ruby script/plugin install http://happygiraffe.net/svn/public/timed_file_store/trunk/

To activate, place something like this at the bottom of config/environment.rb.

  ActionController::Base.fragment_cache_store = TimedFileStore.new("#{RAILS_ROOT}/tmp/cache", :atime => 15.minutes)

NB: This has to come at the bottom, outside of the Rails::Initializer.run block. This is because the plugin isn't loaded until fairly late in the configuration process.

You can specify either :atime to judge based upon the last time that fragment was read, or :mtime to judge based on the time the fragment was last written to.

There is currently no advanced documentation for this plugin.