MultiCurlHead.php

<?php

function getHead($urls){
    $results = array();
    // make sure the rolling window isn't greater than the # of urls
    $rolling_window = 5;
    $rolling_window = (sizeof($urls) < $rolling_window) ? sizeof($urls) : $rolling_window;

    $master = curl_multi_init();
    // $curl_arr = array();

    // add additional curl options here
    $options = array(
      CURLOPT_FOLLOWLOCATION => FALSE,
      CURLOPT_RETURNTRANSFER => TRUE,
      CURLOPT_NOBODY => TRUE,
    );

    // start the first batch of requests
    for ($i = 0; $i < $rolling_window; $i++) {
      $ch = curl_init();
      $options[CURLOPT_URL] = array_pop($urls);
      curl_setopt_array($ch, $options);
      curl_multi_add_handle($master, $ch);
    }

    do {
      while (($execrun = curl_multi_exec($master, $running)) == CURLM_CALL_MULTI_PERFORM) {
        ;
      }
      if ($execrun != CURLM_OK) {
        break;
      }
      // a request was just completed -- find out which one
      while ($done = curl_multi_info_read($master)) {
        $info = curl_getinfo($done['handle']);
        $results[$info['url']] = $info;

        $new_url = array_pop($urls);
        if(isset($new_url)){
          $ch = curl_init();
          $options[CURLOPT_URL] = $new_url;
          curl_setopt_array($ch, $options);
          curl_multi_add_handle($master, $ch);
        }

        // remove the curl handle that just completed
        curl_multi_remove_handle($master, $done['handle']);
      }
    } while ($running);

    curl_multi_close($master);
    return $results;

  }