Merge branch 'reactive-caching-self-cleanup' into 'master'

Make reactive caching clean up after itself

See merge request gitlab-org/gitlab!20111

app/models/concerns/reactive_caching.rb

@@ -129,14 +129,17 @@ module ReactiveCaching
 
     def exclusively_update_reactive_cache!(*args)
       locking_reactive_cache(*args) do
+        key = full_reactive_cache_key(*args)
+
         if within_reactive_cache_lifetime?(*args)
           enqueuing_update(*args) do
-            key = full_reactive_cache_key(*args)
             new_value = calculate_reactive_cache(*args)
             old_value = Rails.cache.read(key)
             Rails.cache.write(key, new_value)
             reactive_cache_updated(*args) if new_value != old_value
           end
+        else
+          Rails.cache.delete(key)
         end
       end
     end

changelogs/unreleased/reactive-caching-self-cleanup.yml

+---
+title: Remove reactive caching value keys once the alive key has expired
+merge_request: 20111
+author:
+type: performance

spec/models/concerns/reactive_caching_spec.rb

@@ -196,6 +196,12 @@ describe ReactiveCaching, :use_clean_rails_memory_store_caching do
         2.times { instance.exclusively_update_reactive_cache! }
       end
 
+      it 'does not delete the value key' do
+        expect(Rails.cache).to receive(:delete).with(cache_key).never
+
+        go!
+      end
+
       context 'and #calculate_reactive_cache raises an exception' do
         before do
           stub_reactive_cache(instance, "preexisting")
@@ -223,6 +229,12 @@ describe ReactiveCaching, :use_clean_rails_memory_store_caching do
 
         go!
       end
+
+      it 'deletes the value key' do
+        expect(Rails.cache).to receive(:delete).with(cache_key).once
+
+        go!
+      end
     end
 
     context 'when the lease is already taken' do