Cache feature flag names in Redis for a minute

We saw on GitLab.com, the SQL query, `SELECT "features"."key" FROM
"features"` peaked at 2300 times per second.

We can quiet this down a bit by caching it in Redis for a minute.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/63435

1 files changed, 6 insertions, 1 deletions

diff --git a/lib/feature.rb b/lib/feature.rb
index 749c861d740..cc9c9d44005 100644
--- a/lib/feature.rb
+++ b/lib/feature.rb
@@ -30,7 +30,12 @@ class Feature
     end
 
     def persisted_names
-      Gitlab::SafeRequestStore[:flipper_persisted_names] ||= FlipperFeature.feature_names
+      Gitlab::SafeRequestStore[:flipper_persisted_names] ||=
+        begin
+          # We saw on GitLab.com, this database request was called 2300
+          # times/s. Let's cache it for a minute to avoid that load.
+          Rails.cache.fetch('flipper:persisted_names', expires_in: 1.minute) { FlipperFeature.feature_names }
+        end
     end
 
     def persisted?(feature)