Merge branch 'memoize-fork-button' into 'master'

Memoize the fork suggestion button partial

See merge request gitlab-org/gitlab!53256

app/helpers/diff_helper.rb

@@ -214,6 +214,15 @@ module DiffHelper
     )
   end
 
+  # As the fork suggestion button is identical every time, we cache it for a full page load
+  def render_fork_suggestion
+    return unless current_user
+
+    strong_memoize(:fork_suggestion) do
+      render partial: "projects/fork_suggestion"
+    end
+  end
+
   private
 
   def diff_btn(title, name, selected)

app/views/projects/_fork_suggestion.html.haml

-- if current_user
-  .js-file-fork-suggestion-section.file-fork-suggestion.hidden
-    %span.file-fork-suggestion-note
-      You're not allowed to
-      %span.js-file-fork-suggestion-section-action
-        edit
-      files in this project directly. Please fork this project,
-      make your changes there, and submit a merge request.
-    = link_to 'Fork', nil, method: :post, class: 'js-fork-suggestion-button gl-button btn btn-grouped btn-inverted btn-success'
-    %button.js-cancel-fork-suggestion-button.gl-button.btn.btn-grouped{ type: 'button' }
-      Cancel
+.js-file-fork-suggestion-section.file-fork-suggestion.hidden
+  %span.file-fork-suggestion-note
+    You're not allowed to
+    %span.js-file-fork-suggestion-section-action
+      edit
+    files in this project directly. Please fork this project,
+    make your changes there, and submit a merge request.
+  = link_to 'Fork', nil, method: :post, class: 'js-fork-suggestion-button gl-button btn btn-grouped btn-inverted btn-success'
+  %button.js-cancel-fork-suggestion-button.gl-button.btn.btn-grouped{ type: 'button' }
+    Cancel

app/views/projects/blob/_header.html.haml

@@ -20,5 +20,5 @@
       = download_blob_button(blob)
       = view_on_environment_button(@commit.sha, @path, @environment) if @environment
 
-= render 'projects/fork_suggestion'
+= render_fork_suggestion
 = render_if_exists 'projects/blob/header_file_locks', project: @project, path: @path

app/views/projects/diffs/_file.html.haml

@@ -30,6 +30,6 @@
         = view_file_button(diff_file.content_sha, diff_file.file_path, project)
         = view_on_environment_button(diff_file.content_sha, diff_file.file_path, environment) if environment
 
-  = render 'projects/fork_suggestion'
+  = render_fork_suggestion
 
   = render 'projects/diffs/content', diff_file: diff_file

changelogs/unreleased/memoize-fork-button.yml

+---
+title: Memoize the fork suggestion button partial
+merge_request: 53256
+author:
+type: performance

spec/helpers/diff_helper_spec.rb

@@ -378,4 +378,28 @@ RSpec.describe DiffHelper do
       expect(subject).to match(/foo\/bar\/-\/commit\/#{commit.sha}\/diff_for_path/)
     end
   end
+
+  describe "#render_fork_suggestion" do
+    subject { helper.render_fork_suggestion }
+
+    before do
+      allow(helper).to receive(:current_user).and_return(current_user)
+    end
+
+    context "user signed in" do
+      let(:current_user) { build(:user) }
+
+      it "renders the partial" do
+        expect(helper).to receive(:render).with(partial: "projects/fork_suggestion").exactly(:once)
+
+        5.times { subject }
+      end
+    end
+
+    context "guest" do
+      let(:current_user) { nil }
+
+      it { is_expected.to be_nil }
+    end
+  end
 end