[TYPO3-team-core-v5] Caching Framework: Tagging of key-value caches

[Philipp Gampe]

Hi all,

lately we discussed in the active contributor chat whether it makes sense to 
let all those key-value caching backend implement the taggable interface.

In CMS we now have more backend (some are not forward ported yet; something 
to do), like the wincache backend, the xcache backend, yac backend 
(pending), etc

What they all have in common is, that this are simple key-value storage that 
do not have native support for tagging and automatically drop the oldest 
entries.
That means that tagging is simulated by a rather complex routine that makes 
sure to save tag references inside additional entries that keep the 
relations between tags and back.
The downside of this approach is that it costs some performance and that it 
is also error prone as tags (or the entries for the tags) may drop out of 
the memory any time.

Christian suggested to just drop the taggable interface for those backends 
to simplify the backend by a big deal.
This relates to APC, Wincache, Xcache, Yac, etc

Of course we should keep this consistent between CMS and Flow.

People can always extend the original backend and implement just the 
taggable interface for a custom backend if they really need tags for simple 
key-value data.

I hereby kindly ask for your opinion on this topic.

Best regards
-- 
Philipp Gampe – PGP-Key 0AD96065 – TYPO3 UG Bonn/Köln
Documentation – linkvalidator
TYPO3 .... inspiring people to share!