public function lockSiteOrExit()
    {
        touch($this->lockFlagPathAndFilename);
        $this->lockResource = fopen($this->lockPathAndFilename, 'w+');
        if (!flock($this->lockResource, LOCK_EX | LOCK_NB)) {
            fclose($this->lockResource);
            $this->doExit();
        }
    }