Trait KeyValueStore

Source

pub trait KeyValueStore: Send + Sync {
Show 28 methods    // Required methods
    fn get(&self, key: &[u8]) -> StorageBackendResult<Option<Vec<u8>>>;
    fn put(&self, key: &[u8], value: &[u8]) -> StorageBackendResult<()>;
    fn delete(&self, key: &[u8]) -> StorageBackendResult<()>;
    fn scan_prefix(
        &self,
        prefix: &[u8],
    ) -> StorageBackendResult<Vec<(Vec<u8>, Vec<u8>)>>;
    fn delete_prefix(&self, prefix: &[u8]) -> StorageBackendResult<usize>;
    fn batch(&self) -> Box<dyn KeyValueBatch + '_>;
    fn in_transaction(&self) -> bool;
    fn transaction_has_written(&self) -> StorageBackendResult<bool>;

    // Provided methods
    fn storage_identity(
        &self,
    ) -> StorageBackendResult<Option<PersistentStorageIdentity>> { ... }
    fn open_session(&self) -> StorageBackendResult<Arc<dyn KeyValueStore>> { ... }
    fn visit_value(
        &self,
        _key: &[u8],
        control: &StorageReadControl,
        _visit: &mut ValueReadVisitor<'_>,
    ) -> StorageBackendResult<()> { ... }
    fn visit_prefix_after(
        &self,
        _prefix: &[u8],
        _after: Option<&[u8]>,
        _limit: usize,
        control: &StorageReadControl,
        _visit: &mut KeyValueReadVisitor<'_>,
    ) -> StorageBackendResult<()> { ... }
    fn contains_prefix_budgeted(
        &self,
        prefix: &[u8],
        control: &StorageReadControl,
    ) -> StorageBackendResult<bool> { ... }
    fn contains_key(&self, key: &[u8]) -> StorageBackendResult<bool> { ... }
    fn scan_prefix_after(
        &self,
        prefix: &[u8],
        after: Option<&[u8]>,
        limit: usize,
    ) -> StorageBackendResult<Vec<(Vec<u8>, Vec<u8>)>> { ... }
    fn scan_prefix_keys_after(
        &self,
        prefix: &[u8],
        after: Option<&[u8]>,
        limit: usize,
    ) -> StorageBackendResult<Vec<Vec<u8>>> { ... }
    fn first_prefix_after(
        &self,
        prefix: &[u8],
        after: Option<&[u8]>,
    ) -> StorageBackendResult<Option<(Vec<u8>, Vec<u8>)>> { ... }
    fn begin_transaction(&self) -> StorageBackendResult<()> { ... }
    fn begin_read_transaction(&self) -> StorageBackendResult<()> { ... }
    fn begin_upgradeable_transaction(&self) -> StorageBackendResult<()> { ... }
    fn change_version(&self) -> StorageBackendResult<Option<u64>> { ... }
    fn change_version_monitor_is_nonblocking(
        &self,
    ) -> StorageBackendResult<bool> { ... }
    fn pin_transaction_snapshot(&self) -> StorageBackendResult<()> { ... }
    fn commit_transaction(&self) -> StorageBackendResult<()> { ... }
    fn rollback_transaction(&self) -> StorageBackendResult<()> { ... }
    fn savepoint(&self, _name: &str) -> StorageBackendResult<()> { ... }
    fn release_savepoint(&self, _name: &str) -> StorageBackendResult<()> { ... }
    fn rollback_to_savepoint(&self, _name: &str) -> StorageBackendResult<()> { ... }
}

Expand description

Ordered byte-key storage used by Key/Value catalog and index backends.

Required Methods§

Source

fn scan_prefix( &self, prefix: &[u8], ) -> StorageBackendResult<Vec<(Vec<u8>, Vec<u8>)>>

Source

fn delete_prefix(&self, prefix: &[u8]) -> StorageBackendResult<usize>

Source

fn batch(&self) -> Box<dyn KeyValueBatch + '_>

Source

fn in_transaction(&self) -> bool

Source

fn transaction_has_written(&self) -> StorageBackendResult<bool>

Provided Methods§

Source

fn storage_identity( &self, ) -> StorageBackendResult<Option<PersistentStorageIdentity>>

Source

fn open_session(&self) -> StorageBackendResult<Arc<dyn KeyValueStore>>

Open an independent transaction session over the same logical store. The default keeps simple test/custom stores source-compatible while making the missing MVCC capability explicit when a persistent engine needs a committed reader alongside a pinned statement snapshot.

Source

fn visit_value( &self, _key: &[u8], control: &StorageReadControl, _visit: &mut ValueReadVisitor<'_>, ) -> StorageBackendResult<()>

Visit one borrowed value under the retained read. Providers reserve any temporary encoded payload before fetching it; callbacks must not reenter the store.

Source

fn visit_prefix_after( &self, _prefix: &[u8], _after: Option<&[u8]>, _limit: usize, control: &StorageReadControl, _visit: &mut KeyValueReadVisitor<'_>, ) -> StorageBackendResult<()>

Visit at most limit entries in key order, strictly after after when supplied. Encoded values remain borrowed from their provider owner and callbacks must not reenter the store.

Source

fn contains_prefix_budgeted( &self, prefix: &[u8], control: &StorageReadControl, ) -> StorageBackendResult<bool>

Test prefix existence under the read allowance. Providers that materialize values should implement a key-only probe.

Source

fn contains_key(&self, key: &[u8]) -> StorageBackendResult<bool>

Source

fn scan_prefix_after( &self, prefix: &[u8], after: Option<&[u8]>, limit: usize, ) -> StorageBackendResult<Vec<(Vec<u8>, Vec<u8>)>>

Return at most limit key/value pairs in key order, strictly after after when supplied. This is the bounded value cursor used by large format migrations and other paged consumers.

Source

fn scan_prefix_keys_after( &self, prefix: &[u8], after: Option<&[u8]>, limit: usize, ) -> StorageBackendResult<Vec<Vec<u8>>>

Return at most limit keys in key order, strictly after after when it is present. Backends should override this method with a key-only, bounded range scan so cursor consumers neither materialize the entire prefix nor read values they do not need on every page.

Source