How do I run cURL request in the background in PHP?

Question

I'm trying to build some kind of web based download manager using PHP and the cURL extension, I am stuck with one problem though, how can I download and save the file with cURL without having to make the user wait, meaning he will make the request and it will be processed in the background.

Now I can't use system calls (exec, system ... etc) as most of the hosts I work with disable these functions, and the other problem is the max execution time for PHP scripts, but I guess this one can be changed in .htaccess or using ini_set or can it not?

I've read somewhere that setting connect_timeout to 1 will work, but does not that terminate the connection?

One solution is to use cronjobs, after the users submits the file he wants to download, a cronjob will check the database and if there is a file in the queue it will start downloading it, but I thought I want to avoid using cron jobs if possible.

So back to the main question, is there a way to tell the php script to run some certain function in the background and delivering the response to the users regardless of the result of that function

Thanks

Answer 1

I think there have been other posts exploring the options already. Given your constraints, I see two other approaches:

• Make an asynchronous call with cURL to another script doing the processing (see http://www.paul-norman.co.uk/2009/06/asynchronous-curl-requests/)
• Use JS to trigger the long running background task from the frontend side

Answer 2

        function background_curl_request($url, $method, $post_parameters){
            if (is_array($post_parameters)){
                $params = "";
                foreach ($post_parameters as $key=>$value){
                    $params .= $key."=".urlencode($value).'&';
                }
                $params = rtrim($params, "&");
            } else {
                $params = $post_parameters;
            }
            $command = "/usr/bin/curl -X '".$method."' -d '".$params."' --url '".$url."' >> /dev/shm/request.log 2> /dev/null &";
            exec($command);
        }