Remove an unnecessary global

The _DISCUSSIONINFO global was originally used as a cache, but has since
lost that capability and is therefore just harmful. This is a precursor
to more refactoring that will improve the performance of the forums and
may itself provide some performance improvement because it separates the
computation done by two functions that each previously computed the
entirety of _DISCUSSIONINFO.

lms/djangoapps/django_comment_client/tests/test_utils.py

@@ -108,7 +108,7 @@ class CoursewareContextTestCase(ModuleStoreTestCase):
             )
 
         test_discussion(self.discussion1, "Chapter / Discussion 1")
-        test_discussion(self.discussion2, " Subsection / Discussion 2")
+        test_discussion(self.discussion2, "Subsection / Discussion 2")
 
 
 @override_settings(MODULESTORE=TEST_DATA_MONGO_MODULESTORE)

lms/djangoapps/django_comment_client/utils.py

@@ -20,8 +20,6 @@ from django.utils.timezone import UTC
 
 log = logging.getLogger(__name__)
 
-_DISCUSSIONINFO = defaultdict(dict)
-
 
 def extract(dic, keys):
     return {k: dic.get(k) for k in keys}
@@ -60,17 +58,30 @@ def has_forum_access(uname, course_id, rolename):
     return role.users.filter(username=uname).exists()
 
 
-def get_discussion_id_map(course):
-    """
-        return a dict of the form {category: modules}
-    """
-    initialize_discussion_info(course)
-    return _DISCUSSIONINFO[course.id]['id_map']
+def _get_discussion_modules(course):
+    all_modules = modulestore().get_items(
+        ['i4x', course.location.org, course.location.course, 'discussion', None],
+        course_id=course.id
+    )
 
+    def has_required_keys(module):
+        for key in ('discussion_id', 'discussion_category', 'discussion_target'):
+            if getattr(module, key) is None:
+                log.warning("Required key '%s' not in discussion %s, leaving out of category map" % (key, module.location))
+                return False
+        return True
 
-def get_discussion_category_map(course):
-    initialize_discussion_info(course)
-    return _filter_unstarted_categories(_DISCUSSIONINFO[course.id]['category_map'])
+    return filter(has_required_keys, all_modules)
+
+
+def _get_discussion_id_map(course):
+    def get_entry(module):
+        discussion_id = module.discussion_id
+        title = module.discussion_target
+        last_category = module.discussion_category.split("/")[-1].strip()
+        return (discussion_id, {"location": module.location, "title": last_category + " / " + title})
+
+    return dict(map(get_entry, _get_discussion_modules(course)))
 
 
 def _filter_unstarted_categories(category_map):
@@ -123,33 +134,18 @@ def _sort_map_entries(category_map, sort_alpha):
     category_map["children"] = [x[0] for x in sorted(things, key=lambda x: x[1]["sort_key"])]
 
 
-def initialize_discussion_info(course):
+def get_discussion_category_map(course):
     course_id = course.id
 
-    discussion_id_map = {}
     unexpanded_category_map = defaultdict(list)
 
-    # get all discussion models within this course_id
-    all_modules = modulestore().get_items(['i4x', course.location.org, course.location.course,
-                                          'discussion', None], course_id=course_id)
-
-    for module in all_modules:
-        skip_module = False
-        for key in ('discussion_id', 'discussion_category', 'discussion_target'):
-            if getattr(module, key) is None:
-                log.warning("Required key '%s' not in discussion %s, leaving out of category map" % (key, module.location))
-                skip_module = True
-
-        if skip_module:
-            continue
+    modules = _get_discussion_modules(course)
 
+    for module in modules:
         id = module.discussion_id
-        category = module.discussion_category
         title = module.discussion_target
         sort_key = module.sort_key
-        category = " / ".join([x.strip() for x in category.split("/")])
-        last_category = category.split("/")[-1]
-        discussion_id_map[id] = {"location": module.location, "title": last_category + " / " + title}
+        category = " / ".join([x.strip() for x in module.discussion_category.split("/")])
         #Handle case where module.start is None
         entry_start_date = module.start if module.start else datetime.max.replace(tzinfo=pytz.UTC)
         unexpanded_category_map[category].append({"title": title, "id": id, "sort_key": sort_key, "start_date": entry_start_date})
@@ -201,9 +197,7 @@ def initialize_discussion_info(course):
 
     _sort_map_entries(category_map, course.discussion_sort_alpha)
 
-    _DISCUSSIONINFO[course.id]['id_map'] = discussion_id_map
-    _DISCUSSIONINFO[course.id]['category_map'] = category_map
-    _DISCUSSIONINFO[course.id]['timestamp'] = datetime.now(UTC())
+    return _filter_unstarted_categories(category_map)
 
 
 class JsonResponse(HttpResponse):
@@ -354,7 +348,7 @@ def extend_content(content):
 
 
 def get_courseware_context(content, course):
-    id_map = get_discussion_id_map(course)
+    id_map = _get_discussion_id_map(course)
     id = content['commentable_id']
     content_info = None
     if id in id_map: