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CacheBackend

lance_core::cache::backend

Trait CacheBackend 

Source 
pub trait CacheBackend:
    Send
    + Sync
    + Debug {
    // Required methods
    fn get<'life0, 'life1, 'async_trait>(
        &'life0 self,
        key: &'life1 InternalCacheKey,
        codec: Option<CacheCodec>,
    ) -> Pin<Box<dyn Future<Output = Option<CacheEntry>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait;
    fn insert<'life0, 'life1, 'async_trait>(
        &'life0 self,
        key: &'life1 InternalCacheKey,
        entry: CacheEntry,
        size_bytes: usize,
        codec: Option<CacheCodec>,
    ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait;
    fn get_or_insert<'a, 'life0, 'life1, 'async_trait>(
        &'life0 self,
        key: &'life1 InternalCacheKey,
        loader: Pin<Box<dyn Future<Output = Result<(CacheEntry, usize)>> + Send + 'a>>,
        codec: Option<CacheCodec>,
    ) -> Pin<Box<dyn Future<Output = Result<(CacheEntry, bool)>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'a: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait;
    fn invalidate_prefix<'life0, 'life1, 'async_trait>(
        &'life0 self,
        prefix: &'life1 str,
    ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait;
    fn clear<'life0, 'async_trait>(
        &'life0 self,
    ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait;
    fn num_entries<'life0, 'async_trait>(
        &'life0 self,
    ) -> Pin<Box<dyn Future<Output = usize> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait;
    fn size_bytes<'life0, 'async_trait>(
        &'life0 self,
    ) -> Pin<Box<dyn Future<Output = usize> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait;

    // Provided methods
    fn approx_num_entries(&self) -> usize { ... }
    fn approx_size_bytes(&self) -> usize { ... }
}
Expand description

Low-level pluggable cache backend.

Implementations store entries keyed by InternalCacheKey and return type-erased CacheEntry values. LanceCache handles key construction and type safety; backend authors only need to implement storage and eviction.

Required Methods§

Source

fn get<'life0, 'life1, 'async_trait>( &'life0 self, key: &'life1 InternalCacheKey, codec: Option<CacheCodec>, ) -> Pin<Box<dyn Future<Output = Option<CacheEntry>> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Look up an entry by its key.

codec is provided so that persistent backends can deserialize the entry from storage. In-memory backends can ignore it. When codec is None, the entry type does not support serialization yet and must be stored in-memory.

The goal is for all cache entry types to eventually have codecs, at which point the Option will be removed.

Source

fn insert<'life0, 'life1, 'async_trait>( &'life0 self, key: &'life1 InternalCacheKey, entry: CacheEntry, size_bytes: usize, codec: Option<CacheCodec>, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Store an entry. size_bytes is used for eviction accounting.

See get for codec semantics.

Source

fn get_or_insert<'a, 'life0, 'life1, 'async_trait>( &'life0 self, key: &'life1 InternalCacheKey, loader: Pin<Box<dyn Future<Output = Result<(CacheEntry, usize)>> + Send + 'a>>, codec: Option<CacheCodec>, ) -> Pin<Box<dyn Future<Output = Result<(CacheEntry, bool)>> + Send + 'async_trait>>
where Self: 'async_trait, 'a: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Get an existing entry or compute it from loader.

Implementations should deduplicate concurrent loads for the same key so the loader runs at most once.

Returns (entry, was_cached) where was_cached is true if the entry was already present in the cache (the loader was not invoked).

See get for codec semantics.

Source

fn invalidate_prefix<'life0, 'life1, 'async_trait>( &'life0 self, prefix: &'life1 str, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Remove all entries whose prefix starts with the given string.

Source

fn clear<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait,

Remove all entries.

Source

fn num_entries<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = usize> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait,

Number of entries currently stored (may flush pending operations).

Source

fn size_bytes<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = usize> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait,

Total weighted size in bytes of all stored entries (may flush pending operations).

Provided Methods§

Source

fn approx_num_entries(&self) -> usize

Approximate number of entries, callable from synchronous contexts. Backends that cannot provide this cheaply should return 0.

Source

fn approx_size_bytes(&self) -> usize

Approximate weighted size in bytes, callable from synchronous contexts. Used by DeepSizeOf to report cache memory usage. Backends that cannot provide this cheaply should return 0.

Assumes entries do not share underlying buffers; if they do, the returned total may overcount.

Implementors§