Merge branch 'external-wiki-helper-speedup' into 'master'

speed up ExternalWikiService#get_project_wiki_path

## What does this MR do?

Speed up ExternalWikiHelper#get_project_wiki_path

## Are there points in the code the reviewer needs to double check?

## Why was this MR needed?

See issue #19886 

## What are the relevant issue numbers?

#19886 

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5305

7 files changed, 77 insertions, 4 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 3d72836835a..1abc4afdddd 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -5,6 +5,7 @@ v 8.11.0 (unreleased)
 
 v 8.10.0 (unreleased)
   - Fix profile activity heatmap to show correct day name (eanplatter)
+  - Speed up ExternalWikiHelper#get_project_wiki_path
   - Expose {should,force}_remove_source_branch (Ben Boeckel)
   - Add the functionality to be able to rename a file. !5049 (tiagonbotelho)
   - Disable PostgreSQL statement timeout during migrations
diff --git a/app/helpers/external_wiki_helper.rb b/app/helpers/external_wiki_helper.rb
index 1f3401f2906..defd87d6bbe 100644
--- a/app/helpers/external_wiki_helper.rb
+++ b/app/helpers/external_wiki_helper.rb
@@ -1,8 +1,7 @@
 module ExternalWikiHelper
   def get_project_wiki_path(project)
-    external_wiki_service = project.services.
-      find { |service| service.to_param == 'external_wiki' }
-    if external_wiki_service.present? && external_wiki_service.active?
+    external_wiki_service = project.external_wiki
+    if external_wiki_service
       external_wiki_service.properties['external_wiki_url']
     else
       namespace_project_wiki_path(project.namespace, project, :home)
diff --git a/app/models/project.rb b/app/models/project.rb
index a805f5d97bc..d08b737e813 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -650,6 +650,22 @@ class Project < ActiveRecord::Base
     update_column(:has_external_issue_tracker, services.external_issue_trackers.any?)
   end
 
+  def external_wiki
+    if has_external_wiki.nil?
+      cache_has_external_wiki # Populate
+    end
+
+    if has_external_wiki
+      @external_wiki ||= services.external_wikis.first
+    else
+      nil
+    end
+  end
+
+  def cache_has_external_wiki
+    update_column(:has_external_wiki, services.external_wikis.any?)
+  end
+
   def build_missing_services
     services_templates = Service.where(template: true)
 
diff --git a/app/models/service.rb b/app/models/service.rb
index 5432f8c7ab4..4821096379c 100644
--- a/app/models/service.rb
+++ b/app/models/service.rb
@@ -17,6 +17,7 @@ class Service < ActiveRecord::Base
 
   after_commit :reset_updated_properties
   after_commit :cache_project_has_external_issue_tracker
+  after_commit :cache_project_has_external_wiki
 
   belongs_to :project, inverse_of: :services
   has_one :service_hook
@@ -25,6 +26,7 @@ class Service < ActiveRecord::Base
 
   scope :visible, -> { where.not(type: ['GitlabIssueTrackerService', 'GitlabCiService']) }
   scope :issue_trackers, -> { where(category: 'issue_tracker') }
+  scope :external_wikis, -> { where(type: 'ExternalWikiService') }
   scope :active, -> { where(active: true) }
   scope :without_defaults, -> { where(default: false) }
 
@@ -212,4 +214,10 @@ class Service < ActiveRecord::Base
       project.cache_has_external_issue_tracker
     end
   end
+
+  def cache_project_has_external_wiki
+    if project && !project.destroyed?
+      project.cache_has_external_wiki
+    end
+  end
 end
diff --git a/db/migrate/20160718153603_add_has_external_wiki_to_projects.rb b/db/migrate/20160718153603_add_has_external_wiki_to_projects.rb
new file mode 100644
index 00000000000..55a3e954292
--- /dev/null
+++ b/db/migrate/20160718153603_add_has_external_wiki_to_projects.rb
@@ -0,0 +1,7 @@
+class AddHasExternalWikiToProjects < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  def change
+    add_column :projects, :has_external_wiki, :boolean
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 8882377f9f4..ebf31ded369 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20160716115710) do
+ActiveRecord::Schema.define(version: 20160718153603) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -842,6 +842,7 @@ ActiveRecord::Schema.define(version: 20160716115710) do
     t.boolean  "only_allow_merge_if_build_succeeds", default: false,     null: false
     t.boolean  "has_external_issue_tracker"
     t.string   "repository_storage",                 default: "default", null: false
+    t.boolean  "has_external_wiki"
   end
 
   add_index "projects", ["builds_enabled", "shared_runners_enabled"], name: "index_projects_on_builds_enabled_and_shared_runners_enabled", using: :btree
diff --git a/spec/models/project_spec.rb b/spec/models/project_spec.rb
index 9dc34276f18..e3e7319beb2 100644
--- a/spec/models/project_spec.rb
+++ b/spec/models/project_spec.rb
@@ -458,6 +458,47 @@ describe Project, models: true do
     end
   end
 
+  describe "#cache_has_external_wiki" do
+    let(:project) { create(:project) }
+
+    it "stores true if there is an external wiki" do
+      services = double(:service, external_wikis: [ExternalWikiService.new])
+      expect(project).to receive(:services).and_return(services)
+
+      expect do
+        project.cache_has_external_wiki
+      end.to change { project.has_external_wiki }.to(true)
+    end
+
+    it "stores false if there is no external wiki" do
+      services = double(:service, external_wikis: [])
+      expect(project).to receive(:services).and_return(services)
+
+      expect do
+        project.cache_has_external_wiki
+      end.to change { project.has_external_wiki }.to(false)
+    end
+
+    it "changes to true if an external wiki service is created later" do
+      expect do
+        project.cache_has_external_wiki
+      end.to change { project.has_external_wiki }.to(false)
+
+      expect do
+        create(:service, type: "ExternalWikiService", project: project)
+      end.to change { project.has_external_wiki }.to(true)
+    end
+
+    it "changes to false if an external wiki service is destroyed later" do
+      service = create(:service, type: "ExternalWikiService", project: project)
+      expect(project.has_external_wiki).to be_truthy
+
+      expect do
+        service.destroy
+      end.to change { project.has_external_wiki }.to(false)
+    end
+  end
+
   describe '#open_branches' do
     let(:project) { create(:project) }