base layer, mostly stolen

pthread_barrier.c

@@ -0,0 +1,102 @@
+/* (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 */