Non-blocking socket connection

nonblock_socket_connect.php

<?php
function nonblock_socket_connect($ip, $port)
{
    $socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);

    if (!socket_set_nonblock($socket)) {
        socket_error($socket);
    }

    $connected = @socket_connect($socket, $ip, $port);
    if (!$connected) {
        // http://php.net/manual/en/function.socket-connect.php#refsect1-function.socket-connect-returnvalues
        // If the socket is non-blocking then socket_connect() function returns FALSE with an error Operation now in progress.
        $in_progress = (strpos(socket_strerror(socket_last_error()), 'in progress') !== false);
        if (!$in_progress) {
            socket_error($socket);
        }
    }

    return $socket;
}

function socket_error($socket)
{
    $errno = socket_last_error($socket);
    $errstr = socket_strerror($errno);

    throw new Exception($errstr, $errno);
}