多路复用io接口-epoll

Posted 2020-06-11

多路复用io接口-epoll的使用.

服务端使用epoll接口处理多个客户的服务请求.

例:

服务端代码

myepoll.c

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <sys/epoll.h>
#include <sys/time.h>
#include <sys/resource.h>

#define MAXBUF 1024
#define MAXEPOLLSIZE 10000

/*
 * setnonblocking - 设置sockfd为非阻塞方式
 */
int setnonblocking(int sockfd)
{
    if (fcntl(sockfd, F_SETFL, fcntl(sockfd, F_GETFD, 0)|O_NONBLOCK) == -1) {
        perror("fcntl");
        return -1;
    }
    return 0;
}

/*
 * handle_message - 处理每个 socket 上的消息收发
 */
int handle_message(int new_fd)
{
    char buf[MAXBUF + 1];
    int len;
    /* 开始处理每个新连接上的数据收发 */
    bzero(buf, MAXBUF + 1);
    /* 接收客户端的消息 */
    len = recv(new_fd, buf, MAXBUF, 0);
    //printf("[%s-%d]*********\n", __func__, __LINE__);
    if (len > 0) {
        printf ("%d接收消息成功:‘%s‘，共%d个字节的数据\n", new_fd, buf, len);
    } else {
        if (len < 0) {
            printf("消息接收失败！错误代码是%d，错误信息是‘%s‘\n", errno, strerror(errno));
        }
        close(new_fd);
        return -1;
    }
    /* 处理每个新连接上的数据收发结束 */
    return len;
}

int main(int argc, char **argv)
{
    int listener, new_fd, kdpfd, nfds, n, ret, curfds;
    socklen_t len;
    struct sockaddr_in my_addr, their_addr;
    unsigned int myport, lisnum;
    struct epoll_event ev;
    struct epoll_event events[MAXEPOLLSIZE];
    struct rlimit rt;

    //if ((argc >= 2) && isdigit(atoi(argv[1])))
    if (argc >= 2) {
        myport = atoi(argv[1]);
    } else {
        myport = 7838;
    }
    printf("myport = %d\n", myport);

    //if ((argc >= 3) && isdigit(atoi(argv[2])))
    if (argc >= 3) {
        lisnum = atoi(argv[2]);
    } else {
        lisnum = 2;
    }
    printf("linum = %d\n", lisnum);

    /* 设置每个进程允许打开的最大文件数 */
    rt.rlim_max = rt.rlim_cur = MAXEPOLLSIZE;
    if (setrlimit(RLIMIT_NOFILE, &rt) == -1) {
        perror("setrlimit");
        exit(1);
    } else { 
        printf("[line-%d]设置系统资源参数成功！\n", __LINE__);
    }

    /* 开启 socket 监听 */
    if ((listener = socket(PF_INET, SOCK_STREAM, 0)) == -1) {
        perror("socket");
        exit(1);
    } else {
        printf("[line-%d]socket 创建成功！\n", __LINE__);
    }
    setnonblocking(listener);

    bzero(&my_addr, sizeof(my_addr));
    my_addr.sin_family = PF_INET;
    my_addr.sin_port = htons(myport);
    if(argv[3]) {
        my_addr.sin_addr.s_addr = inet_addr(argv[3]);
    } else {
        my_addr.sin_addr.s_addr = INADDR_ANY;
    }
    if (bind(listener, (struct sockaddr *) &my_addr, sizeof(struct sockaddr)) == -1) {
        perror("bind");
        exit(1);
    } else {
        printf("[line-%d]IP 地址和端口绑定成功\n", __LINE__);
    }

    if (listen(listener, lisnum) == -1) {
        perror("listen");
        exit(1);
    } else {
        printf("[line-%d]开启服务成功！\n", __LINE__);
    }

    /* 创建 epoll 句柄，把监听 socket 加入到 epoll 集合里 */
    kdpfd = epoll_create(MAXEPOLLSIZE);
    len = sizeof(struct sockaddr_in);
    ev.events = EPOLLIN | EPOLLET;
    ev.data.fd = listener;
    if (epoll_ctl(kdpfd, EPOLL_CTL_ADD, listener, &ev) < 0) {
        fprintf(stderr, "epoll set insertion error: fd=%d\n", listener);
        return -1;
    } else {
        printf("[line-%d]监听 socket 加入 epoll 成功！\n", __LINE__);
    }
    curfds = 1;
    while(1) {
        /* 等待有事件发生 */
        nfds = epoll_wait(kdpfd, events, curfds, -1);
        if (nfds == -1) {
            perror("epoll_wait");
            break;
        }
        /* 处理所有事件 */
        for (n = 0; n < nfds; ++n) {
            if (events[n].data.fd == listener) {
                new_fd = accept(listener, (struct sockaddr *) &their_addr, &len);
                if (new_fd < 0) {
                    perror("accept");
                    continue;
                } else {
                    printf("有连接来自于： %s:%d， 分配的 socket 为:%d\n", 
                            inet_ntoa(their_addr.sin_addr), 
                            ntohs(their_addr.sin_port), new_fd);
                }
                setnonblocking(new_fd);
                ev.events = EPOLLIN | EPOLLET;
                ev.data.fd = new_fd;
                if (epoll_ctl(kdpfd, EPOLL_CTL_ADD, new_fd, &ev) < 0) {
                    fprintf(stderr, "把 socket ‘%d‘ 加入 epoll 失败！%s\n", new_fd, strerror(errno));
                    return -1;
                }
                curfds++;
            } else {
                ret = handle_message(events[n].data.fd);
                if (ret < 1 && errno != 11) {
                    epoll_ctl(kdpfd, EPOLL_CTL_DEL, events[n].data.fd, &ev);
                    curfds--;
                }
            }
        }
    }
    close(listener);
    return 0;
}

 

客户端代码:

client.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/in.h>
#include <unistd.h>
/*
send data as "send ipaddr port message"
*/

int    main(int argc, char *argv[])
{
    int sock_fd;        
    struct sockaddr_in client_addr;
    struct sockaddr_in server_addr;
    char buf[1024];
    int    len;
    int ret;

    if(4 != argc)
    {
        printf("argc\n");
        exit(1);
    }

    if(-1 == (sock_fd = socket(AF_INET, SOCK_STREAM, 0)))
    {
        printf("socket\n");
        exit(2);
    }

    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(atoi(argv[2]));
    server_addr.sin_addr.s_addr = inet_addr(argv[1]);

    if(-1 == (ret = connect(sock_fd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)))){
        perror("connect");
        goto    ERR;
    }
    
    strcpy(buf, argv[3]);
    len = strlen(argv[3]);
    printf("[%s-L%d]\n", __func__, __LINE__);
#if 1
    if(-1 == (ret = send(sock_fd, buf, len, 0))){
        perror("send: ");
    }
#endif
    printf("[%s-L%d]\n", __func__, __LINE__);
    getchar();
ERR:
    close(sock_fd);

}

编译链接, 在两个不同的终端运行,输出如下:

 服务端

客户端. 按如下顺序在不同的终端执行, 并输出结果(上图服务端的输出也对应如下客户端执行顺序):