Make dispatcher instances immutable

actionpack/lib/action_controller/dispatch/dispatcher.rb

@@ -66,16 +66,21 @@ def cleanup_application
     define_callbacks :prepare_dispatch, :before_dispatch, :after_dispatch
 
     def initialize
-      @app = @@middleware.build(lambda { |env| self.dup._call(env) })
+      @app = @@middleware.build(lambda { |env| self._call(env) })
+      freeze
     end
 
-    def dispatch
+    def call(env)
+      @app.call(env)
+    end
+
+    def _call(env)
       begin
         run_callbacks :before_dispatch
-        Routing::Routes.call(@env)
+        Routing::Routes.call(env)
       rescue Exception => exception
         if controller ||= (::ApplicationController rescue Base)
-          controller.call_with_exception(@env, exception).to_a
+          controller.call_with_exception(env, exception).to_a
         else
           raise exception
         end
@@ -84,15 +89,6 @@ def dispatch
       end
     end
 
-    def call(env)
-      @app.call(env)
-    end
-
-    def _call(env)
-      @env = env
-      dispatch
-    end
-
     def flush_logger
       Base.logger.flush
     end

actionpack/test/controller/dispatcher_test.rb

@@ -46,7 +46,7 @@ def log_failsafe_exception(status, exception); end
   end
 
   def test_failsafe_response
-    Dispatcher.any_instance.expects(:dispatch).raises('b00m')
+    Dispatcher.any_instance.expects(:_call).raises('b00m')
     ActionDispatch::Failsafe.any_instance.expects(:log_failsafe_exception)
 
     assert_nothing_raised do