Reduce number of queries made for merge_requests/:id/diffs

CHANGELOG

@@ -25,6 +25,7 @@ v 8.11.0 (unreleased)
   - Add commit stats in commit api. !5517 (dixpac)
   - Make error pages responsive (Takuya Noguchi)
   - Change requests_profiles resource constraint to catch virtually any file
+  - Reduce number of queries made for merge_requests/:id/diffs
 
 v 8.10.3 (unreleased)
 

app/controllers/projects/merge_requests_controller.rb

@@ -407,7 +407,7 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     }
 
     @use_legacy_diff_notes = !@merge_request.support_new_diff_notes?
-    @grouped_diff_discussions = @merge_request.notes.grouped_diff_discussions
+    @grouped_diff_discussions = @merge_request.notes.inc_author_project_award_emoji.grouped_diff_discussions
 
     Banzai::NoteRenderer.render(
       @grouped_diff_discussions.values.flat_map(&:notes),

app/models/concerns/issuable.rb

@@ -17,7 +17,7 @@ module Issuable
     belongs_to :assignee, class_name: "User"
     belongs_to :updated_by, class_name: "User"
     belongs_to :milestone
-    has_many :notes, as: :noteable, dependent: :destroy do
+    has_many :notes, as: :noteable, inverse_of: :noteable, dependent: :destroy do
       def authors_loaded?
         # We check first if we're loaded to not load unnecessarily.
         loaded? && to_a.all? { |note| note.association(:author).loaded? }

app/models/legacy_diff_note.rb

@@ -25,6 +25,14 @@ class LegacyDiffNote < Note
     @discussion_id ||= self.class.build_discussion_id(noteable_type, noteable_id || commit_id, line_code)
   end
 
+  def project_repository
+    if RequestStore.active?
+      RequestStore.fetch("project:#{project_id}:repository") { self.project.repository }
+    else
+      self.project.repository
+    end
+  end
+
   def diff_file_hash
     line_code.split('_')[0] if line_code
   end
@@ -34,7 +42,7 @@ class LegacyDiffNote < Note
   end
 
   def diff_file
-    @diff_file ||= Gitlab::Diff::File.new(diff, repository: self.project.repository) if diff
+    @diff_file ||= Gitlab::Diff::File.new(diff, repository: project_repository) if diff
   end
 
   def diff_line