epoll 案例

分析见下回分解

server.cpp

#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

// 创建套接字并进行绑定
int socket_bind(const char* ip, int port);

// IO多路复用 epoll
void do_epoll(int listenfd);

// 处理事件函数
void handle_events(int epollfd, struct epoll_event *events, int num,
        int listenfd, char* buf);

// 处理接收到的连接
void handle_accept(int epollfd, int listenfd);

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

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

// 添加事件
void add_event(int epollfd, int fd, int state);

// 修改事件
void modify_event(int epollfd, int fd, int state);

// 删除事件
void delete_event(int epollfd, int fd, int state);

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

int socket_bind(const char* ip, int port)
{
    int listenfd = 0;
    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);
    // 创建一个描述符
    epollfd =  epoll_create(FDSIZE);
    // 添加监听描述事件
    add_event(epollfd, listenfd, EPOLLIN);
    while(true) {
        // 获取已经准备好的描述事件
        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) {
    for(int i = 0; i < num; i++ ) {
        int fd = events[i].data.fd;
        // 根据描述符的类型和事件类型进行处理
        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("accpet error:");
    } else {
        printf("accept a new client: %s : %d\n", inet_ntoa(cliaddr.sin_addr), cliaddr.sin_port);
        // 添加一个客户端描述符和事件
        add_event(epollfd, clifd, EPOLLIN);
    }
}

void do_read(int epollfd, int fd, char* buf) {
    int 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 \n", buf);
        modify_event(epollfd, fd, EPOLLOUT);
    }
}

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

client.cpp

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <time.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 SERV_PORT        6666
#define MAXSIZE     1024
#define FDSIZE      1024
#define EPOLLEVENTS 20

int count = 0;

void handle_connection(int sockfd);

// 处理事件函数
void handle_events(int epollfd, struct epoll_event *events, int num,
                   int sockfd, char* buf);

// 读处理
void do_read(int epollfd, int fd, int sockfd, char* buf);

// 写处理
void do_write(int epollfd, int fd, int sockfd, char* buf);

// 添加事件
void add_event(int epollfd, int fd, int state);

// 修改事件
void modify_event(int epollfd, int fd, int state);

// 删除事件
void delete_event(int epollfd, int fd, int state);

int main(int argc, char *argv[])
{
    int sockfd;

    struct sockaddr_in servaddr;
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(SERV_PORT);
    inet_pton(AF_INET, IPADDRESS, &servaddr.sin_addr);
    connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr));
    //处理连接
    handle_connection(sockfd);
    close(sockfd);
    return 0;
}

void handle_connection(int sockfd) {
    int epollfd;
    struct epoll_event events[EPOLLEVENTS];
    char buf[MAXSIZE];

    int ret;
    epollfd = epoll_create(FDSIZE);
    add_event(epollfd, STDIN_FILENO, EPOLLIN);
    while(1) {
        ret = epoll_wait(epollfd, events, EPOLLEVENTS, -1);
        handle_events(epollfd, events, ret, sockfd, buf);
    }
    close(epollfd);
}

void handle_events(int epollfd, struct epoll_event *events, int num,
                   int sockfd, char* buf) {
    for(int i = 0; i < num; i++ ) {
        int fd = events[i].data.fd;
        // 根据描述符的类型和事件类型进行处理
        if(events[i].events & EPOLLIN) {
            do_read(epollfd, fd, sockfd, buf);
        } else if(events[i].events & EPOLLOUT) {
            do_write(epollfd, fd, sockfd, buf);
        }
    }
}

void do_read(int epollfd, int fd, int sockfd, char* buf) {
    int nread = read(fd, buf, MAXSIZE);
    if(nread == -1) {
        perror("read error:");
        close(fd);
    }
    else if(nread == 0) {
        fprintf(stderr, "client close.\n");
        close(fd);
    } else {
        if(fd == STDIN_FILENO) {
            add_event(epollfd, sockfd, EPOLLOUT);
        } else {
            delete_event(epollfd, sockfd, EPOLLIN);
            add_event(epollfd, STDOUT_FILENO, EPOLLOUT);
        }
    }
}

void do_write(int epollfd, int fd, int sockfd, char* buf) {
    int nwrite = write(fd, buf, strlen(buf));
    char tmp[105] = {0};
    snprintf(tmp, sizeof(tmp), "%s_%02d\n", buf, count++);
    nwrite = write(fd, tmp, strlen(tmp));
    if(nwrite == -1) {
        perror("write error:");
        close(fd);
    } else {
        if(fd == STDOUT_FILENO) {
            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);
}