class ActiveSupport::Cache::FileStore

def normalize_key(key, options)
  key = super
  fname = URI.encode_www_form_component(key)
  if fname.size > FILEPATH_MAX_SIZE
    fname = Digest::MD5.hexdigest(key)
  end
  hash = Zlib.adler32(fname)
  hash, dir_1 = hash.divmod(0x1000)
  dir_2 = hash.modulo(0x1000)
  fname_paths = []
  # Make sure file name doesn't exceed file system limits.
  begin
    fname_paths << fname[0, FILENAME_MAX_SIZE]
    fname = fname[FILENAME_MAX_SIZE..-1]
  end until fname.blank?
  File.join(cache_path, DIR_FORMATTER % dir_1, DIR_FORMATTER % dir_2, *fname_paths)
end