Merge branch 'issues-show-performance' into 'master'

Improve performance of viewing individual issues

This MR does two things:

1. `Issue#related_branches` no longer performs Git operations that aren't needed
2. The output of `Repository#exists?` is now cached and flushed properly

Combined these two changes should further cut down the amount of Git operations performed when viewing individual issues (and possibly other pages).

See merge request !3296

app/models/issue.rb

@@ -108,9 +108,9 @@ class Issue < ActiveRecord::Base
   end
 
   def related_branches
-    return [] if self.project.empty_repo?
-    
-    self.project.repository.branch_names.select { |branch| branch.end_with?("-#{iid}") }
+    project.repository.branch_names.select do |branch|
+      branch.end_with?("-#{iid}")
+    end
   end
 
   # Reset issue events cache

app/models/project.rb

@@ -876,6 +876,7 @@ class Project < ActiveRecord::Base
     # Forked import is handled asynchronously
     unless forked?
       if gitlab_shell.add_repository(path_with_namespace)
+        repository.after_create
         true
       else
         errors.add(:base, 'Failed to create repository via gitlab-shell')

app/models/project_wiki.rb

@@ -123,23 +123,27 @@ class ProjectWiki
   end
 
   def repository
-    Repository.new(path_with_namespace, @project)
+    @repository ||= Repository.new(path_with_namespace, @project)
   end
 
   def default_branch
     wiki.class.default_ref
   end
 
-  private
-
   def create_repo!
     if init_repo(path_with_namespace)
-      Gollum::Wiki.new(path_to_repo)
+      wiki = Gollum::Wiki.new(path_to_repo)
     else
       raise CouldNotCreateWikiError
     end
+
+    repository.after_create
+
+    wiki
   end
 
+  private
+
   def init_repo(path_with_namespace)
     gitlab_shell.add_repository(path_with_namespace)
   end

app/models/repository.rb

@@ -42,13 +42,16 @@ class Repository
   end
 
   def exists?
-    return false unless raw_repository
+    return @exists unless @exists.nil?
 
-    raw_repository.rugged
-    true
+    @exists = cache.fetch(:exists?) do
+      begin
+        raw_repository && raw_repository.rugged ? true : false
       rescue Gitlab::Git::Repository::NoRepository
         false
       end
+    end
+  end
 
   def empty?
     return @empty unless @empty.nil?
@@ -320,12 +323,23 @@ class Repository
     @avatar = nil
   end
 
+  def expire_exists_cache
+    cache.expire(:exists?)
+    @exists = nil
+  end
+
+  # Runs code after a repository has been created.
+  def after_create
+    expire_exists_cache
+  end
+
   # Runs code just before a repository is deleted.
   def before_delete
     expire_cache if exists?
 
     expire_root_ref_cache
     expire_emptiness_caches
+    expire_exists_cache
   end
 
   # Runs code just before the HEAD of a repository is changed.
@@ -351,6 +365,7 @@ class Repository
   # Runs code after a repository has been forked/imported.
   def after_import
     expire_emptiness_caches
+    expire_exists_cache
   end
 
   # Runs code after a new commit has been pushed.

app/workers/repository_fork_worker.rb

@@ -20,14 +20,15 @@ class RepositoryForkWorker
       return
     end
 
+    project.repository.after_import
+
     unless project.valid_repo?
-      logger.error("Project #{id} had an invalid repository after fork")
+      logger.error("Project #{project_id} had an invalid repository after fork")
       project.update(import_error: "The forked repository is invalid.")
       project.import_fail
       return
     end
 
-    project.repository.after_import
     project.import_finish
   end
 end

features/project/issues/issues.feature

@@ -160,6 +160,7 @@ Feature: Project Issues
 
   Scenario: Issues on empty project
     Given empty project "Empty Project"
+    And I have an ssh key
     When I visit empty project page
     And I see empty project details with ssh clone info
     When I visit empty project's issues page

features/steps/project/issues/issues.rb

@@ -5,6 +5,7 @@ class Spinach::Features::ProjectIssues < Spinach::FeatureSteps
   include SharedNote
   include SharedPaths
   include SharedMarkdown
+  include SharedUser
 
   step 'I should see "Release 0.4" in issues' do
     expect(page).to have_content "Release 0.4"
@@ -240,7 +241,7 @@ class Spinach::Features::ProjectIssues < Spinach::FeatureSteps
   end
 
   step 'empty project "Empty Project"' do
-    create :empty_project, name: 'Empty Project', namespace: @user.namespace
+    create :project_empty_repo, name: 'Empty Project', namespace: @user.namespace
   end
 
   When 'I visit empty project page' do

spec/controllers/projects/issues_controller_spec.rb

@@ -2,7 +2,7 @@ require('spec_helper')
 
 describe Projects::IssuesController do
   describe "GET #index" do
-    let(:project) { create(:project) }
+    let(:project) { create(:project_empty_repo) }
     let(:user) { create(:user) }
     let(:issue) { create(:issue, project: project) }
 
@@ -41,7 +41,7 @@ describe Projects::IssuesController do
   end
 
   describe 'Confidential Issues' do
-    let(:project) { create(:empty_project, :public) }
+    let(:project) { create(:project_empty_repo, :public) }
     let(:assignee) { create(:assignee) }
     let(:author) { create(:user) }
     let(:non_member) { create(:user) }

spec/models/issue_spec.rb

@@ -185,7 +185,7 @@ describe Issue, models: true do
       allow(subject.project.repository).to receive(:branch_names).
         and_return(["mpempe", "#{subject.iid}mepmep", subject.to_branch_name])
 
-      expect(subject.related_branches).to eq [subject.to_branch_name]
+      expect(subject.related_branches).to eq([subject.to_branch_name])
     end
   end
 

spec/models/project_spec.rb

@@ -720,4 +720,45 @@ describe Project, models: true do
       expect(described_class.search_by_title('KITTENS')).to eq([project])
     end
   end
+
+  describe '#create_repository' do
+    let(:project) { create(:project) }
+    let(:shell) { Gitlab::Shell.new }
+
+    before do
+      allow(project).to receive(:gitlab_shell).and_return(shell)
+    end
+
+    context 'using a regular repository' do
+      it 'creates the repository' do
+        expect(shell).to receive(:add_repository).
+          with(project.path_with_namespace).
+          and_return(true)
+
+        expect(project.repository).to receive(:after_create)
+
+        expect(project.create_repository).to eq(true)
+      end
+
+      it 'adds an error if the repository could not be created' do
+        expect(shell).to receive(:add_repository).
+          with(project.path_with_namespace).
+          and_return(false)
+
+        expect(project.repository).not_to receive(:after_create)
+
+        expect(project.create_repository).to eq(false)
+        expect(project.errors).not_to be_empty
+      end
+    end
+
+    context 'using a forked repository' do
+      it 'does nothing' do
+        expect(project).to receive(:forked?).and_return(true)
+        expect(shell).not_to receive(:add_repository)
+
+        project.create_repository
+      end
+    end
+  end
 end

spec/models/project_wiki_spec.rb

@@ -244,6 +244,18 @@ describe ProjectWiki, models: true do
     end
   end
 
+  describe '#create_repo!' do
+    it 'creates a repository' do
+      expect(subject).to receive(:init_repo).
+        with(subject.path_with_namespace).
+        and_return(true)
+
+      expect(subject.repository).to receive(:after_create)
+
+      expect(subject.create_repo!).to be_an_instance_of(Gollum::Wiki)
+    end
+  end
+
   private
 
   def create_temp_repo(path)

spec/models/repository_spec.rb

@@ -537,6 +537,12 @@ describe Repository, models: true do
 
         repository.before_delete
       end
+
+      it 'flushes the exists cache' do
+        expect(repository).to receive(:expire_exists_cache)
+
+        repository.before_delete
+      end
     end
 
     describe 'when a repository exists' do
@@ -593,6 +599,12 @@ describe Repository, models: true do
 
       repository.after_import
     end
+
+    it 'flushes the exists cache' do
+      expect(repository).to receive(:expire_exists_cache)
+
+      repository.after_import
+    end
   end
 
   describe '#after_push_commit' do
@@ -619,6 +631,14 @@ describe Repository, models: true do
     end
   end
 
+  describe '#after_create' do
+    it 'flushes the exists cache' do
+      expect(repository).to receive(:expire_exists_cache)
+
+      repository.after_create
+    end
+  end
+
   describe "#main_language" do
     it 'shows the main language of the project' do
       expect(repository.main_language).to eq("Ruby")
@@ -781,6 +801,16 @@ describe Repository, models: true do
     end
   end
 
+  describe '#expire_exists_cache' do
+    let(:cache) { repository.send(:cache) }
+
+    it 'expires the cache' do
+      expect(cache).to receive(:expire).with(:exists?)
+
+      repository.expire_exists_cache
+    end
+  end
+
   describe '#build_cache' do
     let(:cache) { repository.send(:cache) }
 

spec/workers/repository_fork_worker_spec.rb

@@ -3,12 +3,17 @@ require 'spec_helper'
 describe RepositoryForkWorker do
   let(:project) { create(:project) }
   let(:fork_project) { create(:project, forked_from_project: project) }
+  let(:shell) { Gitlab::Shell.new }
 
   subject { RepositoryForkWorker.new }
 
+  before do
+    allow(subject).to receive(:gitlab_shell).and_return(shell)
+  end
+
   describe "#perform" do
     it "creates a new repository from a fork" do
-      expect_any_instance_of(Gitlab::Shell).to receive(:fork_repository).with(
+      expect(shell).to receive(:fork_repository).with(
         project.path_with_namespace,
         fork_project.namespace.path
       ).and_return(true)
@@ -19,20 +24,26 @@ describe RepositoryForkWorker do
         fork_project.namespace.path)
     end
 
-    it 'flushes the empty caches' do
-      expect_any_instance_of(Gitlab::Shell).to receive(:fork_repository).
+    it 'flushes various caches' do
+      expect(shell).to receive(:fork_repository).
         with(project.path_with_namespace, fork_project.namespace.path).
         and_return(true)
 
       expect_any_instance_of(Repository).to receive(:expire_emptiness_caches).
         and_call_original
 
+      expect_any_instance_of(Repository).to receive(:expire_exists_cache).
+        and_call_original
+
       subject.perform(project.id, project.path_with_namespace,
                       fork_project.namespace.path)
     end
 
     it "handles bad fork" do
-      expect_any_instance_of(Gitlab::Shell).to receive(:fork_repository).and_return(false)
+      expect(shell).to receive(:fork_repository).and_return(false)
+
+      expect(subject.logger).to receive(:error)
+
       subject.perform(
         project.id,
         project.path_with_namespace,