Get headers using curl--php

get_headers_alternative.php

* In php, the function "get_headers" sometimes is slow, especially if you want to get headers of a batch of urls in parallel.
* In this case, you should use curl.

function get_headers_curl($url){
  $curl = curl_init();
  curl_setopt_array( $curl, array(
      CURLOPT_HEADER => true,
      CURLOPT_NOBODY => true,
      CURLOPT_RETURNTRANSFER => true,
      CURLOPT_URL => $url));
  $headers = explode( "\n", curl_exec($curl));
  curl_close($curl);
  return $headers;
}

function multiCurl_headers(array $urls){
    // array of curl handles
    $handles = array();
    // data to be returned
    $results = array();
    // multi handle
    $mh = curl_multi_init();
    // loop through $data and create curl handles
    // then add them to the multi-handle
    foreach ($urls as $k => $u) {
        $handles[$k] = curl_init();
        curl_setopt($handles[$k], CURLOPT_URL, $u);
        curl_setopt($handles[$k], CURLOPT_HEADER, true);
        curl_setopt($handles[$k], CURLOPT_NOBODY, true);
        curl_setopt($handles[$k], CURLOPT_RETURNTRANSFER, true);
        curl_multi_add_handle($mh, $handles[$k]);
    }

    // execute the handles
    $running = null;
    do {
        curl_multi_exec($mh, $running);
    } while ($running > 0);
    // get content and remove handles
    foreach ($handles as $id => $content) {
         $result = curl_multi_getcontent($content);
         $result = explode("\n", $result);
         $results[$id] = $result;
        //close the handles
        curl_multi_remove_handle($mh, $content);
    }
    // all done
    curl_multi_close($mh);
    return $results;
}