Add cache for elasticsearch_indexes_namespace?

When doing a group scoped search we are spending ~800ms just checking if
ES is enabled for the namespace. This change introduces caching
for elasticsearch_indexes_namespace?

ee/app/models/concerns/elasticsearch_indexed_container.rb

@@ -6,11 +6,11 @@ module ElasticsearchIndexedContainer
   included do
     after_commit :index, on: :create
     after_commit :delete_from_index, on: :destroy
-    after_commit :invalidate_elasticsearch_indexes_project_cache!, on: [:create, :destroy]
+    after_commit :invalidate_elasticsearch_indexes_cache!, on: [:create, :destroy]
   end
 
-  def invalidate_elasticsearch_indexes_project_cache!
-    self.class.invalidate_elasticsearch_indexes_project_cache!
+  def invalidate_elasticsearch_indexes_cache!
+    self.class.invalidate_elasticsearch_indexes_cache!
   end
 
   class_methods do
@@ -24,8 +24,8 @@ module ElasticsearchIndexedContainer
       end
     end
 
-    def invalidate_elasticsearch_indexes_project_cache!
-      ::Gitlab::CurrentSettings.invalidate_elasticsearch_indexes_project_cache!
+    def invalidate_elasticsearch_indexes_cache!
+      ::Gitlab::CurrentSettings.invalidate_elasticsearch_indexes_cache!
     end
   end
 end

ee/app/models/ee/application_setting.rb

@@ -152,15 +152,20 @@ module EE
       end
     end
 
-    def invalidate_elasticsearch_indexes_project_cache!
-      ::Gitlab::Elastic::ElasticsearchEnabledCache.delete(:project)
-    end
-
     def elasticsearch_indexes_namespace?(namespace)
       return false unless elasticsearch_indexing?
       return true unless elasticsearch_limit_indexing?
 
-      elasticsearch_limited_namespaces.exists?(namespace.id)
+      elasticsearch_limited_namespaces.exists?(namespace.id) unless ::Feature.enabled?(:elasticsearch_indexes_namespace_cache)
+
+      ::Gitlab::Elastic::ElasticsearchEnabledCache.fetch(:namespace, namespace.id) do
+        elasticsearch_limited_namespaces.exists?(namespace.id)
+      end
+    end
+
+    def invalidate_elasticsearch_indexes_cache!
+      ::Gitlab::Elastic::ElasticsearchEnabledCache.delete(:project)
+      ::Gitlab::Elastic::ElasticsearchEnabledCache.delete(:namespace)
     end
 
     def elasticsearch_limited_projects(ignore_namespaces = false)

ee/app/models/elasticsearch_indexed_namespace.rb

@@ -38,7 +38,7 @@ class ElasticsearchIndexedNamespace < ApplicationRecord
       end
 
       Gitlab::Database.bulk_insert(table_name, insert_rows) # rubocop:disable Gitlab/BulkInsert
-      invalidate_elasticsearch_indexes_project_cache!
+      invalidate_elasticsearch_indexes_cache!
 
       jobs = batch_ids.map { |id| [id, :index] }
 
@@ -56,7 +56,7 @@ class ElasticsearchIndexedNamespace < ApplicationRecord
 
     ids.in_groups_of(BATCH_OPERATION_SIZE, false) do |batch_ids|
       where(namespace_id: batch_ids).delete_all
-      invalidate_elasticsearch_indexes_project_cache!
+      invalidate_elasticsearch_indexes_cache!
 
       jobs = batch_ids.map { |id| [id, :delete] }
 

ee/changelogs/unreleased/244846-add-es-namespaces-enabled-cache.yml

+---
+title: Add cache for elasticsearch_indexes_namespace check
+merge_request: 41274
+author:
+type: performance

ee/config/feature_flags/development/elasticsearch_indexes_namespace_cache.yml

+---
+name: elasticsearch_indexes_namespace_cache
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/41274
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/244847
+group: group::global search
+type: development
+default_enabled: false

ee/spec/models/application_setting_spec.rb

@@ -397,11 +397,12 @@ RSpec.describe ApplicationSetting do
     end
   end
 
-  describe '#invalidate_elasticsearch_indexes_project_cache!' do
-    it 'deletes the ElasticsearchEnabledCache for projects' do
+  describe '#invalidate_elasticsearch_indexes_cache' do
+    it 'deletes the ElasticsearchEnabledCache for projects and namespaces' do
       expect(::Gitlab::Elastic::ElasticsearchEnabledCache).to receive(:delete).with(:project)
+      expect(::Gitlab::Elastic::ElasticsearchEnabledCache).to receive(:delete).with(:namespace)
 
-      setting.invalidate_elasticsearch_indexes_project_cache!
+      setting.invalidate_elasticsearch_indexes_cache!
     end
   end
 

ee/spec/models/elasticsearch_indexed_namespace_spec.rb

@@ -56,7 +56,7 @@ RSpec.describe ElasticsearchIndexedNamespace do
 
     describe '.index_first_n_namespaces_of_plan' do
       it 'creates records, scoped by plan and ordered by namespace id' do
-        expect(::Gitlab::CurrentSettings).to receive(:invalidate_elasticsearch_indexes_project_cache!).and_call_original.exactly(3).times
+        expect(::Gitlab::CurrentSettings).to receive(:invalidate_elasticsearch_indexes_cache!).and_call_original.exactly(3).times
 
         ids = namespaces.map(&:id)
 
@@ -84,7 +84,7 @@ RSpec.describe ElasticsearchIndexedNamespace do
       end
 
       it 'creates records, scoped by plan and ordered by namespace id' do
-        expect(::Gitlab::CurrentSettings).to receive(:invalidate_elasticsearch_indexes_project_cache!).and_call_original.exactly(3).times
+        expect(::Gitlab::CurrentSettings).to receive(:invalidate_elasticsearch_indexes_cache!).and_call_original.exactly(3).times
 
         ids = namespaces.map(&:id)