xKey Maintenance Mode: what does this mean long-term?

[Dridi Boukelmoune]

> Two tangents.
> 1. Drupal went their own way instead of using xKey and use a BAN with a regex (a regex which has been wrong until recently [2]). Can anyone estimate how much less performant this is than xKey?

I expect a ban with many tags to perform poorly compared to vmod_xkey,
generating a regular expression with a lot of back-tracking and executed
on numerous occasions (roughly up to the number of objects before the
ban was inserted) instead of just once.

However, it should already be possible to take the space-delimited
Cache-Tags header with vmod_xkey. Just create a copy of the header
with the right name (beresp.http.xkey).

Dridi