使用epoll编写TCP服务器示例

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

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

#define IPADDRESS   "127.0.0.1"
#define PORT        6666
#define MAXSIZE     1024
#define LISTENQ     5
#define FDSIZE      1000
#define EPOLLEVENTS 100

int socket_bind(const char* ip, int port);

void do_epoll(int listenfd);

void handle_events(int epollfd, struct epoll_event *events, int num, int listenfd, char *buf);

void handle_accept(int epollfd, int listenfd);

void do_read(int epollfd, int fd, char *buf);

void do_write(int epollfd, int fd, char *buf);

void add_event(int epollfd, int fd, int state);

void modify_event(int epollfd, int fd, int state);

void delete_event(int epollfd, int fd, int state);

int main(int argc, char *argv[]) {
    int listenfd;
    listenfd = socket_bind(IPADDRESS, PORT);
    listen(listenfd, LISTENQ);
    do_epoll(listenfd);
    return 0;
}

int socket_bind(const char* ip, int port) {
    int listenfd;
    struct sockaddr_in servaddr;
    listenfd = socket(AF_INET, SOCK_STREAM, 0);
    if (listenfd == -1) {
        perror("socket error:");
        exit(1);
    }
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    inet_pton(AF_INET, ip, &servaddr.sin_addr);
    servaddr.sin_port = htons(port);
    if (bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) == -1) {
        perror("bind error: ");
        exit(1);
    }
    return listenfd;
}

void do_epoll(int listenfd) {
    int epollfd;
    struct epoll_event events[EPOLLEVENTS];
    int ret;
    char buf[MAXSIZE];
    memset(buf, 0, MAXSIZE);

    //创建一个epoll的描述符
    epollfd = epoll_create(FDSIZE);

    //添加监听的描述符事件
    add_event(epollfd, listenfd, EPOLLIN);
    while (1) {
        /*获取已经准备好的描述符事件*/
        ret = epoll_wait(epollfd, events, EPOLLEVENTS, -1);
        handle_events(epollfd, events, ret, listenfd, buf);
    }
    close(epollfd);
}

void handle_events(int epollfd, struct epoll_event *events, int num, int listenfd, char *buf) {
    int i;
    int fd;
    for (i = 0; i < num; i++) {
        fd = events[i].data.fd;
        if ((fd == listenfd) && (events[i].events & EPOLLIN)) {
            handle_accept(epollfd, listenfd);
        } else if (events[i].events & EPOLLIN) {
            do_read(epollfd, fd, buf);
        } else if (events[i].events & EPOLLOUT) {
            do_write(epollfd, fd, buf);
        }
    }
}

void handle_accept(int epollfd, int listenfd) {
    int clifd;
    struct sockaddr_in cliaddr;
    socklen_t cliaddrlen;
    clifd = accept(listenfd, (struct sockaddr*) &cliaddr, &cliaddrlen);
    if (clifd == -1) {
        perror("accept error:");
    } else {
        printf("accept a new client: %s:%d\n", inet_ntoa(cliaddr.sin_addr), cliaddr.sin_port);
        add_event(epollfd, clifd, EPOLLIN);
    }
}

void do_read(int epollfd, int fd, char *buf) {
    int nread;
    nread = read(fd, buf, MAXSIZE);
    if (nread == -1) {
        perror("read error:");
        close(fd);
        delete_event(epollfd, fd, EPOLLIN);
    } else if (nread == 0) {
        fprintf(stderr, "client close.\n");
        close(fd);
        delete_event(epollfd, fd, EPOLLIN);
    } else {
        printf("read message is : %s", buf);
        modify_event(epollfd, fd, EPOLLOUT);
    }
}

void do_write(int epollfd, int fd, char *buf) {
    int nwrite;
    nwrite = write(fd, buf, strlen(buf));
    if (nwrite == -1) {
        perror("write error:");
        close(fd);
        delete_event(epollfd, fd, EPOLLOUT);
    } else {
        modify_event(epollfd, fd, EPOLLIN);
    }
    memset(buf, 0, MAXSIZE);
}

void add_event(int epollfd, int fd, int state) {
    struct epoll_event ev;
    ev.events = state;
    ev.data.fd = fd;
    epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev);
}

void delete_event(int epollfd, int fd, int state) {
    struct epoll_event ev;
    ev.events = state;
    ev.data.fd = fd;
    epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, &ev);
}

void modify_event(int epollfd, int fd, int state) {
    struct epoll_event ev;
    ev.events = state;
    ev.data.fd = fd;
    epoll_ctl(epollfd, EPOLL_CTL_MOD, fd, &ev);
}