Anecdotally in the cache module, it's unclear what invariants are supposed to be maintained for a big ol struct full of information about this cache lookup, whi

Anecdotally in the cache module, it's unclear what invariants are supposed to be maintained for a big ol struct full of information about this cache lookup, which functions expect to only be called while holding a lock, etc. The module design and the issues you mentioned also causes suboptimal performance :(