Preload Ci::Runner tags to prevent N+1 queries

app/controllers/projects/settings/ci_cd_controller.rb

@@ -119,12 +119,13 @@ module Projects
           .assignable_for(project)
           .ordered
           .page(params[:specific_page]).per(NUMBER_OF_RUNNERS_PER_PAGE)
+          .with_tags
 
-        @shared_runners = ::Ci::Runner.instance_type.active
+        @shared_runners = ::Ci::Runner.instance_type.active.with_tags
 
         @shared_runners_count = @shared_runners.count(:all)
 
-        @group_runners = ::Ci::Runner.belonging_to_parent_group_of_project(@project.id)
+        @group_runners = ::Ci::Runner.belonging_to_parent_group_of_project(@project.id).with_tags
       end
 
       def define_ci_variables

spec/controllers/projects/settings/ci_cd_controller_spec.rb

@@ -14,6 +14,10 @@ RSpec.describe Projects::Settings::CiCdController do
   end
 
   describe 'GET show' do
+    let(:parent_group) { create(:group) }
+    let(:group) { create(:group, parent: parent_group) }
+    let(:other_project) { create(:project, group: group) }
+
     it 'renders show with 200 status code' do
       get :show, params: { namespace_id: project.namespace, project_id: project }
 
@@ -22,10 +26,7 @@ RSpec.describe Projects::Settings::CiCdController do
     end
 
     context 'with group runners' do
-      let(:parent_group) { create(:group) }
-      let(:group) { create(:group, parent: parent_group) }
       let(:group_runner) { create(:ci_runner, :group, groups: [group]) }
-      let(:other_project) { create(:project, group: group) }
       let!(:project_runner) { create(:ci_runner, :project, projects: [other_project]) }
       let!(:shared_runner) { create(:ci_runner, :instance) }
 
@@ -37,6 +38,33 @@ RSpec.describe Projects::Settings::CiCdController do
         expect(assigns(:assignable_runners)).to contain_exactly(project_runner)
       end
     end
+
+    context 'prevents N+1 queries for tags' do
+      render_views
+
+      def show
+        get :show, params: { namespace_id: project.namespace, project_id: project }
+      end
+
+      it 'has the same number of queries with one tag or with many tags', :request_store do
+        group.add_maintainer(user)
+
+        show # warmup
+
+        # with one tag
+        create(:ci_runner, :instance, tag_list: %w(shared_runner))
+        create(:ci_runner, :project, projects: [other_project], tag_list: %w(project_runner))
+        create(:ci_runner, :group, groups: [group], tag_list: %w(group_runner))
+        control = ActiveRecord::QueryRecorder.new { show }
+
+        # with several tags
+        create(:ci_runner, :instance, tag_list: %w(shared_runner tag2 tag3))
+        create(:ci_runner, :project, projects: [other_project], tag_list: %w(project_runner tag2 tag3))
+        create(:ci_runner, :group, groups: [group], tag_list: %w(group_runner tag2 tag3))
+
+        expect { show }.not_to exceed_query_limit(control)
+      end
+    end
   end
 
   describe '#reset_cache' do