Simplify the action endpoint:

* Remove ActionEndpoint in favor of passing a block to MiddlewareStack
  * Always create a Request; the performance win of RackDelegation is around
    the response; the Request object hit is limited to a single object allocation
  * #dispatch takes a Request

actionpack/lib/action_controller/metal.rb

@@ -34,7 +34,8 @@ module ActionController
     # and response object available. You might wish to control the
     # environment and response manually for performance reasons.
 
-    attr_internal :status, :headers, :content_type, :response
+    attr_internal :status, :headers, :content_type, :response, :request
+    delegate :session, :to => "@_request"
 
     def initialize(*)
       @_headers = {}
@@ -66,8 +67,9 @@ module ActionController
     end
 
     # :api: private
-    def dispatch(name, env)
-      @_env = env
+    def dispatch(name, request)
+      @_request = request
+      @_env = request.env
       @_env['action_controller.instance'] = self
       process(name)
       to_a
@@ -78,26 +80,6 @@ module ActionController
       response ? response.to_a : [status, headers, response_body]
     end
 
-    class ActionEndpoint
-      @@endpoints = Hash.new {|h,k| h[k] = Hash.new {|sh,sk| sh[sk] = {} } }
-
-      def self.for(controller, action, stack)
-        @@endpoints[controller][action][stack] ||= begin
-          endpoint = new(controller, action)
-          stack.build(endpoint)
-        end
-      end
-
-      def initialize(controller, action)
-        @controller, @action = controller, action
-        @_formats = [Mime::HTML]
-      end
-
-      def call(env)
-        @controller.new.dispatch(@action, env)
-      end
-    end
-
     class_attribute :middleware_stack
     self.middleware_stack = ActionDispatch::MiddlewareStack.new
 
@@ -127,8 +109,10 @@ module ActionController
     #
     # ==== Returns
     # Proc:: A rack application
-    def self.action(name)
-      ActionEndpoint.for(self, name, middleware_stack)
+    def self.action(name, klass = ActionDispatch::Request)
+      middleware_stack.build do |env|
+        new.dispatch(name, klass.new(env))
+      end
     end
   end
 end

actionpack/lib/action_controller/metal/rack_delegation.rb

@@ -6,14 +6,11 @@ module ActionController
     extend ActiveSupport::Concern
 
     included do
-      delegate :session, :to => "@_request"
       delegate :headers, :status=, :location=, :content_type=,
                :status, :location, :content_type, :to => "@_response"
-      attr_internal :request
     end
 
-    def dispatch(action, env)
-      @_request = ActionDispatch::Request.new(env)
+    def dispatch(action, request)
       @_response = ActionDispatch::Response.new
       @_response.request = request
       super

actionpack/lib/action_controller/middleware.rb

@@ -6,7 +6,8 @@ module ActionController
       end
 
       def call(env)
-        @controller.build(@app).dispatch(:index, env)
+        request = ActionDispatch::Request.new(env)
+        @controller.build(@app).dispatch(:index, request)
       end
     end
 

actionpack/lib/action_dispatch/middleware/stack.rb

@@ -122,7 +122,11 @@ module ActionDispatch
       find_all { |middleware| middleware.active? }
     end
 
-    def build(app)
+    def build(app = nil, &blk)
+      app ||= blk
+
+      raise "MiddlewareStack#build requires an app" unless app
+
       active.reverse.inject(app) { |a, e| e.build(a) }
     end
   end