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

pthread_mutex_t mtx;
pthread_cond_t  cond;


void unlock_mtx(void *a)
{
	pthread_mutex_unlock((pthread_mutex_t *)a);
}

void *thr_routine(void *arg)
{
	printf("%s\n", __func__);
	while (1) {
		pthread_mutex_lock(&mtx);
		pthread_cleanup_push(&unlock_mtx, &mtx);
		pthread_cond_wait(&cond, &mtx);
		pthread_cleanup_pop(0);
		pthread_mutex_unlock(&mtx);
	}
	return (0);
}

void handler(int sig)
{
	write(1, "sig handler\n", 13);
}

int main()
{
	pthread_t td;
	void *retval;
	
	pthread_mutex_init(&mtx, NULL);
	pthread_cond_init(&cond, NULL);

	signal(SIGUSR1, handler);
	for (;;) {
		pthread_create(&td, NULL, thr_routine, NULL);
		sleep(1);
		printf("sending SIGUSR1...\n");
		pthread_kill(td, SIGUSR1);
		sleep(1);
		printf("cancelling thread...\n");
		pthread_cancel(td);
		pthread_join(td, &retval);
		if (retval == PTHREAD_CANCELED)
			printf("canceled\n");
		else
			printf("thread exit code: %d\n", (int)retval);
	}
	return (0);
}