#include <stdio.h>
#include <signal.h>
#include <sys/time.h>
#include <time.h>
#include <stdlib.h>

#define MICRO_FACTOR 1000000
#define MAX_INTERVAL 10

void do_nothing(int signum) { }

int main(void)
{
    struct sigaction action;
    struct itimerval period;
    struct timeval before_time, after_time;
    int delta;
    int interval;
    

    action.sa_handler = &do_nothing;
    action.sa_flags = 0;
    sigaction(SIGALRM, &action, NULL);

    for(;;)
    {
        interval = random() % MAX_INTERVAL;
        if(interval == 0)
            interval = 1;

        period.it_interval.tv_sec  = period.it_value.tv_sec  = interval;
        period.it_interval.tv_usec = period.it_value.tv_usec = 0;
        setitimer(ITIMER_REAL, &period, NULL);

        gettimeofday(&before_time, NULL);

        pause();

        gettimeofday(&after_time, NULL);

        delta = (after_time.tv_sec - before_time.tv_sec) * MICRO_FACTOR +
                (after_time.tv_usec - before_time.tv_usec) - interval * MICRO_FACTOR;

        printf("%ld\n", delta);
    }
}