Trait sov_rollup_interface::stf::StateTransitionRunner

source ·

pub trait StateTransitionRunner<T: StateTransitionConfig, Vm: Zkvm> {
    type RuntimeConfig;
    type Inner: StateTransitionFunction<Vm>;

    // Required methods
    fn new(runtime_config: Self::RuntimeConfig) -> Self;
    fn inner(&self) -> &Self::Inner;
    fn inner_mut(&mut self) -> &mut Self::Inner;
}

Expand description

A StateTransitionRunner (STR) is responsible for running the state transition function. For any particular function, you might have a few different STRs, each with different runtime configs. For example, you might have a STR which takes a path to a data directory as a runtime config, and another which takes a pre-built in-memory database.

Using a separate trait for initialization makes it easy to store extra data in the STR, which would not fit neatly in the state transition logic itself (such as a handle to the database). This way, you can easily support ancillary functions like RPC, p2p networking etc in your full node implementation

The StateTransitionRunner is generic over a StateTransitionConfig, and a Zkvm. The ZKvm is simply forwarded to the inner STF. StateTransitionConfig is a special marker trait which has only 3 possible instantiations: ProverConfig, NativeConfig, and ZkConfig. This Config makes it easy to implement different instantiations of STR on the same struct, which are appropriate for different modes of execution.

For example: might have impl StateTransitionRunner<ProverConfig, Vm> for MyRunner which takes a path to a data directory as a runtime config, and a impl StateTransitionRunner<ZkConfig, Vm> for MyRunner which instead uses a state root as its runtime config.