explore readers/getters cache in RoTx

[sudeepdino008]

protoEntityRoTx needs cache for readers/getters?
explore domainrotx/historyrotx etc.

[VBulikov]

@sudeepdino008 added Imp2 as Importance

[AskAlexSharov]

@sudeepdino008 we already have. Do you mean cache which will survive between txs? Actually easy: just need link it to _visibleFiles and don’t need cache-invalidation. Same as D_LRU does.

Only question is: are getters/readers thread-safe? Probably not. But in-theory they can.