Cache feature names in RequestStore

The GitHub importer (and probably other parts of our code) ends up
calling Feature.persisted? many times (via Gitaly). By storing this data
in RequestStore we can save ourselves _a lot_ of database queries.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/39361

1 files changed, 41 insertions, 0 deletions

diff --git a/spec/lib/feature_spec.rb b/spec/lib/feature_spec.rb
index 1076c63b5f2..10020511bf8 100644
--- a/spec/lib/feature_spec.rb
+++ b/spec/lib/feature_spec.rb
@@ -13,6 +13,47 @@ describe Feature do
     end
   end
 
+  describe '.persisted_names' do
+    it 'returns the names of the persisted features' do
+      Feature::FlipperFeature.create!(key: 'foo')
+
+      expect(described_class.persisted_names).to eq(%w[foo])
+    end
+
+    it 'returns an empty Array when no features are presisted' do
+      expect(described_class.persisted_names).to be_empty
+    end
+
+    it 'caches the feature names when request store is active', :request_store do
+      Feature::FlipperFeature.create!(key: 'foo')
+
+      expect(Feature::FlipperFeature)
+        .to receive(:feature_names)
+        .once
+        .and_call_original
+
+      2.times do
+        expect(described_class.persisted_names).to eq(%w[foo])
+      end
+    end
+  end
+
+  describe '.persisted?' do
+    it 'returns true for a persisted feature' do
+      Feature::FlipperFeature.create!(key: 'foo')
+
+      feature = double(:feature, name: 'foo')
+
+      expect(described_class.persisted?(feature)).to eq(true)
+    end
+
+    it 'returns false for a feature that is not persisted' do
+      feature = double(:feature, name: 'foo')
+
+      expect(described_class.persisted?(feature)).to eq(false)
+    end
+  end
+
   describe '.all' do
     let(:features) { Set.new }