Automatic merge of gitlab-org/gitlab-ce master

app/helpers/issuables_helper.rb

@@ -74,7 +74,7 @@ module IssuablesHelper
     end
   end
 
-  def serialize_issuable(issuable, serializer: nil)
+  def serialize_issuable(issuable, opts = {})
     serializer_klass = case issuable
                        when Issue
                          IssueSerializer
@@ -84,7 +84,7 @@ module IssuablesHelper
 
     serializer_klass
       .new(current_user: current_user, project: issuable.project)
-      .represent(issuable, serializer: serializer)
+      .represent(issuable, opts)
       .to_json
   end
 

app/serializers/merge_request_widget_entity.rb

@@ -116,7 +116,10 @@ class MergeRequestWidgetEntity < IssuableEntity
     presenter(merge_request).ci_status
   end
 
-  expose :issues_links do
+  # Rendering and redacting Markdown can be expensive. These links are
+  # just nice to have in the merge request widget, so only
+  # include them if they are explicitly requested on first load.
+  expose :issues_links, if: -> (_, opts) { opts[:issues_links] } do
     expose :assign_to_closing do |merge_request|
       presenter(merge_request).assign_to_closing_issues_link
     end

app/views/projects/merge_requests/show.html.haml

@@ -19,7 +19,7 @@
     -# haml-lint:disable InlineJavaScript
     :javascript
       window.gl = window.gl || {};
-      window.gl.mrWidgetData = #{serialize_issuable(@merge_request, serializer: 'widget')}
+      window.gl.mrWidgetData = #{serialize_issuable(@merge_request, serializer: 'widget', issues_links: true)}
 
       window.gl.mrWidgetData.squash_before_merge_help_path = '#{help_page_path("user/project/merge_requests/squash_and_merge")}';
       window.gl.mrWidgetData.troubleshooting_docs_path = '#{help_page_path('user/project/merge_requests/index.md', anchor: 'troubleshooting')}';

changelogs/unreleased/sh-omit-issues-links-on-poll.yml

+---
+title: Omit issues links in merge request entity API response
+merge_request: 29917
+author:
+type: performance

spec/serializers/merge_request_widget_entity_spec.rb

@@ -32,6 +32,19 @@ describe MergeRequestWidgetEntity do
     end
   end
 
+  describe 'issues links' do
+    it 'includes issues links when requested' do
+      data = described_class.new(resource, request: request, issues_links: true).as_json
+
+      expect(data).to include(:issues_links)
+      expect(data[:issues_links]).to include(:assign_to_closing, :closing, :mentioned_but_not_closing)
+    end
+
+    it 'omits issue links by default' do
+      expect(subject).not_to include(:issues_links)
+    end
+  end
+
   describe 'pipeline' do
     let(:pipeline) { create(:ci_empty_pipeline, project: project, ref: resource.source_branch, sha: resource.source_branch_sha, head_pipeline_of: resource) }