src/Debug.php
static public function getPersist(): float
    {
        self::$persist = self::timeLog(self::$begin);
        return self::$persist;
    }
static public function getPersist(): float
    {
        self::$persist = self::timeLog(self::$begin);
        return self::$persist;
    }
获取本次Web访问的持续时间
@return float ms