Struct DiskCache 

pub struct DiskCache { /* private fields */ }

Write-through disk cache wrapping a remote PageStore.

The local cache is a LocalPageStore on fast storage (NVMe). Pages are cached on first read and updated on every write.

Implementations

impl DiskCache

pub fn new( cache_dir: impl AsRef<Path>, remote: Box<dyn PageStore>, ) -> KyuResult<Self>

Create a new disk cache.

• cache_dir: local directory for cached pages (should be on fast storage)
• remote: the underlying remote page store (e.g. S3)

pub fn cached_count(&self) -> usize

Number of pages currently in the local cache.

pub fn evict_all(&self)

Evict all cached pages (for testing or memory pressure).

Trait Implementations

impl PageStore for DiskCache

fn read_page(&self, page_id: PageId, buf: &mut [u8]) -> KyuResult<()>

Read a page from storage into the given buffer. The buffer must be exactly PAGE_SIZE bytes.

fn write_page(&self, page_id: PageId, buf: &[u8]) -> KyuResult<()>

Write a page from the given buffer to storage. The buffer must be exactly PAGE_SIZE bytes.

fn allocate_page(&self, file_id: FileId) -> KyuResult<u32>

Allocate a new page in the given file, returning its page index.

fn sync_file(&self, file_id: FileId) -> KyuResult<()>

Sync a file’s data to durable storage.