linux posix 定时器

#include <stdio.h> 
#include <signal.h> 
#include <time.h> 
#include <string.h> 
#include <stdlib.h> 
#include <unistd.h> 
 int newa = 0;
void timer_thread(union sigval v) 
{ 
    printf("timer_thread function! %d  %d\n", v.sival_int,newa++); 
} 
 
int main() 
{ 
    timer_t timerid;                                //定时器 id
    struct sigevent evp; 
    memset(&evp, 0, sizeof(struct sigevent));       //清零初始化 
 
    evp.sigev_value.sival_int = 111;                //也是标识定时器的，回调函数可以获得 
    evp.sigev_notify = SIGEV_THREAD;                //线程通知的方式，派驻新线程 
    evp.sigev_notify_function = timer_thread;       //线程函数地址 
 
    if (timer_create(CLOCK_REALTIME, &evp, &timerid) == -1) 
    {   
        perror("fail to timer_create"); 
        exit(-1); 
    }   
 
    /* 第一次间隔it.it_value这么长,以后每次都是it.it_interval这么长,就是说it.it_value变0的时候会>装载it.it_interval的值 */
    struct itimerspec it; 
    it.it_interval.tv_sec = 1;  // 回调函数执行频率为1s运行1次，如果设置为0，则只执行 1 次回调函数
    it.it_interval.tv_nsec = 0; 
    it.it_value.tv_sec = 5;     // 定时多长时间
    it.it_value.tv_nsec = 0; 
    
    struct itimerspec stop; 
    stop.it_interval.tv_sec = 0;  
    stop.it_interval.tv_nsec = 0; 
    stop.it_value.tv_sec = 0;     
    stop.it_value.tv_nsec = 0; 
 
    if (timer_settime(timerid, 0, &it, NULL) == -1) 
    {   
        perror("fail to timer_settime"); 
        exit(-1); 
    }
    sleep (100);
    if (timer_settime(timerid, 0, &stop, NULL) == -1) //通过设置为 0，暂停定时器
    {   
        perror("fail to timer_settime"); 
        exit(-1); 
    }    
 
    //pause();
    while (1);
 
    return 0; 
} 

参考：【C程序】timer_create系列定时器函数