Cselect、poll、epoll、以及手写简易libevent反应堆源码

ゞ浴缸里的玫瑰 2022-12-11 09:24 106阅读 0赞

### 文章目录 ###

*  select
 *  poll
 *  epoll
 *  反应堆

# select #

#include <stdio.h>
    #include <sys/socket.h>
    #include <stdlib.h>
    #include <unistd.h>
    #include <ctype.h>
    #include <arpa/inet.h>
    #include  "warp_socket.h"
    
    #define PORT 8080
    
    /**
     * select
     * 缺点:受操作系统文件描述符影响,最多只能1024连接
     *      需要遍历所有监听的fd(lfd~maxfd ,但是中间有很多失效的fd),虽然可以用数组解决,但是增加了复杂度.
     * @return
     */
    int main() {
        
        int lfd, cfd, maxfd;
        int n, nready, client[FD_SETSIZE], i;   //client防止遍历所有的文件描述符,FD_SETSIZE=1024
        char buf[BUFSIZ], str[INET_ADDRSTRLEN];  //INET_ADDRSTRLEN=16
        struct sockaddr_in srv_addr, cli_addr;
        socklen_t cli_addr_len = sizeof(cli_addr);
        create_ipv4_for_localhost(&srv_addr, PORT);
        lfd = default_my_socket_ipv4_tcp();
        my_bind(lfd, (struct sockaddr *) &srv_addr, sizeof(srv_addr));
        my_listen(lfd, 128);
    
        maxfd = lfd;
        int maxi = -1;
        for (i = 0; i < FD_SETSIZE; i++) {
        
            client[i] = -1;
        }
        //读集合,和备份集合(用于注册所有读事件)
        fd_set rset, allset;
        //置0
        FD_ZERO(&allset);
        //监听lfd
        FD_SET(lfd, &allset);
    
        while (1) {
        
            rset = allset;
            /**
           int select(int nfds, fd_set *readfds, fd_set *writefds,fd_set *exceptfds, struct timeval *timeout);
             nfds：监听的所有文件描述符中,最大文件描述符+1
             readfds：读文件描述符监听集合
             writefds：写文件描述符监听集合
             exceptfds: 异常文件描述符监听集合
             timeout:
                    >0:设置监听时长
                    NULL:阻塞监听
                    0:非阻塞监听,需要轮询
             返回值:
                  0，尚未有读写事件来
                   -1:error
                   >0:所有监听集合有满足的.
             */
            nready = select(maxfd + 1, &rset, NULL, NULL, NULL);
            check(nready, "select error");
    
            //说明有读写事件来了,因为是lfd,说明有新的客户端连接请求
            if (FD_ISSET(lfd, &rset)) {
        
                //这里accept不会阻塞
                cfd = my_accept(lfd, (struct sockaddr *) &cli_addr, &cli_addr_len);
    
                printf("received from %s at PORT %d \n", inet_ntop(AF_INET, &cli_addr.sin_addr, str, INET_ADDRSTRLEN),
                       ntohs(cli_addr.sin_port));
                for (i = 0; i < FD_SETSIZE; i++) {
        
                    if (client[i] == -1) {
        
                        client[i] = cfd;
                        break;
                    }
                }
                if (i == FD_SETSIZE) {
        
                    fputs("too many clients \n", stderr);
                    exit(1);
                }
    
                //将新建立的客户端连接添加到select监听
                FD_SET(cfd, &allset);
                //记录最大的fd,主要用于遍历事件
                if (maxfd < cfd) {
        
                    maxfd = cfd;
                }
                //记录最大索引
                if (maxi < i) {
        
                    maxi = i;
                }
    
    
                //若监听事件是lfd,且只有一个事件,就直接跳过当前循环
                if (0 == --nready)continue;
            }
            //从4开始，因为0~3,分别被in,out,err以及lfd占用了
            for (i = 0; i <= maxi; i++) {
        
                if (client[i] < 0)continue;
    
                //处理读事件
                if (FD_ISSET(client[i], &rset)) {
        
                    //读取失败或读到末尾,则关闭文件描述符,以及清空select监听的事件.
                    if ((n = my_read(client[i], buf, BUFSIZ)) <= 0) {
        
                        close(client[i]);
                        FD_CLR(client[i], &allset);
                        client[i] = -1;
                    } else {
        
                        my_write(STDOUT_FILENO, buf, n);
                        for (int j = 0; j < n; j++) {
        
                            buf[j] = toupper(buf[j]);
                        }
                        my_write(client[i], buf, n);
                    }
                    //匹配固定个数后,跳出当前循环
                    if (--nready == 0)break;
                }
            }
    
    /*     for (int i = lfd + 1; i <= maxfd; i++) {
                //处理读事件
                if (FD_ISSET(i, &rset)) {
                    //读取失败或读到末尾,则关闭文件描述符,以及清空select监听的事件.
                    if ((n = my_read(i, buf, BUFSIZ)) <= 0) {
                        close(i);
                        FD_CLR(i, &allset);
                    } else {
                        my_write(STDOUT_FILENO, buf, n);
                        for (int i = 0; i < n; i++) {
                            buf[i] = toupper(buf[i]);
                        }
                        my_write(i, buf, n);
                    }
                }
            }*/
        }
        close(lfd);
    
        return 0;
    }

# poll #

#include <stdio.h>
    #include <sys/socket.h>
    #include <stdlib.h>
    #include <unistd.h>
    #include <ctype.h>
    #include <arpa/inet.h>
    #include  "warp_socket.h"
    #include <poll.h>
    #include <errno.h>
    
    #define PORT 8080
    
    /**
     * poll
     *
     * 缺点:相当于对select浅浅的封装,多提供了一个数据结构.且监听事件和返回事件集合分离
     * 优点:扩展监听上限.
     * @return
     */
    #define OPEN_MAX 1024
    int main() {
        
        int lfd, cfd;
        int n, nready, i;
        char buf[OPEN_MAX], str[INET_ADDRSTRLEN];
        struct pollfd client[OPEN_MAX];
        struct sockaddr_in srv_addr, cli_addr;
        socklen_t cli_addr_len = sizeof(cli_addr);
        create_ipv4_for_localhost(&srv_addr, PORT);
        lfd = default_my_socket_ipv4_tcp();
        my_bind(lfd, (struct sockaddr *) &srv_addr, sizeof(srv_addr));
        my_listen(lfd, 128);
    
        //设置待监听的文件描述符
        client[0].fd = lfd;
        //设置带监听的文件描述符的监听事件
        /**POLLIN:读
         * POLLOUT:写
         * POLLERR:错误
         */
        client[0].events = POLLIN;
        for (i = 1; i < FD_SETSIZE; i++) {
        
            client[i].fd = -1;
        }
        int maxi = 0;
    
        while (1) {
        
    
            /**  int poll(  struct pollfd *fds, nfds_t nfds, int timeout);
             *fds : 监听的文件描述符数组
             * nfds ：实际有效监听个数,也就是数组中具体监听多少个
             * timeout ：-1阻塞,0不阻塞,>0超时多少毫秒
             */
            nready = poll(client, maxi + 1, -1);
            check(nready, "select error");
    
            //说明lfd有读写事件来了
            if (client[0].revents & POLLIN) {
        
                cfd = my_accept(lfd, (struct sockaddr *) &cli_addr, &cli_addr_len);
    
                printf("received from %s at PORT %d \n", inet_ntop(AF_INET, &cli_addr.sin_addr, str, INET_ADDRSTRLEN),
                       ntohs(cli_addr.sin_port));
    
                for (i = 1; i < OPEN_MAX; i++) {
        
                    if (client[i].fd == -1) {
        
                        client[i].fd = cfd;
                        break;
                    }
                }
                if (i == OPEN_MAX) {
        
                    fputs("too many clients \n", stderr);
                    exit(1);
                }
    
                client[i].events = POLLIN;
    
                if (maxi < i) {
        
                    maxi = i;
                }
    
                //若监听事件是lfd,且只有一个事件,就直接跳过当前循环
                if (0 == --nready)continue;
            }
            for (i = 1; i <= maxi; i++) {
        
                if (client[i].fd < 0)continue;
                //处理读事件
                if (client[i].revents & POLLIN) {
        
                    //读取失败或读到末尾,则关闭文件描述符,以及清空select监听的事件.
                    if ((n = my_read(client[i].fd, buf, OPEN_MAX)) < 0) {
        
                        //收到RST标志
                        if (errno == ECONNRESET) {
        
                            printf("client %d \n", i);
                            close(client[i].fd);
                            //POLL不监控该文件描述符,设置-1即可
                            client[i].fd = -1;
                        } else {
        
                            fputs("read error \n", stderr);
                        }
                    } else if (n == 0) {
        
                        //读到文件末尾,说明客户端先关闭连接.
                        close(client[i].fd);
                        client[i].fd = -1;
                    } else {
        
                        my_write(STDOUT_FILENO, buf, n);
                        for (int j = 0; j < n; j++) {
        
                            buf[j] = toupper(buf[j]);
                        }
                        my_write(client[i].fd, buf, n);
                    }
                    //匹配固定个数后,跳出当前循环
                    if (--nready == 0)break;
                }
            }
    
        }
        close(lfd);
    
        return 0;
    }

# epoll #

#include <stdio.h>
    #include <sys/socket.h>
    #include <stdlib.h>
    #include <unistd.h>
    #include <ctype.h>
    #include <arpa/inet.h>
    #include  "../warp_socket.h"
    #include <errno.h>
    #include <sys/epoll.h>
    
    #define PORT 8080
    
    /**
     * epoll
     *
     * 事件模型
     *      边沿触发：缓冲区剩余未读尽的数据不会导致epoll_wait返回,新的事件满足监听条件,才会触发
     *      水平出发(默认)：缓冲区剩余未读尽的数据会导致epoll_wait返回
     *
     *  ET边沿触发,高效,只支持文件非阻塞
     *
     *  epoll还可以适用管道之内用文件描述符的
     * @return
     */
    #define OPEN_MAX 1024
    
    int main() {
        
        int efd, lfd, cfd, handle_cfd;
        int n, nready, i;
        char buf[OPEN_MAX], str[INET_ADDRSTRLEN];
        struct sockaddr_in srv_addr, cli_addr;
        socklen_t cli_addr_len = sizeof(cli_addr);
        create_ipv4_for_localhost(&srv_addr, PORT);
        lfd = default_my_socket_ipv4_tcp();
        my_bind(lfd, (struct sockaddr *) &srv_addr, sizeof(srv_addr));
        my_listen(lfd, 128);
    
        //创建epoll红黑树节点(内核会自动调整,仅供参考)
    //    int epoll_create(int size);
        efd = epoll_create(OPEN_MAX);
        check(efd, "epoll_create error");
    
        //将lfd以及结构体设置树上
        struct epoll_event tep, ep[OPEN_MAX];
        //监听读事件
        tep.events = EPOLLIN;//LT水平出发(默认)
    //    tep.events = EPOLLIN|EPOLLET;//ET边沿触发
        tep.data.fd = lfd;
    /**
     *  int epoll_ctl(int epfd, int op, int fd, struct epoll_event *event);
     *  epfd: 红黑树根节点
     *  op：设置加入红黑树节点的监听事件
     *          EPOLL_CTL_ADD 添加节点到红黑树上
     *          EPOLL_CTL_DEL 删除节点,从红黑树上
     *          EPOLL_CTL_MOD 修改节点,从红黑树上
     *
     *  fd：加入红黑树的待监听节点
     *  event：
     *
                struct epoll_event {
                         uint32_t     events; 感兴趣的事件  EPOLLIN/EPOLLOUT/EPOLLERR
                         epoll_data_t data;
                    };
                typedef union epoll_data {
                        void        *ptr;
                        int          fd;    添加的带监听fd
                        uint32_t     u32;
                        uint64_t     u64;
                    } epoll_data_t;
     *
     *
     */
        int res = epoll_ctl(efd, EPOLL_CTL_ADD, lfd, &tep);
        check(res, "epoll_create error");
    
        while (1) {
        
            /**
             *  int epoll_wait(int epfd, struct epoll_event *events,int maxevents, int timeout);
             *  epfd：红黑树根节点
             *  events：传出参数,主要记录那些满足了监听条件的fd
             *  maxevents：传出参数数组总个数
             *  timeout：-1阻塞,0不阻塞,>0超时多少毫秒
             *
             *  返回:满足监听的个数
             */
            nready = epoll_wait(efd, ep, OPEN_MAX, -1);
            check(nready, "select error");
    
            for (i = 0; i < nready; i++) {
        
                if (!ep[i].events & EPOLLIN) {
        
                    continue;
                }
                //说明是建立连接的事件
                if (ep[i].data.fd == lfd) {
        
                    cfd = my_accept(lfd, (struct sockaddr *) &cli_addr, &cli_addr_len);
                    printf("received from %s at PORT %d \n", inet_ntop(AF_INET, &cli_addr.sin_addr, str, INET_ADDRSTRLEN),
                           ntohs(cli_addr.sin_port));
    
                    //新建立连接的fd,加入红黑树
                    tep.events = EPOLLIN;
                    tep.data.fd = cfd;
                    res = epoll_ctl(efd, EPOLL_CTL_ADD, cfd, &tep);
                    check(res, "epoll_create error");
                } else {
        
                    //说明是读事件
                    handle_cfd = ep[i].data.fd;
                    if ((n = my_read(handle_cfd, buf, OPEN_MAX)) <= 0) {
        
                        //从红黑树上移除该监听fd
                        res = epoll_ctl(efd, EPOLL_CTL_DEL, handle_cfd, NULL);
                        check(res, "epoll_create error");
                        perror("close con \n");
                        close(handle_cfd);
                    } else {
        
                        my_write(STDOUT_FILENO, buf, n);
                        for (int j = 0; j < n; j++) {
        
                            buf[j] = toupper(buf[j]);
                        }
                        my_write(handle_cfd, buf, n);
                    }
                }
            }
    
        }
        close(lfd);
        close(efd);
    
        return 0;
    }

# 反应堆 #

#include <stdio.h>
    #include <sys/socket.h>
    #include <sys/epoll.h>
    #include <arpa/inet.h>
    #include <fcntl.h>
    #include <unistd.h>
    #include <errno.h>
    #include <string.h>
    #include <stdlib.h>
    #include <time.h>
    
    #define MAX_EVENTS  1024                                    //监听上限数
    #define BUFLEN 4096
    #define SERV_PORT   8080
    
    void recvdata(int fd, int events, void *arg);
    
    void senddata(int fd, int events, void *arg);
    
    /* 描述就绪文件描述符相关信息 */
    
    struct myevent_s {
        
        int fd;                                                 //要监听的文件描述符
        int events;                                             //对应的监听事件
        void *arg;                                              //泛型参数
        void (*call_back)(int fd, int events, void *arg);       //回调函数
        int status;                                             //是否在监听:1->在红黑树上(监听), 0->不在(不监听)
        char buf[BUFLEN];
        int len;
        long last_active;                                       //记录每次加入红黑树 g_efd 的时间值
    };
    
    int g_efd;                                                  //全局变量, 保存epoll_create返回的文件描述符
    struct myevent_s g_events[MAX_EVENTS + 1];                    //自定义结构体类型数组. +1-->listen fd
    
    
    /*将结构体 myevent_s 成员变量 初始化*/
    
    void eventset(struct myevent_s *ev, int fd, void (*call_back)(int, int, void *), void *arg) {
        
        ev->fd = fd;
        ev->call_back = call_back;
        ev->events = 0;
        ev->arg = arg;
        ev->status = 0;
        //memset(ev->buf, 0, sizeof(ev->buf));
        //ev->len = 0;
        ev->last_active = time(NULL);                       //调用eventset函数的时间
    
        return;
    }
    
    /* 向 epoll监听的红黑树 添加一个 文件描述符 */
    
    void eventadd(int efd, int events, struct myevent_s *ev) {
        
        struct epoll_event epv = {
        0, {
        0}};
        int op;
        epv.data.ptr = ev;
        epv.events = ev->events = events;       //EPOLLIN 或 EPOLLOUT
    
        if (ev->status == 1) {
                                                  //已经在红黑树 g_efd 里
            op = EPOLL_CTL_MOD;                                         //修改其属性
        } else {
                                        //不在红黑树里
            op = EPOLL_CTL_ADD;                 //将其加入红黑树 g_efd, 并将status置1
            ev->status = 1;
        }
    
        if (epoll_ctl(efd, op, ev->fd, &epv) < 0)                       //实际添加/修改
            printf("event add failed [fd=%d], events[%d]\n", ev->fd, events);
        else
            printf("event add OK [fd=%d], op=%d, events[%0X]\n", ev->fd, op, events);
    
        return;
    }
    
    /* 从epoll 监听的 红黑树中删除一个 文件描述符*/
    
    void eventdel(int efd, struct myevent_s *ev) {
        
        struct epoll_event epv = {
        0, {
        0}};
    
        if (ev->status != 1)                                        //不在红黑树上
            return;
    
        epv.data.ptr = ev;
        ev->status = 0;                                             //修改状态
        epoll_ctl(efd, EPOLL_CTL_DEL, ev->fd, &epv);                //从红黑树 efd 上将 ev->fd 摘除
    
        return;
    }
    
    /*  当有文件描述符就绪, epoll返回, 调用该函数 与客户端建立链接 */
    
    void acceptconn(int lfd, int events, void *arg) {
        
        struct sockaddr_in cin;
        socklen_t len = sizeof(cin);
        int cfd, i;
    
        if ((cfd = accept(lfd, (struct sockaddr *) &cin, &len)) == -1) {
        
            if (errno != EAGAIN && errno != EINTR) {
        
                /* 暂时不做出错处理 */
            }
            printf("%s: accept, %s\n", __func__, strerror(errno));
            return;
        }
    
        do {
        
            for (i = 0; i < MAX_EVENTS; i++)                                //从全局数组g_events中找一个空闲元素
                if (g_events[i].status == 0)                                //类似于select中找值为-1的元素
                    break;                                                  //跳出 for
    
            if (i == MAX_EVENTS) {
        
                printf("%s: max connect limit[%d]\n", __func__, MAX_EVENTS);
                break;                                                      //跳出do while(0) 不执行后续代码
            }
    
            int flag = 0;
            if ((flag = fcntl(cfd, F_SETFL, O_NONBLOCK)) < 0) {
                     //将cfd也设置为非阻塞
                printf("%s: fcntl nonblocking failed, %s\n", __func__, strerror(errno));
                break;
            }
    
            /* 给cfd设置一个 myevent_s 结构体, 回调函数 设置为 recvdata */
    
            eventset(&g_events[i], cfd, recvdata, &g_events[i]);
            eventadd(g_efd, EPOLLIN, &g_events[i]);                         //将cfd添加到红黑树g_efd中,监听读事件
    
        } while (0);
    
        printf("new connect [%s:%d][time:%ld], pos[%d]\n",
               inet_ntoa(cin.sin_addr), ntohs(cin.sin_port), g_events[i].last_active, i);
        return;
    }
    
    void recvdata(int fd, int events, void *arg) {
        
        struct myevent_s *ev = (struct myevent_s *) arg;
        int len;
    
        len = recv(fd, ev->buf, sizeof(ev->buf), 0);            //读文件描述符, 数据存入myevent_s成员buf中
    
        eventdel(g_efd, ev);        //将该节点从红黑树上摘除
    
        if (len > 0) {
        
    
            ev->len = len;
            ev->buf[len] = '\0';                                //手动添加字符串结束标记
            printf("C[%d]:%s\n", fd, ev->buf);
    
            eventset(ev, fd, senddata, ev);                     //设置该 fd 对应的回调函数为 senddata
            eventadd(g_efd, EPOLLOUT, ev);                      //将fd加入红黑树g_efd中,监听其写事件
    
        } else if (len == 0) {
        
            close(ev->fd);
            /* ev-g_events 地址相减得到偏移元素位置 */
            printf("[fd=%d] pos[%ld], closed\n", fd, ev - g_events);
        } else {
        
            close(ev->fd);
            printf("recv[fd=%d] error[%d]:%s\n", fd, errno, strerror(errno));
        }
    
        return;
    }
    
    void senddata(int fd, int events, void *arg) {
        
        struct myevent_s *ev = (struct myevent_s *) arg;
        int len;
    
        len = send(fd, ev->buf, ev->len, 0);                    //直接将数据 回写给客户端。未作处理
        /*
        printf("fd=%d\tev->buf=%s\ttev->len=%d\n", fd, ev->buf, ev->len);
        printf("send len = %d\n", len);
        */
    
        if (len > 0) {
        
    
            printf("send[fd=%d], [%d]%s\n", fd, len, ev->buf);
            eventdel(g_efd, ev);                                //从红黑树g_efd中移除
            eventset(ev, fd, recvdata, ev);                     //将该fd的 回调函数改为 recvdata
            eventadd(g_efd, EPOLLIN, ev);                       //从新添加到红黑树上， 设为监听读事件
    
        } else {
        
            close(ev->fd);                                      //关闭链接
            eventdel(g_efd, ev);                                //从红黑树g_efd中移除
            printf("send[fd=%d] error %s\n", fd, strerror(errno));
        }
    
        return;
    }
    
    /*创建 socket, 初始化lfd */
    
    void initlistensocket(int efd, short port) {
        
        int lfd = socket(AF_INET, SOCK_STREAM, 0);
        fcntl(lfd, F_SETFL, O_NONBLOCK);                                            //将socket设为非阻塞
    
        /* void eventset(struct myevent_s *ev, int fd, void (*call_back)(int, int, void *), void *arg);  */
        eventset(&g_events[MAX_EVENTS], lfd, acceptconn, &g_events[MAX_EVENTS]);
    
        /* void eventadd(int efd, int events, struct myevent_s *ev) */
        eventadd(efd, EPOLLIN, &g_events[MAX_EVENTS]);
    
        struct sockaddr_in sin;
        memset(&sin, 0, sizeof(sin));                                               //bzero(&sin, sizeof(sin))
        sin.sin_family = AF_INET;
        sin.sin_addr.s_addr = INADDR_ANY;
        sin.sin_port = htons(port);
    
        bind(lfd, (struct sockaddr *) &sin, sizeof(sin));
    
        listen(lfd, 20);
    
        return;
    }
    
    int main(int argc, char *argv[]) {
        
        unsigned short port = SERV_PORT;
    
        if (argc == 2)
            port = atoi(argv[1]);                           //使用用户指定端口.如未指定,用默认端口
    
        g_efd = epoll_create(MAX_EVENTS + 1);                 //创建红黑树,返回给全局 g_efd
        if (g_efd <= 0)
            printf("create efd in %s err %s\n", __func__, strerror(errno));
    
        initlistensocket(g_efd, port);                      //初始化监听socket
    
        struct epoll_event events[MAX_EVENTS + 1];            //保存已经满足就绪事件的文件描述符数组
        printf("server running:port[%d]\n", port);
    
        int checkpos = 0, i;
        while (1) {
        
            /* 超时验证，每次测试100个链接，不测试listenfd 当客户端60秒内没有和服务器通信，则关闭此客户端链接 */
    
            long now = time(NULL);                          //当前时间
            for (i = 0; i < 100; i++, checkpos++) {
                 //一次循环检测100个。 使用checkpos控制检测对象
                if (checkpos == MAX_EVENTS)
                    checkpos = 0;
                if (g_events[checkpos].status != 1)         //不在红黑树 g_efd 上
                    continue;
    
                long duration = now - g_events[checkpos].last_active;       //客户端不活跃的世间
    
                if (duration >= 60) {
        
                    close(g_events[checkpos].fd);                           //关闭与该客户端链接
                    printf("[fd=%d] timeout\n", g_events[checkpos].fd);
                    eventdel(g_efd, &g_events[checkpos]);                   //将该客户端 从红黑树 g_efd移除
                }
            }
    
            /*监听红黑树g_efd, 将满足的事件的文件描述符加至events数组中, 1秒没有事件满足, 返回 0*/
            int nfd = epoll_wait(g_efd, events, MAX_EVENTS + 1, 1000);
            if (nfd < 0) {
        
                printf("epoll_wait error, exit\n");
                break;
            }
    
            for (i = 0; i < nfd; i++) {
        
                /*使用自定义结构体myevent_s类型指针, 接收 联合体data的void *ptr成员*/
                struct myevent_s *ev = (struct myevent_s *) events[i].data.ptr;
    
                if ((events[i].events & EPOLLIN) && (ev->events & EPOLLIN) || //读就绪事件
                    ((events[i].events & EPOLLOUT) && (ev->events & EPOLLOUT))) {
                //写就绪事件
                    ev->call_back(ev->fd, events[i].events, ev->arg);
                }
    
            }
        }
    
        /* 退出前释放所有资源 */
        return 0;
    }