More perf work:

  * Move #set_cookie and #delete_cookie inline to optimize. These optimizations should
    almost certainly be sent back upstream to Rack. The optimization involves using
    an ivar for cookies instead of indexing into the headers each time.
  * Was able to use a bare Hash for headers now that cookies have their own joining
    semantics (some code assumed that the raw cookies were an Array).
  * Cache blankness of body on body=
  * Improve expand_cache_key for Arrays of a single element (common in our case)
  * Use a simple layout condition check unless conditions are used
  * Cache visible actions
  * Lazily load the UrlRewriter
  * Make etag an ivar that is set on prepare!

actionpack/lib/abstract_controller/layouts.rb

@@ -6,17 +6,21 @@ module Layouts
 
     included do
       extlib_inheritable_accessor(:_layout_conditions) { Hash.new }
+      extlib_inheritable_accessor(:_action_has_layout) { Hash.new }
       _write_layout_method
     end
 
     module ClassMethods
       def inherited(klass)
         super
-        klass._write_layout_method
+        klass.class_eval do
+          _write_layout_method
+          @found_layouts = {}
+        end
       end
 
       def cache_layout(details)
-        layout = @found_layouts ||= {}
+        layout = @found_layouts
         values = details.values_at(:formats, :locale)
 
         # Cache nil
@@ -27,6 +31,28 @@ def cache_layout(details)
         end
       end
 
+      # This module is mixed in if layout conditions are provided. This means
+      # that if no layout conditions are used, this method is not used
+      module LayoutConditions
+        # Determines whether the current action has a layout by checking the
+        # action name against the :only and :except conditions set on the
+        # layout.
+        #
+        # ==== Returns
+        # Boolean:: True if the action has a layout, false otherwise.
+        def _action_has_layout?
+          conditions = _layout_conditions
+
+          if only = conditions[:only]
+            only.include?(action_name)
+          elsif except = conditions[:except]
+            !except.include?(action_name)
+          else
+            true
+          end
+        end
+      end
+
       # Specify the layout to use for this class.
       #
       # If the specified layout is a:
@@ -43,6 +69,8 @@ def cache_layout(details)
       # :only<#to_s, Array[#to_s]>:: A list of actions to apply this layout to.
       # :except<#to_s, Array[#to_s]>:: Apply this layout to all actions but this one
       def layout(layout, conditions = {})
+        include LayoutConditions unless conditions.empty?
+
         conditions.each {|k, v| conditions[k] = Array(v).map {|a| a.to_s} }
         self._layout_conditions = conditions
 
@@ -150,7 +178,7 @@ def _find_layout(name, details)
       view_paths.find(name, details, prefix)
     end
 
-    # Returns the default layout for this controller and a given set of details. 
+    # Returns the default layout for this controller and a given set of details.
     # Optionally raises an exception if the layout could not be found.
     #
     # ==== Parameters
@@ -176,21 +204,8 @@ def _default_layout(details, require_layout = false)
       end
     end
 
-    # Determines whether the current action has a layout by checking the
-    # action name against the :only and :except conditions set on the
-    # layout.
-    #
-    # ==== Returns
-    # Boolean:: True if the action has a layout, false otherwise.
     def _action_has_layout?
-      conditions = _layout_conditions
-      if only = conditions[:only]
-        only.include?(action_name)
-      elsif except = conditions[:except]
-        !except.include?(action_name)
-      else
-        true
-      end
+      true
     end
   end
 end

actionpack/lib/action_controller/metal/compatibility.rb

@@ -102,11 +102,10 @@ def render_to_body(options)
         options[:template].sub!(/^\//, '')
       end
 
-      options[:text] = nil if options[:nothing] == true
+      options[:text] = nil if options.delete(:nothing) == true
+      options[:text] = " " if options.key?(:text) && options[:text].nil?
 
-      body = super
-      body = [' '] if body.blank?
-      body
+      super || " "
     end
 
     def _handle_method_missing

actionpack/lib/action_controller/metal/hide_actions.rb

@@ -13,7 +13,9 @@ module HideActions
     # Overrides AbstractController::Base#action_method? to return false if the
     # action name is in the list of hidden actions.
     def action_method?(action_name)
-      !hidden_actions.include?(action_name) && super
+      self.class.visible_action?(action_name) do
+        !hidden_actions.include?(action_name) && super
+      end
     end
 
     module ClassMethods
@@ -25,6 +27,16 @@ def hide_action(*args)
         hidden_actions.merge(args.map! {|a| a.to_s })
       end
 
+      def inherited(klass)
+        klass.instance_variable_set("@visible_actions", {})
+        super
+      end
+
+      def visible_action?(action_name)
+        return @visible_actions[action_name] if @visible_actions.key?(action_name)
+        @visible_actions[action_name] = yield
+      end
+
       # Overrides AbstractController::Base#action_methods to remove any methods
       # that are listed as hidden methods.
       def action_methods

actionpack/lib/action_controller/metal/url_for.rb

@@ -4,15 +4,6 @@ module UrlFor
 
     include RackConvenience
 
-    def process_action(*)
-      initialize_current_url
-      super
-    end
-
-    def initialize_current_url
-      @url = UrlRewriter.new(request, params.clone)
-    end
-
     # Overwrite to implement a number of default options that all url_for-based methods will use. The default options should come in
     # the form of a hash, just like the one you would use for url_for directly. Example:
     #
@@ -40,6 +31,7 @@ def url_for(options = {})
         when String
           options
         when Hash
+          @url ||= UrlRewriter.new(request, params)
           @url.rewrite(rewrite_options(options))
         else
           polymorphic_url(options)

actionpack/lib/action_controller/testing/process.rb

@@ -52,7 +52,7 @@ def recycle!
   class TestResponse < ActionDispatch::TestResponse
     def recycle!
       @status = 200
-      @header = ActionDispatch::Response::SimpleHeaderHash.new
+      @header = {}
       @writer = lambda { |x| @body << x }
       @block = nil
       @length = 0

actionpack/lib/action_controller/testing/test_case.rb

@@ -179,7 +179,6 @@ def setup_controller_request_and_response
       if @controller
         @controller.request = @request
         @controller.params = {}
-        @controller.send(:initialize_current_url)
       end
     end
 

actionpack/lib/action_dispatch/http/request.rb

@@ -173,21 +173,16 @@ def format(view_path = [])
         end
     end
 
-    # Expand raw_formats by converting Mime::ALL to the Mime::SET.
-    #
     def formats
-      return raw_formats
-      # if ActionController::Base.use_accept_header
-      #   raw_formats.tap do |ret|
-      #     if ret == ONLY_ALL
-      #       ret.replace Mime::SET
-      #     elsif all = ret.index(Mime::ALL)
-      #       ret.delete_at(all) && ret.insert(all, *Mime::SET)
-      #     end
-      #   end
-      # else
-      #   raw_formats + Mime::SET
-      # end
+      if ActionController::Base.use_accept_header
+        if param = parameters[:format]
+          Array.wrap(Mime[param])
+        else
+          accepts.dup
+        end
+      else
+        [format]
+      end
     end
 
     # Sets the \format by string extension, which can be used to force custom formats
@@ -488,7 +483,7 @@ def flash
     # matches the order array.
     #
     def negotiate_mime(order)
-      raw_formats.each do |priority|
+      formats.each do |priority|
         if priority == Mime::ALL
           return order.first
         elsif order.include?(priority)
@@ -501,18 +496,6 @@ def negotiate_mime(order)
 
     private
 
-      def raw_formats
-        if ActionController::Base.use_accept_header
-          if param = parameters[:format]
-            Array.wrap(Mime[param])
-          else
-            accepts.dup
-          end
-        else
-          [format]
-        end
-      end
-
       def named_host?(host)
         !(host.nil? || /\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/.match(host))
       end