linux中怎么利用timerfd_create实现一个计时器

linux中怎么利用timerfd_create实现一个计时器，很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。

timer_poll.h

代码如下:

/*
 * File:   timer_poll.h
 * Author: Administrator
 */

#ifndef TIMER_POLL_H
#define TIMER_POLL_H
#include <sys/types.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/epoll.h>
#include <stdlib.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/timerfd.h>
#include <unistd.h>
#include <pthread.h>
#include <map>

#define MAXFDS 128
#define EVENTS 100
class timer;
typedef int(*timer_callback)(timer &);//user callback

class timer
{
public:

    timer() : timer_internal(0.0), cb(0), timer_id(0), repeat(0), userdata(0){}
    timer(double internal_value, int  (*callback)(timer &ptimer), void *data, int rep) : timer_internal(internal_value), cb(callback), userdata(data), repeat(rep)
    {
        timer_id = timerfd_create(CLOCK_REALTIME, 0);
        setNonBlock(timer_id);
    }

    timer(const timer &ptimer);
    timer & operator=(const timer &ptimer);
    int timer_start();
    int timer_stop();
    int timer_modify_internal(double timer_internal);

    int timer_get_id()
    {
        return timer_id;
    }

    void *timer_get_userdata()
    {
        return userdata;
    }

    timer_callback get_user_callback()
    {
        return cb;
    }

    ~timer()
    {
        timer_stop();
    }

private:

    bool setNonBlock (int fd)
    {
        int flags = fcntl (fd, F_GETFL, 0);
        flags |= O_NONBLOCK;
        if (-1 == fcntl (fd, F_SETFL, flags))
        {
            return false;
        }
        return true;
    }
    int     timer_id;
    double  timer_internal;
    void    *userdata;
    bool    repeat;//will the timer repeat or only once
    timer_callback cb;
} ;
class timers_poll
{
public:
    timers_poll(int max_num=128)
    {
        active = 1;
        epfd = epoll_create(max_num);
    }

    int timers_poll_add_timer(timer &ptimer);
    int timers_poll_del_timer(timer &ptimer);
    int run();

    int timers_poll_deactive()
    {
        active = 0;
    }

    ~ timers_poll()
    {

    }
private:
    int epfd;
    int active;
    std::map<int, timer> timers_map;
    /* data */
} ;
#endif /* TIMER_POLL_H */

timer_poll.cpp

代码如下:

/*
 * File:   timer_poll.cpp
 * Author: Administrator
 */

#include <cstdlib>
#include "timer_poll.h"

using namespace std;

timer::timer(const timer& ptimer)
{
    timer_internal = ptimer.timer_internal;
    cb = ptimer.cb;
    timer_id = ptimer.timer_id;
    repeat = ptimer.repeat;
    userdata = ptimer.userdata;
}

timer & timer::operator =(const timer& ptimer)
{
    if (this == &ptimer)
    {
        return *this;
    }

    timer_internal = ptimer.timer_internal;
    cb = ptimer.cb;
    timer_id = ptimer.timer_id;
    repeat = ptimer.repeat;
    userdata = ptimer.userdata;
    return *this;
}

int timer::timer_start()
{
    struct itimerspec ptime_internal = {0};
    ptime_internal.it_value.tv_sec = (int) timer_internal;
    ptime_internal.it_value.tv_nsec = (timer_internal - (int) timer_internal)*1000000;
    if(repeat)
    {
        ptime_internal.it_interval.tv_sec = ptime_internal.it_value.tv_sec;
        ptime_internal.it_interval.tv_nsec = ptime_internal.it_value.tv_nsec;
    }

    timerfd_settime(timer_id, 0, &ptime_internal, NULL);
    return 0;
}

int timer::timer_stop()
{
    close(timer_id);
    return 0;
}

int timer::timer_modify_internal(double timer_internal)
{
    this->timer_internal = timer_internal;
    timer_start();
}

int timers_poll::timers_poll_add_timer(timer& ptimer)
{
    int timer_id = ptimer.timer_get_id();
    struct epoll_event ev;
    ev.data.fd = timer_id;
    ev.events = EPOLLIN | EPOLLET;
    timers_map[timer_id] = ptimer; //add or modify
    epoll_ctl (epfd, EPOLL_CTL_ADD, timer_id, &ev);
    ptimer.timer_start();

    return 0;
}

int timers_poll::timers_poll_del_timer(timer& ptimer)
{
    int timer_id = ptimer.timer_get_id();
    struct epoll_event ev;
    ev.data.fd = timer_id;
    ev.events = EPOLLIN | EPOLLET;
    epoll_ctl (epfd, EPOLL_CTL_DEL, timer_id, &ev);
    timers_map.erase(timer_id);

    return 0;
}

int timers_poll::run()
{
    char buf[128] ={0};
    for (; active ; )
    {
        struct epoll_event events[MAXFDS] ={0};
        int nfds = epoll_wait (epfd, events, MAXFDS, -1);
        for (int i = 0; i < nfds; ++i)
        {
            std::map<int, timer>::iterator itmp = timers_map.find(events[i].data.fd);
            if (itmp != timers_map.end())
            {
                //timer ptimer = itmp->second;
                while (read(events[i].data.fd, buf, 128) > 0);
                itmp->second.get_user_callback()(itmp->second);
            }
        }
    }
}

main.cpp

代码如下:

/*
 * File:   main.cpp
 * Author: Administrator
 */

#include <cstdlib>
#include <iostream>

#include "timer_poll.h"

using namespace std;

int callback(timer &ptimer)
{
    printf("timer id=%d:%s\n", ptimer.timer_get_id(), (char *) ptimer.timer_get_userdata());
    return 0;
}

void *thread_fun(void *data)
{
    timers_poll *my_timers = (timers_poll *)data;
    my_timers->run();
}

/*
 *
 */
int main(int argc, char** argv)
{
    timers_poll my_timers(128);
    pthread_t thread_id = 0;
    pthread_create(&thread_id, NULL, thread_fun, &my_timers);

   
    timer timer1(1.05, callback, (void *) "hello 1",0);
    timer timer2(1.10, callback, (void *) "hello 2",0);

   // timer1.timer_start();
   // timer2.timer_start();

    my_timers.timers_poll_add_timer(timer1);
    my_timers.timers_poll_add_timer(timer2);

    sleep(5);
    my_timers.timers_poll_del_timer(timer2);
    cout<<"del complete"<<endl;
    timer1.timer_modify_internal(5.1);
    //timer2.timer_modify_internal(10.1);
    cout<<"modify complete"<<endl;
    sleep(4);
    //my_timers.timers_poll_del_timer(timer2);

    //sleep(5);

    //my_timers.timers_poll_deactive();

    pthread_join(thread_id,NULL);
    return 0;
}

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