RLP encoding for logged out validators

[darcius]

Currently trusted nodes need to perform at least one tx per day with the checkin. Once validators can logout though, at least > 51% of trusted nodes need to agree for each one to be processed. This means if a lot logout at once, it could make running a trusted node pricey if tx gas prices are steep. So we'll need to investigate solutions to reduce these tx's, hopefully down to just 1 per day.

Since trusted nodes already checkin once every 24hrs(ish), could they create an RLP list of all validators that logged out since the last checkpoint (along with balances etc), then submit that at the checkin? RLP lists can be enoded fairly easily in Go and also read in Solidity. The nodes would still be required to agree > 51% on that checkin data obvs too.

There would need to be a cap on the list that's sent, it would just mean that everytime they checked in, they could process only x amount. Then if there's more than that, it just creates a backlog which can be worked through, rather than overloading the trusted nodes. This cap amount would need to be added to the smart contract settings where the smart contracts could read it and also the nodes that build the list.