原文:
C#高性能大容量SOCKET并发（三）：接收、发送
异步数据接收有可能收到的数据不是一个完整包，或者接收到的数据超过一个包的大小，因此我们需要把接收的数据进行缓存。异步发送我们也需要把每个发送的包加入到一个队列，然后通过队列逐个发送出去，如果每个都实时发送，有可能造成上一个数据包未发送完成，这时再调用SendAsync会抛出异常，提示SocketAsyncEventArgs正在进行异步操作，因此我们需要建立接收缓存和发送缓存。
接收
发送通过Completed事件响应后调用AsyncSocketInvokeElement.ProcessReceive，在ProcessReceive中，我们把收到数据先写入一个缓存，然后进行分包，分包后压给包处理函数ProcessPacket，ProcessPacket函数然后调用ProcessCommand处理具体的命令，也是各个协议实现业务逻辑的地方，具体代码如下：
public virtual bool ProcessReceive(byte[] buffer, int offset, int count) //接收异步事件返回的数据，用于对数据进行缓存和分包 { m_activeDT = DateTime.UtcNow; DynamicBufferManager receiveBuffer = m_asyncSocketUserToken.ReceiveBuffer; receiveBuffer.WriteBuffer(buffer, offset, count); if (receiveBuffer.DataCount > sizeof(int)) { //按照长度分包 int packetLength = BitConverter.ToInt32(receiveBuffer.Buffer, 0); //获取包长度 if (NetByteOrder) packetLength = System.Net.IPAddress.NetworkToHostOrder(packetLength); //把网络字节顺序转为本地字节顺序 if ((packetLength > 10 * 1024 * 1024) | (receiveBuffer.DataCount > 10 * 1024 * 1024)) //最大Buffer异常保护 return false; if ((receiveBuffer.DataCount - sizeof(int)) >= packetLength) //收到的数据达到包长度 { bool result = ProcessPacket(receiveBuffer.Buffer, sizeof(int), packetLength); if (result) receiveBuffer.Clear(packetLength + sizeof(int)); //从缓存中清理 return result; } else { return true; } } else { return true; } } public virtual bool ProcessPacket(byte[] buffer, int offset, int count) //处理分完包后的数据，把命令和数据分开，并对命令进行解析 { if (count < sizeof(int)) return false; int commandLen = BitConverter.ToInt32(buffer, offset); //取出命令长度 string tmpStr = Encoding.UTF8.GetString(buffer, offset + sizeof(int), commandLen); if (!m_incomingDataParser.DecodeProtocolText(tmpStr)) //解析命令 return false; return ProcessCommand(buffer, offset + sizeof(int) + commandLen, count - sizeof(int) - commandLen); //处理命令 } public virtual bool ProcessCommand(byte[] buffer, int offset, int count) //处理具体命令，子类从这个方法继承，buffer是收到的数据 { return true; }
通过Completed事件响应后调用AsyncSocketInvokeElement.SendCompleted，在SendCompleted中我们需要在队列中清除已发送的包，并检测是否还有剩余需要发送的数据包，如果有，则继续发送，具体实现如下：
public virtual bool SendCompleted() { m_activeDT = DateTime.UtcNow; m_sendAsync = false; AsyncSendBufferManager asyncSendBufferManager = m_asyncSocketUserToken.SendBuffer; asyncSendBufferManager.ClearFirstPacket(); //清除已发送的包 int offset = 0; int count = 0; if (asyncSendBufferManager.GetFirstPacket(ref offset, ref count)) { m_sendAsync = true; return m_asyncSocketServer.SendAsyncEvent(m_asyncSocketUserToken.ConnectSocket, m_asyncSocketUserToken.SendEventArgs, asyncSendBufferManager.DynamicBufferManager.Buffer, offset, count); } else return SendCallback(); } //发送回调函数，用于连续下发数据 public virtual bool SendCallback() { return true; }在AsyncSocketInvokeElement中提供函数给子类发送数据，业务逻辑是把当前数据包写入缓存，并检测当前是否正在发送包，如果正在发送，则等待回调，如果没有正在发送的数据包，则投递发送请求。
public bool DoSendResult() { string commandText = m_outgoingDataAssembler.GetProtocolText(); byte[] bufferUTF8 = Encoding.UTF8.GetBytes(commandText); int totalLength = sizeof(int) + bufferUTF8.Length; //获取总大小 AsyncSendBufferManager asyncSendBufferManager = m_asyncSocketUserToken.SendBuffer; asyncSendBufferManager.StartPacket(); asyncSendBufferManager.DynamicBufferManager.WriteInt(totalLength, false); //写入总大小 asyncSendBufferManager.DynamicBufferManager.WriteInt(bufferUTF8.Length, false); //写入命令大小 asyncSendBufferManager.DynamicBufferManager.WriteBuffer(bufferUTF8); //写入命令内容 asyncSendBufferManager.EndPacket(); bool result = true; if (!m_sendAsync) { int packetOffset = 0; int packetCount = 0; if (asyncSendBufferManager.GetFirstPacket(ref packetOffset, ref packetCount)) { m_sendAsync = true; result = m_asyncSocketServer.SendAsyncEvent(m_asyncSocketUserToken.ConnectSocket, m_asyncSocketUserToken.SendEventArgs, asyncSendBufferManager.DynamicBufferManager.Buffer, packetOffset, packetCount); } } return result; } public bool DoSendResult(byte[] buffer, int offset, int count) { string commandText = m_outgoingDataAssembler.GetProtocolText(); byte[] bufferUTF8 = Encoding.UTF8.GetBytes(commandText); int totalLength = sizeof(int) + bufferUTF8.Length + count; //获取总大小 AsyncSendBufferManager asyncSendBufferManager = m_asyncSocketUserToken.SendBuffer; asyncSendBufferManager.StartPacket(); asyncSendBufferManager.DynamicBufferManager.WriteInt(totalLength, false); //写入总大小 asyncSendBufferManager.DynamicBufferManager.WriteInt(bufferUTF8.Length, false); //写入命令大小 asyncSendBufferManager.DynamicBufferManager.WriteBuffer(bufferUTF8); //写入命令内容 asyncSendBufferManager.DynamicBufferManager.WriteBuffer(buffer, offset, count); //写入二进制数据 asyncSendBufferManager.EndPacket(); bool result = true; if (!m_sendAsync) { int packetOffset = 0; int packetCount = 0; if (asyncSendBufferManager.GetFirstPacket(ref packetOffset, ref packetCount)) { m_sendAsync = true; result = m_asyncSocketServer.SendAsyncEvent(m_asyncSocketUserToken.ConnectSocket, m_asyncSocketUserToken.SendEventArgs, asyncSendBufferManager.DynamicBufferManager.Buffer, packetOffset, packetCount); } } return result; } public bool DoSendBuffer(byte[] buffer, int offset, int count) { AsyncSendBufferManager asyncSendBufferManager = m_asyncSocketUserToken.SendBuffer; asyncSendBufferManager.StartPacket(); asyncSendBufferManager.DynamicBufferManager.WriteBuffer(buffer, offset, count); asyncSendBufferManager.EndPacket(); bool result = true; if (!m_sendAsync) { int packetOffset = 0; int packetCount = 0; if (asyncSendBufferManager.GetFirstPacket(ref packetOffset, ref packetCount)) { m_sendAsync = true; result = m_asyncSocketServer.SendAsyncEvent(m_asyncSocketUserToken.ConnectSocket, m_asyncSocketUserToken.SendEventArgs, asyncSendBufferManager.DynamicBufferManager.Buffer, packetOffset, packetCount); } } return result; }
DEMO下载地址： http://download.csdn.net/detail/sqldebug_fan/7467745
免责声明：此代码只是为了演示C#完成端口编程，仅用于学习和研究，切勿用于商业用途。水平有限，C#也属于初学，错误在所难免，欢迎指正和指导。邮箱地址：fansheng_hx@163.com。
