app_engine.py 文件源码

def set_token(unique_key, token_str):
  """Saves the serialized auth token in the datastore.

  The token is also stored in memcache to speed up retrieval on a cache hit.

  Args:
    unique_key: The unique name for this token as a string. It is up to your
        code to ensure that this token value is unique in your application.
        Previous values will be silently overwitten.
    token_str: A serialized auth token as a string. I expect that this string
        will be generated by gdata.gauth.token_to_blob.

  Returns:
    True if the token was stored sucessfully, False if the token could not be
    safely cached (if an old value could not be cleared). If the token was
    set in memcache, but not in the datastore, this function will return None.
    However, in that situation an exception will likely be raised.

  Raises:
    Datastore exceptions may be raised from the App Engine SDK in the event of
    failure.
  """
  # First try to save in memcache.
  result = memcache.set(unique_key, token_str)
  # If memcache fails to save the value, clear the cached value.
  if not result:
    result = memcache.delete(unique_key)
    # If we could not clear the cached value for this token, refuse to save.
    if result == 0:
      return False
  # Save to the datastore.
  if Token(key_name=unique_key, t=token_str).put():
    return True
  return None