// Ivan Novick
// November 26, 2009
// example code to set a timer using setitimer and catch the SIGALRM with a handler

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

void alarm_handler(int signum){
    // not a great idea to call system calls inside signal handlers
    fprintf(stdout, "alarm_handler\n");
    fflush(stdout);
}

int main(int argc, char** argv){

	struct sigaction new_action;
	new_action.sa_handler = alarm_handler;
	sigemptyset (&new_action.sa_mask);
	new_action.sa_flags = 0;
	
	if (sigaction(SIGALRM, &new_action, NULL) < 0){
	    fprintf(stderr, "setting SIGALRM handler failed\n");
	    exit(1);
	}
	
	struct itimerval timerval;
	
	timerval.it_value.tv_sec = 10;
	timerval.it_value.tv_usec = 0; // first sleep is 10 seconds
	
	timerval.it_interval.tv_sec = 4;
	timerval.it_interval.tv_usec = 0; // renewal sleeps are 4 seconds
	
	if (setitimer(ITIMER_REAL, &timerval, NULL) < 0){
	    fprintf(stderr, "setting timer failed\n");
	    exit(1);
	}
	
	int slept = 0;
	while (1){
	    sleep(1);
	    fprintf(stdout, "slept %d sec\n", ++slept);
	    fflush(stdout);
	}
	
	return 0;
}