如何向PHP发送一个简短的Ajax请求，得到确认，不要等待完整的处理完成

first post here :) I have a mobile app (Phonegap) that sends an ajax request to a PHP server, say a friend invite. When receiving the request, a few things have to be done (create links, authorisations, send e-mails, etc) which take a long time (5 sec). During that time, the user on the app is looking at a spinner, waiting for the ajax request to complete.

Ideally:

• return a confirmation "Friend request received", without waiting for the process to finish.
• No Cron jobs because waiting 1 min is too long.
• Something simple (Gearman is scary)

On the app :

$.ajax({
    url: 'http://www.my_site.com/action.php',
    type: 'POST',
    data: "my_guid="+my_guid+"&friend_guid="+friend_guid, 
    dataType: 'json',
    success: function(json) {
        // Send confirmation
    },
    error: function(json) {
        // Show error
    }
}

On the server (PHP):

$my_guid = $_POST['my_guid'];
$friend_guid = $_POST['friend_guid'];
// return here confirmation to the app
veryLongFunction($my_guid,$friend_guid); //continue executing long function