make queue thread-safe

queue/myqueue.c

@@ -1,5 +1,6 @@
 #include "myqueue.h"
 
+#include <pthread.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -16,6 +17,14 @@ mcl_queue *mcl_queue_init(size_t queue_size, size_t elem_size) {
 		return NULL;
 	}
 
+	int ret = pthread_mutex_init(&queue->lock, NULL);
+	if (ret != 0) {
+		free(queue->buffer);
+		free(queue);
+
+		return NULL;
+	}
+
 	queue->front = 0;
 	queue->rear = 0;
 	queue->size = 0;
@@ -26,8 +35,15 @@ mcl_queue *mcl_queue_init(size_t queue_size, size_t elem_size) {
 }
 
 int mcl_queue_push(mcl_queue *queue, const void *elem) {
+	int ret = pthread_mutex_lock(&queue->lock);
+	if (ret != 0) {
+		return -1;
+	}
+
 	if (queue->size == queue->capacity) {
 		/* Queue full */
+		pthread_mutex_unlock(&queue->lock);
+
 		return -1;
 	}
 
@@ -38,12 +54,21 @@ int mcl_queue_push(mcl_queue *queue, const void *elem) {
 	queue->size++;
 	queue->rear = (queue->rear + 1) % queue->capacity;
 
+	pthread_mutex_unlock(&queue->lock);
+
 	return 0;
 }
 
 int mcl_queue_pop(mcl_queue *queue, void *out_elem) {
+	int ret = pthread_mutex_lock(&queue->lock);
+	if (ret != 0) {
+		return -1;
+	}
+
 	if (queue->size == 0) {
 		/* Queue empty */
+		pthread_mutex_unlock(&queue->lock);
+
 		return -1;
 	}
 
@@ -53,20 +78,41 @@ int mcl_queue_pop(mcl_queue *queue, void *out_elem) {
 	queue->front = (queue->front + 1) % queue->capacity;
 	queue->size--;
 
+	pthread_mutex_unlock(&queue->lock);
+
 	return 0;
 }
 
-void *mcl_queue_get_front(mcl_queue *queue) {
-	if (queue->size == 0) {
-		return NULL;
+int mcl_queue_get_front(mcl_queue *queue, void *out) {
+	int ret = pthread_mutex_lock(&queue->lock);
+	if (ret != 0) {
+		return -1;
 	}
 
-	return (void *)queue->buffer + (queue->front * queue->elem_size);
+	if (queue->size == 0) {
+		pthread_mutex_unlock(&queue->lock);
+
+		return -1;
+	}
+
+	void *front = (void *)queue->buffer + (queue->front * queue->elem_size);
+	memcpy(out, front, queue->elem_size);
+
+	pthread_mutex_unlock(&queue->lock);
+
+	return 0;
 }
 
-void *mcl_queue_get_rear(mcl_queue *queue) {
+int mcl_queue_get_rear(mcl_queue *queue, void *out) {
+	int ret = pthread_mutex_lock(&queue->lock);
+	if (ret != 0) {
+		return -1;
+	}
+
 	if (queue->size == 0) {
-		return NULL;
+		pthread_mutex_unlock(&queue->lock);
+
+		return -1;
 	}
 
 	size_t rear_index;
@@ -76,7 +122,12 @@ void *mcl_queue_get_rear(mcl_queue *queue) {
 		rear_index = queue->rear - 1;
 	}
 
-	return (void *)queue->buffer + (rear_index * queue->elem_size);
+	void *rear = (void *)queue->buffer + (rear_index * queue->elem_size);
+	memcpy(out, rear, queue->elem_size);
+
+	pthread_mutex_unlock(&queue->lock);
+
+	return 0;
 }
 
 void mcl_queue_free(mcl_queue *queue) {
@@ -84,6 +135,8 @@ void mcl_queue_free(mcl_queue *queue) {
 		return;
 	}
 
+	pthread_mutex_destroy(&queue->lock);
+
 	free(queue->buffer);
 	free(queue);
 }