some render cache adjustments

app/node/processor/renderer/rendererprocessthread.h

@@ -42,6 +42,9 @@ public:
 
   RenderTexturePtr texture();
 
+public slots:
+  virtual void Cancel() override;
+
 protected:
   virtual void ProcessLoop() override;
 
@@ -61,6 +64,8 @@ private:
 
   RenderTexturePtr texture_;
 
+  QAtomicInt cancelled_;
+
 };
 
 using RendererProcessThreadPtr = std::shared_ptr<RendererProcessThread>;