unhook node bag from element notifications on shutdown to speed up cleanup

assignment-client/src/octree/OctreeQueryNode.cpp

@@ -62,6 +62,7 @@ void OctreeQueryNode::nodeKilled() {
         // while the thread actually shuts down
         _octreeSendThread->setIsShuttingDown();
     }
+    nodeBag.unhookNotifications(); // if our node is shutting down, then we no longer need octree element notifications
 }
 
 void OctreeQueryNode::forceNodeShutdown() {

libraries/octree/src/OctreeElementBag.cpp

@@ -16,13 +16,20 @@ OctreeElementBag::OctreeElementBag() :
     _bagElements()
 {
     OctreeElement::addDeleteHook(this);
+    _hooked = true;
 };
 
 OctreeElementBag::~OctreeElementBag() {
-    OctreeElement::removeDeleteHook(this);
+    unhookNotifications();
     deleteAll();
 }
 
+void OctreeElementBag::unhookNotifications() {
+    if (_hooked) {
+        OctreeElement::removeDeleteHook(this);
+    }
+}
+
 void OctreeElementBag::elementDeleted(OctreeElement* element) {
 qDebug() << "OctreeElementBag::elementDeleted()...";
     remove(element); // note: remove can safely handle nodes that aren't in it, so we don't need to check contains()

libraries/octree/src/OctreeElementBag.h

@@ -36,8 +36,11 @@ public:
     void deleteAll();
     virtual void elementDeleted(OctreeElement* element);
 
+    void unhookNotifications();
+
 private:
     QSet<OctreeElement*> _bagElements;
+    bool _hooked;
 };
 
 #endif // hifi_OctreeElementBag_h