Merge branch 'osw-remove-dead-code-on-mr-show' into 'master'

Removes expensive dead code on main MR page request

Closes #51172

See merge request gitlab-org/gitlab-ce!22153

Author: Robert Speicher

app/controllers/projects/merge_requests_controller.rb

@@ -44,12 +44,6 @@ def show
         @noteable = @merge_request
         @commits_count = @merge_request.commits_count
 
-        # TODO cleanup- Fatih Simon Create an issue to remove these after the refactoring
-        # we no longer render notes here. I see it will require a small frontend refactoring,
-        # since we gather some data from this collection.
-        @discussions = @merge_request.discussions
-        @notes = prepare_notes_for_rendering(@discussions.flat_map(&:notes), @noteable)
-
         labels
 
         set_pipeline_variables

app/helpers/notes_helper.rb

@@ -142,7 +142,7 @@ def can_create_note?
   def initial_notes_data(autocomplete)
     {
       notesUrl: notes_url,
-      notesIds: @notes.map(&:id),
+      notesIds: @noteable.notes.pluck(:id), # rubocop: disable CodeReuse/ActiveRecord
       now: Time.now.to_i,
       diffView: diff_view,
       enableGFM: {

changelogs/unreleased/osw-remove-dead-code-on-mr-show.yml

@@ -0,0 +1,5 @@
+---
+title: Removes expensive dead code on main MR page request
+merge_request: 22153
+author:
+type: performance

spec/controllers/projects/merge_requests_controller_spec.rb

@@ -76,28 +76,6 @@ def go(extra_params = {})
         expect(response).to be_success
       end
 
-      context "loads notes" do
-        let(:first_contributor) { create(:user) }
-        let(:contributor) { create(:user) }
-        let(:merge_request) { create(:merge_request, author: first_contributor, target_project: project, source_project: project) }
-        let(:contributor_merge_request) { create(:merge_request, :merged, author: contributor, target_project: project, source_project: project) }
-        # the order here is important
-        # as the controller reloads these from DB, references doesn't correspond after
-        let!(:first_contributor_note) { create(:note, author: first_contributor, noteable: merge_request, project: project) }
-        let!(:contributor_note) { create(:note, author: contributor, noteable: merge_request, project: project) }
-        let!(:owner_note) { create(:note, author: user, noteable: merge_request, project: project) }
-
-        it "with special_role FIRST_TIME_CONTRIBUTOR" do
-          go(format: :html)
-
-          notes = assigns(:notes)
-          expect(notes).to match(a_collection_containing_exactly(an_object_having_attributes(special_role: Note::SpecialRole::FIRST_TIME_CONTRIBUTOR),
-                                                                 an_object_having_attributes(special_role: nil),
-                                                                 an_object_having_attributes(special_role: nil)
-                                                                ))
-        end
-      end
-
       context "that is invalid" do
         let(:merge_request) { create(:invalid_merge_request, target_project: project, source_project: project) }