Eager load controllers view_context_class

These classes are relatively small, however they include lots of
modules as helpers. And if any of the included module hold constants
including it cause the global constant cache to be invalidated
which is really bad for performance.

So when eager loading is enabled we create all the possible classes
as part of the application boot.

Author: byroot

actionmailer/lib/action_mailer.rb

@@ -58,6 +58,10 @@ def self.eager_load!
 
     require "mail"
     Mail.eager_autoload!
+
+    Base.descendants.each do |mailer|
+      mailer.eager_load! unless mailer.abstract?
+    end
   end
 end
 

actionmailer/lib/action_mailer/railtie.rb

@@ -74,12 +74,6 @@ class Railtie < Rails::Railtie # :nodoc:
       end
     end
 
-    initializer "action_mailer.eager_load_actions" do
-      ActiveSupport.on_load(:after_initialize) do
-        ActionMailer::Base.descendants.each(&:action_methods) if config.eager_load
-      end
-    end
-
     config.after_initialize do |app|
       options = app.config.action_mailer
 

actionpack/lib/abstract_controller.rb

@@ -24,5 +24,10 @@ module AbstractController
   def self.eager_load!
     super
     AbstractController::Caching.eager_load!
+    AbstractController::Base.descendants.each do |controller|
+      unless controller.abstract?
+        controller.eager_load!
+      end
+    end
   end
 end

actionpack/lib/abstract_controller/base.rb

@@ -127,6 +127,11 @@ def method_added(name)
         super
         clear_action_methods!
       end
+
+      def eager_load! # :nodoc:
+        action_methods
+        nil
+      end
     end
 
     abstract!

actionpack/lib/action_controller/railtie.rb

@@ -14,6 +14,7 @@ class Railtie < Rails::Railtie # :nodoc:
     config.action_controller.log_query_tags_around_actions = true
     config.action_controller.wrap_parameters_by_default = false
 
+    config.eager_load_namespaces << AbstractController
     config.eager_load_namespaces << ActionController
 
     initializer "action_controller.assets_config", group: :all do |app|
@@ -99,12 +100,6 @@ class Railtie < Rails::Railtie # :nodoc:
       end
     end
 
-    initializer "action_controller.eager_load_actions" do
-      ActiveSupport.on_load(:after_initialize) do
-        ActionController::Metal.descendants.each(&:action_methods) if config.eager_load
-      end
-    end
-
     initializer "action_controller.query_log_tags" do |app|
       query_logs_tags_enabled = app.config.respond_to?(:active_record) &&
         app.config.active_record.query_log_tags_enabled &&

actionview/lib/action_view/rendering.rb

@@ -72,6 +72,12 @@ def build_view_context_class(klass, supports_path, routes, helpers)
         end
       end
 
+      def eager_load!
+        super
+        view_context_class
+        nil
+      end
+
       def view_context_class
         klass = ActionView::LookupContext::DetailsKey.view_context_class(ActionView::Base)
 

railties/test/application/configuration_test.rb

@@ -291,7 +291,7 @@ def change
       assert_instance_of Pathname, Rails.public_path
     end
 
-    test "does not eager load controller actions in development" do
+    test "does not eager load controllers state actions in development" do
       app_file "app/controllers/posts_controller.rb", <<-RUBY
         class PostsController < ActionController::Base
           def index;end
@@ -302,9 +302,10 @@ def show;end
       app "development"
 
       assert_nil PostsController.instance_variable_get(:@action_methods)
+      assert_nil PostsController.instance_variable_get(:@view_context_class)
     end
 
-    test "eager loads controller actions in production" do
+    test "eager loads controllers state in production" do
       app_file "app/controllers/posts_controller.rb", <<-RUBY
         class PostsController < ActionController::Base
           def index;end
@@ -320,6 +321,7 @@ def show;end
       app "production"
 
       assert_equal %w(index show).to_set, PostsController.instance_variable_get(:@action_methods)
+      assert_not_nil PostsController.instance_variable_get(:@view_context_class)
     end
 
     test "does not eager load mailer actions in development" do