pke: HACK: avoid modifying in-use vulkan buffers

Replace me with a memory barrier helper fn.

4 files changed, 51 insertions, 2 deletions

diff --git a/src/game.cpp b/src/game.cpp
index aea1039..27c42ac 100644
--- a/src/game.cpp
+++ b/src/game.cpp
@@ -114,6 +114,7 @@ void Game_Tick(double delta) {
 
 	EntityType_Tick_Late(delta);
 	ECS_Tick_Late(delta);
+	window_tick_late(delta);
 }
 
 void Game_Main(PKEWindowProperties windowProps, const char *executablePath) {
diff --git a/src/static-ui.cpp b/src/static-ui.cpp
index 1179028..7e500d9 100644
--- a/src/static-ui.cpp
+++ b/src/static-ui.cpp
@@ -464,10 +464,10 @@ void pke_ui_update_instance_buffer(pk_arr_t<pke_ui_box_instance_buffer_item> &ar
 		vkResult = vkBindBufferMemory(vkDevice, newBuffer, new_memory, 0);
 		assert(vkResult == VK_SUCCESS);
 		if (pke_ui_master.bindings.bd_instance.buffer != VK_NULL_HANDLE) {
-			vkDestroyBuffer(vkDevice, pke_ui_master.bindings.bd_instance.buffer, vkAllocator);
+			pkvk_queue_vk_buffer_destroy(pke_ui_master.bindings.bd_instance.buffer);
 		}
 		if (pke_ui_master.bindings.deviceMemoryInst != VK_NULL_HANDLE) {
-			vkFreeMemory(vkDevice, pke_ui_master.bindings.deviceMemoryInst, vkAllocator);
+			pkvk_queue_vk_memory_free(pke_ui_master.bindings.deviceMemoryInst);
 		}
 		pke_ui_master.bindings.bd_instance.buffer = newBuffer;
 		pke_ui_master.bindings.deviceMemoryInst = new_memory;
diff --git a/src/window.cpp b/src/window.cpp
index fa28e34..0c7f281 100644
--- a/src/window.cpp
+++ b/src/window.cpp
@@ -74,6 +74,13 @@ VkExtent2D Extent;
 VkSampler global_sampler;
 VkSampleCountFlagBits global_sample_count;
 
+struct pkvk_queued_actions {
+	struct pkvk_queued_actions_delete {
+		pk_arr_t<VkBuffer> buffers{};
+		pk_arr_t<VkDeviceMemory> memory{};
+	} destroy;
+} pkvk_actn_queue;
+
 // pkvk_shared.descr_set_layout.single_sampler
 // 	the pke default, works for:
 // 	2025-01-28 - present
@@ -705,6 +712,14 @@ void pkvk_texture_upload(pkvk_texture_upload_data *data, pkvk_texture_upload_dat
 	PKVK_EndBuffer(tmpBufferDetails);
 }
 
+void pkvk_queue_vk_buffer_destroy(VkBuffer buffer) {
+	pk_arr_append_t(&pkvk_actn_queue.destroy.buffers, buffer);
+}
+
+void pkvk_queue_vk_memory_free(VkDeviceMemory memory) {
+	pk_arr_append_t(&pkvk_actn_queue.destroy.memory, memory);
+}
+
 unsigned int FindQueueFamilyIndex(VkPhysicalDevice device, char hasPresentSupport = -1, VkQueueFlagBits includeBits = (VkQueueFlagBits)0U, VkQueueFlagBits excludeBits = (VkQueueFlagBits)0U) {
 
 	if (hasPresentSupport == -1 && includeBits == 0 && excludeBits == 0) {
@@ -3845,6 +3860,8 @@ void DestroyWindow() {
 		fprintf(stderr, "VkAllocator has '%u' outstanding allocations!", vulkanAllocs.next);
 	}
 	pk_arr_reset(&vulkanAllocs);
+	pk_arr_reset(&pkvk_actn_queue.destroy.buffers);
+	pk_arr_reset(&pkvk_actn_queue.destroy.memory);
 	// TODO there's un-freed vulkan stuff in the bucket
 	// comment this out to see it in the debug printout
 	pk_mem_bucket_destroy(MemBkt_Vulkan);
@@ -3909,6 +3926,33 @@ void CalculateCombinedMemReqs(uint64_t memReqsCount, VkMemoryRequirements *memRe
 	}
 }
 
+/* 2025-08-07 - JCB DEBT
+ * This function was a result of buffer synchronization issues.
+ * Specifically, the UI module was trying to reallocate its instance buffer.
+ * Vulkan was emitting an error that the buffer was in use by a command buffer.
+ * Processing these actions after the graphics queue is idle solved that specific issue.
+ * This is a stop-gap measure so I can keep working and is not intended to be permanent.
+ * PERF
+ * This will block the main thread until all in-flight renders are no longer using any of the resources needed to render a scene.
+ * Move this to a fire-and-forget background thread that uses a memory barrier and a semaphore specifically for the target resource.
+ */
+void window_tick_late(double delta) {
+	(void)delta;
+	uint32_t i;
+	if (pkvk_actn_queue.destroy.buffers.next > 0
+			|| pkvk_actn_queue.destroy.memory.next > 0) {
+		vkQueueWaitIdle(pkvk_shared.queue.graphics);
+	}
+	for (i = 0; i < pkvk_actn_queue.destroy.buffers.next; ++i) {
+		vkDestroyBuffer(vkDevice, pkvk_actn_queue.destroy.buffers[i], vkAllocator);
+	}
+	for (i = 0; i < pkvk_actn_queue.destroy.memory.next; ++i) {
+		vkFreeMemory(vkDevice, pkvk_actn_queue.destroy.memory[i], vkAllocator);
+	}
+	pk_arr_clear(&pkvk_actn_queue.destroy.buffers);
+	pk_arr_clear(&pkvk_actn_queue.destroy.memory);
+}
+
 void Render() {
 	vkWaitForFences(vkDevice, 1, &pkvk_present.fences_in_flight[CURRENT_FRAME], VK_TRUE, UINT64_MAX);
 
diff --git a/src/window.hpp b/src/window.hpp
index 1df25b7..90793ed 100644
--- a/src/window.hpp
+++ b/src/window.hpp
@@ -96,6 +96,7 @@ extern ImplementedPKVK pkePipelines;
 void CreateWindow(PKEWindowProperties wp);
 void DestroyWindow();
 VkShaderModule UploadShader(AssetHandle handle);
+void window_tick_late(double delta);
 void Render();
 
 unsigned int FindMemoryTypeIndex(uint32_t typeFilter, VkMemoryPropertyFlags memPropertyFlags);
@@ -150,4 +151,7 @@ struct pkvk_texture_upload_data_out {
 };
 void pkvk_texture_upload(pkvk_texture_upload_data *data, pkvk_texture_upload_data_out *out);
 
+void pkvk_queue_vk_buffer_destroy(VkBuffer buffer);
+void pkvk_queue_vk_memory_free(VkDeviceMemory memory);
+
 #endif /* PKE_WINDOW_HPP */