fixed, and now my randomized cache set/get/remove testing loop is just going speedy, no crashes :))
where a normal least-recent-used cache just removes the oldest entry when you add a new one but hit the max entry limit, this has a constraint set based on total size used, and can invalidate multiple old smaller entries to make space for a new bigger one, and as such dynamically shrinks/grows the amount of entries stored
will be used for the caching in synapse-media-proxy
in the end didn't even use the index tracking method the Computer Organization book recommended, but instead a linked list across the Map entries