php redis 限ip或api访问

同事去某公司面试，有道题关于同一ip一小时限5次，redis实现

$ip="127.0.0.1";
$api = "/get_user_info.php";
$allow_num = 5;
$allow_time = 3600;


function check_allow($allow_num,$allow_time,$ip,$api="")
{
    $redis = new Redis();
    $redis->connect('127.0.0.1', 6379);
    $api_key = md5($api.$ip);
    $redis->lpush($api_key,time());
    if($redis->llen($api_key)>$allow_num)
    {
        $old_time = $redis->rpop($api_key);
        if(time()-$old_time>$allow_time)
        {
            return true;
        }
        return false;
    }

    return true;
}


var_dump(check_allow($allow_num,$allow_time,$ip,$api));