<?php
function rolling_curl($curl_multi_data = []) 
{
    $queue = curl_multi_init();
    $map = array();
 
    foreach ($curl_multi_data as $curl_data) {
        $ch = curl_init();
        $data = $curl_data['data'];
        if($curl_data['is_post'])
        {
            curl_setopt($ch, CURLOPT_POST, TRUE);
            curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($data));
        }
        curl_setopt($ch, CURLOPT_URL, $curl_data['api']);
        curl_setopt($ch, CURLOPT_TIMEOUT, 1);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_HEADER, 0);
        curl_setopt($ch, CURLOPT_NOSIGNAL, true);
        $header = array();
        if(@$data['is_ajax'])
        {
            $header[] = 'X-REQUESTED-WITH: XMLHttpRequest';
        }
        curl_setopt($ch, CURLOPT_HTTPHEADER, $header);
        curl_multi_add_handle($queue, $ch);
        $map[(string) $ch] = $curl_data['api'];
    }
 
    $responses = array();
    do {
        /**
         * 对curl队列进行遍历，当请求有完成的请求时，返回的code不为 CURLM_CALL_MULTI_PERFORM （实为 -1）
         * @var [type]
         */
        while (($code = curl_multi_exec($queue, $active)) == CURLM_CALL_MULTI_PERFORM) ;
    
        /**
         * 当code为 CURLM_OK 0时，则代表队列完成
         */
        if ($code != CURLM_OK) { break; }
        
        /**
         * 当队列完成后，select出
         */
        // 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
        /**
         * 当错误发生时，进行阻塞，不再遍历queue，直到批处理文件中有活动链接
         */
        if ($active > 0) {
            curl_multi_select($queue, 0.5);
        }
 
    } while ($active);
 
    curl_multi_close($queue);
    return $responses;
}