sov_rollup_interface::stf

Trait StateTransitionFunction

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pub trait StateTransitionFunction<Vm: Zkvm, Da: DaSpec> {
    type StateRoot: Serialize + DeserializeOwned + Clone + AsRef<[u8]>;
    type InitialState;
    type TxReceiptContents: Serialize + DeserializeOwned + Clone;
    type BatchReceiptContents: Serialize + DeserializeOwned + Clone;
    type Witness: Default + Serialize + DeserializeOwned;
    type Condition: ValidityCondition;

    // Required methods
    fn init_chain(&mut self, params: Self::InitialState) -> Self::StateRoot;
    fn apply_slot<'a, I>(
        &mut self,
        pre_state_root: &Self::StateRoot,
        witness: Self::Witness,
        slot_header: &Da::BlockHeader,
        validity_condition: &Da::ValidityCondition,
        blobs: I,
    ) -> SlotResult<Self::StateRoot, Self::BatchReceiptContents, Self::TxReceiptContents, Self::Witness>
       where I: IntoIterator<Item = &'a mut Da::BlobTransaction>;
}
Expand description

State transition function defines business logic that responsible for changing state. Terminology:

  • state root: root hash of state merkle tree
  • block: DA layer block
  • batch: Set of transactions grouped together, or block on L2
  • blob: Non serialised batch or anything else that can be posted on DA layer, like attestation or proof.

Required Associated Types§

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type StateRoot: Serialize + DeserializeOwned + Clone + AsRef<[u8]>

Root hash of state merkle tree

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type InitialState

The initial state of the rollup.

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type TxReceiptContents: Serialize + DeserializeOwned + Clone

The contents of a transaction receipt. This is the data that is persisted in the database

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type BatchReceiptContents: Serialize + DeserializeOwned + Clone

The contents of a batch receipt. This is the data that is persisted in the database

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type Witness: Default + Serialize + DeserializeOwned

Witness is a data that is produced during actual batch execution or validated together with proof during verification

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type Condition: ValidityCondition

The validity condition that must be verified outside of the Vm

Required Methods§

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fn init_chain(&mut self, params: Self::InitialState) -> Self::StateRoot

Perform one-time initialization for the genesis block and returns the resulting root hash wrapped in a result. If the init chain fails we panic.

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fn apply_slot<'a, I>( &mut self, pre_state_root: &Self::StateRoot, witness: Self::Witness, slot_header: &Da::BlockHeader, validity_condition: &Da::ValidityCondition, blobs: I, ) -> SlotResult<Self::StateRoot, Self::BatchReceiptContents, Self::TxReceiptContents, Self::Witness>
where I: IntoIterator<Item = &'a mut Da::BlobTransaction>,

Called at each DA-layer block - whether or not that block contains any data relevant to the rollup. If slot is started in Full Node mode, default witness should be provided. If slot is started in Zero Knowledge mode, witness from execution should be provided.

Applies batches of transactions to the rollup, slashing the sequencer who proposed the blob on failure. The blobs are contained into a slot whose data is contained within the slot_data parameter, this parameter is mainly used within the begin_slot hook. The concrete blob type is defined by the DA layer implementation, which is why we use a generic here instead of an associated type.

Commits state changes to the database

Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors§