11-3-close-unactive-connection.c

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.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];
/*利用代码清单11-2中的升序链表来管理定时器*/
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)
{
    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;
    sigfillset(&sa.sa_mask);
    assert(sigaction(sig, &sa, NULL) != -1);
}

void timer_handler()
{
    /*定时处理任务，实际上就是调用tick函数*/
    timer_lst.tick();
    /*因为一次alarm调用只会引起一次SIGALRM信号，所以我们要重新定时，以不断触发
     *SIGALRM信号 
     **/
    alarm(TIMESLOT);
}

/*定时器回调函数， 它删除非活动连接socket上的注册事件，并关闭之*/
void cb_func(client_data *user_data)
{
    epoll_ctl(epollfd, EPOLL_CTL_DEL, user_data->sockfd, 0);
    assert(user_data);
    close(user_data->sockfd);
    fprintf(stdout, "close fd %d\n", user_data->sockfd);
}

int main(int argc, const char *argv[])
{
    if (argc <= 2) 
    {
        fprintf(stderr, "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);

    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);
    assert(ret != -1);
    setnonblocking(pipefd[1]);
    addfd(epollfd, pipefd[0]);

    /*设置信号处理函数*/
    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))
        {
            fprintf(stderr, "epoll failure\n");
            break;
        }

        for(int i = 0; i < number; i++) 
        {
            int sockfd = events[i].data.fd;
            /*处理新到的客户连接*/
            if (sockfd == listenfd) 
            {
                struct sockaddr_in client_address;
                socklen_t client_addrlength = sizeof(client_addrlength);
                int connfd = accept(listenfd, (struct sockaddr *)&client_address,
                        &client_addrlength);
                addfd(epollfd, connfd);
                users[connfd].address = client_address;
                users[connfd].sockfd  = connfd;
                
                /*创建定时器， 设置其回调函数与超时时间，
                 * 然后绑定定时器与用户数据，
                 * 最后将定时器添加到链表timer_lst中*/
                util_timer *timer = new util_timer;
                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);
            }
            /*处理信号*/
            else if ((sockfd == pipefd[0]) && (events[i].events & EPOLLIN)) 
            {
                char signals[1024];
                ret = recv(pipefd[0], signals, sizeof(signals), 0);
                if (ret == -1) 
                {
                    //handle the error
                    continue;
                }
                else if (ret == 0) 
                {
                    continue;
                }
                else
                {
                     for(int i = 0; i < ret; i++) 
                     {
                         switch(signals[i])
                         {
                             case SIGALRM:
                                 {
                                     /*用timeout变量标记有定时任务需要处理,
                                      * 但不立即处理定时任务，
                                      * 这是因为定时任务的优先级不是很高，
                                      * 我们优先处理其他更重要的任务*/
                                     timeout = true;
                                     break;
                                 }
                            case SIGTERM:
                                 {
                                     stop_server = true;
                                 }
                         }
                
                     }
                }
            }
            /*处理客户连接上接收到的数据*/
            else if (events[i].events & EPOLLIN) 
            {
                memset(users[sockfd].buf, '\0', BUFFER_SIZE - 1);
                ret = recv(sockfd, users[sockfd].buf, BUFFER_SIZE - 1, 0);
                fprintf(stdout, "get %d bytes of client data %s from %d \n", ret,
                        users[sockfd].buf, sockfd);

                util_timer *timer = users[sockfd].timer;
                if (ret < 0) 
                {
                    /*如果发生错误，则关闭连接，并移除其对应的定时器*/
                    if (errno != EAGAIN) 
                    {
                        cb_func( &users[sockfd]);
                        if(timer)
                        {
                            timer_lst.del_timer(timer);
                        }
                    }
                }
                else if (ret == 0) 
                {
                    /*如果对方已经关闭连接，则我们也关闭连接，并移除对应的定时器*/
                    cb_func(&users[sockfd]);
                    if(timer)
                    {
                        timer_lst.del_timer(timer);
                    }
                }
                else
                {
                    /*如果某个客户连接上有数据可读，
                     * 则我们要调整该连接对应的定时器，
                     * 以延迟该连接被关闭的时间*/
                    if (timer) 
                    {
                        time_t cur = time(NULL);
                        timer->expire = cur + 3*TIMESLOT;
                        fprintf(stdout, "adjust timer once\n");
                        timer_lst.adjust_timer(timer);
                    }
                }
            }
            else
            {
                //others
            }
        }

        /*最后处理定时事件，
         * 因为I/O事件有更高的优先级。当然，这样做将导致定时任务不能精确
         * 地按照预期的时间执行
         * */
        if (timeout) 
        {
            timer_handler();
            timeout = false;
        }
    }

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