Struct TieredCache 

pub struct TieredCache { /* private fields */ }

A multi-tier cache where each tier has its own TierConfig.

Reads check tiers in order (L1 first); a hit in tier i > 0 promotes the entry to tier i-1 when the key’s access frequency in that tier meets or exceeds the tier’s TierConfig::promotion_threshold. Writes always go to L1 only.

Implementations

impl TieredCache

pub fn new(tiers: Vec<TierConfig>) -> Self

Construct a TieredCache from a list of tier configurations. The first element is L1 (fastest / smallest), last is the slowest.

pub fn get(&mut self, key: &str) -> Option<Vec<u8>>

Look up key across all tiers in order.

On a hit in tier i > 0, the entry is promoted to tier i-1 if the key’s frequency in that tier meets or exceeds the effective promotion threshold (static or P²-adaptive depending on configuration).

pub fn put(&mut self, key: &str, data: Vec<u8>)

Insert (key, data) into the L1 tier.

pub fn put_at_tier(&mut self, tier_idx: usize, key: &str, data: Vec<u8>)

Insert (key, data) directly into tier tier_idx.

Useful for pre-populating lower tiers (e.g. from a warm-up snapshot).

pub fn evict_tier(&mut self, tier_idx: usize) -> Option<(String, Vec<u8>)>

Evict one entry from tier tier_idx according to that tier’s policy. Returns the evicted (key, data) or None if the tier is empty.

pub fn stats(&self) -> TieredCacheStats

Return an aggregate statistics snapshot.

pub fn warmup(&mut self, entries: &[(String, Vec<u8>)])

Bulk-insert entries into L1 without triggering eviction.

pub fn invalidate(&mut self, key: &str) -> bool

Remove key from every tier. Returns true if it was found in at least one tier.

pub fn tier_count(&self) -> usize

Return the number of tiers.

pub fn tier_promotions(&self, tier_idx: usize) -> u64

Return the number of promotions from tier tier_idx to the tier above.

pub fn tier_hit_count(&self, tier_idx: usize) -> u64

Return the number of hits recorded for tier tier_idx.

pub fn reset_tier_arena(&mut self, tier_idx: usize)

Reset the bump arena of tier tier_idx (reclaims all arena memory).

After a reset, all previously stored arena handles for that tier are invalid; this is intended for use after a bulk eviction sweep.