/* (C) Copyright 2019 Robert Sauter
 * SPDX-License-Identifier: MIT
 */

/** Pthread-barrier implementation for macOS using a pthread mutex and condition variable */


#include "pthread_barrier.h"
#include <errno.h>

#ifdef __APPLE__

int pthread_barrier_init(pthread_barrier_t *__restrict barrier,
                         const pthread_barrierattr_t * __restrict attr,
                         unsigned count) {
	if (count == 0) {
		return EINVAL;
	}

	int ret;

	pthread_condattr_t condattr;
	pthread_condattr_init(&condattr);
	if (attr) {
		int pshared;
		ret = pthread_barrierattr_getpshared(attr, &pshared);
		if (ret) {
			return ret;
		}
		ret = pthread_condattr_setpshared(&condattr, pshared);
		if (ret) {
			return ret;
		}
	}

	ret = pthread_mutex_init(&barrier->mutex, attr);
	if (ret) {
		return ret;
	}

	ret = pthread_cond_init(&barrier->cond, &condattr);
	if (ret) {
		pthread_mutex_destroy(&barrier->mutex);
		return ret;
	}

	barrier->count = count;
	barrier->left = count;
	barrier->round = 0;

	return 0;
}

int pthread_barrier_destroy(pthread_barrier_t *barrier) {
	if (barrier->count == 0) {
		return EINVAL;
	}

	barrier->count = 0;
	int rm = pthread_mutex_destroy(&barrier->mutex);
	int rc = pthread_cond_destroy(&barrier->cond);
	return rm ? rm : rc;
}


int pthread_barrier_wait(pthread_barrier_t *barrier) {
	pthread_mutex_lock(&barrier->mutex);
	if (--barrier->left) {
		unsigned round = barrier->round;
		do {
			pthread_cond_wait(&barrier->cond, &barrier->mutex);
		} while (round == barrier->round);
		pthread_mutex_unlock(&barrier->mutex);
		return 0;
	} else {
		barrier->round += 1;
		barrier->left = barrier->count;
		pthread_cond_broadcast(&barrier->cond);
		pthread_mutex_unlock(&barrier->mutex);
		return PTHREAD_BARRIER_SERIAL_THREAD;
	}
}


int pthread_barrierattr_init(pthread_barrierattr_t *attr) {
	return pthread_mutexattr_init(attr);
}

int pthread_barrierattr_destroy(pthread_barrierattr_t *attr) {
	return pthread_mutexattr_destroy(attr);
}

int pthread_barrierattr_getpshared(const pthread_barrierattr_t *__restrict attr,
                                   int *__restrict pshared) {
	return pthread_mutexattr_getpshared(attr, pshared);
}

int pthread_barrierattr_setpshared(pthread_barrierattr_t *attr, int pshared) {
	return pthread_mutexattr_setpshared(attr, pshared);
}

#endif  /* __APPLE */