[TYPO3-core] Cachingframework implementation for lang sysext

[Dominique Feyer]

Christian Kuhn wrote:
> We should answer some questions to decide how a caching layer for lang
> should look like:
> - Is the parsing process 'expensive' at all? Is this profiled? I the
> answer is a definate 'yes', we can benefit a lot from caching.

Yes it's really an expensive process, so we need the cache. I try to
disable the cache part ... and the backend become really really slow.

> - Does it maybe make sense to rely on the first 'in memory' cache alone?
> This would invalidate all clearing issues and we still have a cache for
> consecutive calls of keys to the same ll file.

Consecutive calls are handle by the current implementation, if a ll file
is parsed and/or getted from cache ... the second or third call just
return the data from the first call without much processing.

> - How many ll files are typically parsed in a frontend / backend access?
> For FE this probably depends heavily on the number of plugins that are
> added to a page, but for BE I'd guess these are not too many, what do
> you think? Do we have some numbers?

Per exemple CSH are quit big and the processing use a lot of memory (a
lot more than the unserialize from cache)

Before TYPO3 4.6 we use a file based cached.

I check to have more metrics, and answer this question during the week.