Struct FrameArena 

pub struct FrameArena {
    pub total_allocated: usize,
    pub reset_count: usize,
    /* private fields */
}

A bump-arena that allocates sequentially within fixed-size pages.

Bulk-freed via reset() at function return. Pages are never returned to the OS during execution — they are retained for reuse.

Fields

total_allocated: usize

Total bytes allocated across all arena lifetimes (monotonic counter).

reset_count: usize

Number of reset() calls.

Implementations

impl FrameArena

pub fn new() -> Self

Create a new arena with one pre-allocated page.

pub fn with_page_size(page_size: usize) -> Self

Create an arena with a custom page size (for testing).

pub fn alloc_bytes(&mut self, size: usize) -> (usize, usize)

Allocate size bytes from the arena. Returns the (page_index, offset) pair that identifies the allocation.

If the current page doesn’t have enough room, advances to the next page (allocating a new one if needed).

pub fn get_bytes(&self, page: usize, offset: usize, len: usize) -> Option<&[u8]>

Get a reference to the bytes at the given (page, offset) location.

pub fn get_bytes_mut( &mut self, page: usize, offset: usize, len: usize, ) -> Option<&mut [u8]>

Get a mutable reference to the bytes at the given (page, offset) location.

pub fn reset(&mut self)

Reset the arena for reuse. All previous allocations are invalidated. Pages are NOT freed — they are retained for the next frame.

pub fn page_count(&self) -> usize

Number of pages currently allocated (including unused retained pages).

pub fn capacity(&self) -> usize

Total capacity in bytes across all pages.

pub fn used_bytes(&self) -> usize

Bytes currently in use (from start of page 0 to current cursor).

Trait Implementations

impl Default for FrameArena

fn default() -> Self

Returns the “default value” for a type.