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 reset_snapshot_status(self, snapshot_id, status):
        """Reset the specified snapshot's status."""
        post_body = json.dumps({'os-reset_status': {"status": status}})
        resp, body = self.post('snapshots/%s/action' % snapshot_id, post_body)
        return resp, body