def get_next_id(self):
        try:
            query = {'_id': 'last_id'}
            update = {'$inc': {'id': 1}}
            fn = self.db.internal.find_and_modify
            row = fn(query, update, upsert=True, new=True)
        except Exception as e:
            raise DatabaseException(e)
        return row['id']
def query_vpp_config(self):
        ds = list(self._test.vapi.vpp.details_iter(
            self._test.vapi.ip_path_mtu_get))

        for d in ds:
            if self.nh == str(d.pmtu.nh) \
               and self.table_id == d.pmtu.table_id \
               and self.pmtu == d.pmtu.path_mtu:
                return True
        return False