php使用curl的模拟多线程并发访问

最近写个程序需要抓取多个远程页面，如果按照正常的 php 程序需要一个页面抓完再抓下一个页面，但一个页面的抓取时间又比较长，如果能像 js 一样用 ajax 效果就好了。查了下，发现可以使用 curl 多多线程来模拟并发访问，可以加快访问的速度。

function rolling_curl($urls, $delay) {
    $queue = curl_multi_init();
    $map = array();
 
    foreach ($urls as $url) {
        $ch = curl_init();
 
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_TIMEOUT, 1);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_HEADER, 0);
        curl_setopt($ch, CURLOPT_NOSIGNAL, true);
 
        curl_multi_add_handle($queue, $ch);
        $map[(string) $ch] = $url;
    }
 
    $responses = array();
    do {
        while (($code = curl_multi_exec($queue, $active)) == CURLM_CALL_MULTI_PERFORM) ;
 
        if ($code != CURLM_OK) { break; }
 
        // a request was just completed -- find out which one
        while ($done = curl_multi_info_read($queue)) {
 
            // get the info and content returned on the request
            $info = curl_getinfo($done['handle']);
            $error = curl_error($done['handle']);
            $results = callback(curl_multi_getcontent($done['handle']), $delay);
            $responses[$map[(string) $done['handle']]] = compact('info', 'error', 'results');
 
            // remove the curl handle that just completed
            curl_multi_remove_handle($queue, $done['handle']);
            curl_close($done['handle']);
        }
 
        // Block for data in / output; error handling is done by curl_multi_exec
        if ($active > 0) {
            curl_multi_select($queue, 0.5);
        }
 
    } while ($active);
 
    curl_multi_close($queue);
    return $responses;
}

这个函数可以直接使用。 $delay 建议设成 5 ，单位是毫秒。

$urls = array(
"http://www.cnn.com/",
"http://www.canada.com/",
"http://www.yahoo.com/"
);

rolling_curl($urls,5);