[Cache] Locking / atomic updates

[Rasmus Schultz]

I've seen the subject of locking and/or atomic updates brought up several times, but I don't see any evidence of any conclusions or decisions made - shouldn't this be in the meta document?

Or has no definitive conclusion on these subjects been reached?

For one, I was hoping to use a PSR cache provider as a back-end for session storage - but since locking is absent, this would imply potentially inconsistent session data updates. I could implement my own locking mechanism, of course, but it seems like this would be generally useful (and/or necessary) for a number of other use cases?