def _save(self, expiration_time):
q = None
try:
q = SqlQuery(self._db, 'sessions', SESSION_TABLE, trans=True)
q.delete({'id': self.id})
data = pickle.dumps((self._data, expiration_time), self._proto)
q.insert((self.id, base64.b64encode(data), expiration_time))
q.commit()
except Exception: # pylint: disable=broad-except
if q:
q.rollback()
raise
