instance method execute_if_updated

# File actionview/lib/action_view/cache_expiry.rb, line 41
      def execute_if_updated
        @mutex.synchronize do
          watched_dirs = dirs_to_watch
          return if watched_dirs.empty?

          if watched_dirs != @watched_dirs
            @watched_dirs = watched_dirs
            @watcher = @watcher_class.new([], watched_dirs, &@block)
            @watcher.execute
          else
            @watcher.execute_if_updated
          end
        end
      end