/* copyright(c) 2010 davidxu@freebsd.org */

#include <stdio.h>
#include <pthread.h>
#include <signal.h>
#include <semaphore.h>
#include <stdlib.h>

pthread_key_t	sem_key;
int		loops;

void
usr1_handler(int sig)
{
	sem_t *s = (sem_t *)pthread_getspecific(sem_key);
	sem_post(s);
}

void *
sub_routine(void *arg)
{
	sem_t *s = (sem_t *)arg;
	pthread_setspecific(sem_key, arg);
	sem_post(s);
	for (;;)
		sleep(1);
}

void *
thr_routine(void *arg)
{
	pthread_t subtd;
	sem_t sem;
	int i;

	sem_init(&sem, 0, 0);
	if (pthread_create(&subtd, NULL, sub_routine, &sem)) {
		printf("can not create thread\n");
		exit(2);
	}
	sem_wait(&sem);
	for (i = 0; i < loops; ++i) {
		pthread_kill(subtd, SIGUSR1);
		sem_wait(&sem);
	}
	pthread_cancel(subtd);
	pthread_join(subtd, NULL);
	return (NULL);
}

int
main(int argc, char *argv[])
{
	pthread_t	*td;
	int		i;
	int		pairs;

	if (argc < 3) {
		printf("usage:\n\t %s <thread pairs> <signal loops>\n", argv[0]);
		return (1);
	}
	pairs = atoi(argv[1]);
	loops = atoi(argv[2]);
	td = malloc(sizeof(pthread_t) * pairs);
	pthread_key_create(&sem_key, NULL);
	signal(SIGUSR1, usr1_handler);

	for (i = 0; i < pairs; ++i) {
		if (pthread_create(&td[i], NULL, thr_routine, NULL)) {
			printf("can not create thread\n");
			return (2);
		}
	}
	for (i = 0; i < pairs; ++i)
		pthread_join(td[i], NULL);
	free(td);
	return (0);
}