基于epoll实现简单的web服务器

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/sysinfo.h>
#include <sys/epoll.h>
#include <signal.h>
#include <fcntl.h>
#include <sys/wait.h>
#include <sys/types.h>
#include "httpd.h"

#define DEFAULT_PORT 8080
#define MAX_EVENT_NUM 1024
#define INFTIM -1

void process(int);

void handle_subprocess_exit(int);

int main(int argc, char *argv[])  
{
    struct sockaddr_in server_addr;
    int listen_fd;
    int cpu_core_num;
    int on = 1;
    
    listen_fd = socket(AF_INET, SOCK_STREAM, 0);
    fcntl(listen_fd, F_SETFL, O_NONBLOCK);    // 设置 listen_fd 为非阻塞
    setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));

    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    server_addr.sin_port = htons(DEFAULT_PORT);

    if (bind(listen_fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {
        perror("bind error, message: ");
        exit(1);
    }

    if (listen(listen_fd, 5) == -1) {
        perror("listen error, message: ");
        exit(1);
    }

    printf("listening 8080\n");

    signal(SIGCHLD, handle_subprocess_exit);

    cpu_core_num = get_nprocs();
    printf("cpu core num: %d\n", cpu_core_num);
    // 根据 CPU 数量创建子进程，为了演示“惊群现象”，这里多创建一些子进程
    for (int i = 0; i < cpu_core_num * 2; i++) {
        pid_t pid = fork();
        if (pid == 0) {    // 子进程执行此条件分支
            process(listen_fd);
            exit(0);
        }
    }

    while (1) {
        sleep(1);
    }

    return 0;
}

void process(int listen_fd) 
{
    int conn_fd;
    int ready_fd_num;
    struct sockaddr_in client_addr;
    int client_addr_size = sizeof(client_addr);
    char buf[128];

    struct epoll_event ev, events[MAX_EVENT_NUM];
    // 创建 epoll 实例，并返回 epoll 文件描述符
    int epoll_fd = epoll_create(MAX_EVENT_NUM);
    ev.data.fd = listen_fd;
    ev.events = EPOLLIN;

    // 将 listen_fd 注册到刚刚创建的 epoll 中
    if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, listen_fd, &ev) == -1) {
        perror("epoll_ctl error, message: ");
        exit(1);
    }

    while(1) {
        // 等待事件发生
        ready_fd_num = epoll_wait(epoll_fd, events, MAX_EVENT_NUM, INFTIM);
        printf("[pid %d]  震惊！我又被唤醒了...\n", getpid());
        if (ready_fd_num == -1) {
            perror("epoll_wait error, message: ");
            continue;
        }
        for(int i = 0; i < ready_fd_num; i++) {
            if (events[i].data.fd == listen_fd) { // 有新的连接
                conn_fd = accept(listen_fd, (struct sockaddr *)&client_addr, &client_addr_size);
                if (conn_fd == -1) {
                    sprintf(buf, "[pid %d]  accept 出错了: ", getpid());
                    perror(buf);
                    continue;
                }

                // 设置 conn_fd 为非阻塞
                if (fcntl(conn_fd, F_SETFL, fcntl(conn_fd, F_GETFD, 0) | O_NONBLOCK) == -1) {
                    continue;
                }

                ev.data.fd = conn_fd;
                ev.events = EPOLLIN;
                if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, conn_fd, &ev) == -1) {
                    perror("epoll_ctl error, message: ");
                    close(conn_fd);
                }
                printf("[pid %d]  收到来自 %s:%d 的请求\n", getpid(), inet_ntoa(client_addr.sin_addr), client_addr.sin_port);
                
            } else if (events[i].events & EPOLLIN) {    // 某个 socket 数据已准备好，可以读取了
                printf("[pid %d]  处理来自 %s:%d 的请求\n", getpid(), inet_ntoa(client_addr.sin_addr), client_addr.sin_port);
                conn_fd = events[i].data.fd;
                // 调用 TinyHttpd 的 accept_request 函数处理请求
                accept_request(conn_fd, &client_addr);
                close(conn_fd);
            } else if (events[i].events & EPOLLERR) {
                fprintf(stderr, "epoll error\n");
                close(conn_fd);
            }
        }
    }
}

void handle_subprocess_exit(int signo)
{
    printf("clean subprocess.\n");
    int status;  
    while(waitpid(-1, &status, WNOHANG) > 0);
}