8bacb2b01c
A cancelled async worker now abandons its body at its next suspend instead
of running to completion.
- Cancel-flag back-ref (D4): SpawnOpts.cancel_flag (core.sx) + Fiber.cancel_flag
(sched.sx), set from opts.cancel_flag in Scheduler.spawn_raw; async passes
xx @f.canceled (the Future.canceled Atomic(bool) erased to *void).
- Delivery: Scheduler.suspend_raw consults fiber_canceled(self.current) PRE-park
(raise without parking — no deadlock if cancel landed before the worker ran)
and POST-resume (cancel landed while parked), raising error.Canceled.
cancel(f) flips the sticky flag, marks .canceled, and wakes the worker.
- async worker is failable Closure() -> ($R, !); the completion closure
f.value = worker() catch {…} marks .canceled/.failed and wakes the awaiter,
so post-suspend side effects never run. New failable io.sleep(ms) is the
cancellation point.
- Compiler: a -> ! fn whose only error source is try-ing a protocol method
(io.suspend_raw) was wrongly flagged 'declared ! but never errors';
collectErrorSites now marks a try of a non-identifier callee as a dynamic
(opaque) error source, suppressing the warning.
- Two UAFs found by adversarial review and fixed: (1) cancel-before-park
orphaned io.sleep's armed timer — suspend_raw's pre-park raise now evicts the
current fiber's timer/waiter first; (2) cancel(f) could wake a reaped worker —
now only wakes when was_pending.
Migrated 1805/1806/1824 to failable workers. Lock: example 1825 (seq: 1 -99,
post-suspend line never runs); byte-identical on aarch64-macOS + aarch64-linux.
.ir churn is the SpawnOpts layout change (type-table string renumbering).
19 lines
789 B
Plaintext
19 lines
789 B
Plaintext
// B1.2 — cancellation rides the `!` error channel (model (a)). `f.cancel()`
|
|
// sets the per-future cancel flag + marks `state = .canceled`, so a
|
|
// subsequent `f.await()` raises `error.Canceled` out of its value-failable
|
|
// `($R, !IoErr)` — caught here with `or`. A future that is NOT canceled
|
|
// awaits its value normally.
|
|
#import "modules/std.sx";
|
|
|
|
main :: () {
|
|
// Not canceled → await yields the value. The worker is FAILABLE
|
|
// (`Closure() -> ($R, !)`) — the unified Phase 3 shape.
|
|
ok := context.io.async(() -> (i64, !) => 7);
|
|
print("ok: {}\n", ok.await() or { -1 });
|
|
|
|
// Canceled → await raises .Canceled → the `or` default is taken.
|
|
c := context.io.async(() -> (i64, !) => 7);
|
|
c.cancel();
|
|
print("canceled: {}\n", c.await() or { -99 });
|
|
}
|