Proxy Cache - Check if file has been cached

[digger18]

Hi,
I have implemented nginx with proxy cache successfully, however, I need
to have the ability to check if a certain file is already cached or
not.
Is there a way to get a list of cached files?
Maybe another way will be to send a HEAD request which contains the file
URI to the proxy cache server to check if a file is already in cache?

Are these methods possible?

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,162263,162263#msg-162263