Struct CacheRef 

pub struct CacheRef { /* private fields */ }

A reference to a page cache that can be shared across threads via cloning, along with the page size that will be used with it. Provides the API for interacting with the page cache in a thread-safe manner.

Implementations

impl CacheRef

pub fn new( pool: BufferPool, page_size: NonZeroU16, capacity: NonZeroUsize, ) -> Self

Create a shared page-cache handle backed by pool.

The cache stores at most capacity pages, each exactly page_size bytes (see Self::page_size for how this relates to a page’s physical size on disk). Initialization eagerly allocates and zeroes all cache slots from pool.

Any page_size is accepted, but physical pages that do not align with storage pages (see the module docs) amplify cold random reads. Use super::page_size to pick an aligned value. Cache misses request ReadOptions::DONT_CACHE because the fetched page is retained here.

pub fn from_pooler( pooler: &impl BufferPooler, page_size: NonZeroU16, capacity: NonZeroUsize, ) -> Self

Create a shared page-cache handle, extracting the storage BufferPool from a BufferPooler. Cache misses request ReadOptions::DONT_CACHE.

pub const fn page_size(&self) -> NonZeroU16

The page size used by this page cache: the logical payload bytes stored per page. Each page occupies page_size() + CHECKSUM_SIZE bytes on disk (its physical size).

pub const fn pool(&self) -> &BufferPool

Returns the storage buffer pool associated with this cache.

pub fn next_id(&self) -> u64

Returns a unique id for the next blob that will use this page cache.

pub fn offset_to_page(&self, offset: u64) -> (u64, u64)

Convert a logical offset into the number of the page it belongs to and the offset within that page.

pub fn cache(&self, blob_id: u64, buf: &[u8], offset: u64) -> usize

Cache the provided pages of data in the page cache, returning the remaining bytes that didn’t fill a whole page. offset must be page aligned.

Panics

• Panics if offset is not page aligned.
• If the buffer is not the size of a page.

Trait Implementations

impl Clone for CacheRef

fn clone(&self) -> CacheRef

Returns a duplicate of the value.

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

Performs copy-assignment from source.