StatsCache currently holds 1000 entries. QO team would like to switch it to 100mb instead. This requires teaching the ReadThroughCache to estimate element cost in bytes, not count, just like LRUKeyValue does.

QO relies on ReadThroughCache because StatsCache is accessed from multiple threads, and LRUKeyValue does not provide thread-safety. Forking all the thread-safety logic from ReadThroughCache and its base InvalidatingLRUCache would lead to a code duplication. That's why we request changes to the ReadThroughCache.

I attempted to work-around missing ReadThroughCache functionality, but this attempt provided low performance.