c++ iocp 服务端程序例子

以下是一个使用IOCP实现的简单服务端程序的示例代码：

#include <WinSock2.h>
#include <Windows.h>
#include <iostream>

#pragma comment(lib, "ws2_32.lib")

#define BUFFER_SIZE 1024
#define MAX_CLIENTS 10

struct ClientContext {
    SOCKET socket;
    char buffer[BUFFER_SIZE];
    int bytesReceived;
    OVERLAPPED overlapped;
};

int main() {
    WSADATA wsaData;
    WSAStartup(MAKEWORD(2, 2), &wsaData);

    // 创建监听socket
    SOCKET listenSocket = WSASocket(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, 0, WSA_FLAG_OVERLAPPED);
    SOCKADDR_IN serverAddr;
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_addr.s_addr = htonl(INADDR_ANY);
    serverAddr.sin_port = htons(12345);
    bind(listenSocket, (SOCKADDR*)&serverAddr, sizeof(serverAddr));
    listen(listenSocket, SOMAXCONN);

    // 创建IOCP
    HANDLE iocpHandle = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0);

    // 将监听socket加入IOCP
    CreateIoCompletionPort((HANDLE)listenSocket, iocpHandle, (ULONG_PTR)listenSocket, 0);

    // 创建客户端上下文数组
    ClientContext clientContexts[MAX_CLIENTS];
    for (int i = 0; i < MAX_CLIENTS; i++) {
        clientContexts[i].socket = INVALID_SOCKET;
        clientContexts[i].bytesReceived = 0;
        ZeroMemory(&clientContexts[i].overlapped, sizeof(OVERLAPPED));
    }

    // 不断等待客户端连接
    while (true) {
        // 接收客户端连接请求
        SOCKET clientSocket = accept(listenSocket, NULL, NULL);

        // 将客户端socket加入IOCP
        CreateIoCompletionPort((HANDLE)clientSocket, iocpHandle, (ULONG_PTR)clientSocket, 0);

        // 找到一个空闲的客户端上下文
        ClientContext* clientContext = NULL;
        for (int i = 0; i < MAX_CLIENTS; i++) {
            if (clientContexts[i].socket == INVALID_SOCKET) {
                clientContext = &clientContexts[i];
                break;
            }
        }

        if (clientContext == NULL) {
            std::cout << "Too many clients." << std::endl;
            closesocket(clientSocket);
            continue;
        }

        // 初始化客户端上下文
        clientContext->socket = clientSocket;
        clientContext->bytesReceived = 0;
        ZeroMemory(&clientContext->overlapped, sizeof(OVERLAPPED));

        // 异步接收数据
        DWORD flags = 0;
        WSARecv(clientSocket, &clientContext->buffer[clientContext->bytesReceived], BUFFER_SIZE - clientContext->bytesReceived, NULL, &flags, &clientContext->overlapped, NULL);
    }

    // 关闭监听socket
    closesocket(listenSocket);

    // 关闭IOCP
    CloseHandle(iocpHandle);

    WSACleanup();
    return 0;
}

该程序使用IOCP监听客户端连接请求，并异步接收客户端发送的数据。程序中使用了一个客户端上下文数组来保存每个客户端的状态信息。在接收到客户端连接请求时，程序会找到一个空闲的客户端上下文，并将连接的客户端socket加入IOCP。在异步接收数据时，程序使用客户端上下文中的缓冲区来保存已接收到的数据，并在数据接收完成后再次调用WSARecv函数来继续接收数据。程序中使用了OVERLAPPED结构体来实现异步操作。程序使用了WSARecv函数来异步接收数据。