ETag Support from Edge-Rails

Added ETag support from

   http://dev.rubyonrails.org/changeset/6158

vendor/rails/actionpack/lib/action_controller/base.rb

@@ -7,6 +7,7 @@ require 'action_controller/url_rewriter'
 require 'action_controller/status_codes'
 require 'drb'
 require 'set'
+require 'md5' 
 
 module ActionController #:nodoc:
   class ActionControllerError < StandardError #:nodoc:
@@ -599,6 +600,12 @@ module ActionController #:nodoc:
       # _Deprecation_ _notice_: This used to have the signatures
       # <tt>render_partial(partial_path = default_template_name, object = nil, local_assigns = {})</tt> and
       # <tt>render_partial_collection(partial_name, collection, partial_spacer_template = nil, local_assigns = {})</tt>.
+      # == Automatic etagging 
+      # 
+      # Rendering will automatically insert the etag header on 200 OK responses. The etag is calculated using MD5 of the 
+      # response body. If a request comes in that has a matching etag, the response will be changed to a 304 Not Modified 
+      # and the response body will be set to an empty string. 
+      # 
       #
       # === Rendering a template
       #
@@ -822,6 +829,16 @@ module ActionController #:nodoc:
         else
           response.body = text
         end
+        if response.headers['Status'] == "200 OK" && response.body.size > 0 
+          response.headers['Etag'] = "\"#{MD5.new(text).to_s}\"" 
+           
+          if request.headers['HTTP_IF_NONE_MATCH'] == response.headers['Etag'] 
+            response.headers['Status'] = "304 Not Modified" 
+            response.body = '' 
+          end 
+        end 
+         
+        response.body 
       end
 
       def render_javascript(javascript, status = nil, append_response = true) #:nodoc: