def update_retention(self):
        """Call hook point 'save_retention'.
        Retention modules will write back retention (to file, db etc)

        :param forced: is update forced?
        :type forced: bool
        :return: None
        """
        # If we set the retention update to 0, we do not want to manage retention
        # If we are not forced (like at stopping)
        if self.pushed_conf.retention_update_interval == 0:
            logger.debug("Should have saved retention but it is not enabled")
            return

        _t0 = time.time()
        self.hook_point('save_retention')
        statsmgr.timer('hook.retention-save', time.time() - _t0)

        self.add(make_monitoring_log('INFO', 'RETENTION SAVE: %s' % self.my_daemon.name))
        logger.info('Retention data saved: %.2f seconds', time.time() - _t0)
Call hook point 'save_retention'.
        Retention modules will write back retention (to file, db etc)

        :param forced: is update forced?
        :type forced: bool
        :return: None