なぜ thinkphp はこれを行うのでしょうか?

public function run(&$params) {        if (C('UPGRADE_NOTICE_ON') && (!S('think_upgrade_interval') || C('UPGRADE_NOTICE_DEBUG'))) {            if(IS_SAE && C('UPGRADE_NOTICE_QUEUE') && !isset($_POST['think_upgrade_queque'])){                $queue=new SaeTaskQueue(C('UPGRADE_NOTICE_QUEUE'));                $queue->addTask('http://'.$_SERVER['HTTP_HOST'].__APP__,'think_upgrade_queque=1');                if(!$queue->push()){                    trace('升级提醒队列执行失败,错误原因：'.$queue->errmsg(), '升级通知出错', 'NOTIC', true);                }                return ;            }            $akey = C('UPGRADE_NOTICE_AKEY');            $skey = C('UPGRADE_NOTICE_SKEY');            $this->accesskey_ = $akey ? $akey : (defined('SAE_ACCESSKEY') ? SAE_ACCESSKEY : '');            $this->secretkey_ = $skey ? $skey : (defined('SAE_SECRETKEY') ? SAE_SECRETKEY : '');            $current_version = C('UPGRADE_CURRENT_VERSION');            //读取接口            $info = $this->send('http://sinaclouds.sinaapp.com/thinkapi/upgrade.php?v=' . $current_version);             if ($info['version'] != $current_version) {                    if($this->send_sms($info['msg']))  trace($info['msg'], '升级通知成功', 'NOTIC', true); //发送升级短信            }            S('think_upgrade_interval', true, C('UPGRADE_NOTICE_CHECK_INTERVAL'));        }    }