make queue thread-safe

queue/myqueue.h

@@ -1,26 +1,28 @@
 #ifndef MYCLIB_QUEUE_H
 #define MYCLIB_QUEUE_H
 
+#include <pthread.h>
 #include <stddef.h>
 
 /**
- * @brief A generic circular queue (ring buffer).
+ * @brief A simple circular queue (ring buffer).
  */
 typedef struct mcl_queue_t {
-	size_t front;	  /**< Index of the first element (read position). */
-	size_t rear;	  /**< Index where the next element will be written (write position). */
-	size_t size;	  /**< Current number of elements in the queue. */
-	size_t capacity;  /**< Maximum number of elements the queue can hold. */
-	size_t elem_size; /**< Size in bytes of each element in the queue. */
-	void *buffer;	  /**< Pointer to the memory buffer that stores the elements. */
+	size_t front;		  /**< Index of the next element to read. */
+	size_t rear;		  /**< Index where the next element will be written. */
+	size_t size;		  /**< Current number of elements in the queue. */
+	size_t capacity;	  /**< Maximum number of elements the queue can hold. */
+	size_t elem_size;	  /**< Size in bytes of each element. */
+	void *buffer;		  /**< Memory buffer that holds the elements. */
+	pthread_mutex_t lock; /**< Mutex to protect concurrent access. */
 } mcl_queue;
 
 /**
  * @brief Create and initialize a new queue.
  *
  * @param queue_size Number of elements the queue can hold.
- * @param elem_size Size (in bytes) of each element in the queue.
- * @return Pointer to the new queue, or NULL if allocation fails.
+ * @param elem_size  Size in bytes of each element.
+ * @return Pointer to the new queue, or NULL on failure.
  */
 mcl_queue *mcl_queue_init(size_t queue_size, size_t elem_size);
 
@@ -28,41 +30,43 @@ mcl_queue *mcl_queue_init(size_t queue_size, size_t elem_size);
  * @brief Add an element to the queue.
  *
  * @param queue Pointer to the queue.
- * @param elem Pointer to the element to insert.
- * @return 0 on success, -1 if the queue is full.
+ * @param elem  Pointer to the data to add.
+ * @return 0 on success, -1 if the queue is full or on error.
  */
 int mcl_queue_push(mcl_queue *queue, const void *elem);
 
 /**
  * @brief Remove an element from the queue.
  *
- * @param queue Pointer to the queue.
- * @param out_elem Pointer where the removed element will be copied.
- * @return 0 on success, -1 if the queue is empty.
+ * @param queue    Pointer to the queue.
+ * @param out_elem Pointer to memory where the removed element will be copied.
+ * @return 0 on success, -1 if the queue is empty or on error.
  */
 int mcl_queue_pop(mcl_queue *queue, void *out_elem);
 
 /**
- * @brief Get a pointer to the front element of the queue (oldest one).
+ * @brief Copy the front element without removing it.
  *
  * @param queue Pointer to the queue.
- * @return Pointer to the front element, or NULL if the queue is empty.
+ * @param out   Pointer to memory where the element will be copied.
+ * @return 0 on success, -1 if the queue is empty or on error.
  */
-void *mcl_queue_get_front(mcl_queue *queue);
+int mcl_queue_get_front(mcl_queue *queue, void *out);
 
 /**
- * @brief Get a pointer to the rear element of the queue (most recently added).
+ * @brief Copy the last element without removing it.
  *
  * @param queue Pointer to the queue.
- * @return Pointer to the rear element, or NULL if the queue is empty.
+ * @param out   Pointer to memory where the element will be copied.
+ * @return 0 on success, -1 if the queue is empty or on error.
  */
-void *mcl_queue_get_rear(mcl_queue *queue);
+int mcl_queue_get_rear(mcl_queue *queue, void *out);
 
 /**
- * @brief Free all memory used by the queue.
+ * @brief Free all resources used by the queue.
  *
  * @param queue Pointer to the queue to free.
  */
 void mcl_queue_free(mcl_queue *queue);
 
-#endif
+#endif	// MYCLIB_QUEUE_H