Trait CacheStore 

pub trait CacheStore: Send + Sync {
    // Required methods
    fn get(&self, key: &CacheKey) -> Result<Option<Value>>;
    fn put(&self, key: &CacheKey, value: &Value) -> Result<()>;
    fn exists(&self, key: &CacheKey) -> Result<bool>;
    fn remove(&self, key: &CacheKey) -> Result<()>;
    fn metadata(&self, key: &CacheKey) -> Result<Option<EntryMeta>>;

    // Provided methods
    fn put_with_origin(
        &self,
        key: &CacheKey,
        value: &Value,
        origin: &Origin,
    ) -> Result<()> { ... }
    fn put_computed(
        &self,
        key: &CacheKey,
        value: &Value,
        origin: &Origin,
        compute: Duration,
        deterministic: bool,
    ) -> Result<()> { ... }
    fn tier(&self) -> CacheTier { ... }
    fn get_located(&self, key: &CacheKey) -> Result<Option<(Value, CacheTier)>> { ... }
}

The K/V cache store interface.

Implementations may be in-memory, on-disk (RocksDB/sled), or remote (S3). The tiered cache composes multiple stores.

Required Methods

fn get(&self, key: &CacheKey) -> Result<Option<Value>>

Look up the value stored under key, None on a miss.

fn put(&self, key: &CacheKey, value: &Value) -> Result<()>

Store value under key, replacing any existing entry.

fn exists(&self, key: &CacheKey) -> Result<bool>

Whether key has an entry, without loading the value.

fn remove(&self, key: &CacheKey) -> Result<()>

Delete the entry under key; absent keys are not an error.

fn metadata(&self, key: &CacheKey) -> Result<Option<EntryMeta>>

The entry’s EntryMeta, without loading the value.

Provided Methods

fn put_with_origin( &self, key: &CacheKey, value: &Value, origin: &Origin, ) -> Result<()>

Store a value together with its provenance. Stores that persist metadata should override this; the default discards the origin.

fn put_computed( &self, key: &CacheKey, value: &Value, origin: &Origin, compute: Duration, deterministic: bool, ) -> Result<()>

Store a freshly-computed value with its full provenance record: origin, wall-clock compute cost, and the producer’s determinism declaration. Cost-aware eviction needs the compute time — a tiny value that took days must outlive a huge one that took seconds. The default discards the extra metadata.

fn tier(&self) -> CacheTier

Which tier this store is, for reporting.

A single-tier store answers with its own kind. CacheTier::Memory is the default because the in-memory store is the one people write by hand; a store that is anything else should say so.

fn get_located(&self, key: &CacheKey) -> Result<Option<(Value, CacheTier)>>

Like CacheStore::get, but also reports which tier served the value.

A composed store overrides this — that is the whole point. Without it, a hit served from disk is indistinguishable from one served from RAM, and the numbers that are supposed to tell you whether the disk tier is earning its keep say only that the cache was used.

Implementors