pub trait Backend<H: Hasher>: Debug {
    type Error: Error;
    type TrieBackendStorage: TrieBackendStorage<H>;
    type RawIter: StorageIterator<H, Backend = Self, Error = Self::Error>;

Show 24 methods // Required methods fn storage(&self, key: &[u8]) -> Result<Option<StorageValue>, Self::Error>; fn storage_hash(&self, key: &[u8]) -> Result<Option<H::Out>, Self::Error>; fn child_storage( &self, child_info: &ChildInfo, key: &[u8] ) -> Result<Option<StorageValue>, Self::Error>; fn child_storage_hash( &self, child_info: &ChildInfo, key: &[u8] ) -> Result<Option<H::Out>, 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 storage_root<'a>( &self, delta: impl Iterator<Item = (&'a [u8], Option<&'a [u8]>)>, state_version: StateVersion ) -> (H::Out, BackendTransaction<H>) where H::Out: Ord; fn child_storage_root<'a>( &self, child_info: &ChildInfo, delta: impl Iterator<Item = (&'a [u8], Option<&'a [u8]>)>, state_version: StateVersion ) -> (H::Out, bool, BackendTransaction<H>) where H::Out: Ord; fn raw_iter(&self, args: IterArgs<'_>) -> Result<Self::RawIter, Self::Error>; fn register_overlay_stats(&self, _stats: &StateMachineStats); fn usage_info(&self) -> UsageInfo; // Provided methods 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 pairs<'a>( &'a self, args: IterArgs<'_> ) -> Result<PairsIter<'a, H, Self::RawIter>, Self::Error> { ... } fn keys<'a>( &'a self, args: IterArgs<'_> ) -> Result<KeysIter<'a, H, Self::RawIter>, Self::Error> { ... } 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]>)>)>, state_version: StateVersion ) -> (H::Out, BackendTransaction<H>) where H::Out: Ord + Encode { ... } fn wipe(&self) -> Result<(), Self::Error> { ... } fn commit( &self, _: H::Out, _: BackendTransaction<H>, _: StorageCollection, _: ChildStorageCollection ) -> Result<(), Self::Error> { ... } fn read_write_count(&self) -> (u32, u32, u32, u32) { ... } fn reset_read_write_count(&self) { ... } fn get_whitelist(&self) -> Vec<TrackedStorageKey> { ... } fn set_whitelist(&self, _: Vec<TrackedStorageKey>) { ... } fn proof_size(&self) -> Option<u32> { ... } fn get_read_and_written_keys(&self) -> Vec<(Vec<u8>, u32, u32, bool)> { ... }
}
Expand description

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

The clone operation (if implemented) should be cheap.

Required Associated Types§

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type Error: Error

An error type when fetching data is not possible.

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type TrieBackendStorage: TrieBackendStorage<H>

Type of trie backend storage.

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type RawIter: StorageIterator<H, Backend = Self, Error = Self::Error>

Type of the raw storage iterator.

Required Methods§

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

Get keyed storage or None if there is nothing associated.

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

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

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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.

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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.

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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.

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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.

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fn storage_root<'a>( &self, delta: impl Iterator<Item = (&'a [u8], Option<&'a [u8]>)>, state_version: StateVersion ) -> (H::Out, BackendTransaction<H>)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.

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fn child_storage_root<'a>( &self, child_info: &ChildInfo, delta: impl Iterator<Item = (&'a [u8], Option<&'a [u8]>)>, state_version: StateVersion ) -> (H::Out, bool, BackendTransaction<H>)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.

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fn raw_iter(&self, args: IterArgs<'_>) -> Result<Self::RawIter, Self::Error>

Returns a lifetimeless raw storage iterator.

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fn register_overlay_stats(&self, _stats: &StateMachineStats)

Register stats from overlay of state machine.

By default nothing is registered.

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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.

Provided Methods§

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

true if a key exists in storage.

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

true if a key exists in child storage.

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fn pairs<'a>( &'a self, args: IterArgs<'_> ) -> Result<PairsIter<'a, H, Self::RawIter>, Self::Error>

Get an iterator over key/value pairs.

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fn keys<'a>( &'a self, args: IterArgs<'_> ) -> Result<KeysIter<'a, H, Self::RawIter>, Self::Error>

Get an iterator over keys.

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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]>)>)>, state_version: StateVersion ) -> (H::Out, BackendTransaction<H>)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.

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

Wipe the state database.

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

Commit given transaction to storage.

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fn read_write_count(&self) -> (u32, u32, u32, u32)

Get the read/write count of the db

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fn reset_read_write_count(&self)

Get the read/write count of the db

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fn get_whitelist(&self) -> Vec<TrackedStorageKey>

Get the whitelist for tracking db reads/writes

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fn set_whitelist(&self, _: Vec<TrackedStorageKey>)

Update the whitelist for tracking db reads/writes

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fn proof_size(&self) -> Option<u32>

Estimate proof size

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fn get_read_and_written_keys(&self) -> Vec<(Vec<u8>, u32, u32, bool)>

Extend storage info for benchmarking db

Implementors§

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impl<S: TrieBackendStorage<H>, H: Hasher, C: TrieCacheProvider<H> + Send + Sync> Backend<H> for TrieBackend<S, H, C>where H::Out: Ord + Codec,

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type Error = String

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type TrieBackendStorage = S

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type RawIter = RawIter<S, H, C>