处理非活动连接

其中依赖的lst_timer.h见上篇文章

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/epoll.h>
#include <pthread.h>
#include "lst_timer.h"

#define FD_LIMIT 65535
#define MAX_EVENT_NUMBER 1024
#define TIMESLOT 5
static int pipefd[2];

static sort_timer_lst timer_lst;
static int epollfd = 0;

int setnonblocking(int fd)
{
    int old_option = fcntl(fd, F_GETFL);
    int new_option = old_option | O_NONBLOCK;
    fcntl(fd, F_SETFL, new_option);
    return old_option;
}

void addfd(int epollfd, int fd)
{
    epoll_event event;
    event.data.fd = fd;
    event.events = EPOLLIN | EPOLLET;
    epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &event);
    setnonblocking(fd);
}

void sig_handler(int sig) // 将信号发往pipefd[1]
{
    int save_errno = errno;
    int msg = sig;
    send(pipefd[1], (char*)&msg, 1, 0);
    errno = save_errno;
}

void addsig(int sig)
{
    struct sigaction sa;
    memset(&sa, '\0', sizeof(sa));
    sa.sa_handler = sig_handler;
    sa.sa_flags |= SA_RESTART; // 重新调用被该信号终止的系统调用 P182
    sigfillset(&sa.sa_mask); // 在信号集中设置所有信号
    assert(sigaction(sig, &sa, NULL) != -1);
}

void timer_handler()
{
    timer_lst.tick();
    alarm(TIMESLOT); 
}

void cb_func(client_data* user_data)
{
    epoll_ctl(epollfd, EPOLL_CTL_DEL, user_data->sockfd, 0); // 把user_data->sockfd从监听的fd中删除
    assert(user_data);
    close(user_data->sockfd);
    printf("close fd %d\n", user_data->sockfd);
}

int main(int argc, char* argv[])
{
    if (argc <= 2) {
        printf("usage:%s ip_address port_number\n", basename(argv[0]));
        return 1;
    }
    const char* ip = argv[1];
    int port = atoi(argv[2]);

    int ret = 0;
    struct sockaddr_in address;
    bzero(&address, sizeof(address));
    address.sin_family = AF_INET;
    inet_pton(AF_INET, ip, &address.sin_addr);
    address.sin_port = htons(port);

    int listenfd = socket(PF_INET, SOCK_STREAM, 0);
    assert(listenfd >= 0);

    ret = bind(listenfd, (struct sockaddr*)&address, sizeof(address));
    assert(ret != -1);

    ret = listen(listenfd, 5);
    assert(ret != -1);

    epoll_event events[MAX_EVENT_NUMBER];
    int epollfd = epoll_create(5);
    assert(epollfd != -1);
    addfd(epollfd, listenfd);

    ret = socketpair(PF_UNIX, SOCK_STREAM, 0, pipefd); // 双向管道
    assert(ret != -1);
    setnonblocking(pipefd[1]);
    addfd(epollfd, pipefd[0]);
    
    addsig(SIGALRM);
    addsig(SIGTERM);
    bool stop_server = false;

    client_data* users = new client_data[FD_LIMIT];
    bool timeout = false;
    alarm(TIMESLOT); // 定时

    while (!stop_server) {
        int number = epoll_wait(epollfd, events, MAX_EVENT_NUMBER, -1);
        if ((number < 0) && (errno != EINTR)) { // EINTR代表临时性失败,进行系统调用时执行信号处理函数去了。 再次调用有可能成功
            printf("epoll failure\n");
            break;
        }

        for (int i = 0; i < number; i++) {
            int sockfd = events[i].data.fd;
            if (sockfd == listenfd) {
                struct sockaddr_in client_address;
                socklen_t client_addrlength = sizeof(client_address);
                int connfd = accept(listenfd, (struct sockaddr*)&client_address, &client_addrlength);
                addfd(epollfd, connfd);
                users[connfd].address = client_address;
                users[connfd].sockfd = connfd;

                util_timer* timer = new util_timer; // 加入定时器
                timer->user_data = &users[connfd];
                timer->cb_func = cb_func;
                time_t cur = time(NULL);
                timer->expire = cur + 3 * TIMESLOT;
                users[connfd].timer = timer;
                timer_lst.add_timer(timer);
            } else if ((sockfd == pipefd[0]) && (events[i].events & EPOLLIN)) { // 处理信号
                int sig;
                char signals[1024];
                ret = recv(pipefd[0], signals, sizeof(signals), 0);
                if (ret == -1) {
                    continue;
                } else if (ret == 0) {
                    continue;
                } else {
                    for (int i = 0; i < ret; ++i) {
                        switch(signals[i]) {
                            case SIGALRM: {
                                printf("SIGALARM has been triggered!\n");
                                timeout = true; // 标记有定时任务要处理
                                break;
                            }
                            case SIGTERM: {
                                stop_server = true;
                            }
                        }
                    }
                }
            } else if (events[i].events & EPOLLIN) { // 处理接收数据
                memset(users[sockfd].buf, '\0', BUFFER_SIZE);
                ret = recv(sockfd, users[sockfd].buf, BUFFER_SIZE - 1, 0);
                printf("get %d bytes of clinet data %s from %d\n", ret, users[sockfd].buf, sockfd);
                util_timer* timer = users[sockfd].timer;
                if (ret < 0) {
                    if (errno != EAGAIN) { // 非阻塞系统调用由于资源限制，意思很明显，让你再次尝试
                        cb_func(&users[sockfd]); // 发生读错误，sockfd可以删了
                        if (timer) {
                            timer_lst.del_timer(timer);
                        }
                    }
                } else if (ret == 0) { // 对方关闭连接 服务器也关闭连接
                    cb_func(&users[sockfd]);
                    if (timer) {
                        timer_lst.del_timer(timer);
                    }
                } else {
                    if (timer) {
                        time_t cur = time(NULL);
                        timer->expire = cur + 3 * TIMESLOT;
                        printf("adjust timer once\n");
                        timer_lst.adjust_timer(timer);
                    }
                }
            } else {

            }
        }
        if (timeout) { // 处理定时事件（清理链表中超时的事件），优先级比io低。
            timer_handler();
            timeout = false;
        }
    }

    close(listenfd);
    close(pipefd[1]);
    close(pipefd[0]);
    delete[] users;
    return 0;

}

每过五秒就会发送一个SIGALRM信号，每个客户端和服务器的过期连接时常是3个timeslot，超时后服务器会自动断开与客户端的连接。每次客户端向服务器发送信息后，会调用adjust_timer来重新调整这个连接的到期时间，至发送信息后+三个timeslot。

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服务器：

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客户端：

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reference: Linux高性能服务器编程——游双