Struct ConstMapShard 

pub struct ConstMapShard<'a, K: Key + Send + Sync + Hash + Eq, const V: usize, H: WriteHook<K> = NoHook, D: Durability = Bitcask> { /* private fields */ }

Handle for atomic multi-key operations within a single shard. Obtained via ConstMap::atomic. The shard + index locks are held for the lifetime of this struct — keep the closure short.

Implementations

impl<K: Key + Send + Sync + Hash + Eq, const V: usize, H: WriteHook<K>, D: Durability> ConstMapShard<'_, K, V, H, D>

pub fn put(&mut self, key: &K, value: &[u8; V]) -> DbResult<Option<[u8; V]>>

pub fn insert(&mut self, key: &K, value: &[u8; V]) -> DbResult<()>

pub fn delete(&mut self, key: &K) -> DbResult<Option<[u8; V]>>

pub fn update( &mut self, key: &K, f: impl FnOnce(&[u8; V]) -> [u8; V], ) -> DbResult<Option<[u8; V]>>

Read-modify-write within this shard: applies f to the current value and stores the result. Returns Some(new_value) if the key existed, None otherwise (closure not invoked). The closure must not be heavy — the shard

• index locks are held.

pub fn fetch_update( &mut self, key: &K, f: impl FnOnce(&[u8; V]) -> [u8; V], ) -> DbResult<Option<[u8; V]>>

Like update(), but returns Some(old_value) instead of the new one.

pub fn upsert<U: IntoUpsert<[u8; V]>>( &mut self, key: &K, f: impl FnOnce(Option<&[u8; V]>) -> U, ) -> DbResult<U::Out>

Decide-and-write within this shard. The closure must be short — shard lock is held.

pub fn try_get(&self, key: &K) -> DbResult<Option<[u8; V]>>

pub fn get_or_err(&self, key: &K) -> DbResult<[u8; V]>

pub fn try_contains(&self, key: &K) -> DbResult<bool>