Use cached readme path for projects#show

Repository#readme_path is cached, while Repository#readme isn't
We need only path on projects#show, so let's use it

app/controllers/projects_controller.rb

@@ -20,8 +20,6 @@ class ProjectsController < Projects::ApplicationController
   before_action :project, except: [:index, :new, :create, :resolve]
   before_action :repository, except: [:index, :new, :create, :resolve]
   before_action :assign_ref_vars, if: -> { action_name == 'show' && repo_exists? }
-  before_action :tree,
-    if: -> { action_name == 'show' && repo_exists? && project_view_files? }
   before_action :project_export_enabled, only: [:export, :download_export, :remove_export, :generate_new_export]
   before_action :present_project, only: [:edit]
   before_action :authorize_download_code!, only: [:refs]

app/models/repository.rb

@@ -618,7 +618,7 @@ class Repository
   end
 
   def readme_path
-    readme&.path
+    head_tree&.readme_path
   end
   cache_method :readme_path
 

app/presenters/project_presenter.rb

@@ -77,19 +77,19 @@ class ProjectPresenter < Gitlab::View::Presenter::Delegated
   end
 
   def readme_path
-    filename_path(:readme)
+    filename_path(repository.readme_path)
   end
 
   def changelog_path
-    filename_path(:changelog)
+    filename_path(repository.changelog&.name)
   end
 
   def license_path
-    filename_path(:license_blob)
+    filename_path(repository.license_blob&.name)
   end
 
   def ci_configuration_path
-    filename_path(:gitlab_ci_yml)
+    filename_path(repository.gitlab_ci_yml&.name)
   end
 
   def contribution_guide_path
@@ -244,11 +244,11 @@ class ProjectPresenter < Gitlab::View::Presenter::Delegated
   end
 
   def readme_anchor_data
-    if current_user && can_current_user_push_to_default_branch? && repository.readme.nil?
+    if current_user && can_current_user_push_to_default_branch? && readme_path.nil?
       AnchorData.new(false,
                      statistic_icon + _('Add README'),
                      empty_repo? ? add_readme_ide_path : add_readme_path)
-    elsif repository.readme
+    elsif readme_path
       AnchorData.new(false,
                      statistic_icon('doc-text') + _('README'),
                      default_view != 'readme' ? readme_path : '#readme',
@@ -397,13 +397,10 @@ class ProjectPresenter < Gitlab::View::Presenter::Delegated
     current_user && can?(current_user, :create_cluster, project)
   end
 
-  def filename_path(filename)
-    if blob = repository.public_send(filename) # rubocop:disable GitlabSecurity/PublicSend
-      project_blob_path(
-        project,
-        tree_join(default_branch, blob.name)
-      )
-    end
+  def filename_path(filepath)
+    return if filepath.blank?
+
+    project_blob_path(project, tree_join(default_branch, filepath))
   end
 
   def anonymous_project_view

app/views/projects/_files.html.haml

@@ -3,8 +3,8 @@
 - project = local_assigns.fetch(:project) { @project }
 - show_auto_devops_callout = show_auto_devops_callout?(@project)
 - add_page_startup_api_call logs_file_project_ref_path(@project, ref, @path, format: "json", offset: 0)
-- if @tree.readme
-  - add_page_startup_api_call project_blob_path(@project, tree_join(@ref, @tree.readme.path), viewer: "rich", format: "json")
+- if readme_path = @project.repository.readme_path
+  - add_page_startup_api_call project_blob_path(@project, tree_join(@ref, readme_path), viewer: "rich", format: "json")
 
 #tree-holder.tree-holder.clearfix
   .nav-block

spec/features/projects/show/user_sees_setup_shortcut_buttons_spec.rb

@@ -165,7 +165,7 @@ RSpec.describe 'Projects > Show > User sees setup shortcut buttons' do
 
         context 'when the project does not have a README' do
           it 'shows the single file editor "Add README" button' do
-            allow(project.repository).to receive(:readme).and_return(nil)
+            allow(project.repository).to receive(:readme_path).and_return(nil)
 
             visit project_path(project)
 

spec/models/repository_spec.rb

@@ -2335,7 +2335,7 @@ RSpec.describe Repository do
         end
 
         it 'caches the response' do
-          expect(repository).to receive(:readme).and_call_original.once
+          expect(repository.head_tree).to receive(:readme_path).and_call_original.once
 
           2.times do
             expect(repository.readme_path).to eq("README.md")

spec/presenters/project_presenter_spec.rb

@@ -375,7 +375,7 @@ RSpec.describe ProjectPresenter do
         it 'returns anchor data' do
           project.add_developer(user)
 
-          allow(project.repository).to receive(:readme).and_return(nil)
+          allow(project.repository).to receive(:readme_path).and_return(nil)
 
           expect(presenter.readme_anchor_data).to have_attributes(
             is_link: false,
@@ -387,7 +387,7 @@ RSpec.describe ProjectPresenter do
 
       context 'when README exists' do
         it 'returns anchor data' do
-          allow(project.repository).to receive(:readme).and_return(double(name: 'readme'))
+          allow(project.repository).to receive(:readme_path).and_return('readme')
 
           expect(presenter.readme_anchor_data).to have_attributes(
             is_link: false,
@@ -561,7 +561,7 @@ RSpec.describe ProjectPresenter do
     let(:project) { build_stubbed(:project) }
 
     it 'orders the items correctly' do
-      allow(project.repository).to receive(:readme).and_return(double(name: 'readme'))
+      allow(project.repository).to receive(:readme_path).and_return('readme')
       allow(project.repository).to receive(:license_blob).and_return(nil)
       allow(project.repository).to receive(:changelog).and_return(nil)
       allow(project.repository).to receive(:contribution_guide).and_return(double(name: 'foo'))