So... I quickly discussed the possibility of re-rolling the Cache API on top the k/v interface with @pounard on IRC. @catch You also mentioned that idea briefly over at. What's your opinion now? Currently, the only incompatibility is ->getAll() which might be troublesome for some backends?! We wouldn't really gain much from this other than consistent APIs. And I think the foundation for both APIs actually IS identical.
Also, the KeyValueStore has an $options argument in the constructor. We currently don't have that in the CacheBackenInterface. However, I think that could actually make sense.