[−][src]Trait sp_state_machine::backend::Backend

pub trait Backend<H: Hasher>: Debug {
    type Error: Error;
    type Transaction: Consolidate + Default + Send;
    type TrieBackendStorage: TrieBackendStorage<H>;
    fn storage(&self, key: &[u8]) -> Result<Option<StorageValue>, Self::Error>;

    fn child_storage(
        &self, 
        child_info: &ChildInfo, 
        key: &[u8]
    ) -> Result<Option<StorageValue>, Self::Error>;

    fn next_storage_key(
        &self, 
        key: &[u8]
    ) -> Result<Option<StorageKey>, Self::Error>;

    fn next_child_storage_key(
        &self, 
        child_info: &ChildInfo, 
        key: &[u8]
    ) -> Result<Option<StorageKey>, Self::Error>;

    fn for_keys_in_child_storage<F: FnMut(&[u8])>(
        &self, 
        child_info: &ChildInfo, 
        f: F
    );

    fn for_key_values_with_prefix<F: FnMut(&[u8], &[u8])>(
        &self, 
        prefix: &[u8], 
        f: F
    );

    fn for_child_keys_with_prefix<F: FnMut(&[u8])>(
        &self, 
        child_info: &ChildInfo, 
        prefix: &[u8], 
        f: F
    );

    fn storage_root<'a>(
        &self, 
        delta: impl Iterator<Item = (&'a [u8], Option<&'a [u8]>)>
    ) -> (H::Out, Self::Transaction)
    where
        H::Out: Ord;

    fn child_storage_root<'a>(
        &self, 
        child_info: &ChildInfo, 
        delta: impl Iterator<Item = (&'a [u8], Option<&'a [u8]>)>
    ) -> (H::Out, bool, Self::Transaction)
    where
        H::Out: Ord;

    fn pairs(&self) -> Vec<(StorageKey, StorageValue)>;

    fn register_overlay_stats(&mut self, _stats: &StateMachineStats);

    fn usage_info(&self) -> UsageInfo;

    fn storage_hash(&self, key: &[u8]) -> Result<Option<H::Out>, Self::Error> { ... }

    fn child_storage_hash(
        &self, 
        child_info: &ChildInfo, 
        key: &[u8]
    ) -> Result<Option<H::Out>, Self::Error> { ... }

    fn exists_storage(&self, key: &[u8]) -> Result<bool, Self::Error> { ... }

    fn exists_child_storage(
        &self, 
        child_info: &ChildInfo, 
        key: &[u8]
    ) -> Result<bool, Self::Error> { ... }

    fn for_keys_with_prefix<F: FnMut(&[u8])>(&self, prefix: &[u8], f: F) { ... }

    fn keys(&self, prefix: &[u8]) -> Vec<StorageKey> { ... }

    fn child_keys(
        &self, 
        child_info: &ChildInfo, 
        prefix: &[u8]
    ) -> Vec<StorageKey> { ... }

    fn as_trie_backend(
        &mut self
    ) -> Option<&TrieBackend<Self::TrieBackendStorage, H>> { ... }

    fn full_storage_root<'a>(
        &self, 
        delta: impl Iterator<Item = (&'a [u8], Option<&'a [u8]>)>, 
        child_deltas: impl Iterator<Item = (&'a ChildInfo, impl Iterator<Item = (&'a [u8], Option<&'a [u8]>)>)>
    ) -> (H::Out, Self::Transaction)
    where
        H::Out: Ord + Encode,
    { ... }

    fn wipe(&self) -> Result<(), Self::Error> { ... }

    fn commit(&self, _: H::Out, _: Self::Transaction) -> Result<(), Self::Error> { ... }
}

A state backend is used to read state data and can have changes committed to it.

The clone operation (if implemented) should be cheap.

Associated Types

type Error: Error

An error type when fetching data is not possible.

type Transaction: Consolidate + Default + Send

Storage changes to be applied if committing

type TrieBackendStorage: TrieBackendStorage<H>

Type of trie backend storage.

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Required methods

fn storage(&self, key: &[u8]) -> Result<Option<StorageValue>, Self::Error>

Get keyed storage or None if there is nothing associated.

fn child_storage(
    &self,
    child_info: &ChildInfo,
    key: &[u8]
) -> Result<Option<StorageValue>, Self::Error>

Get keyed child storage or None if there is nothing associated.

fn next_storage_key(
    &self,
    key: &[u8]
) -> Result<Option<StorageKey>, Self::Error>

Return the next key in storage in lexicographic order or None if there is no value.

fn next_child_storage_key(
    &self,
    child_info: &ChildInfo,
    key: &[u8]
) -> Result<Option<StorageKey>, Self::Error>

Return the next key in child storage in lexicographic order or None if there is no value.

fn for_keys_in_child_storage<F: FnMut(&[u8])>(
    &self,
    child_info: &ChildInfo,
    f: F
)

Retrieve all entries keys of child storage and call f for each of those keys.

fn for_key_values_with_prefix<F: FnMut(&[u8], &[u8])>(
    &self,
    prefix: &[u8],
    f: F
)

Retrieve all entries keys and values of which start with the given prefix and call f for each of those keys.

fn for_child_keys_with_prefix<F: FnMut(&[u8])>(
    &self,
    child_info: &ChildInfo,
    prefix: &[u8],
    f: F
)

Retrieve all child entries keys which start with the given prefix and call f for each of those keys.

fn storage_root<'a>(
    &self,
    delta: impl Iterator<Item = (&'a [u8], Option<&'a [u8]>)>
) -> (H::Out, Self::Transaction) where
    H::Out: Ord, 

Calculate the storage root, with given delta over what is already stored in the backend, and produce a "transaction" that can be used to commit. Does not include child storage updates.

fn child_storage_root<'a>(
    &self,
    child_info: &ChildInfo,
    delta: impl Iterator<Item = (&'a [u8], Option<&'a [u8]>)>
) -> (H::Out, bool, Self::Transaction) where
    H::Out: Ord, 

Calculate the child storage root, with given delta over what is already stored in the backend, and produce a "transaction" that can be used to commit. The second argument is true if child storage root equals default storage root.

fn pairs(&self) -> Vec<(StorageKey, StorageValue)>

Get all key/value pairs into a Vec.

fn register_overlay_stats(&mut self, _stats: &StateMachineStats)

Register stats from overlay of state machine.

By default nothing is registered.

fn usage_info(&self) -> UsageInfo

Query backend usage statistics (i/o, memory)

Not all implementations are expected to be able to do this. In the case when they don't, empty statistics is returned.

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Provided methods

fn storage_hash(&self, key: &[u8]) -> Result<Option<H::Out>, Self::Error>

Get keyed storage value hash or None if there is nothing associated.

fn child_storage_hash(
    &self,
    child_info: &ChildInfo,
    key: &[u8]
) -> Result<Option<H::Out>, Self::Error>

Get child keyed storage value hash or None if there is nothing associated.

fn exists_storage(&self, key: &[u8]) -> Result<bool, Self::Error>

true if a key exists in storage.

fn exists_child_storage(
    &self,
    child_info: &ChildInfo,
    key: &[u8]
) -> Result<bool, Self::Error>

true if a key exists in child storage.

fn for_keys_with_prefix<F: FnMut(&[u8])>(&self, prefix: &[u8], f: F)

Retrieve all entries keys which start with the given prefix and call f for each of those keys.

fn keys(&self, prefix: &[u8]) -> Vec<StorageKey>

Get all keys with given prefix

fn child_keys(&self, child_info: &ChildInfo, prefix: &[u8]) -> Vec<StorageKey>

Get all keys of child storage with given prefix

fn as_trie_backend(
    &mut self
) -> Option<&TrieBackend<Self::TrieBackendStorage, H>>

Try convert into trie backend.

fn full_storage_root<'a>(
    &self,
    delta: impl Iterator<Item = (&'a [u8], Option<&'a [u8]>)>,
    child_deltas: impl Iterator<Item = (&'a ChildInfo, impl Iterator<Item = (&'a [u8], Option<&'a [u8]>)>)>
) -> (H::Out, Self::Transaction) where
    H::Out: Ord + Encode, 

Calculate the storage root, with given delta over what is already stored in the backend, and produce a "transaction" that can be used to commit. Does include child storage updates.

fn wipe(&self) -> Result<(), Self::Error>

Wipe the state database.

fn commit(&self, _: H::Out, _: Self::Transaction) -> Result<(), Self::Error>

Commit given transaction to storage.

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Implementations on Foreign Types

impl<'a, T: Backend<H>, H: Hasher> Backend<H> for &'a T[src]

type Error = T::Error

type Transaction = T::Transaction

type TrieBackendStorage = T::TrieBackendStorage

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Implementors

impl<'a, S, H> Backend<H> for ProvingBackend<'a, S, H> where
    S: 'a + TrieBackendStorage<H>,
    H: 'a + Hasher,
    H::Out: Ord + Codec, [src]

type Error = String

type Transaction = S::Overlay

type TrieBackendStorage = S

impl<S: TrieBackendStorage<H>, H: Hasher> Backend<H> for TrieBackend<S, H> where
    H::Out: Ord + Codec, [src]

type Error = String

type Transaction = S::Overlay

type TrieBackendStorage = S

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