0cf6b80396611d369b6c5c86305e32f823e2307c
7
Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 smarm-agent
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f5fbb5b144 |
mailbox: Phase 3 — typed Pid<A> over a raw inner identity (RFC 014)
Fold the made-up Addr<A> back into the pid, where it belonged. The typed
handle IS the pid now.
- RawPid { index, generation }: today's Pid, renamed — the raw numbers, the key
for identity-only plumbing and the heterogeneous monitor/link/pg tables.
- Pid<A = Erased>: RawPid + phantom actor type. Both an identity and a direct,
identity-bound address; when A: Addressable a send delivers A::Msg to exactly
this incarnation (next phase). Hand-written impls (eq/hash/fmt on the raw
only, no A bounds); fn()->A phantom keeps it Copy+Send+Sync for any A.
- Erased: uninhabited, deliberately NOT Addressable, so a typed send to a
Pid<Erased> won't compile — that's what send_dyn (section 4.6) will be for. It
is the default type arg, so every plain "Pid" written today still compiles as
Pid<Erased>; that, plus the fact that nothing destructures pid fields, is why
an identity change touching 18 files cascaded to zero internal edits.
- Addr<A> deleted; Name<M> / the Phase-2 registry unchanged (they key on raw).
Per the call to make the consumers take typed pids: the user-facing identity
APIs — monitor, link, unlink, request_stop, spawn_under(supervisor), pg::join,
pg::leave — are now generic over A and erase at the boundary; their bodies are
byte-for-byte unchanged. Pure plumbing (unpark, set_current_pid,
register_supervisor_channel) stays erased — it only ever sees internal identity.
Phase 1's Addr tests become Pid<A> tests (identity/copy/erase/Debug, Send+Sync).
Full suite + order-checker green, warning-free across all targets.
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smarm
|
8ff6cf4afd |
feat(channel): migrate Inner to RawMutex; two-class lock order (Leaf -> Channel)
Phase 2 surfaced the hole this closes: channel guards were held with preemption enabled, so a timeslice switch inside a channel critical section could release the pthread mutex from a different OS thread (UB). RawMutex disables preemption for the guard span and is cross-thread-release sound by construction; poison goes away with it. The strict single-class leaf rule cannot survive the migration: finalize clones the supervisor/trap senders and monitor() clones the Down sender, all under a cold lock, and those senders live in the slot - the nesting is structural. The leaf check is therefore generalized to two classes: Leaf (cold locks, free list, stack pool) and Channel. Order is Leaf -> Channel, at most one of each; both directions of violation are debug-asserted at the acquisition site. Channel critical sections call only the lock-free unpark protocol, so the order is acyclic. Tests: class-ordering unit tests in raw_mutex (allowed nesting + all three rejected shapes), plus a multi-scheduler integration test driving channels through monitor churn and actor death so any ordering regression trips the debug assert instead of deadlocking. |
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|
Claude
|
5e0c9d45da |
feat(runtime): phase 2 — fixed slab, per-slot packed-atomic state machine, raw cold locks
The slot table split (ROADMAP_v0.5 phase 2): slot lookup is lock-free, the
run path (yield/park/unpark/pop/resume) takes zero locks beyond the queue
mutex itself, and SharedState shrinks to { run_queue }.
Core pieces:
- src/raw_mutex.rs: hand-rolled 3-state futex mutex (Drepper mutex3),
non-poisoning; the guard enters NoPreempt, which both bounds hold times and
structurally closes the unwind-under-lock hole (the stop sentinel shares
the gate). Used for per-slot cold data, the free list, and the stack pool.
- Fixed slab Box<[Slot]> (default max_actors = 16_384, ~4 MiB, align(128)
against false sharing). Slots never move -> stable addresses, lock-free
index. Exhaustion panics loudly, naming Config::max_actors(n) as the fix.
Unbounded/segmented slab stays deferred (see ROADMAP).
- Per-slot AtomicU64 packing (generation << 32 | state), states
Vacant/Queued/Running/RunningNotified/Parked/Done. Every transition CASes
the packed word, so the generation check is atomic with the transition: no
ABA, no spurious unparks on recycled slots. RunningNotified replaces the
pending_unpark bool (the lost-wakeup window is a state, not a flag) and
uniformly fixes a LATENT LOST WAKEUP in the old Blocking-IO completion
path, which set the result for a still-Running actor without flagging it.
- Invariant: a pid is in the run queue at most once (pushes pair 1:1 with
transitions into Queued; only the scheduler does Queued->Running). This is
what makes phase 3's bounded rings sound.
- sp -> relaxed AtomicUsize; stop flag + first-resume closure as AtomicPtrs
(closure double-boxed for a thin pointer, swap-to-take): the resume path is
fully atomic.
- finalize_actor: Done published under the dying slot's cold lock (join's
check-or-register is linearized by it); link cascade locks peers ONE AT A
TIME (cold locks are leaves) with the acyclicity argument written at the
site; link() registers on the target first, then self (stale self-entries
are benign, every walk re-verifies the peer's word).
- Termination by counters: live_actors incremented in spawn pre-enqueue,
decremented at the very END of finalize after all wakeup enqueues; exit on
io_out == 0 (read before the queue lock, phase-1 ordering) && queue empty
&& live == 0. Soundness note at the site: any enqueue targets a live actor.
- spawn boxes the closure and acquires the stack BEFORE any runtime lock: no
allocation ever happens under a global lock anymore.
- with_runtime/try_with_runtime now enter NoPreempt for their full span.
This fixes a bug the rework exposed: install_actor allocated with
preemption enabled while the RUNTIME RefCell borrow was live; a timeslice
preemption there migrates the actor across OS threads and the borrow guard
increments one thread's RefCell count and decrements another's — underflow
to 'permanently mutably borrowed', cascading panics (caught by stress
suite: deterministic non-unwinding-panic abort in lost_wakeup_many_pairs).
The old code was safe only by accident; now it's structural.
- Behavior note: request_stop on a RUNNING target now marks it
RunningNotified, so its next park returns immediately to an observation
point — faster stop observation; parked/queued/done semantics unchanged.
Validated: 22 suites green in release (1/2/8-thread oversubscribed on the
1-core sandbox) and in debug with all debug_asserts live; stress suite x5.
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|
Claude
|
3c7e26bc98 |
feat(runtime): phase 1 — peel timers/io/monitor-id out of SharedState; gate stop sentinel behind PREEMPTION_ENABLED
- next_monitor_id -> AtomicU64 on RuntimeInner - timers -> own Mutex<Timers>; io -> own Mutex<Option<IoThread>> (lock order: io-before-shared) - pending_closures Vec folded into Slot::pending_closure - termination check reads io liveness before shared; ordering argument documented - poison fix: check_cancelled() no longer fires while preemption is disabled, so a cancellation unwind can never poison a runtime/channel mutex - regression test: tests/poison_stop.rs - ROADMAP_v0.5.md added |
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|
smarm-dev
|
518103750b |
feat(monitor): demonitor + per-monitor MonitorId (roadmap #5)
Monitors could be installed but never taken down. That gap was about to
bite: the gen_server call timeout we want next is the Erlang dance —
monitor the server, wait for the reply or a Down or a deadline, then
demonitor — and without a way to remove a registration, every timed-out
call would leak a monitor on the server's slot and risk a stale Down
arriving later. So this lands the cleanup primitive before anything
depends on the old shape.
The decision flagged in the roadmap ("decide the monitor API NOW") is
resolved by giving each registration a process-unique MonitorId and
returning it to the caller. monitor() now hands back a
Monitor { id, target, rx } rather than a bare Receiver<Down>: read the
notice from rx as before, and pass &Monitor to demonitor to tear exactly
that registration down. The id comes from a monotonic counter in shared
state, bumped under the same lock that does the registration, so it's
deterministic and never reused — which is what lets demonitor name one of
several monitors on the same target unambiguously. target rode along on
the struct (over the sketched {id, rx}) purely so demonitor can go
straight to the slot instead of scanning every slot for the id.
demonitor returns Option<MonitorId> rather than a bool: Some(id) when a
live registration was found and removed, None when there was nothing left
to remove — it already fired (the registration is drained on finalize),
it was a NoProc, or the slot has been reclaimed. The generation half of
the pid quietly protects that last case: a recycled slot index fails
slot_mut's generation check, so a late demonitor is a clean no-op and can
never strip a different actor's monitor that happens to share the index.
The one piece of real care is reentrancy. Removing a registration drops
the slot's Sender, and Sender::drop can unpark a parked receiver, which
re-enters the shared mutex — which is not reentrant. So demonitor moves
the sender out of the Vec under the lock and lets it drop only after the
lock is released, the same discipline finalize_actor already follows for
its monitor and supervisor sends.
Flushing a Down the target already queued isn't a separate flag; it falls
out of dropping the Monitor. demonitor(&m); drop(m) stops future notices
and discards any queued one — the gen_server-call cleanup in one move.
Storage is now Vec<(MonitorId, Sender<Down>)>. The three slot-reset sites
were left alone on purpose: they clear/rebuild the Vec, which doesn't care
about the element type, so there's no fourth reset obligation. finalize
just destructures (_, m). Because chained_spawn and yield_many register no
monitors, that Vec stays empty on the hot path — taking an empty Vec costs
the same and the notify loop runs zero times — and a before/after general
probe confirmed both medians sit within noise.
Tests cover the three behaviours that matter: a demonitored watcher gets
no Down (its channel closes), demonitoring one of several leaves the
siblings firing normally, and demonitoring after the Down has already
fired reports None.
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smarm-dev
|
d9a6520a24 |
feat(cancel): cooperative cancellation via sentinel unwind
request_stop(pid) sets a per-actor flag and wakes a parked target. The actor realizes the stop as a controlled unwind at its next observation point (check!()/alloc via maybe_preempt, or the wakeup side of any blocking park): a StopSentinel panic tears the stack down via the trampoline's existing catch_unwind, running Drop, and is reported as the new Outcome::Stopped (distinct from a user Panic). Death surface kept distinct from Exit: Signal::Stopped(pid) + DownReason::Stopped, so the supervisor await logic to come can tell a requested stop apart from a self-termination. Flag lives on Actor behind Arc<AtomicBool>; the scheduler resume path takes a raw pointer into it (no per-resume refcount traffic), keeping yield throughput at baseline. |
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smarm-dev
|
461de2c451 |
feat(monitor): unidirectional one-shot process monitors
`monitor(pid) -> Receiver<Down>` lets any actor watch any other and
receive a single Down{pid, reason} when it terminates. Generalizes the
existing single supervisor_channel (which is just a hard-wired monitor
the parent installs at spawn).
- src/monitor.rs: Down / DownReason{Exit,Panic,NoProc} + monitor().
Payload-free: a panic payload has one owner and goes to the joiner via
JoinError, so monitors learn only that it panicked. Monitoring an
already-gone pid yields NoProc immediately.
- runtime: Slot grows `monitors: Vec<Sender<Down>>`; finalize_actor
drains and notifies them outside the shared lock (send can unpark a
receiver, which re-takes the non-reentrant mutex). Cleared in
reclaim_slot and on slot reuse at spawn.
- Registration and finalize both serialize on the shared mutex, so a
target alive at registration always delivers a real Down (no race
between liveness check and registration).
tests/monitor.rs: Exit, Panic, NoProc-on-dead-target, and fan-out to
multiple monitors. Full suite green.
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