int pthread_cond_init (pthread_cond_t *cond, pthread_condattr_t *cond_attr);
int pthread_cond_destroy (pthread_cond_t *cond);

int pthread_cond_signal (pthread_cond_t *cond);
int pthread_cond_broadcast (pthread_cond_t *cond);
int pthread_cond_wait (pthread_cond_t *cond, pthread_mutex_t *mutex);
int pthread_cond_timedwait (pthread_cond_t *cond,
                            pthread_mutex_t *mutex,
                            const struct timespec *abstime);