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 get_metrics(self):
        """Returns the stored metrics.

        The metrics are type checked against the set schema.

        Returns:
          Dictionary of metrics data in the format of the set schema.
        """
        artifact_utils.verify_schema_instance(self._schema, self._values)
        return self._values