Added & use Gitlab::Routing for URL helpers

Rails' "url_helpers" method creates an anonymous Module (which a bunch
of methods) on every call. By caching the output of this method in a
dedicated method we can shave off about 10 seconds of loading time for
an issue with around 200 comments.

app/models/milestone.rb

@@ -89,7 +89,7 @@ class Milestone < ActiveRecord::Base
   def to_reference(from_project = nil)
     escaped_title = self.title.gsub("]", "\\]")
-    h = Gitlab::Application.routes.url_helpers
+    h = Gitlab::Routing.url_helpers
     url = h.namespace_project_milestone_url(self.project.namespace, self.project, self)
     "[#{escaped_title}](#{url})"

app/models/project.rb

@@ -471,7 +471,7 @@ class Project < ActiveRecord::Base
   end
   def web_url
-    Gitlab::Application.routes.url_helpers.namespace_project_url(self.namespace, self)
+    Gitlab::Routing.url_helpers.namespace_project_url(self.namespace, self)
   end
   def web_url_without_protocol
@@ -592,7 +592,7 @@ class Project < ActiveRecord::Base
     if avatar.present?
       [gitlab_config.url, avatar.url].join
     elsif avatar_in_git
-      Gitlab::Application.routes.url_helpers.namespace_project_avatar_url(namespace, self)
+      Gitlab::Routing.url_helpers.namespace_project_avatar_url(namespace, self)
     end
   end

app/models/project_services/gitlab_issue_tracker_service.rb

@@ -20,7 +20,7 @@
 #
 class GitlabIssueTrackerService < IssueTrackerService
-  include Gitlab::Application.routes.url_helpers
+  include Gitlab::Routing.url_helpers
   prop_accessor :title, :description, :project_url, :issues_url, :new_issue_url

app/models/project_services/jira_service.rb

@@ -21,7 +21,7 @@
 class JiraService < IssueTrackerService
   include HTTParty
-  include Gitlab::Application.routes.url_helpers
+  include Gitlab::Routing.url_helpers
   DEFAULT_API_VERSION = 2

app/services/system_note_service.rb

@@ -224,7 +224,7 @@ class SystemNoteService
   #
   #   "Started branch `issue-branch-button-201`"
   def self.new_issue_branch(issue, project, author, branch)
-    h = Gitlab::Application.routes.url_helpers
+    h = Gitlab::Routing.url_helpers
     link = h.namespace_project_compare_url(project.namespace, project, from: project.default_branch, to: branch)
     body = "Started branch [`#{branch}`](#{link})"

lib/api/entities.rb

@@ -8,7 +8,7 @@ module API
       expose :id, :state, :avatar_url
       expose :web_url do |user, options|
-        Gitlab::Application.routes.url_helpers.user_url(user)
+        Gitlab::Routing.url_helpers.user_url(user)
       end
     end
@@ -89,7 +89,7 @@ module API
       expose :avatar_url
       expose :web_url do |group, options|
-        Gitlab::Application.routes.url_helpers.group_url(group)
+        Gitlab::Routing.url_helpers.group_url(group)
       end
     end

lib/banzai/filter/commit_range_reference_filter.rb

@@ -43,7 +43,7 @@ module Banzai
       end
       def url_for_object(range, project)
-        h = Gitlab::Application.routes.url_helpers
+        h = Gitlab::Routing.url_helpers
         h.namespace_project_compare_url(project.namespace, project,
                                         range.to_param.merge(only_path: context[:only_path]))
       end

lib/banzai/filter/commit_reference_filter.rb

@@ -37,7 +37,7 @@ module Banzai
       end
       def url_for_object(commit, project)
-        h = Gitlab::Application.routes.url_helpers
+        h = Gitlab::Routing.url_helpers
         h.namespace_project_commit_url(project.namespace, project, commit,
                                         only_path: context[:only_path])
       end

lib/banzai/filter/label_reference_filter.rb

@@ -31,7 +31,7 @@ module Banzai
       end
       def url_for_object(label, project)
-        h = Gitlab::Application.routes.url_helpers
+        h = Gitlab::Routing.url_helpers
         h.namespace_project_issues_url(project.namespace, project, label_name: label.name,
                                                                    only_path:  context[:only_path])
       end

lib/banzai/filter/merge_request_reference_filter.rb

@@ -14,7 +14,7 @@ module Banzai
       end
       def url_for_object(mr, project)
-        h = Gitlab::Application.routes.url_helpers
+        h = Gitlab::Routing.url_helpers
         h.namespace_project_merge_request_url(project.namespace, project, mr,
                                             only_path: context[:only_path])
       end

lib/banzai/filter/milestone_reference_filter.rb

@@ -11,7 +11,7 @@ module Banzai
       end
       def url_for_object(issue, project)
-        h = Gitlab::Application.routes.url_helpers
+        h = Gitlab::Routing.url_helpers
         h.namespace_project_milestone_url(project.namespace, project, milestone,
                                         only_path: context[:only_path])
       end

lib/banzai/filter/snippet_reference_filter.rb

@@ -14,7 +14,7 @@ module Banzai
       end
       def url_for_object(snippet, project)
-        h = Gitlab::Application.routes.url_helpers
+        h = Gitlab::Routing.url_helpers
         h.namespace_project_snippet_url(project.namespace, project, snippet,
                                         only_path: context[:only_path])
       end

lib/banzai/filter/user_reference_filter.rb

@@ -90,7 +90,7 @@ module Banzai
       private
       def urls
-        Gitlab::Application.routes.url_helpers
+        Gitlab::Routing.url_helpers
       end
       def link_class

lib/gitlab/email/message/repository_push.rb

@@ -5,7 +5,7 @@ module Gitlab
         attr_accessor :recipient
         attr_reader :author_id, :ref, :action
-        include Gitlab::Application.routes.url_helpers
+        include Gitlab::Routing.url_helpers
         delegate :namespace, :name_with_namespace, to: :project, prefix: :project
         delegate :name, to: :author, prefix: :author

lib/gitlab/routing.rb

+module Gitlab
+  module Routing
+    # Returns the URL helpers Module.
+    #
+    # This method caches the output as Rails' "url_helpers" method creates an
+    # anonymous module every time it's called.
+    #
+    # Returns a Module.
+    def self.url_helpers
+      @url_helpers ||= Gitlab::Application.routes.url_helpers
+    end
+  end
+end

lib/gitlab/url_builder.rb

 module Gitlab
   class UrlBuilder
-    include Gitlab::Application.routes.url_helpers
+    include Gitlab::Routing.url_helpers
     include GitlabRoutingHelper
     def initialize(type)

spec/lib/extracts_path_spec.rb

@@ -3,7 +3,7 @@ require 'spec_helper'
 describe ExtractsPath, lib: true do
   include ExtractsPath
   include RepoHelpers
-  include Gitlab::Application.routes.url_helpers
+  include Gitlab::Routing.url_helpers
   let(:project) { double('project') }

spec/lib/gitlab/closing_issue_extractor_spec.rb

@@ -236,6 +236,6 @@ describe Gitlab::ClosingIssueExtractor, lib: true do
   end
   def urls
-    Gitlab::Application.routes.url_helpers
+    Gitlab::Routing.url_helpers
   end
 end

spec/support/filter_spec_helper.rb

@@ -78,6 +78,6 @@ module FilterSpecHelper
   # Shortcut to Rails' auto-generated routes helpers, to avoid including the
   # module
   def urls
-    Gitlab::Application.routes.url_helpers
+    Gitlab::Routing.url_helpers
   end
 end

spec/support/markdown_feature.rb

@@ -106,7 +106,7 @@ class MarkdownFeature
   end
   def urls
-    Gitlab::Application.routes.url_helpers
+    Gitlab::Routing.url_helpers
   end
   def raw_markdown