连入, 共有 {1} 个连接。",  s.RemoteEndPoint.ToString(),this.numConnectedSockets);
mainForm.Invoke(mainForm.setlistboxcallback,outStr);
//Console.WriteLine("Client connection accepted. There are {0} clients connected to the server",
//this.numConnectedSockets);

if (!s.ReceiveAsync(ioContext))
{
this.ProcessReceive(ioContext);
}
}
else        //已经达到最大客户连接数量，在这接受连接，发送“连接已经达到最大数”，然后断开连接
{
s.Send(Encoding.Default.GetBytes("连接已经达到最大数!"));
string outStr = String.Format("连接已满，拒绝 {0} 的连接。", s.RemoteEndPoint);
mainForm.Invoke(mainForm.setlistboxcallback, outStr);
s.Close();
}
}
catch (SocketException ex)
{
Socket token = e.UserToken as Socket;
string outStr = String.Format("接收客户 {0} 数据出错, 异常信息： {1} 。", token.RemoteEndPoint, ex.ToString());
mainForm.Invoke(mainForm.setlistboxcallback, outStr);
//Console.WriteLine("Error when processing data received from {0}:\r\n{1}", token.RemoteEndPoint, ex.ToString());
}
catch (Exception ex)
{
mainForm.Invoke(mainForm.setlistboxcallback, "异常：" + ex.ToString());
}
// 投递下一个接受请求
this.StartAccept(e);
}
}

/// <summary>
/// 从客户端开始接受一个连接操作
/// </summary>
/// <param name="acceptEventArg">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>(OnAcceptCompleted);
}
else
{
// 重用前进行对象清理
acceptEventArg.AcceptSocket = null;
}

if (!this.listenSocket.AcceptAsync(acceptEventArg))
{
this.ProcessAccept(acceptEventArg);
}
}

/// <summary>
/// 启动服务，开始监听
/// </summary>
/// <param name="port">Port where the server will listen for connection requests.</param>
internal void Start(Int32 port)
{
// 获得主机相关信息
IPAddress[] addressList = Dns.GetHostEntry(Environment.MachineName).AddressList;
IPEndPoint localEndPoint = new IPEndPoint(addressList[addressList.Length - 1], port);

// 创建监听socket
this.listenSocket = new Socket(localEndPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
this.listenSocket.ReceiveBufferSize = this.bufferSize;
this.listenSocket.SendBufferSize = this.bufferSize;

if (localEndPoint.AddressFamily == AddressFamily.InterNetworkV6)
{
// 配置监听socket为 dual-mode (IPv4 & IPv6)
// 27 is equivalent to IPV6_V6ONLY socket option in the winsock snippet below,
this.listenSocket.SetSocketOption(SocketOptionLevel.IPv6, (SocketOptionName)27, false);
this.listenSocket.Bind(new IPEndPoint(IPAddress.IPv6Any, localEndPoint.Port));
}
else
{
this.listenSocket.Bind(localEndPoint);
}

// 开始监听
this.listenSocket.Listen(this.numConnections);

// 在监听Socket上投递一个接受请求。
this.StartAccept(null);

// Blocks the current thread to receive incoming messages.
mutex.WaitOne();
}

/// <summary>
/// 停止服务
/// </summary>
internal void Stop()
{
this.listenSocket.Close();
mutex.ReleaseMutex();
}

}
}

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