Merge pull request #8837 from edx/benmcmorran/discussion-caching-3

TNL-2389 Use discussion id map cache for thread creation and update

lms/djangoapps/django_comment_client/base/views.py

@@ -27,8 +27,7 @@ from django_comment_client.utils import (
     JsonResponse,
     prepare_content,
     get_group_id_for_comments_service,
-    get_discussion_categories_ids,
-    get_discussion_id_map,
+    discussion_category_id_access,
     get_cached_discussion_id_map,
 )
 from django_comment_client.permissions import check_permissions_by_view, has_permission
@@ -82,7 +81,7 @@ def track_forum_event(request, event_name, course, obj, data, id_map=None):
     commentable_id = data['commentable_id']
 
     if id_map is None:
-        id_map = get_cached_discussion_id_map(course, commentable_id, user)
+        id_map = get_cached_discussion_id_map(course, [commentable_id], user)
 
     if commentable_id in id_map:
         data['category_name'] = id_map[commentable_id]["title"]
@@ -209,14 +208,9 @@ def create_thread(request, course_id, commentable_id):
     event_data = get_thread_created_event_data(thread, follow)
     data = thread.to_dict()
 
-    # Calls to id map are expensive, but we need this more than once.
-    # Prefetch it.
-    id_map = get_discussion_id_map(course, request.user)
+    add_courseware_context([data], course, request.user)
 
-    add_courseware_context([data], course, request.user, id_map=id_map)
-
-    track_forum_event(request, THREAD_CREATED_EVENT_NAME,
-                      course, thread, event_data, id_map=id_map)
+    track_forum_event(request, THREAD_CREATED_EVENT_NAME, course, thread, event_data)
 
     if request.is_ajax():
         return ajax_content_response(request, course_key, data)
@@ -246,8 +240,7 @@ def update_thread(request, course_id, thread_id):
         thread.thread_type = request.POST["thread_type"]
     if "commentable_id" in request.POST:
         course = get_course_with_access(request.user, 'load', course_key)
-        commentable_ids = get_discussion_categories_ids(course, request.user)
-        if request.POST.get("commentable_id") in commentable_ids:
+        if discussion_category_id_access(course, request.user, request.POST.get("commentable_id")):
             thread.commentable_id = request.POST["commentable_id"]
         else:
             return JsonError(_("Topic doesn't exist"))

lms/djangoapps/django_comment_client/forum/tests.py

@@ -316,11 +316,11 @@ class SingleThreadQueryCountTestCase(ModuleStoreTestCase):
 
     @ddt.data(
         # old mongo with cache
-        (ModuleStoreEnum.Type.mongo, 1, 7, 5, 12, 7),
-        (ModuleStoreEnum.Type.mongo, 50, 7, 5, 12, 7),
+        (ModuleStoreEnum.Type.mongo, 1, 7, 5, 13, 8),
+        (ModuleStoreEnum.Type.mongo, 50, 7, 5, 13, 8),
         # split mongo: 3 queries, regardless of thread response size.
-        (ModuleStoreEnum.Type.split, 1, 3, 3, 12, 7),
-        (ModuleStoreEnum.Type.split, 50, 3, 3, 12, 7),
+        (ModuleStoreEnum.Type.split, 1, 3, 3, 13, 8),
+        (ModuleStoreEnum.Type.split, 50, 3, 3, 13, 8),
     )
     @ddt.unpack
     def test_number_of_mongo_queries(

lms/djangoapps/django_comment_client/tests/test_utils.py

@@ -170,6 +170,13 @@ class CachedDiscussionIdMapTestCase(ModuleStoreTestCase):
             discussion_category='Chapter',
             discussion_target='Discussion 1'
         )
+        self.discussion2 = ItemFactory.create(
+            parent_location=self.course.location,
+            category='discussion',
+            discussion_id='test_discussion_id_2',
+            discussion_category='Chapter 2',
+            discussion_target='Discussion 2'
+        )
         self.private_discussion = ItemFactory.create(
             parent_location=self.course.location,
             category='discussion',
@@ -212,11 +219,18 @@ class CachedDiscussionIdMapTestCase(ModuleStoreTestCase):
         self.assertFalse(utils.has_required_keys(self.bad_discussion))
 
     def verify_discussion_metadata(self):
-        """Retrieves the metadata for self.discussion and verifies that it is correct"""
-        metadata = utils.get_cached_discussion_id_map(self.course, 'test_discussion_id', self.user)
-        metadata = metadata[self.discussion.discussion_id]
-        self.assertEqual(metadata['location'], self.discussion.location)
-        self.assertEqual(metadata['title'], 'Chapter / Discussion 1')
+        """Retrieves the metadata for self.discussion and self.discussion2 and verifies that it is correct"""
+        metadata = utils.get_cached_discussion_id_map(
+            self.course,
+            ['test_discussion_id', 'test_discussion_id_2'],
+            self.user
+        )
+        discussion1 = metadata[self.discussion.discussion_id]
+        discussion2 = metadata[self.discussion2.discussion_id]
+        self.assertEqual(discussion1['location'], self.discussion.location)
+        self.assertEqual(discussion1['title'], 'Chapter / Discussion 1')
+        self.assertEqual(discussion2['location'], self.discussion2.location)
+        self.assertEqual(discussion2['title'], 'Chapter 2 / Discussion 2')
 
     def test_get_discussion_id_map_from_cache(self):
         self.verify_discussion_metadata()
@@ -226,22 +240,36 @@ class CachedDiscussionIdMapTestCase(ModuleStoreTestCase):
         self.verify_discussion_metadata()
 
     def test_get_missing_discussion_id_map_from_cache(self):
-        metadata = utils.get_cached_discussion_id_map(self.course, 'bogus_id', self.user)
+        metadata = utils.get_cached_discussion_id_map(self.course, ['bogus_id'], self.user)
         self.assertEqual(metadata, {})
 
     def test_get_discussion_id_map_from_cache_without_access(self):
         user = UserFactory.create()
 
-        metadata = utils.get_cached_discussion_id_map(self.course, 'private_discussion_id', self.user)
+        metadata = utils.get_cached_discussion_id_map(self.course, ['private_discussion_id'], self.user)
         self.assertEqual(metadata['private_discussion_id']['title'], 'Chapter 3 / Beta Testing')
 
-        metadata = utils.get_cached_discussion_id_map(self.course, 'private_discussion_id', user)
+        metadata = utils.get_cached_discussion_id_map(self.course, ['private_discussion_id'], user)
         self.assertEqual(metadata, {})
 
     def test_get_bad_discussion_id(self):
-        metadata = utils.get_cached_discussion_id_map(self.course, 'bad_discussion_id', self.user)
+        metadata = utils.get_cached_discussion_id_map(self.course, ['bad_discussion_id'], self.user)
         self.assertEqual(metadata, {})
 
+    def test_discussion_id_accessible(self):
+        self.assertTrue(utils.discussion_category_id_access(self.course, self.user, 'test_discussion_id'))
+
+    def test_bad_discussion_id_not_accessible(self):
+        self.assertFalse(utils.discussion_category_id_access(self.course, self.user, 'bad_discussion_id'))
+
+    def test_missing_discussion_id_not_accessible(self):
+        self.assertFalse(utils.discussion_category_id_access(self.course, self.user, 'bogus_id'))
+
+    def test_discussion_id_not_accessible_without_access(self):
+        user = UserFactory.create()
+        self.assertTrue(utils.discussion_category_id_access(self.course, self.user, 'private_discussion_id'))
+        self.assertFalse(utils.discussion_category_id_access(self.course, user, 'private_discussion_id'))
+
 
 class CategoryMapTestMixin(object):
     """

lms/djangoapps/django_comment_client/utils.py

@@ -118,19 +118,22 @@ def get_cached_discussion_key(course, discussion_id):
         raise DiscussionIdMapIsNotCached()
 
 
-def get_cached_discussion_id_map(course, discussion_id, user):
+def get_cached_discussion_id_map(course, discussion_ids, user):
     """
-    Returns a dict mapping discussion_id to discussion module metadata if it is cached and visible to the user.
-    If not, returns the result of get_discussion_id_map
+    Returns a dict mapping discussion_ids to respective discussion module metadata if it is cached and visible to the
+    user. If not, returns the result of get_discussion_id_map
     """
     try:
-        key = get_cached_discussion_key(course, discussion_id)
-        if not key:
-            return {}
-        module = modulestore().get_item(key)
-        if not (has_required_keys(module) and has_access(user, 'load', module, course.id)):
-            return {}
-        return dict([get_discussion_id_map_entry(module)])
+        entries = []
+        for discussion_id in discussion_ids:
+            key = get_cached_discussion_key(course, discussion_id)
+            if not key:
+                continue
+            module = modulestore().get_item(key)
+            if not (has_required_keys(module) and has_access(user, 'load', module, course.id)):
+                continue
+            entries.append(get_discussion_id_map_entry(module))
+        return dict(entries)
     except DiscussionIdMapIsNotCached:
         return get_discussion_id_map(course, user)
 
@@ -324,6 +327,24 @@ def get_discussion_category_map(course, user, cohorted_if_in_list=False, exclude
     return _filter_unstarted_categories(category_map) if exclude_unstarted else category_map
 
 
+def discussion_category_id_access(course, user, discussion_id):
+    """
+    Returns True iff the given discussion_id is accessible for user in course.
+    Uses the discussion id cache if available, falling back to
+    get_discussion_categories_ids if there is no cache.
+    """
+    if discussion_id in course.top_level_discussion_topic_ids:
+        return True
+    try:
+        key = get_cached_discussion_key(course, discussion_id)
+        if not key:
+            return False
+        module = modulestore().get_item(key)
+        return has_required_keys(module) and has_access(user, 'load', module, course.id)
+    except DiscussionIdMapIsNotCached:
+        return discussion_id in get_discussion_categories_ids(course, user)
+
+
 def get_discussion_categories_ids(course, user, include_all=False):
     """
     Returns a list of available ids of categories for the course that
@@ -494,10 +515,14 @@ def extend_content(content):
 
 def add_courseware_context(content_list, course, user, id_map=None):
     """
-    Decorates `content_list` with courseware metadata.
+    Decorates `content_list` with courseware metadata using the discussion id map cache if available.
     """
     if id_map is None:
-        id_map = get_discussion_id_map(course, user)
+        id_map = get_cached_discussion_id_map(
+            course,
+            [content['commentable_id'] for content in content_list],
+            user
+        )
 
     for content in content_list:
         commentable_id = content['commentable_id']