Stop asynchronous ROS updates with synchronous ones

VisualizationManager uses [start|stop]Update() to pause ROS updates during dialog box interaction (ros-visualization#631).
However, asynchronous updates via threaded_queue_ were still performed, leading to a memory leak (ros-visualization#1621),
because messages were partially processed by the thread (i.e. kept in memory), but not finally processed
(and cleaned up) by the synchronous Display::update() call.
Pausing threaded processing too resolves that issue.

src/rviz/visualization_manager.cpp

@@ -222,25 +222,26 @@ VisualizationManager::VisualizationManager(RenderPanel* render_panel,
 
   selection_manager_ = new SelectionManager(this);
 
+  update_timer_ = new QTimer;
+  connect(update_timer_, SIGNAL(timeout()), this, SLOT(onUpdate()));
+
   private_->threaded_queue_threads_.create_thread(
       boost::bind(&VisualizationManager::threadedQueueThreadFunc, this));
 
   display_factory_ = new DisplayFactory();
 
   ogre_render_queue_clearer_ = new OgreRenderQueueClearer();
   Ogre::Root::getSingletonPtr()->addFrameListener(ogre_render_queue_clearer_);
-
-  update_timer_ = new QTimer;
-  connect(update_timer_, SIGNAL(timeout()), this, SLOT(onUpdate()));
 }
 
 VisualizationManager::~VisualizationManager()
 {
-  delete update_timer_;
-
+  update_timer_->stop();
   shutting_down_ = true;
   private_->threaded_queue_threads_.join_all();
 
+  delete update_timer_;
+
   if (selection_manager_)
   {
     selection_manager_->setSelection(M_Picked());
@@ -630,9 +631,13 @@ void VisualizationManager::handleChar(QKeyEvent* event, RenderPanel* panel)
 
 void VisualizationManager::threadedQueueThreadFunc()
 {
+  ros::WallDuration timeout(0.1);
   while (!shutting_down_)
   {
-    private_->threaded_queue_.callOne(ros::WallDuration(0.1));
+    if (update_timer_->isActive())
+      private_->threaded_queue_.callOne(timeout);
+    else
+      timeout.sleep();
   }
 }