IOCP小记

IOCP事实上是一个Tread pool,但是它运行于内核，所以相对于用户态的select效率应该高了一点点。

它的工作过程一般是这样的：

0.CreateIoCompletionPort创建一个完成端口

1.事先开好N个线程，这线程的个数一般为处理器个数的二倍+2,线程的参数传完成端口的句柄

2.服务器有一个listen线程，当它从已完成三次握手队列中取出一个临时accept套接字时

3.accept绑定到0步创建的完成端口

4.accept使用WSARecv读取客户端发送的数据，并放入缓冲区，使用OVERLAPPED开头的自定义数据结构，WSARecv接收客户端的数据，并把数据放入缓冲区，让工作线程(事先开好的N个线程)来取。注意dwFlags通常设为0，否则会出错

5.工作线程通过GetQueuedCompletionStatus查询，从缓冲区取出数据并加以处理

基本代码：

BOOL CIMServerThread::InitServer(){WSADATA wsadata;if (0 != WSAStartup(WINSOCK_VERSION, &wsadata)){return FALSE;}SYSTEM_INFO syminfo;GetSystemInfo(&syminfo);// 确定创建多少个IOCP处理线程m_dwThreads = syminfo.dwNumberOfProcessors*2;m_phThread = new HANDLE[m_dwThreads];return TRUE;}BOOL CIMServerThread::Run(){InitServer();   // 创建监听线程   if (NULL == m_hListenThread)   {   m_hListenThread = CreateThread(NULL, 0, ListenThread,    NULL, 0, NULL);   }return TRUE;}DWORD WINAPI CIMServerThread::ListenThread(LPVOID lp){HANDLE hCompletionPort    = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0);if (NULL == hCompletionPort){return TRUE;}// 为每个CPU创建两个工作线程for (DWORD i=0; i<m_dwThreads; i++){m_phThread[i] = CreateThread(NULL, 0, WorkThread, hCompletionPort, 0, NULL);}// WSASocket可以使用WinSock特有功能，比如重叠IO，用dwflags指定。SOCKET listenSock = WSASocket(AF_INET, SOCK_STREAM, 0, NULL, 0, WSA_FLAG_OVERLAPPED);if (INVALID_SOCKET == listenSock){return TRUE;}SOCKADDR_IN sin;sin.sin_family = AF_INET;sin.sin_port = htons(PORT);sin.sin_addr.s_addr = htonl(INADDR_ANY);if (SOCKET_ERROR == bind(listenSock, (sockaddr*)&sin, sizeof(sin))){return TRUE;}if (SOCKET_ERROR == listen(listenSock, 5)){return TRUE;}// 接受连接，并分配给完成端口SOCKET acceptSock;LPPER_HANDLE_DATA PerHandleDate = NULL;DWORD RecvBytes = 0;DWORD Flags = 0;while (TRUE){acceptSock = WSAAccept(listenSock, NULL, NULL, NULL, 0);if (INVALID_SOCKET == acceptSock){return TRUE;}PerHandleDate = (LPPER_HANDLE_DATA)GlobalAlloc(GPTR, sizeof(PER_HEANDLE_DATA));        if (NULL == PerHandleDate)        {return TRUE;        }// 对临时socket启动突发断线检测BOOL bKeepAlive = TRUE;int nRet = setsockopt(acceptSock, SOL_SOCKET,SO_KEEPALIVE,(char*)&bKeepAlive,sizeof(bKeepAlive));if (SOCKET_ERROR == nRet){return TRUE;}tcp_keepalive alive_in;tcp_keepalive alive_out;alive_in.keepalivetime = 5000;alive_in.keepaliveinterval = 5000;alive_in.onoff = TRUE;unsigned long ulBytesReturn = 0;nRet = WSAIoctl(acceptSock, SIO_KEEPALIVE_VALS,&alive_in, sizeof(alive_in),&alive_out, sizeof(alive_out),&ulBytesReturn, NULL, NULL);if (SOCKET_ERROR == nRet){return TRUE;}//PerHandleDate->Sock = acceptSock;if (NULL == CreateIoCompletionPort((HANDLE)acceptSock, hCompletionPort,(ULONG_PTR)PerHandleDate, 0)){return TRUE;}LPPER_IO_OPERATION_DATA PerIoData = (LPPER_IO_OPERATION_DATA)GlobalAlloc(GPTR, sizeof(PER_IO_OPERATION_DATA));if (NULL == PerIoData){return TRUE;}memset(&(PerIoData->Overlapped), 0, sizeof(OVERLAPPED));PerIoData->DataBuf.len = DATA_BUFSIZE;PerIoData->DataBuf.buf = PerIoData->Buffer;PerIoData->hWnd = AfxGetApp()->m_pMainWnd->GetSafeHwnd();PerIoData->send = 1;Flags = 0;if (SOCKET_ERROR == WSARecv(acceptSock, &(PerIoData->DataBuf), 1, &RecvBytes, &Flags, &(PerIoData->Overlapped), NULL)){if (ERROR_IO_PENDING != WSAGetLastError()){return TRUE;}}}return TRUE;}DWORD WINAPI CIMServerThread::WorkThread(LPVOID lp){while (TRUE){HANDLE hCompletionPort = (HANDLE)lp;DWORD BytesTransferred = 0;LPPER_HANDLE_DATA PerHanleData;LPPER_IO_OPERATION_DATA PerIoData;HWND hWnd = NULL;SOCKET socket = INVALID_SOCKET;if (0 == GetQueuedCompletionStatus(hCompletionPort,&BytesTransferred, (LPDWORD)&PerHanleData,(LPOVERLAPPED*)&PerIoData,INFINITE))//为0表示失败{hWnd = PerIoData->hWnd;    socket = PerHanleData->Sock;FreeAndNull(PerIoData);FreeAndNull(PerHanleData);// 获取错误代码int nLastErr = WSAGetLastError();// 错误处理switch (nLastErr){case ERROR_NETNAME_DELETED:case ERROR_OPERATION_ABORTED:{::SendMessage(hWnd, IM_S_LOGOFF, NULL, socket);closesocket(socket);}break;default:// 发生严重错误{return 0;}break;}// 继续工作continue;}// 下面表示成功的从一个完成端口出列一个完成包hWnd = PerIoData->hWnd;socket = PerHanleData->Sock;// 客户正常退出程序，会接收到0字节if (0 == BytesTransferred){FreeAndNull(PerHanleData);FreeAndNull(PerIoData);::SendMessage(hWnd, IM_S_LOGOFF, NULL, socket);closesocket(socket);// 继续工作continue;}// 数据包过大if (1024*2<BytesTransferred){FreeAndNull(PerHanleData);FreeAndNull(PerIoData);::SendMessage(hWnd, IM_S_LOGOFF, NULL, socket);closesocket(socket);// 继续工作continue;}        // 开始正确处理数据包 ---------------------------------switch (PerIoData->send){case 1:{}break;case 2:{}break;default:break;}}// while(TRUE)return TRUE;}