gistfile1.php

<?php
function httpGet($host, $base) {

    global $index;
	
	//使用fsockopen会导致阻塞
    //$fd = fsockopen($host, 80, $errno, $errstr, 3);
    $fd = stream_socket_client("{$host}:80", $errno, $errstr, 3, STREAM_CLIENT_ASYNC_CONNECT | STREAM_CLIENT_CONNECT); 
    $index[$fd] = 0;
	$event = event_new();
	//设置一个事件
	//回调函数有两个默认参数，第三个为传递值
    event_set($event, $fd, EV_WRITE | EV_PERSIST, function($fd, $events, $arg) use($host) {

		global $times, $limit, $index;
		
		if (!$index[$fd]) {
            $index[$fd] = 1;
            $out = "GET / HTTP/1.1\r\n";
            $out .= "Host: $host\r\n";
            $out .= "Connection: Close\r\n\r\n";
            fwrite($fd, $out);
        } else {
			//这里没有显示全部内容，这里获取的内容按照自己的需要去处理
            echo substr(fread($fd, 4096), 0, 20);
            if(feof($fd)) {
                fclose($fd);
                $times++;
                echo "done\n";
				//如果执行到最后一个事件了那么执行完毕退出
                if($times == $limit) {
                    event_base_loopexit($arg[1]);
                }
            }
		}
    }, array($event, $base));
    event_base_set($event, $base);
	//添加事件
    event_add($event);
}

$times = 0;
$limit = 2;
$index = array();

$base = event_base_new();

$urls = array('http://www.baidu.com', 'http://www.fbbin.com');

for($i = 0; $i < $limit; $i++) {
    echo "$i\n";
    httpGet($urls[$i], $base);
}

event_base_loop($base);

?>