Re-cache image with CURL

[Nygganh]

Hi,

 

I have a image upload script and a image viewer. The image viewer works something like this:

http://www.website.com/image/id_of_image/width/height

 

That will cache and render an image with headers looking something like this:

header('Content-Type: ' . $content_type);

header('Content-Length: ' . strlen($image_data));

header('Cache-Control: max-age=' . Date::HOUR . ', public, must-revalidate');

header('Expires: ' . gmdate('D, d M Y H:i:s', (isset($_GET['clear_cache']) ? NOW - Date::YEAR : NOW + Date::HOUR)) . ' GMT');

header('Last-Modified: ' . gmdate('D, d M Y H:i:s', $this->last_modified_time) . ' GMT');

header('ETag: ' . $etag);

 

Everything's working great, expect for when I'm uploading a new image over an existing one (with same filename), I automatically refresh the page after the upload but the image doesn't get refreshed until I manually refresh the page.

 

I have tried to make a CURL request to the image right after the image is uploaded, but that doesn't seem to trigger the cache to get renewed.

It looks something like this:

$ch = curl_init('http://www.website.com/image/id_of_image/width/height?clear_cache=1');

curl_setopt($ch, CURLOPT_FORBID_REUSE, TRUE);

curl_setopt($ch, CURLOPT_FRESH_CONNECT, TRUE);

curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);

curl_setopt($ch, CURLOPT_HEADER, TRUE);

curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE);

curl_exec($ch);

 

The CURL request is made correctly and I can see the request in my access log.

In my CURL request, I pass ?clear_cache=1. This trick, to change the Expires-header on the CURL request only seems to work in Chrome, but that's because Chrome doesn't give me the "If-None-Match" and is not cached correctly. But maybe that's on the right track?

 

What is a good approach here? I don't want to add a timestamp to my image URL:s since that would trigger the images to never cache.

 

Thanks!

[Nygganh]

I resolved this by my own by adding the timestamp to the URL ONLY after users changes their avatars.