PHP에서 차단을 구현하는 방법

public function index(){
    $fp = fopen("lock.txt", "w+");
    if(flock($fp,LOCK_EX))
    {
        $find=Db::name('user')->where('username','name2')->find();
        if($find){
            $data['username']='name3';
            $data['password']='';
            $data['password_m']='';
            Db::name('user')->insert($data);
        }else{
            $data['username']='name2';
            $data['password']='';
            $data['password_m']='';
            Db::name('user')->insert($data);
        }
        flock($fp,LOCK_UN);
    }
    fclose($fp);
    return 'success';
}