Struct Manager 

pub struct Manager<const N: usize>(/* private fields */);

A shared LRU cache manager designed to manage a large volume of assets.

• Space optimized in-memory LRU (see pingora_lru).
• Instead of a single giant LRU, this struct shards the assets into N independent LRUs.

This allows EvictionManager::save() not to lock the entire cache manager while performing serialization.

Implementations

impl<const N: usize> Manager<N>

pub fn with_capacity(limit: usize, capacity: usize) -> Self

Create a Manager with the given size limit and estimated per shard capacity.

The capacity is for preallocating to avoid reallocation cost when the LRU grows.

pub fn with_capacity_and_watermark( limit: usize, capacity: usize, watermark: Option<usize>, ) -> Self

Create a Manager with an optional watermark in addition to weight limit.

When watermark is set, the underlying LRU will also evict to keep total item count under or equal to that watermark.

pub fn weight_limit(&self) -> usize

Return the current total cache weight limit.

pub fn set_weight_limit(&self, limit: usize)

Set the total cache weight limit used by future eviction decisions.

pub fn shards(&self) -> usize

Get the number of shards

pub fn shard_weight(&self, shard: usize) -> usize

Get the weight (total size) of a specific shard

pub fn shard_len(&self, shard: usize) -> usize

Get the number of items in a specific shard. Best-effort lock-free read; see pingora_lru::Lru::shard_len for the consistency semantics.

pub fn get_shard_for_key(&self, key: &CacheEntryKey) -> usize

Get the shard index for a given cache entry

This allows callers to know which shard was affected by an operation without acquiring any locks.

pub fn peek_lru(&self, shard: usize) -> Option<CacheEntryKey>

Peek at the least-recently-used key in the given shard without evicting it.

Returns the cache entry at the LRU tail of the shard, or None if empty. Useful for reporting the eviction frontier (the age of the next item that would be evicted).

pub fn serialize_shard(&self, shard: usize) -> Result<Vec<u8>>

Serialize the given shard

pub fn deserialize_shard(&self, buf: &[u8]) -> Result<()>

Deserialize a shard

Shard number is not needed because the key itself will hash to the correct shard.

pub fn peek_weight(&self, item: &CacheEntryKey) -> Option<usize>

Peek the weight associated with a cache entry without changing its LRU order.

Trait Implementations

impl<const N: usize> EvictionManager for Manager<N>

fn total_size(&self) -> usize

Total size of the cache in bytes tracked by this eviction manager

fn total_items(&self) -> usize

Number of assets tracked by this eviction manager

fn evicted_size(&self) -> usize

Number of bytes that are already evicted

fn evicted_items(&self) -> usize

Number of assets that are already evicted

fn admit( &self, item: CacheEntryKey, size: usize, _fresh_until: SystemTime, ) -> Vec<CacheEntryKey>

Admit an item

fn increment_weight( &self, item: &CacheEntryKey, delta: usize, max_weight: Option<usize>, ) -> Vec<CacheEntryKey>

Adjust an item’s weight upwards by a delta. If the item is not already admitted, track it with the delta as its initial weight, capped by max_weight, and floored to 1.

fn remove(&self, item: CacheEntryKeyRef<'_>)

Remove an item from the eviction manager.

fn access( &self, item: &CacheEntryKey, size: usize, _fresh_until: SystemTime, ) -> bool

Access an item that should already be in cache.

fn peek(&self, item: &CacheEntryKey) -> bool

Peek into the manager to see if the item is already tracked by the system

fn save<'life0, 'life1, 'async_trait>( &'life0 self, dir_path: &'life1 str, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Serialize to save the state of this eviction manager to disk

fn load<'life0, 'life1, 'async_trait>( &'life0 self, dir_path: &'life1 str, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

The counterpart of Self::save().