before

# File actionpack/lib/action_controller/caching/actions.rb, line 79
        def before(controller)
          cache_path = ActionCachePath.new(controller, path_options_for(controller, @options))
          if cache = controller.read_fragment(cache_path.path)
            controller.rendered_action_cache = true
            set_content_type!(controller, cache_path.extension)
            controller.send!(:render_for_text, cache)
            false
          else
            controller.action_cache_path = cache_path
          end
        end