Struct WriteOverlay

pub struct WriteOverlay<R> { /* private fields */ }

A wrapper around a JellyfishMerkleTree that buffers pending writes to the tree, and overlays the effect of those writes on the tree state for reading.

Implementations

impl<R> WriteOverlay<R>

pub const PRE_GENESIS_VERSION: Version = 18_446_744_073_709_551_615u64

Use this Version with Self::new to specify that the writes should be committed with version 0.

impl<R> WriteOverlay<R>

where R: TreeReader + Sync,

pub fn new(reader: R, version: Version) -> Self

Constructs a new WriteOverlay with the given reader and version.

All reads performed with get will use version when querying the underlying backing store. The buffered writes created with put will be written as version + 1, so version should probably be the latest version if commit will be called.

To initialize an empty tree, use Self::PRE_GENESIS_VERSION here.

pub async fn get(&self, key: KeyHash) -> Result<Option<OwnedValue>>

Gets a value by key.

This method reflects the results of any pending writes made by put.

pub async fn get_with_proof( &self, key: Vec<u8>, ) -> Result<(OwnedValue, ExistenceProof)>

Gets a value by key alongside an ICS23 existence proof of that value.

This method does not reflect results of any pending writes to the WriteOverlay. An error will be returned if the key exists in the WriteOverlay, or if the key does not exist in the tree.

pub fn put(&mut self, key: KeyHash, value: OwnedValue)

Puts a key/value pair in the overlay.

Assuming it is not overwritten by a subsequent put, the value will be written to the tree when commit is called.

pub async fn commit<W>(&mut self, writer: W) -> Result<(RootHash, Version)>

where W: TreeWriter + Sync,

Clears the overlay, committing all pending writes to the provided writer and returning the new RootHash and Version.

The overlay will then point at the newly written state and tree version.