Struct ArenaPool 

pub struct ArenaPool { /* private fields */ }

Pool of reusable byte buffers for arena-backed frame allocations.

Construct one per decoder via ArenaPool::new. Lease an Arena per frame via ArenaPool::lease; drop the arena (or drop the last clone of a Frame holding it) to return its buffer to the pool.

Backpressure: when all max_arenas slots are checked out the next ArenaPool::lease returns Error::ResourceExhausted. A decoder that hits this should surface the error to its caller rather than busy-loop — the upstream pipeline is supposed to drop frames it no longer needs, which returns a buffer to the pool.

ArenaPool is Send + Sync (the inner Mutex<Vec<…>> makes it safe to share across threads even though Arena / Frame themselves are !Send due to their Rc/Cell contents). This asymmetry is intentional: a parallel-decoder thread can share a single pool while each thread owns its own arenas — see also the sibling sync::ArenaPool whose leases are themselves Send + Sync.

Implementations

impl ArenaPool

pub fn new(max_arenas: usize, cap_per_arena: usize) -> Arc<Self>

Construct a new pool with max_arenas buffer slots, each of cap_per_arena bytes. Buffers are allocated lazily on first lease — a freshly constructed pool holds no memory.

Per-arena allocation count is capped at max_alloc_count (use ArenaPool::new which defaults to a generous 1M, or ArenaPool::with_alloc_count_cap to tighten further).

pub fn with_alloc_count_cap( max_arenas: usize, cap_per_arena: usize, max_alloc_count_per_arena: u32, ) -> Arc<Self>

Like ArenaPool::new but lets the caller set the per-arena allocation-count cap. Useful when the caller is plumbing crate::DecoderLimits through.

pub fn cap_per_arena(&self) -> usize

Capacity of each arena buffer this pool hands out, in bytes.

pub fn max_arenas(&self) -> usize

Maximum number of arenas that may be checked out at once.

pub fn lease(self: &Arc<Self>) -> Result<Arena>

Lease one arena from the pool. Returns Error::ResourceExhausted if every arena slot is already checked out by an Arena (or a Frame holding one).