protected function doExit()
    {
        if (FLOW_SAPITYPE === 'Web') {
            header('HTTP/1.1 503 Service Temporarily Unavailable');
            readfile($this->lockHoldingPage);
        } else {
            $expiresIn = abs((time() - self::LOCKFILE_MAXIMUM_AGE - filemtime($this->lockFlagPathAndFilename)));
            echo 'Site is currently locked, exiting.' . PHP_EOL . 'The current lock will expire after ' . $expiresIn . ' seconds.' . PHP_EOL;
        }
        exit(1);
    }