Module mailbox 

Guest mailbox integration: exposes host-side wakers to guest tasks.

Safety: the mailbox views raw Wasm linear memory as a trio of shared AtomicU32 slots (flag, tail, ring[..]). The guest owns the memory allocation but must treat the region as host-only: only the host may mutate the indices, while guests read them using matching atomic orderings. The memory outlives the mailbox because we leak the structure via create_guest_mailbox; use one Wasmtime store per guest instance to avoid aliasing. The offsets match the layout emitted by selium-guest:

struct Mailbox {
    head: u32,
    flag: AtomicU32,
    capacity: u32,
    tail: AtomicU32,
    ring: [AtomicU32; CAP]
}

enqueue uses relaxed ordering for the per-slot write, release when signalling writers, and AcqRel on the tail counter so concurrent wakers are totally ordered.

Structs

GuestMailbox

Mailbox exposing guest task IDs to the host async scheduler.

Functions

create_guest_mailbox^⚠

Safety