The current cache implementation uses this call to generate the name of a given file :
Which means it generates a different cache .xhtml file for each vhost : example.com and www.example.com which host the wiki
(in our case we have more : doc.ubuntu-fr.org, doc.xubuntu-fr.org, doc.kubuntu-fr.org, doc.edubuntu-fr.org).
I don't understand why you need to put the vhost and port, I'm quite sure there is a good reason but I can't figure it out.
(thanks again for your work on Dokuwiki, great software !)