Redis防止重複請求鎖功能

class Lock
{
    const PREFIX_KEY = "MY_LOCK:";
    static private $LOCKED = [];

    static public function tryLock($key, $expire = 300)
    {
        $lock = self::PREFIX_KEY.$key;

        //已取得到lock(防止同行程重覆要求造成deadlock)
        if(self::$LOCKED[$lock]) {
            ++self::$LOCKED[$lock];
            return true;
        }

        //處理lock
        $redis = &AppBase::getRedis();
        if(!$redis->setnx($lock, '')) {
            return false;
        }
        $redis->expire($lock, $expire); //防止crash沒解鎖

        //成功lock
        ++self::$LOCKED[$lock];
        return true;
    }

    static public function unlock($key)
    {
        $lock = self::PREFIX_KEY.$key;

        if(--self::$LOCKED[$lock] <= 0) {
            AppBase::getRedis()->delete($lock);
            unset(self::$LOCKED[$lock]);
        }
    }

    static public function blockLock($key, $max_try = 60, $sleep = 1, $expire = 300)
    {
        $t = 0;
        while(++$t <= $max_try) {
            if(self::tryLock($key, $expire)) {
                return true;
            }
            usleep(intval($sleep * 1000000));
        }
        return false;
    }

}