src/cancel.rs

This file holds your cooperative cancellation flag, shareable as Arc<CancelSignal> and honored at every level of your engine.

Key items

cancel() fires your signal. It is idempotent and wakes all waiters.

is_cancelled() lets you poll without blocking.

notified().await gives you a race-free async wait that completes immediately if someone already fired.

reset() swaps in a fresh token, because the underlying tokio CancellationToken is one-shot by design.

Behavior notes

This wraps tokio_util::sync::CancellationToken precisely to avoid the check-then-act race you inherit from hand-rolled AtomicBool plus Notify.

Your engine re-arms in finalize(), after the run observed the cancel, so a cancel arriving between runs is observed by exactly one run and then cleared. One cancel can never permanently kill an agent.

A task already waiting on the old token when reset() happens still completes against the old fired token, so keep your waits short.

Lock poisoning is recovered here. The data is a single value, so the recover_guard policy applies.

Deep dive: Cancellation.