Struct FileCache 

pub struct FileCache { /* private fields */ }

Global LRU cache for parquet file contents, shared across all readers and queries.

Memory budget is based on file size. Uses moka’s try_get_with to prevent thundering herd - concurrent requests for the same uncached file will coalesce into a single load operation.

Implementations

impl FileCache

pub fn new(max_capacity_bytes: u64, max_file_size_bytes: u64) -> FileCache

Creates a new file cache with the specified memory budget and max file size.

pub fn should_cache(&self, file_size: u64) -> bool

Check if a file should be cached based on its size

pub async fn get_or_load<F, Fut, E>( &self, file_path: &str, file_size: u64, loader: F, ) -> Result<Bytes, Error>

where F: FnOnce() -> Fut, Fut: Future<Output = Result<Bytes, E>>, E: Send + Sync + Error + 'static,

Gets file contents, loading from the provided async function on cache miss.

Uses moka’s try_get_with to coalesce concurrent requests - if multiple callers request the same uncached file simultaneously, only one will execute the loader while others wait for the result.

Returns an error if file_size >= 4GB (moka weigher uses u32).

pub fn stats(&self) -> (u64, u64)

Returns cache statistics (entry_count, weighted_size_bytes).

pub async fn run_pending_tasks(&self)

Runs pending cache maintenance tasks.

This should be called to ensure cache statistics are up-to-date, particularly useful in test scenarios.

Trait Implementations

impl Debug for FileCache

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for FileCache

fn default() -> FileCache

Returns the “default value” for a type.