Got overhead down from 127 to 85. All tests pass:

  * Tentatively replaced HeaderHash with SimpleHeaderHash, which does not preserve
    case but does handle converting Arrays to Strings in to_hash. This requires
    further discussion.
  * Moved default_charset to ActionDispatch::Response to avoid having to hop over
    to ActionController. Ideally, this would be a constant on AD::Response, but
    some tests expect to be able to change it dynamically and I didn't want to change
    them yet.
  * Completely override #initialize from Rack::Response. Previously, it was creating
    a HeaderHash, and then we were creating an entirely new one. There is no way to
    call super without incurring the overhead of creating a HeaderHash.
  * Override #write from Rack::Response. Its implementation tracks Content-Length,
    and doing so adds additional overhead that could be mooted if other middleware
    changes the body. It is more efficiently done at the top-level server.
  * Change sending_file to an instance_variable instead of header inspection. In
    general, if a state is important, it should be set as a property of the response
    not reconstructed later.
  * Set the Etag to @body instead of .body. AS::Cache.expand_cache_key handles
    Arrays fine, and it's more efficient to let it handle the body parts, since
    it is not forced to create a joined String.
  * If we detect the default cache control case, just set it, rather than setting
    the constituent parts and then running the normal (expensive) code to generate
    the string.

1 files changed, 3 insertions, 2 deletions

diff --git a/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb b/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb
index 74ce85a1c2..1602a609eb 100644
--- a/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb
+++ b/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb
@@ -46,11 +46,12 @@ class Class
         end                                            # end
         " unless options[:instance_writer] == false }  # # instance writer above is generated unless options[:instance_writer] == false
       EOS
+      self.send("#{sym}=", yield) if block_given?
     end
   end
 
-  def cattr_accessor(*syms)
+  def cattr_accessor(*syms, &blk)
     cattr_reader(*syms)
-    cattr_writer(*syms)
+    cattr_writer(*syms, &blk)
   end
 end