Addons: improve performance of translations (#12353)

~10ms off

I also found an optimization for the projects API, but will do that in a
separate PR.

Author: stsewd

readthedocs/api/v3/serializers.py

@@ -860,10 +860,15 @@ def get_translation_of(self, obj):
         return None
 
     def get_subproject_of(self, obj):
-        parent_relationship = obj.superprojects.first()
-        if parent_relationship:
+        if obj.main_language_project:
+            # If the project is a translation, it can't be a subproject,
+            # so it doesn't have a superproject.
+            return None
+
+        superproject = obj.superproject
+        if superproject:
             # Since the related project can be private, we use a restricted serializer.
-            return self.related_project_serializer(parent_relationship.parent).data
+            return self.related_project_serializer(superproject).data
         return None
 
 

readthedocs/proxito/tests/test_hosting.py

@@ -785,7 +785,7 @@ def test_number_of_queries_project_version_slug(self):
                 active=True,
             )
 
-        with self.assertNumQueries(17):
+        with self.assertNumQueries(16):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -814,7 +814,7 @@ def test_number_of_queries_url(self):
                 active=True,
             )
 
-        with self.assertNumQueries(18):
+        with self.assertNumQueries(17):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -850,7 +850,7 @@ def test_number_of_queries_url_subproject(self):
                 active=True,
             )
 
-        with self.assertNumQueries(22):
+        with self.assertNumQueries(20):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -866,7 +866,7 @@ def test_number_of_queries_url_subproject(self):
         assert r.status_code == 200
 
         # Test parent project has fewer queries
-        with self.assertNumQueries(17):
+        with self.assertNumQueries(16):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -892,7 +892,7 @@ def test_number_of_queries_url_translations(self):
                 language=language,
             )
 
-        with self.assertNumQueries(35):
+        with self.assertNumQueries(29):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -1042,7 +1042,7 @@ def test_file_tree_diff(self, get_manifest):
                 ],
             ),
         ]
-        with self.assertNumQueries(25):
+        with self.assertNumQueries(24):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {

readthedocs/proxito/views/hosting.py

@@ -591,7 +591,10 @@ def _get_projects_response(self, *, request, project, version, resolver):
             .exclude(pk=project.pk)
             .order_by("language")
             .select_related("main_language_project")
-            .prefetch_related("tags", "domains", "related_projects", "users")
+            # NOTE: there is no need to prefetch superprojects,
+            # as translations are not expected to have superprojects,
+            # and the serializer already checks for that.
+            .prefetch_related("tags", "domains", "users")
         )
         # NOTE: we check if there are translations first,
         # otherwise evaluating the queryset will be more expensive