Bulk-render commit titles in the tree view to improve performance

app/controllers/projects/refs_controller.rb

@@ -59,13 +59,18 @@ class Projects::RefsController < Projects::ApplicationController
         commit_path = project_commit_path(@project, last_commit) if last_commit
         {
           file_name: content.name,
-          commit: last_commit,
+          # TODO: deduplicate commits so we don't render the same one multiple times
+          commit: (Commit.new(last_commit, project) if last_commit),
           type: content.type,
           commit_path: commit_path
         }
       end
     end
 
+    # The commit titles must be passed through Banzai before being shown.
+    # Doing this here in bulk allows significant database work to be skipped.
+    prerender_commits!(@logs.map { |log| log[:commit] })
+
     offset = (@offset + @limit)
     if contents.size > offset
       @more_log_url = logs_file_project_ref_path(@project, @ref, @path || '', offset: offset)
@@ -84,6 +89,11 @@ class Projects::RefsController < Projects::ApplicationController
 
   private
 
+  def prerender_commits!(commits)
+    renderer = Banzai::ObjectRenderer.new(user: current_user, default_project: @project)
+    renderer.render(commits, :full_title) # modifies the commit objects inplace
+  end
+
   def validate_ref_id
     return not_found! if params[:id].present? && params[:id] !~ Gitlab::PathRegex.git_reference_regex
   end

app/models/commit.rb

@@ -22,6 +22,7 @@ class Commit
   attr_accessor :project, :author
   attr_accessor :redacted_description_html
   attr_accessor :redacted_title_html
+  attr_accessor :redacted_full_title_html
   attr_reader :gpg_commit
 
   DIFF_SAFE_LINES = Gitlab::Git::DiffCollection::DEFAULT_LIMITS[:max_lines]
@@ -38,7 +39,12 @@ class Commit
   def banzai_render_context(field)
     pipeline = field == :description ? :commit_description : :single_line
     context = { pipeline: pipeline, project: self.project }
-    context[:author] = self.author if self.author
+
+    # The author is only needed when rendering the description
+    if field == :description
+      author = self.author
+      context[:author] = author if author
+    end
 
     context
   end

app/views/projects/tree/_tree_commit_column.html.haml

 %span.str-truncated
-  = link_to_markdown commit.full_title, project_commit_path(@project, commit.id), class: "tree-commit-link"
+  = link_to_html commit.redacted_full_title_html, project_commit_path(@project, commit.id), class: 'tree-commit-link'

spec/features/projects/tree/tree_show_spec.rb

@@ -4,16 +4,30 @@ describe 'Projects tree', :js do
   let(:user) { create(:user) }
   let(:project) { create(:project, :repository) }
 
+  # This commit has a known state on the master branch of gitlab-test
+  let(:test_sha) { '7975be0116940bf2ad4321f79d02a55c5f7779aa' }
+
   before do
     project.add_maintainer(user)
     sign_in(user)
   end
 
   it 'renders tree table without errors' do
-    visit project_tree_path(project, 'master')
+    visit project_tree_path(project, test_sha)
+    wait_for_requests
+
+    expect(page).to have_selector('.tree-item')
+    expect(page).to have_content('add tests for .gitattributes custom highlighting')
+    expect(page).not_to have_selector('.flash-alert')
+    expect(page).not_to have_selector('.label-lfs', text: 'LFS')
+  end
+
+  it 'renders tree table for a subtree without errors' do
+    visit project_tree_path(project, File.join(test_sha, 'files'))
     wait_for_requests
 
     expect(page).to have_selector('.tree-item')
+    expect(page).to have_content('add spaces in whitespace file')
     expect(page).not_to have_selector('.label-lfs', text: 'LFS')
     expect(page).not_to have_selector('.flash-alert')
   end