### IOCP *****  **IOCP**的核心就在于维护一个公共的消息队列。首先创建2*CPU核心数的线程，作为Worker，初始的时候它们是空闲，被挂起的。然后再开辟一个单独的线程，来监听连接请求，每当有连接请求，就accept，并将网络操作放入消息队列中。此时，Worker线程排队从队列中取出这些操作请求并处理。注意，整个过程中主线程是非常空闲的，完全有能力去执行其他的任务。也就是说，现在我们有一条主线程，若干条Worker线程，还有一条监听线程。主线程把网络请求扔给Worker线程去做，自己就可以同步做别的事情，而不用被阻塞挂起，等待外部I/O完成了。而这个公共消息队列，就叫做”完成端口“，因为它是”完成“网络操作（属于外部I/O）之后再通知主线程把数据拿走...大概就是这么个模型 ### 示例代码 ***** **iocp_s.cpp** ``` #include <winsock2.h> #include <stdio.h> #include <iostream> #pragma comment(lib, "ws2_32.lib") using namespace::std; #define BUF_SIZE 1024 void CALLBACK ReadCompRoutine(DWORD, DWORD, LPWSAOVERLAPPED, DWORD); void CALLBACK WriteCompRoutine(DWORD, DWORD, LPWSAOVERLAPPED, DWORD); void ErrorHanding(char * message); typedef struct { SOCKET hClntSock; //套接字句柄 char buf[BUF_SIZE]; //缓冲 WSABUF wsaBuf; //缓冲相关信息 }PER_IO_DATA,*LPPER_IO_DATA; int main() { WSADATA wsaData; SOCKET hLisnSock, hRecvSock; SOCKADDR_IN lisnAdr, recvAdr; LPWSAOVERLAPPED lpOvlap; DWORD recvBytes; LPPER_IO_DATA hbInfo; int recvAdrSz; DWORD flagInfo = 0; u_long mode = 1; if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)//加载库并获取库信息填至wsaData ErrorHanding("socket start error!"); //参数：协议族，套接字传输方式，使用的协议，WSA_PROTOCOL_INFO结构体地址/不需要时传null，扩展保留参数，套接字属性信息 hLisnSock = WSASocket(PF_INET, SOCK_STREAM, 0, NULL, 0, WSA_FLAG_OVERLAPPED); //将hLisnSock句柄的套接字I/O模式(FIONBIO)改为mode中指定的形式:非阻塞模式 ioctlsocket(hLisnSock, FIONBIO, &mode); //设置目标地址端口 memset(&lisnAdr, 0, sizeof(lisnAdr)); lisnAdr.sin_family = AF_INET; lisnAdr.sin_addr.S_un.S_addr = inet_addr("127.0.0.1"); lisnAdr.sin_port = htons(5099); //套接字绑定 if (bind(hLisnSock, (SOCKADDR*)&lisnAdr, sizeof(lisnAdr)) == SOCKET_ERROR) ErrorHanding("socket bind error!"); //设置为监听模式 if (listen(hLisnSock, 5) == SOCKET_ERROR) ErrorHanding("socket listen error!"); recvAdrSz = sizeof(recvAdr); while (1) { //进入短暂alertable wait 模式，运行ReadCompRoutine、WriteCompRoutine函数 SleepEx(100, TRUE); //非阻塞套接字，需要处理INVALID_SOCKET //返回的新的套接字也是非阻塞的 hRecvSock = accept(hLisnSock, (SOCKADDR*)&recvAdr, &recvAdrSz); if (hRecvSock == INVALID_SOCKET) { //无客户端连接时，accept返回INVALID_SOCKET，WSAGetLastError()返回WSAEWOULDBLOCK if (WSAGetLastError() == WSAEWOULDBLOCK) continue; else ErrorHanding("accept() error"); } puts("Client connected"); //申请重叠I/O需要使用的结构体变量的内存空间并初始化 //在循环内部申请：每个客户端需要独立的WSAOVERLAPPED结构体变量 lpOvlap = (LPWSAOVERLAPPED)malloc(sizeof(WSAOVERLAPPED)); memset(lpOvlap, 0, sizeof(WSAOVERLAPPED)); hbInfo = (LPPER_IO_DATA)malloc(sizeof(PER_IO_DATA)); hbInfo->hClntSock = (DWORD)hRecvSock; (hbInfo->wsaBuf).buf = hbInfo->buf; (hbInfo->wsaBuf).len = BUF_SIZE; //基于CR的重叠I/O不需要事件对象，故可以用来传递其他信息 lpOvlap->hEvent = (HANDLE)hbInfo; //接收第一条信息 WSARecv(hRecvSock, &(hbInfo->wsaBuf), 1, &recvBytes, &flagInfo, lpOvlap, ReadCompRoutine); } closesocket(hRecvSock); closesocket(hLisnSock); WSACleanup(); return 1; } //参数：错误信息，实际收发字节数，OVERLAPPED类型对象，调用I/O函数时传入的特性信息 void CALLBACK ReadCompRoutine(DWORD dwError, DWORD szRecvBytes, LPWSAOVERLAPPED lpOverlapped, DWORD flags) { //从lpoverlapped中恢复传递的信息 LPPER_IO_DATA hbInfo = (LPPER_IO_DATA)(lpOverlapped->hEvent); SOCKET hSock = hbInfo->hClntSock; LPWSABUF bufInfo = &(hbInfo->wsaBuf); DWORD sentBytes; //接收到EOF，断开连接 if (szRecvBytes == 0) { closesocket(hSock); free(hbInfo); free(lpOverlapped); puts("Client disconnected"); } else { bufInfo->len = szRecvBytes; //将接收到的信息回传回去，传递完毕执行WriteCompRoutine(): 接收信息 WSASend(hSock, bufInfo, 1, &sentBytes, 0, lpOverlapped, WriteCompRoutine); } } //参数：错误信息，实际收发字节数，OVERLAPPED类型对象，调用I/O函数时传入的特性信息 void CALLBACK WriteCompRoutine(DWORD dwError, DWORD szRecvBytes, LPWSAOVERLAPPED lpOverlapped, DWORD flags) { //从lpoverlapped中恢复传递的信息 LPPER_IO_DATA hbInfo = (LPPER_IO_DATA)(lpOverlapped->hEvent); SOCKET hSock = hbInfo->hClntSock; LPWSABUF bufInfo = &(hbInfo->wsaBuf); DWORD recvBytes; DWORD flagInfo = 0; //接收数据，接收完毕执行ReadCompRoutine：发送数据 WSARecv(hSock, bufInfo, 1, &recvBytes, &flagInfo, lpOverlapped, ReadCompRoutine); } void ErrorHanding(char * message) { cout << message << endl; exit(1); } ```