C-Linux_定时器示例使用

#include <stdlib.h>
#include <signal.h>

static int count = 0;
static struct itimerval oldtv;
struct itimerval itv;
void set_timer()
{
        itv.it_interval.tv_sec = 0;
        itv.it_interval.tv_usec = 990000;  //启动后的定时器每隔990ms唤醒一次
        itv.it_value.tv_sec = 0;
        itv.it_value.tv_usec = 50000;   //定时器在50ms后启动
        setitimer(ITIMER_REAL, &itv, &oldtv); 
           //ITIMER_REAL表示每次定时器唤醒时将会触发SIGALRM信号
}

void shut_timer()
{
        itv.it_value.tv_sec = 0;        //将启动参数设置为0,表示定时器不启动
        itv.it_value.tv_usec = 0;
        setitimer(ITIMER_REAL, &itv, &oldtv);
}

void signal_handler(int m)
{
        count ++;
        printf("%d\n", count);
        if(count==4)     //调用4次后,关闭定时器
          shut_timer();
}

int main()
{
        signal(SIGALRM, signal_handler);  //将SIGALRM信号与signal_handler函数建立关系,当信号触发时便会调用该函数.
        set_timer();
        while(count < 10000);
        exit(0);
        return 1;
}