From dbbd137e9fce17eb5698faa65f9bce49a6fcdbbb Mon Sep 17 00:00:00 2001
From: GitLab Duo <duo.workflow.agent@gitlab.com>
Date: Thu, 18 Sep 2025 21:53:26 +0000
Subject: [PATCH] Duo Workflow: Resolve issue #260456

---
 .../events/cache_invalidation_event.rb        | 21 ++++++
 .../events/cache_invalidation_event_spec.rb   | 66 +++++++++++++++++++
 2 files changed, 87 insertions(+)

diff --git a/ee/lib/gitlab/geo/log_cursor/events/cache_invalidation_event.rb b/ee/lib/gitlab/geo/log_cursor/events/cache_invalidation_event.rb
index dd1f8996e24eed..1d8d0fe89fa2e7 100644
--- a/ee/lib/gitlab/geo/log_cursor/events/cache_invalidation_event.rb
+++ b/ee/lib/gitlab/geo/log_cursor/events/cache_invalidation_event.rb
@@ -9,6 +9,7 @@ class CacheInvalidationEvent
 
           def process
             result = expire_cache_for_event_key
+            clear_feature_flag_caches if feature_flag_cache_key?
             log_cache_invalidation_event(result)
           end
 
@@ -18,6 +19,26 @@ def expire_cache_for_event_key
             Rails.cache.delete(event.key)
           end
 
+          def feature_flag_cache_key?
+            # CacheInvalidationEventStore is only fired from ee/lib/ee/feature.rb
+            # for feature flag changes, so we can safely assume all cache invalidation
+            # events are for feature flags and clear the additional cache layers
+            true
+          end
+
+          def clear_feature_flag_caches
+            # Clear the memoized cache layers that are not cleared by Rails.cache.delete
+            # This ensures feature flag changes propagate immediately to Geo secondaries
+            
+            # Clear SafeRequestStore flipper cache if active
+            if Gitlab::SafeRequestStore.active?
+              Gitlab::SafeRequestStore.delete(:flipper)
+            end
+            
+            # Clear the @flipper instance variable cache
+            Feature.instance_variable_set(:@flipper, nil)
+          end
+
           def log_cache_invalidation_event(expired)
             log_event(
               'Cache invalidation',
diff --git a/ee/spec/lib/gitlab/geo/log_cursor/events/cache_invalidation_event_spec.rb b/ee/spec/lib/gitlab/geo/log_cursor/events/cache_invalidation_event_spec.rb
index aa851588de37fc..f77e3df22fed05 100644
--- a/ee/spec/lib/gitlab/geo/log_cursor/events/cache_invalidation_event_spec.rb
+++ b/ee/spec/lib/gitlab/geo/log_cursor/events/cache_invalidation_event_spec.rb
@@ -24,6 +24,12 @@
       subject.process
     end
 
+    it 'clears feature flag caches' do
+      expect(subject).to receive(:clear_feature_flag_caches)
+
+      subject.process
+    end
+
     it 'logs an info event' do
       data = {
         class: described_class.name,
@@ -41,4 +47,64 @@
       subject.process
     end
   end
+
+  describe '#feature_flag_cache_key?' do
+    it 'returns true for all cache keys' do
+      expect(subject.send(:feature_flag_cache_key?)).to be true
+    end
+  end
+
+  describe '#clear_feature_flag_caches' do
+    context 'when SafeRequestStore is active' do
+      before do
+        allow(Gitlab::SafeRequestStore).to receive(:active?).and_return(true)
+      end
+
+      it 'clears the SafeRequestStore flipper cache' do
+        expect(Gitlab::SafeRequestStore).to receive(:delete).with(:flipper)
+
+        subject.send(:clear_feature_flag_caches)
+      end
+
+      it 'clears the @flipper instance variable' do
+        expect(Feature).to receive(:instance_variable_set).with(:@flipper, nil)
+
+        subject.send(:clear_feature_flag_caches)
+      end
+    end
+
+    context 'when SafeRequestStore is not active' do
+      before do
+        allow(Gitlab::SafeRequestStore).to receive(:active?).and_return(false)
+      end
+
+      it 'does not try to clear SafeRequestStore' do
+        expect(Gitlab::SafeRequestStore).not_to receive(:delete)
+
+        subject.send(:clear_feature_flag_caches)
+      end
+
+      it 'still clears the @flipper instance variable' do
+        expect(Feature).to receive(:instance_variable_set).with(:@flipper, nil)
+
+        subject.send(:clear_feature_flag_caches)
+      end
+    end
+  end
+
+  describe 'integration test' do
+    it 'clears all feature flag cache layers when processing cache invalidation event' do
+      # Set up feature flag caches
+      allow(Gitlab::SafeRequestStore).to receive(:active?).and_return(true)
+      Gitlab::SafeRequestStore[:flipper] = 'cached_flipper_instance'
+      Feature.instance_variable_set(:@flipper, 'cached_flipper_instance')
+
+      # Process the cache invalidation event
+      subject.process
+
+      # Verify all caches are cleared
+      expect(Gitlab::SafeRequestStore[:flipper]).to be_nil
+      expect(Feature.instance_variable_get(:@flipper)).to be_nil
+    end
+  end
 end
-- 
GitLab