Performance: patch cgi/session to require digest/md5 once rather than per #create_new_id.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6143 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/CHANGELOG

 *SVN*
 
+* Performance: patch cgi/session to require digest/md5 once rather than per #create_new_id.  [Stefan Kaes]
+
 * Add a :url_based_filename => true option to ActionController::Streaming::send_file, which allows URL-based filenames.  [Thomas Fuchs]
 
 * Fix that FormTagHelper#submit_tag using :disable_with should trigger the onsubmit handler of its form if available [DHH]

actionpack/lib/action_controller/cgi_ext/session_performance_fix.rb

+# CGI::Session#create_new_id requires 'digest/md5' on every call.  This makes
+# sense when spawning processes per request, but is unnecessarily expensive
+# when serving requests from a long-lived process.
+#
+# http://railsexpress.de/blog/articles/2005/11/22/speeding-up-the-creation-of-new-sessions
+require 'cgi/session'
+require 'digest/md5'
+
+class CGI
+  class Session #:nodoc:
+    private
+      # Create a new session id.
+      #
+      # The session id is an MD5 hash based upon the time,
+      # a random number, and a constant string.  This routine
+      # is used internally for automatically generated
+      # session ids.
+      def create_new_id
+        md5 = Digest::MD5::new
+        now = Time::now
+        md5.update(now.to_s)
+        md5.update(String(now.usec))
+        md5.update(String(rand(0)))
+        md5.update(String($$))
+        md5.update('foobar')
+        @new_session = true
+        md5.hexdigest
+      end
+  end
+end

actionpack/lib/action_controller/cgi_process.rb

 require 'action_controller/cgi_ext/cgi_ext'
 require 'action_controller/cgi_ext/cookie_performance_fix'
 require 'action_controller/cgi_ext/raw_post_data_fix'
+require 'action_controller/cgi_ext/session_performance_fix'
 
 module ActionController #:nodoc:
   class Base