ParallelCurl with CURLOPT_WRITEFUNCTION

Question

I am trying to use ParallelCurl with a callback when cURL receives data from the server it is connected to. Here is the code I currently have:

function request_finished($content, $url, $ch, $user_data) {
    echo "Request Finished: ", $content, "\n";
}

$pc=new ParallelCurl();
$servers=Server::loadNewAllFromDB();  //Returns an array of 'Server' objects which store connection information

foreach ($servers as $server) {

    $pc->setOptions(
        array(
            CURLOPT_USERAGENT=>'My UserAgent String',
            CURLOPT_WRITEFUNCTION=>
                function ($ch, $string) {
                    echo "WRITEFUNCTION Called!  |  ", $string; 
                    return strlen($string); 
                }
        )
    );
    //print_r($pc->options);
    $pc->startRequest(
        'http://' . $server->address . ':' . $server->portbase . '/someurl'), 
        'request_finished'
    );

}

$pc->finishAllRequests();

Now, what I expect to happen is for my anonymous function to be called when cURL has data to output. Instead, it simply seems to ignore the fact that CURLOPT_WRITEFUNCTION is set at all.

Note that if I am not using ParallelCurl, I can set the very same anonymous function as CURLOPT_WRITEFUNCTION just fine. It as if my function is being overridden somewhere later. I have also verified that it is in fact being set. You can see the line that I have commented out, //print_r($pc->options) . It outputs my closure object.

Any thoughts on this would be most appreciated. Thanks.

Answer 1

This turned out to be a bug with either ParallelCurl, or curl_set_opt_array(). Here is the function in ParallelCurl as-is:

// Start a fetch from the $url address, calling the $callback function passing the optional
// $user_data value. The callback should accept 3 arguments, the url, curl handle and user
// data, eg on_request_done($url, $ch, $user_data);
public function startRequest($url, $callback, $user_data = array(), $post_fields=null) {

    if( $this->max_requests > 0 )
        $this->waitForOutstandingRequestsToDropBelow($this->max_requests);

    $ch = curl_init();
    curl_setopt_array($ch, $this->options);

    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);

    if (isset($post_fields)) {
        curl_setopt($ch, CURLOPT_POST, TRUE);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $post_fields);
    }



    curl_multi_add_handle($this->multi_handle, $ch);

    $this->outstanding_requests[$ch] = array(
        'url' => $url,
        'callback' => $callback,
        'user_data' => $user_data,
    );

    $this->checkForCompletedRequests();
}

Now the problem lies in where curl_setopt_array($ch, $this->options) sits. If I move it below all of the other curl_setopt() , then it works fine. Funny thing is, is that my User-Agent parameter that I pass in the same array as CURLPOT_WRITEFUNCTION was working fine. So, it seems that curl_setpot_array() behaves differently when given objects as values in the array. Anyway, simply moving the call worked fine. My modified function:

// Start a fetch from the $url address, calling the $callback function passing the optional
// $user_data value. The callback should accept 3 arguments, the url, curl handle and user
// data, eg on_request_done($url, $ch, $user_data);
public function startRequest($url, $callback, $user_data = array(), $post_fields=null) {

    if( $this->max_requests > 0 )
        $this->waitForOutstandingRequestsToDropBelow($this->max_requests);

    $ch = curl_init();


    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);

    if (isset($post_fields)) {
        curl_setopt($ch, CURLOPT_POST, TRUE);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $post_fields);
    }

     curl_setopt_array($ch, $this->options);

    curl_multi_add_handle($this->multi_handle, $ch);

    $this->outstanding_requests[$ch] = array(
        'url' => $url,
        'callback' => $callback,
        'user_data' => $user_data,
    );

    $this->checkForCompletedRequests();
}