non blocking i/o php socket

gistfile1.txt

$urls = ['www.amazon.com',...];

foreach ($url as $ip => $url) {
   // create a stream that returns immediately
   // STREAM_CLIENT_CONNECT _MUST_ be passed
   // STREAM_CLIENT_ASYNC_CONNECT says create connection
   // asyncrhronously

   $socket = stream_socket_client("tcp://$ip:80", $errno, $errstr, 0, 
    STREAM_CLIENT_CONNECT, STREAM_CLIENT_ASYNC_CONNECT);

   // set stream as non blockcing with 0, deafult is 1
   stream_set_blocking($socket, 0);

   $sockets[(int) $socket] = $socket;
   $requests[(int) $socket] = $socket;
}

while (!empty($sockets)) {
 // run the loop
}