file_path_key

# File activesupport/lib/active_support/cache/file_store.rb, line 157
        def file_path_key(path)
          fname = path[cache_path.size, path.size].split(File::SEPARATOR, 4).last
          fname.gsub(UNESCAPE_FILENAME_CHARS){|match| $1.ord.to_s(16)}
        end