Struct PageManager 

pub struct PageManager { /* private fields */ }

Manages a file-backed page store with free-list allocation.

Implementations

impl PageManager

pub fn open(dir_path: &Path) -> MenteResult<Self>

Open (or create) a page file at dir_path/pages.db.

pub fn reload_header(&mut self) -> MenteResult<()>

Re-read the file header from disk to pick up changes made by another process.

pub fn allocate_page(&mut self) -> MenteResult<PageId>

Allocate a new page, reusing from the free list when possible.

pub fn read_page(&mut self, page_id: PageId) -> MenteResult<Box<Page>>

Read a page from disk.

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

Write a page to disk.

pub fn free_page(&mut self, page_id: PageId) -> MenteResult<()>

Return a page to the free list.

pub fn rebuild_free_list(&mut self) -> MenteResult<()>

Rebuild the free list by scanning page types.

Used after WAL recovery: header updates are not fsynced per write, so the persisted free list can disagree with WAL-replayed page states. Page types are WAL-authoritative; the chain is derived from them.

pub fn rebuild_free_list_from( &mut self, pages: &BTreeSet<u64>, ) -> MenteResult<bool>

Rebuild the free list from a known set of free pages instead of scanning every page. Every listed page is read first and must be typed Free; if any is not, nothing is written and false is returned so the caller falls back to Self::rebuild_free_list. A Data page must never be put on the free list, since the next allocation would overwrite it.

pub fn reads(&self) -> u64

Pages read from disk since this manager was opened.

pub fn page_count(&self) -> u64

Total number of pages (including the header page).

pub fn sync(&mut self) -> MenteResult<()>

Sync page file data to disk.