Enum SnapshotRequest

pub enum SnapshotRequest {
    ListSnapshots,
    OfferSnapshot(OfferSnapshot),
    LoadSnapshotChunk(LoadSnapshotChunk),
    ApplySnapshotChunk(ApplySnapshotChunk),
}

The snapshot category of ABCI requests.

Variants

ListSnapshots

Asks the application for a list of snapshots.

ABCI documentation

OfferSnapshot(OfferSnapshot)

Offers a list of snapshots to the application.

OfferSnapshot is called when bootstrapping a node using state sync. The application may accept or reject snapshots as appropriate. Upon accepting, Tendermint will retrieve and apply snapshot chunks via ApplySnapshotChunk. The application may also choose to reject a snapshot in the chunk response, in which case it should be prepared to accept further OfferSnapshot calls.

Only app_hash can be trusted, as it has been verified by the light client. Any other data can be spoofed by adversaries, so applications should employ additional verification schemes to avoid denial-of-service attacks. The verified app_hash is automatically checked against the restored application at the end of snapshot restoration.

See also the Snapshot data type and the ABCI state sync documentation.

ABCI documentation

LoadSnapshotChunk(LoadSnapshotChunk)

Used during state sync to retrieve snapshot chunks from peers.

ABCI documentation

ApplySnapshotChunk(ApplySnapshotChunk)

Applies a snapshot chunk.

The application can choose to refetch chunks and/or ban P2P peers as appropriate. Tendermint will not do this unless instructed by the application.

The application may want to verify each chunk, e.g., by attaching chunk hashes in Snapshot::metadata and/or incrementally verifying contents against app_hash.

When all chunks have been accepted, Tendermint will make an ABCI Info request to verify that last_block_app_hash and last_block_height match the expected values, and record the app_version in the node state. It then switches to fast sync or consensus and joins the network.

If Tendermint is unable to retrieve the next chunk after some time (e.g., because no suitable peers are available), it will reject the snapshot and try a different one via OfferSnapshot. The application should be prepared to reset and accept it or abort as appropriate.

ABCI documentation

Trait Implementations

impl Clone for SnapshotRequest

fn clone(&self) -> SnapshotRequest

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SnapshotRequest

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<SnapshotRequest> for Request

fn from(req: SnapshotRequest) -> Self

Converts to this type from the input type.

impl PartialEq for SnapshotRequest

fn eq(&self, other: &SnapshotRequest) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl TryFrom<Request> for SnapshotRequest

type Error = Error

The type returned in the event of a conversion error.

fn try_from(req: Request) -> Result<Self, Self::Error>

Performs the conversion.

impl Eq for SnapshotRequest

impl StructuralPartialEq for SnapshotRequest