#include <stdio.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include <sys/epoll.h>
#include <sys/timerfd.h>

void
main()
{
    struct epoll_event ev;
    struct epoll_event evs[16];
	struct itimerspec its;
    struct timespec t;
	unsigned long long v;
    int efd, tfd, n, i, interval = 5;

    tfd = timerfd_create(CLOCK_MONOTONIC, 0);
    if (tfd < 0){
        perror("timerfd_create() error");
		return;
    }

    if (clock_gettime(CLOCK_MONOTONIC, &t) != 0){
        perror("clock_gettime() error");
        return;
    }

    its.it_value.tv_sec = t.tv_sec + interval;
    its.it_value.tv_nsec = 0;
    its.it_interval.tv_sec = interval;
    its.it_interval.tv_nsec = 0;

    if (timerfd_settime(tfd, TFD_TIMER_ABSTIME, &its, NULL) != 0) {
        perror("timerfd_settime() error");
        return;
    }

    efd = epoll_create1(0);
    if (efd < 0){
        perror("epoll_create1() error");
        return;
    }

    ev.events = EPOLLIN;
    if (epoll_ctl(efd, EPOLL_CTL_ADD, tfd, &ev) != 0){
        perror("epoll_ctl() error");
        return;
    }

    while(1) {
        n = epoll_wait(efd, evs, 16, -1);
        if (n == -1){
            perror("epoll_wait() error");
            break;
        } else if(n == 0){
            break;
        }
        for (i = 0; i < n; i++){
			printf("get timer\n");
			memset(&its, 0, sizeof(its));	
			timerfd_settime(tfd, TFD_TIMER_ABSTIME, &its, NULL);
		}
	}
}