Added is_empty function

Author: Griezn

include/queue.h

@@ -11,7 +11,7 @@ typedef struct {
     _Alignas(64) atomic_size_t  head;
     _Alignas(64) atomic_size_t  tail;
     size_t                      mask;
-    data_t                        **buffer;
+    data_t                      **buffer;
 } spsc_queue_t;
 
 bool spsc_init(spsc_queue_t *q, size_t size);
@@ -22,4 +22,6 @@ bool spsc_enqueue(spsc_queue_t *q, data_t *item);
 
 bool spsc_dequeue(spsc_queue_t *q, data_t **item);
 
+bool spsc_is_empty(spsc_queue_t *q);
+
 #endif //SPSC_QUEUE_LIBRARY_H

src/queue.c

@@ -58,3 +58,11 @@ bool spsc_dequeue(spsc_queue_t *q, data_t **item)
     atomic_store_explicit(&q->head, current_head + 1, memory_order_release);
     return true;
 }
+
+bool spsc_is_empty(spsc_queue_t *q)
+{
+    size_t head = atomic_load_explicit(&q->head, memory_order_acquire);
+    size_t tail = atomic_load_explicit(&q->tail, memory_order_acquire);
+    return head == tail;
+}
+

tests/QueueTests.cpp

@@ -13,16 +13,21 @@ TEST(QueueTests, test1)
     spsc_queue_t queue;
     spsc_init(&queue, 512);
 
+    ASSERT_TRUE(spsc_is_empty(&queue));
+
     data_t test = {nullptr, 1, 2, 3};
     ASSERT_TRUE(spsc_enqueue(&queue, &test));
+    ASSERT_FALSE(spsc_is_empty(&queue));
 
     data_t *test2 = nullptr;
     ASSERT_TRUE(spsc_dequeue(&queue, &test2));
     ASSERT_EQ(test.size, (*test2).size);
     ASSERT_EQ(test.width, (*test2).width);
     ASSERT_EQ(test.cap, (*test2).cap);
+    ASSERT_TRUE(spsc_is_empty(&queue));
 
     ASSERT_FALSE(spsc_dequeue(&queue, &test2));
+    ASSERT_TRUE(spsc_is_empty(&queue));
 
     spsc_destroy(&queue);
 }