source/blender/render/hydra/preview_engine.cc

@@ -9,32 +9,47 @@
 
 namespace blender::render::hydra {
 
-std::unique_ptr<PreviewEngine> PreviewEngine::preview_engine;
+const double LIFETIME = 180.0;
 
-void PreviewEngine::free()
+std::unique_ptr<PreviewEngine> PreviewEngine::instance;
+
+void PreviewEngine::schedule_free()
 {
-  if (preview_engine) {
-    BLI_timer_register((uintptr_t)preview_engine.get(),
-                       preview_engine->delete_preview_engine,
-                       &preview_engine,
-                       nullptr,
-                       preview_engine->preview_engine_lifetime,
-                       true);
-  }
+  instance->render_delegate->Stop();
+
+  /* Register timer for schedule free PreviewEngine instance */
+  BLI_timer_register((uintptr_t)instance.get(),
+                      free_instance,
+                      nullptr,
+                      nullptr,
+                      LIFETIME,
+                      true);
 }
 
-std::unique_ptr<PreviewEngine> *PreviewEngine::get(RenderEngine *bl_engine,
-                                                   char *render_delegate_id)
+PreviewEngine *PreviewEngine::get_instance(RenderEngine *bl_engine, const std::string &render_delegate_id)
 {
-  if (!preview_engine) {
-    preview_engine = std::make_unique<PreviewEngine>(bl_engine, render_delegate_id);
+  if (!instance) {
+    instance = std::make_unique<PreviewEngine>(bl_engine, render_delegate_id);
   }
-  if (BLI_timer_is_registered((uintptr_t)preview_engine.get())) {
-    BLI_timer_unregister((uintptr_t)preview_engine.get());
+  if (BLI_timer_is_registered((uintptr_t)instance.get())) {
+    /* Unregister timer while PreviewEngine is working */
+    BLI_timer_unregister((uintptr_t)instance.get());
   }
-  preview_engine->update_bl_engine(bl_engine);
+  instance->update_bl_engine(bl_engine);
 
-  return &preview_engine;
+  return instance.get();
+}
+
+double PreviewEngine::free_instance(uintptr_t uuid, void *user_data)
+{
+  if (!instance->render_task_delegate->is_converged()) {
+    /* Restart timer if render isn't completed */
+    return LIFETIME;
+  }
+
+  CLOG_INFO(LOG_EN, 2, "");
+  instance = nullptr;
+  return -1;
 }
 
 void PreviewEngine::sync(Depsgraph *depsgraph,
@@ -107,18 +122,6 @@ void PreviewEngine::update_bl_engine(RenderEngine *bl_engine)
   this->bl_engine = bl_engine;
 }
 
-double PreviewEngine::delete_preview_engine(uintptr_t uuid, void *user_data)
-{
-  std::unique_ptr<PreviewEngine> *preview_engine = static_cast<std::unique_ptr<PreviewEngine>*>(user_data);
-  if (preview_engine && preview_engine->get()->render_task_delegate->is_converged()) {
-    CLOG_INFO(LOG_EN, uuid, "Delete preview engine");
-    preview_engine->reset();
-    return -1;
-  }
-
-  return preview_engine_lifetime;
-}
-
 void PreviewEngine::update_render_result(const std::string &layer_name,
                                          int width,
                                          int height,

source/blender/render/hydra/preview_engine.h

@@ -8,17 +8,21 @@
 namespace blender::render::hydra {
 
 class PreviewEngine : public FinalEngine {
+ private:
+  /* Singleton class instance */
+  static std::unique_ptr<PreviewEngine> instance;
+  static double free_instance(uintptr_t uuid, void *user_data);
+
  public:
+  static PreviewEngine *get_instance(RenderEngine *bl_engine, const std::string &render_delegate_id);
+  static void schedule_free();
+
   using FinalEngine::FinalEngine;
-  static void free();
-  static std::unique_ptr<PreviewEngine> *get(RenderEngine *bl_engine = nullptr,
-                                             char *render_delegate_id = nullptr);
   void sync(Depsgraph *depsgraph,
             bContext *context,
             pxr::HdRenderSettingsMap &render_settings) override;
   void render(Depsgraph *depsgraph) override;
   void update_bl_engine(RenderEngine *bl_engine);
-  static double delete_preview_engine(uintptr_t uuid, void *user_data);
 
  protected:
   void update_render_result(const std::string &layer_name,
@@ -26,12 +30,6 @@ class PreviewEngine : public FinalEngine {
                             int height,
                             std::vector<float> &pixels);
 
- public:
-  static inline double preview_engine_lifetime = 180.0;
-
- protected:
-  static std::unique_ptr<PreviewEngine> preview_engine;
-  pxr::HdRenderSettingsMap render_settings;
 };
 
 }  // namespace blender::render::hydra

source/blender/render/hydra/python.cc

@@ -114,7 +114,7 @@ static PyObject *engine_create_func(PyObject * /*self*/, PyObject *args)
     engine = new ViewportEngine(bl_engine, render_delegate_id);
   }
   else if (STREQ(engine_type, "PREVIEW")) {
-    engine = PreviewEngine::get(bl_engine, render_delegate_id)->get();
+    engine = PreviewEngine::get_instance(bl_engine, render_delegate_id);
   }
   else {
     if (bl_engine->type->flag & RE_USE_GPU_CONTEXT) {
@@ -140,11 +140,11 @@ static PyObject *engine_free_func(PyObject * /*self*/, PyObject *args)
   Engine *engine = (Engine *)PyLong_AsVoidPtr(pyengine);
   PreviewEngine *preview_engine = dynamic_cast<PreviewEngine *>(engine);
   if (preview_engine) {
-    preview_engine->free();
-    Py_RETURN_NONE;
+    PreviewEngine::schedule_free();
+  }
+  else {
+    delete engine;
   }
-
-  delete engine;
 
   CLOG_INFO(LOG_EN, 2, "Engine %016llx", engine);
   Py_RETURN_NONE;