Struct Arena 

pub struct Arena { /* private fields */ }

A bump allocator backing one request’s allocations.

alloc returns an unaligned byte cursor; callers responsible for alignment. Drop releases all pages at once — no per-value destructor is run, so callers must put only POD-shaped data here today (slice-1 doesn’t actually allocate Values into the arena; this is purely a lifecycle harness).

Implementations

impl Arena

pub fn new() -> Self

Create an empty arena. No pages allocated until the first alloc call.

pub fn alloc(&self, len: usize) -> &mut [u8]

Allocate len bytes from the arena. Returns a &mut [u8] bound to the arena’s lifetime. Grows by appending a fresh page if the request doesn’t fit in the active page.

Panics if len > PAGE_BYTES. Larger allocations would require multi-page allocation (boxed slice). Out of scope for the scaffolding — the IndexMap / VecDeque values the arena will eventually carry are well under 64 KiB.

Safety

The returned slice is uninitialized.

pub fn bytes_allocated(&self) -> usize

Total bytes allocated across all pages. Useful for tests and a future arena.stat builtin that surfaces per-request allocation pressure.

pub fn page_count(&self) -> usize

Page count. Tests use this to confirm grow-on-demand fires at the right thresholds.

Trait Implementations

impl Default for Arena

fn default() -> Self

Returns the “default value” for a type.