(PHP 5 >= 5.2.0, PHP 7, PECL swoole >= 1.9.0)
swoole_async_dns_lookup — Async and non-blocking hostname to IP lookup
$hostname
$callback
hostname
The host name.
callback
$ip
IP
The IP address.
成功时返回 TRUE， 或者在失败时返回 FALSE。
TRUE
FALSE