Struct FreeList 

pub struct FreeList { /* private fields */ }

In-memory freelist tracking

Maintains a fast in-memory list of free pages, with persistence through trunk pages.

Implementations

impl FreeList

pub fn new() -> FreeList

Create an empty freelist

pub fn from_header(trunk_head: u32, total_free: u32) -> FreeList

Create freelist from header page info

pub fn trunk_head(&self) -> u32

Get trunk head page ID

pub fn total_free(&self) -> u32

Get total count of free pages

pub fn is_empty(&self) -> bool

Check if freelist is empty

pub fn is_dirty(&self) -> bool

Check if freelist has been modified

pub fn mark_clean(&mut self)

Mark freelist as clean

pub fn allocate(&mut self) -> Option<u32>

Allocate a free page

Returns None if no free pages available.

pub fn free(&mut self, page_id: u32)

Return a page to the freelist

pub fn free_batch(&mut self, page_ids: &[u32])

Add multiple pages to freelist

pub fn in_memory_count(&self) -> usize

Get count of pages in memory (not including trunk pages)

pub fn load_from_trunk( &mut self, trunk: &Page, ) -> Result<Option<u32>, FreeListError>

Load free pages from a trunk page

pub fn create_trunk(&mut self, trunk_page_id: u32, next_trunk: u32) -> Page

Create a trunk page from current free pages

Moves pages from in-memory list to a trunk page. Returns the trunk page and remaining pages.

pub fn flush_to_trunks( &mut self, threshold: usize, allocate_page: impl FnMut() -> u32, ) -> Vec<Page>

Flush excess free pages to trunk pages

If we have more than threshold pages in memory, create trunk pages. Returns trunk pages that need to be written.

pub fn merge_all_trunks( &mut self, load_page: impl Fn(u32) -> Option<Page>, ) -> Result<Vec<u32>, FreeListError>

Merge all trunk pages into memory

Used during compaction to reclaim trunk pages.

Trait Implementations

impl Debug for FreeList

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

Formats the value using the given formatter.

impl Default for FreeList

fn default() -> FreeList

Returns the “default value” for a type.