Struct oasis_core_runtime::storage::mkvs::OverlayTree

pub struct OverlayTree<T: FallibleMKVS> { /* private fields */ }

A key-value tree overlay that holds all updates in memory and only commits them if requested. This can be used to create snapshots that can be discarded.

While updates (inserts, removes) are stored in the overlay, reads are not cached in the overlay as the inner tree has its own cache and double caching makes less sense.

Implementations

impl<T: FallibleMKVS> OverlayTree<T>

pub fn new(inner: T) -> Self

Create a new overlay tree.

pub fn get(&self, key: &[u8]) -> Result<Option<Vec<u8>>>

Get an existing key.

pub fn insert(&mut self, key: &[u8], value: &[u8]) -> Result<Option<Vec<u8>>>

Insert a key/value pair into the tree.

pub fn remove(&mut self, key: &[u8]) -> Result<Option<Vec<u8>>>

Remove entry with given key, returning the value at the key if the key was previously in the database.

pub fn iter(&self) -> OverlayTreeIterator<'_, T>

Return an iterator over the tree.

pub fn commit(&mut self) -> Result<WriteLog>

Commit any modifications to the underlying tree.

pub fn commit_both( &mut self, namespace: Namespace, version: u64 ) -> Result<(WriteLog, Hash)>

Commit any modifications to the underlying tree and then immediately commit the underlying tree, returning the new root hash.

Trait Implementations

impl<T: FallibleMKVS> MKVS for OverlayTree<T>

fn get(&self, key: &[u8]) -> Option<Vec<u8>>

Fetch entry with given key.

fn cache_contains_key(&self, key: &[u8]) -> bool

Check if the local MKVS cache contains the given key.

fn insert(&mut self, key: &[u8], value: &[u8]) -> Option<Vec<u8>>

Update entry with given key.

fn remove(&mut self, key: &[u8]) -> Option<Vec<u8>>

Remove entry with given key, returning the value at the key if the key was previously in the database.

fn prefetch_prefixes(&self, prefixes: &[Prefix], limit: u16)

Populate the in-memory tree with nodes for keys starting with given prefixes.

fn iter(&self) -> Box<dyn Iterator + '_>

Returns an iterator over the tree.

fn commit( &mut self, namespace: Namespace, version: u64 ) -> Result<(WriteLog, Hash)>

Commit all database changes to the underlying store.