Update queue implementation to use ring buffer

src/base/queue/queue.c

@@ -3,24 +3,83 @@
 #include "queue.h"
 #include "../array/array.h"
 #include "../../common/assert/assert.h"
+#include "../../common/misc/misc_utils.h"
 #include <string.h>
 
-void _queue_pop_front(GenericQueue *queue, void *output, u64 item_size) {
-	wapp_debug_assert(queue != NULL && output != NULL, "`queue` and `output` should not be NULL");
+void _queue_push(GenericQueue *queue, void *item, u64 item_size) {
+	wapp_debug_assert(queue != NULL, "`queue` should not be NULL");
 	wapp_runtime_assert(item_size == wapp_array_item_size(queue->items), "Invalid type");
 
-	memcpy(output, queue->items, item_size);
+	u64 capacity = wapp_array_capacity(queue->items);
+	if (queue->count >= capacity) { return; }
 
-	// NOTE (Abdelrahman): Uses a while loop instead of a for loop to get rid of
-	// MSVC Spectre mitigation warnings
-	u64 new_count = wapp_array_count(queue->items) - 1;
-	u64 index     = 0;
-	b8 running    = index < new_count;
-	while (running) {
-		_array_set(queue->items, index, _array_get(queue->items, index + 1, item_size), item_size);
-		++index;
-		running = index < new_count;
+	u64 index = (queue->back)++;
+	_array_set(queue->items, index, item, item_size);
+	++(queue->count);
+
+	if (queue->back >= capacity) {
+		queue->back = 0;
+	}
+}
+
+GenericQueue *_queue_push_alloc(const Allocator *allocator, GenericQueue *queue, void *item, u64 item_size) {
+	wapp_debug_assert(allocator != NULL && queue != NULL && item != NULL,
+	                  "`allocator`, `queue` and `item` should not be NULL");
+	wapp_runtime_assert(item_size == wapp_array_item_size(queue->items), "Invalid type");
+
+	GenericQueue *output = queue;
+
+	u64 capacity = wapp_array_capacity(queue->items);
+	if (queue->count >= capacity) {
+		u64 new_capacity = wapp_misc_utils_u64_round_up_pow2(capacity * 2);
+		u64 array_size   = _array_calc_alloc_size(new_capacity, item_size);
+		u64 alloc_size   = sizeof(GenericQueue) + array_size;
+		void *buffer     = wapp_mem_allocator_alloc(allocator, alloc_size);
+		if (!buffer) {
+			goto RETURN_QUEUE_PUSH_ALLOC;
+		}
+
+		memset((void *)buffer, 0, alloc_size);
+
+		output        = (GenericQueue *)buffer;
+		output->items = _array_from_preallocated_buffer((void *)(output + 1), array_size, ARRAY_INIT_FILLED, item_size);
+
+		// NOTE (Abdelrahman): When the queue is full, the front and back indices should
+		// always be the same
+		u64 front_count     = capacity - queue->front;
+		u64 back_count      = queue->back;
+		void *copy_boundary = (void *)((uptr)(queue->items) + (queue->front * item_size));
+
+		memcpy(output->items, copy_boundary, front_count * item_size);
+		if (back_count > 0) {
+			void *back_copy_dst = (void *)((uptr)(output->items) + (front_count * item_size));
+			memcpy(back_copy_dst, queue->items, back_count * item_size);
+		}
+
+		output->front = 0;
+		output->back  = front_count + back_count;
+		output->count = queue->count;
 	}
 
-	wapp_array_set_count(queue->items, new_count);
+	_queue_push(output, item, item_size);
+
+RETURN_QUEUE_PUSH_ALLOC:
+	return output;
+}
+
+void *_queue_pop(GenericQueue *queue, u64 item_size) {
+	wapp_debug_assert(queue != NULL, "`queue` should not be NULL");
+	wapp_runtime_assert(item_size == wapp_array_item_size(queue->items), "Invalid type");
+
+	if (queue->count == 0) { return NULL; }
+
+	u64 index = (queue->front)++;
+	--(queue->count);
+
+	u64 capacity = wapp_array_capacity(queue->items);
+	if (queue->front >= capacity) {
+		queue->front = 0;
+	}
+
+	return _array_get(queue->items, index, item_size);
 }