Struct nebari::ChunkCache

pub struct ChunkCache { /* private fields */ }

A configurable cache that operates at the “chunk” level.

While writing databases, individual portions of data are often written as a single chunk. These chunks may be stored encrypted on-disk, but the in-memory cache will be after decryption.

To keep memory usage low, the maximum size for a cached value can be set. It is important that this value be large enough to fit most B-Tree nodes, and that size will depend on how big the tree grows.

Implementations

impl ChunkCache

pub fn new(capacity: usize, max_chunk_length: usize) -> Self

Create a new cache with a maximum number of entries (capacity) and max_chunk_length. Any chunks longer than max_chunk_length will not be cached. The maximum memory usage of this cache can be calculated as capacity * max_chunk_length, although the actual memory usage will likely be much smaller as many chunks are small.

pub fn insert(&self, file_id: u64, position: u64, buffer: ArcBytes<'static>)

Adds a new cached chunk for file_path at position.

pub fn replace_with_decoded<T: AnySendSync + 'static>(
    &self,
    file_id: u64,
    position: u64,
    value: T
)

Adds a new cached chunk for file_path at position.

pub fn get(&self, file_id: u64, position: u64) -> Option<CacheEntry>

Looks up a previously read chunk for file_path at position,

Trait Implementations

impl Clone for ChunkCache

fn clone(&self) -> ChunkCache

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ChunkCache

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

Formats the value using the given formatter.