Circuit breaker proposal

[bedeho]

Background

There may be cases where it is critical to stop some subset of on-chain feature on very short notice, and example is the Acala aUSD bug. A runtime upgrade needs to be a very slow process, as it effectively is an unconstrained change, so it is not fit for purpose.

Proposal

A new circuit breaker proposal to augment the extrinsic filtering in the chain. This is of course not a full freeze, as code may still be running in on_initialize or on_finalize in all the pallets, but its a big step in the right direction, and interfering with those routines will require augmenting lots of pallets, and also is much more risky in terms of breaking invariants in the runtime.