Fixed slow transaction on xblock outline handler.

TNL-2425

cms/djangoapps/contentstore/views/item.py

@@ -332,13 +332,14 @@ def xblock_outline_handler(request, usage_key_string):
     response_format = request.REQUEST.get('format', 'html')
     if response_format == 'json' or 'application/json' in request.META.get('HTTP_ACCEPT', 'application/json'):
         store = modulestore()
-        root_xblock = store.get_item(usage_key)
-        return JsonResponse(create_xblock_info(
-            root_xblock,
-            include_child_info=True,
-            course_outline=True,
-            include_children_predicate=lambda xblock: not xblock.category == 'vertical'
-        ))
+        with store.bulk_operations(usage_key.course_key):
+            root_xblock = store.get_item(usage_key)
+            return JsonResponse(create_xblock_info(
+                root_xblock,
+                include_child_info=True,
+                course_outline=True,
+                include_children_predicate=lambda xblock: not xblock.category == 'vertical'
+            ))
     else:
         return Http404
 

cms/djangoapps/contentstore/views/tests/test_item.py

@@ -1410,6 +1410,28 @@ class TestXBlockInfo(ItemTest):
         json_response = json.loads(resp.content)
         self.validate_course_xblock_info(json_response, course_outline=True)
 
+    def test_xblock_outline_handler_mongo_calls(self):
+        expected_calls = 5
+        with self.store.default_store(ModuleStoreEnum.Type.split):
+            course = CourseFactory.create()
+            chapter = ItemFactory.create(
+                parent_location=course.location, category='chapter', display_name='Week 1'
+            )
+            outline_url = reverse_usage_url('xblock_outline_handler', chapter.location)
+            with check_mongo_calls(expected_calls):
+                self.client.get(outline_url, HTTP_ACCEPT='application/json')
+
+            sequential = ItemFactory.create(
+                parent_location=chapter.location, category='sequential', display_name='Sequential 1'
+            )
+
+            ItemFactory.create(
+                parent_location=sequential.location, category='vertical', display_name='Vertical 1'
+            )
+            # calls should be same after adding two new children.
+            with check_mongo_calls(expected_calls):
+                self.client.get(outline_url, HTTP_ACCEPT='application/json')
+
     def test_entrance_exam_chapter_xblock_info(self):
         chapter = ItemFactory.create(
             parent_location=self.course.location, category='chapter', display_name="Entrance Exam",