regex_revalidate immutable rules confusing

[traeak]

Through traffic control we have a limited way for end users to issue revalidations. Unfortunately the regex_revalidate plugin as-is will skip new rules with a certain regex if that rule has already been loaded. If an end user sets a 30 day revalidation for a live linear asset manifest endpoint the reissue has no effect and we end up issuing a new equivalent regex but different regex to start new invalidations.

Based on communication with the traffic control team it may be best for the regex_revalidate plugin to be able to switch from first rule wins to last rule wins and also to "reset" the revalidation if the end time is changed.

[mitchell852]

Here is what we are experiencing:

Path: /opt/trafficserver/etc/trafficserver/regex_revalidate.config

http://my.origin.net/foo.png 1606758714 <-- this rule was created on 11/13 with an expiration (TTL) of 11/30 (the invalidation may occur at anytime betwen 11/13 - 11/30)
http://my.origin.net/foo.png 1606845114 <-- this rule was created because the user needed to invalidate foo.png AGAIN...but it is blocked until 11/30 due to rule #1

Since we don't really know when the invalidation for rule #1 occurs, we leave that rule in until it expires (11/30)....which basically blocks subsequent rules...

If the ATS regex reval plugin considers the last rule to be the winner (instead of the first), the last rule would be loaded and the content invalidation would be reset (because it is different based on expiration date/epoch) allowing users to create additional rules for the same regex.

More than anything, the first/last thing is not a big deal, it's the immutable part. I would expect ATS to say "hey, look this rule changed as it has a different epoch. let me start over and respect the new rule".

[traeak]

I'll change this to what we know is a mess, which is duplicated rules will be constantly reloaded.

[traeak]

Just ensure non duplicate rules in a file being loaded.