calculate the ivars to remove in advance as a set and cache them in a

constant.

`view_assigns` can use the precalculated sets and remove instance
variables without allocating any extra arrays

2 files changed, 12 insertions, 11 deletions

diff --git a/actionpack/lib/abstract_controller/rendering.rb b/actionpack/lib/abstract_controller/rendering.rb
index 9d2199a7b1..fb8f40cb9b 100644
--- a/actionpack/lib/abstract_controller/rendering.rb
+++ b/actionpack/lib/abstract_controller/rendering.rb
@@ -1,5 +1,6 @@
 require 'active_support/concern'
 require 'active_support/core_ext/class/attribute'
+require 'set'
 
 module AbstractController
   class DoubleRenderError < Error
@@ -13,11 +14,6 @@ module AbstractController
   module Rendering
     extend ActiveSupport::Concern
 
-    included do
-      class_attribute :protected_instance_variables
-      self.protected_instance_variables = []
-    end
-
     # Normalize arguments, options and then delegates render_to_body and
     # sticks the result in self.response_body.
     # :api: public
@@ -55,8 +51,6 @@ module AbstractController
       Mime::TEXT
     end
 
-    require 'set'
-
     DEFAULT_PROTECTED_INSTANCE_VARIABLES = Set.new %w(
       @_action_name @_response_body @_formats @_prefixes @_config
       @_view_context_class @_view_renderer @_lookup_context
@@ -113,7 +107,7 @@ module AbstractController
     end
 
     def _protected_ivars # :nodoc:
-      DEFAULT_PROTECTED_INSTANCE_VARIABLES + protected_instance_variables
+      DEFAULT_PROTECTED_INSTANCE_VARIABLES
     end
   end
 end
diff --git a/actionpack/lib/action_controller/base.rb b/actionpack/lib/action_controller/base.rb
index 3b0d094f4f..c84776ab7a 100644
--- a/actionpack/lib/action_controller/base.rb
+++ b/actionpack/lib/action_controller/base.rb
@@ -261,10 +261,17 @@ module ActionController
     end
 
     # Define some internal variables that should not be propagated to the view.
-    self.protected_instance_variables = [
+    PROTECTED_IVARS = AbstractController::Rendering::DEFAULT_PROTECTED_INSTANCE_VARIABLES + [
       :@_status, :@_headers, :@_params, :@_env, :@_response, :@_request,
-      :@_view_runtime, :@_stream, :@_url_options, :@_action_has_layout
-    ]
+      :@_view_runtime, :@_stream, :@_url_options, :@_action_has_layout ]
+
+    def _protected_ivars # :nodoc:
+      PROTECTED_IVARS
+    end
+
+    def self.protected_instance_variables
+      PROTECTED_IVARS
+    end
 
     ActiveSupport.run_load_hooks(:action_controller, self)
   end