Struct diem_vm::data_cache::StateViewCache

pub struct StateViewCache<'a, S> { /* fields omitted */ }

A local cache for a given a StateView. The cache is private to the Diem layer but can be used as a one shot cache for systems that need a simple RemoteCache implementation (e.g. tests or benchmarks).

The cache is responsible to track all changes to the StateView that are the result of transaction execution. Those side effects are published at the end of a transaction execution via StateViewCache::push_write_set.

StateViewCache is responsible to give an up to date view over the data store, so that changes executed but not yet committed are visible to subsequent transactions.

If a system wishes to execute a block of transaction on a given view, a cache that keeps track of incremental changes is vital to the consistency of the data store and the system.

Implementations

impl<'a, S: StateView> StateViewCache<'a, S>

pub fn new(data_view: &'a S) -> Self

Create a StateViewCache give a StateView. Hold updates to the data store and forward data request to the StateView if not in the local cache.

Trait Implementations

impl<'block, S: StateView> ConfigStorage for StateViewCache<'block, S>

fn fetch_config(&self, access_path: AccessPath) -> Option<Vec<u8>>

impl<'block, S: StateView> ModuleResolver for StateViewCache<'block, S>

type Error = VMError

fn get_module(
    &self,
    module_id: &ModuleId
) -> Result<Option<Vec<u8>>, Self::Error>

impl<'block, S: StateView> ResourceResolver for StateViewCache<'block, S>

type Error = VMError

fn get_resource(
    &self,
    address: &AccountAddress,
    tag: &StructTag
) -> Result<Option<Vec<u8>>, Self::Error>

impl<'block, S: StateView> StateView for StateViewCache<'block, S>

fn get(&self, access_path: &AccessPath) -> Result<Option<Vec<u8>>>

Gets the state for a single access path.

fn is_genesis(&self) -> bool

VM needs this method to know whether the current state view is for genesis state creation. Currently TransactionPayload::WriteSet is only valid for genesis state creation.

fn id(&self) -> StateViewId

For logging and debugging purpose, identifies what this view is for.