def _put(userhost, user):
"""Release a system account to user credential server.
:param userhost: (`server`, `port`) of the user credential server.
:type userhost: :class:`tuple`
:param user: The name of acquired user.
:type user: :class:`str`
:raises: Various :class:`Exception` if the user cannot be released.
"""
client = UserHostClient(userhost[0], userhost[1])
if not client.release(user):
raise RuntimeError('Could not release system account.')
def _acquire(userhost, expires):
"""Acquire a free account from user credential server.
:param userhost: (`server`, `port`) of the user credential server.
:type userhost: :class:`tuple`
:param expires: Seconds for this user to expire.
:type expires: :class:`int`
:return: The acquired user account name.
:raises: Various :class:`Exception` if the user cannot be acquired.
"""
client = UserHostClient(userhost[0], userhost[1])
ret = client.acquire(expires)
if ret is None:
raise RuntimeError('System account exhausted.')
return ret