Extract burnt funds account state

[alanshaw]

The burnt funds account is a special account where all burnt funds resulting from gas costs are sent.

https://github.com/filecoin-project/specs-actors/blob/585b71e2b89642f2b01157c94e72a4ca9a8e869a/actors/builtin/singletons.go#L17-L18

Funds do not arrive via messages but are instead transferred by the VM implicitly. Tracking the f099 actor state allows us to analyse burn rates since we cannot inspect sent messages to see value transfer.

[frrist]

Can we query the actors balance from the actor_states table? I believe it's balance is stored in the state column.

[alanshaw]

I don't think we extract state from any account actors.

[frrist]

closed via #278