Trim main task queue, recording label, and canvas draw callbacks

src/main.cpp

@@ -54,8 +54,6 @@ struct RetainedState
     std::map<kKey, int> vkey_map;
     wchar_t window_title[512]{};
     std::jthread hmd_renderer;
-    std::deque<std::packaged_task<void()>> main_tasklist;
-    std::mutex main_task_mutex;
     float timer_stylus = 0;
     float timer_ink_touch = 0;
     float timer_ink_pen = 0;
@@ -72,6 +70,46 @@ RetainedState& retained_state()
     return state;
 }
 
+namespace {
+
+struct RetainedMainTaskQueue final
+{
+    std::deque<std::packaged_task<void()>> tasklist;
+    std::mutex task_mutex;
+};
+
+RetainedMainTaskQueue& retained_main_task_queue()
+{
+    static RetainedMainTaskQueue queue;
+    return queue;
+}
+
+template <typename Callable>
+void enqueue_main_task(Callable&& task)
+{
+    auto& queue = retained_main_task_queue();
+    std::lock_guard<std::mutex> lock(queue.task_mutex);
+    queue.tasklist.emplace_back(std::forward<Callable>(task));
+}
+
+void drain_main_tasks()
+{
+    std::deque<std::packaged_task<void()>> working_list;
+    {
+        auto& queue = retained_main_task_queue();
+        std::lock_guard<std::mutex> lock(queue.task_mutex);
+        working_list = std::move(queue.tasklist);
+    }
+
+    while (!working_list.empty())
+    {
+        working_list.front()();
+        working_list.pop_front();
+    }
+}
+
+}
+
 std::atomic<int> vr_frames{0};
 std::atomic<int> running{-1};
 std::atomic_bool vr_running{false};
@@ -163,8 +201,7 @@ std::string GetLastErrorAsString()
 void destroy_window()
 {
     auto& state = retained_state();
-    std::lock_guard<std::mutex> lock(state.main_task_mutex);
-    state.main_tasklist.emplace_back([hWnd = state.hWnd] {
+    enqueue_main_task([hWnd = state.hWnd] {
         PostMessage(hWnd, WM_USER_CLOSE, 0, 0);
     });
 }
@@ -225,8 +262,7 @@ void win32_update_fps(int frames)
         swprintf_s(title_fps, L"%s - %d fps", state.window_title, frames);
 
     {
-        std::lock_guard<std::mutex> lock(state.main_task_mutex);
-        state.main_tasklist.emplace_back([hWnd = state.hWnd] {
+        enqueue_main_task([hWnd = state.hWnd] {
             SetWindowText(hWnd, title_fps);
         });
     }
@@ -991,22 +1027,7 @@ int main(int argc, char** argv)
         }
 
         // list of tasks for the main thread
-        {
-            std::deque<std::packaged_task<void()>> working_list;
-            {
-                std::lock_guard<std::mutex> lock(state.main_task_mutex);
-                working_list = std::move(state.main_tasklist);
-            }
-
-            if (!working_list.empty())
-            {
-                while (!working_list.empty())
-                {
-                    working_list.front()();
-                    working_list.pop_front();
-                }
-            }
-        }
+        drain_main_tasks();
     }
     // Clean up
     WacomTablet::I.terminate();