C epoll 通讯 源代码

Epoll 是 Linux 系统提供的一种高效事件驱动的 I/O 处理模型，用于监控多个文件描述符（如套接字）是否就绪，包括读取、写入等事件。以下是使用 C 语言编写的一个简单 Epoll 示例，它创建了一个服务器监听端口，并通过 Epoll 实现了非阻塞的通信：

#include <stdio.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

#define MAX_EVENTS 10
#define EPOLL_PORT 8080

typedef struct {
    int socket_fd;
    struct epoll_event event;
} SocketInfo;

void handle_client(int socket_fd, struct epoll_event* ev) {
    char buffer[1024];
    ssize_t read_size;
    write(socket_fd, "Welcome to the server!\r\n", sizeof("Welcome to the server!\r\n"));
    
    // Read client's message
    read_size = read(socket_fd, buffer, sizeof(buffer));
    if (read_size > 0)
        printf("Received from client: %.*s\n", (int)read_size, buffer);
    else
        perror("Reading client data");

    close(socket_fd);
}

int main() {
    int server_socket, epoll_fd;
    struct sockaddr_in server_addr, client_addr;
    socklen_t client_len = sizeof(client_addr);
    char buffer[1024];
    SocketInfo sockets[MAX_EVENTS];

    // Create a listening socket
    server_socket = socket(AF_INET, SOCK_STREAM, 0);
    if (server_socket < 0) {
        perror("Creating server socket");
        exit(EXIT_FAILURE);
    }
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(EPOLL_PORT);
    server_addr.sin_addr.s_addr = INADDR_ANY;
    if (bind(server_socket, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0) {
        perror("Binding server socket");
        close(server_socket);
        exit(EXIT_FAILURE);
    }
    listen(server_socket, 5);

    // Create an epoll instance
    epoll_fd = epoll_create1(0);
    if (epoll_fd < 0) {
        perror("Creating epoll");
        exit(EXIT_FAILURE);
    }

    // Add server socket to epoll
    sockets[0].socket_fd = server_socket;
    sockets[0].event.events = EPOLLIN | EPOLLET;
    sockets[0].event.data.fd = server_socket;
    if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, sockets[0].socket_fd, &sockets[0].event) < 0) {
        perror("Adding server socket to epoll");
        close(epoll_fd);
        exit(EXIT_FAILURE);
    }

    // Listen for new connections
    while (true) {
        int events_num = epoll_wait(epoll_fd, sockets, MAX_EVENTS, -1);
        if (events_num <= 0) {
            perror("epoll_wait");
            break;
        }

        for (int i = 0; i < events_num; i++) {
            if (sockets[i].event.events & EPOLLIN && sockets[i].socket_fd == server_socket) {
                // Accept new client connection
                client_fd = accept(server_socket, (struct sockaddr*)&client_addr, &client_len);
                if (client_fd >= 0) {
                    printf("Accepted connection from %s:%d\n",
                           inet_ntoa(client_addr.sin_addr),
                           ntohs(client_addr.sin_port));

                    // Add client socket to epoll
                    sockets[i + 1] = sockets[i]; // Copy existing info
                    sockets[i + 1].socket_fd = client_fd;
                    sockets[i + 1].event.events = EPOLLIN | EPOLLET;
                    sockets[i + 1].event.data.fd = client_fd;
                    epoll_ctl(epoll_fd, EPOLL_CTL_MOD, sockets[i + 1].socket_fd, &sockets[i + 1].event);
                    i++; // Increment index after adding client
                } else {
                    perror("Accepting client");
                }
            } else if (sockets[i].event.events & EPOLLIN) {
                handle_client(sockets[i].socket_fd, &sockets[i].event);
            }
        }
    }

    close(epoll_fd);
    close(server_socket);
    return 0;
}