Struct BufferPool 

pub struct BufferPool { /* private fields */ }

Buffer pool: caches decrypted pages in memory with SIEVE eviction.

Keyed by physical disk offset (not logical page_id) because under CoW/MVCC the same logical page_id can exist at different disk locations.

Invariants:

• HMAC is verified BEFORE decryption on every page fetch (cache miss).
• Dirty pages are PINNED and never evictable until commit.
• Transaction size is bounded by buffer pool capacity.

Implementations

impl BufferPool

pub fn new(capacity: usize) -> Self

pub fn fetch( &mut self, io: &dyn PageIO, page_id: PageId, dek: &[u8; 32], mac_key: &[u8; 32], encryption_epoch: u32, ) -> Result<&Page>

Fetch a page by page_id. Reads from cache or disk.

On cache miss: reads from disk, verifies HMAC BEFORE decrypting, verifies xxHash64 checksum after decrypting.

pub fn fetch_mut( &mut self, io: &dyn PageIO, page_id: PageId, dek: &[u8; 32], mac_key: &[u8; 32], encryption_epoch: u32, ) -> Result<&mut Page>

Fetch a page mutably (for modification during write transaction).

pub fn insert_new(&mut self, page_id: PageId, page: Page) -> Result<()>

Insert a new page directly into the buffer pool (for newly allocated pages). Marks it as dirty immediately.

pub fn mark_dirty(&mut self, page_id: PageId)

Mark a page as dirty (modified in current write transaction).

pub fn flush_dirty( &mut self, io: &dyn PageIO, dek: &[u8; 32], mac_key: &[u8; 32], encryption_epoch: u32, ) -> Result<()>

Flush all dirty pages to disk: encrypt + compute MAC + write. Clears dirty flags after successful flush.

pub fn discard_dirty(&mut self)

Discard all dirty pages (on transaction abort). Removes dirty entries from the cache.

pub fn len(&self) -> usize

Number of pages currently in the cache.

pub fn is_empty(&self) -> bool

Whether the cache is empty.

pub fn dirty_count(&self) -> usize

Number of dirty pages.

pub fn capacity(&self) -> usize

Cache capacity.

pub fn is_cached(&self, page_id: PageId) -> bool

Check if a page is cached.

pub fn clear(&mut self)

Clear all entries from the cache.