Function decorator to retry on a service unavailable exception.

def RetryOnUnavailable(func):
  """Function decorator to retry on a service unavailable exception."""

  @functools.wraps(func)
  def Wrapper(*args, **kwargs):
    while True:
      try:
        response = func(*args, **kwargs)
      except (httpclient.HTTPException, socket.error, urlerror.URLError) as e:
        time.sleep(5)
        if (isinstance(e, urlerror.HTTPError)
            and e.getcode() == httpclient.SERVICE_UNAVAILABLE):
          continue
        elif isinstance(e, socket.timeout):
          continue
        raise
      else:
        if response.getcode() == httpclient.OK:
          return response
        else:
          raise StatusException(response)
  return Wrapper