Multiple timers in MacOS/FreeBSD without timer_t.

POSIX extensions strike again, as I did not have timer_t. dispatch functions allow multiple timers in C under MacOS.

#include 
#include 
#include 

int i = 0;
dispatch_queue_t queue;
dispatch_source_t timer1;
dispatch_source_t timer2;


void sigtrap(int sig)
{
    dispatch_source_cancel(timer1);
    dispatch_source_cancel(timer2);
    printf("CTRL-C received, exiting program\n");
    exit(EXIT_SUCCESS);
}

void vector1(dispatch_source_t timer)
{
  printf("a: %d\n", i);
  i++;
  if (i >= 20) 
  {
   dispatch_source_cancel(timer);
  } 
}
void vector2(dispatch_source_t timer)
{
  printf("b: %d\n", i);
  i++;
  if (i >= 20)  //at 20 count cancel the 
  {
   dispatch_source_cancel(timer);
  } 
}

int main(int argc, const char* argv[]) {

 signal(SIGINT, &sigtrap);   //catch the cntl-c
 queue = dispatch_queue_create("timerQueue", 0);

 // Create dispatch timer source
 timer1 = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
 timer2 = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
 
 // Set block for dispatch source when catched events
 dispatch_source_set_event_handler(timer1, ^{vector1(timer1);});
 dispatch_source_set_event_handler(timer2, ^{vector2(timer2);});

 // Set block for dispatch source when cancel source
 dispatch_source_set_cancel_handler(timer1, ^{
  dispatch_release(timer1);
  dispatch_release(queue);
  printf("end\n");
  exit(0);
 });
 dispatch_source_set_cancel_handler(timer2, ^{
  dispatch_release(timer2);
  dispatch_release(queue);
  printf("end\n");
  exit(0);
 }); 

 dispatch_time_t start = dispatch_time(DISPATCH_TIME_NOW, NSEC_PER_SEC); // after 1 sec

 // Set timer
 dispatch_source_set_timer(timer1, start, NSEC_PER_SEC / 5, 0);  // 0.2 sec
 dispatch_source_set_timer(timer2, start, NSEC_PER_SEC / 2, 0);  // 0.5 sec
 printf("start\n");

 dispatch_resume(timer1);
 dispatch_resume(timer2);
 dispatch_main();
 return 0;
}