Struct CellCache 

pub struct CellCache { /* private fields */ }

Local cell cache with LRU eviction policy.

The cache stores recently accessed cells from object storage in the local filesystem. When the cache exceeds its size limit, the least recently accessed entries are evicted.

Thread Safety

The cache is designed for concurrent access from multiple bees. All operations use interior mutability via RwLock and atomic operations.

Implementations

impl CellCache

pub async fn new( cache_dir: PathBuf, max_size: u64, storage: Arc<dyn StorageBackend>, ) -> Result<Self>

Create a new CellCache with the specified directory and size limit.

Arguments

• cache_dir — Directory where cached cells will be stored.
• max_size — Maximum total size of cached files in bytes.
• storage — Storage backend for fetching cells on cache miss.

Errors

Returns an error if the cache directory cannot be created.

pub async fn get(&self, storage_key: &str) -> Result<PathBuf>

Get a cell from the cache or fetch it from storage on cache miss.

Arguments

• storage_key — The storage key for the cell (e.g., “cells/frame_id/cell_abc.parquet”).

Returns

Returns the local filesystem path to the cached cell.

Behavior

• Cache hit: Updates last accessed time and returns the local path.
• Cache miss: Fetches the cell from storage, adds it to the cache, and returns the path.
• Automatically evicts LRU entries if the cache exceeds its size limit.

pub fn size(&self) -> u64

Get the current size of the cache in bytes.

pub async fn list_cached_cells(&self) -> HashMap<String, u64>

Get a list of all cached cells for heartbeat reporting.

Returns a map of storage keys to their sizes in bytes.