taskvisor 0.8.0

In-process Tokio task supervisor with retries, graceful shutdown, reliable final outcomes, and per-key admission control
Documentation
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
//! Tests for submission admission and registry decisions.

use super::support::*;
use crate::controller::engine::state::{PendingSubmission, SlotPhase, SlotState};
use crate::controller::engine::{AdmissionResult, Controller, Submission};

#[tokio::test]
async fn stale_admission_ok_and_err_do_not_mutate_new_owner() {
    let ctrl = make_controller(ControllerConfig::default(), Bus::new(64));
    let stale_id = TaskId::next();
    let current_id = TaskId::next();
    let slot_arc = ctrl.get_or_create_slot("s");
    {
        let mut slot = slot_arc.lock().await;
        *slot = admitting_slot(current_id);
    }

    let mut operations = tracked_operations(&ctrl);
    ctrl.handle_admission_result(
        AdmissionResult {
            id: stale_id,
            slot_name: Arc::from("s"),
            decision: Ok(crate::core::RemovalCompletion::new()),
        },
        &mut operations,
    )
    .await;
    ctrl.handle_admission_result(
        AdmissionResult {
            id: stale_id,
            slot_name: Arc::from("s"),
            decision: Err(RuntimeError::ShuttingDown),
        },
        &mut operations,
    )
    .await;

    let slot = slot_arc.lock().await;
    assert_eq!(slot.owner_id(), Some(current_id));
    assert!(matches!(
        slot.phase(),
        SlotPhase::Admitting { owner, .. } if owner == current_id
    ));
    assert!(operations.completions.is_empty());
    assert!(operations.removals.is_empty());
}

#[tokio::test]
async fn explicit_slot_drop_if_running_rejects_before_pending_ownership() {
    let supervisor = Supervisor::new(crate::SupervisorConfig::default(), vec![]);
    let bus = Bus::new(64);
    let ctrl = Controller::new(ControllerConfig::default(), supervisor.core(), bus.clone());
    let mut events = bus.subscribe();
    let owner = TaskId::next();
    ctrl.state().slots.insert(
        Arc::from("busy-slot"),
        Arc::new(Mutex::new(running_slot(owner))),
    );
    let id = TaskId::next();
    let (done, outcome) = oneshot::channel();
    let mut operations = tracked_operations(&ctrl);

    ctrl.handle_submission(
        Submission {
            id,
            owned: owned_controller_spec(
                ControllerSpec::drop_if_running(TaskSpec::once(
                    "busy-slot-task",
                    Arc::new(SpawnBombTask),
                ))
                .with_slot("busy-slot"),
            ),
            done: Some(done),
        },
        &mut operations,
    )
    .await;

    let outcome = receive_oneshot(outcome, "busy-rejection watcher").await;
    assert!(matches!(
        outcome,
        TaskOutcome::Rejected {
            kind: crate::RejectionKind::SlotBusy,
            ..
        }
    ));
    let slot = ctrl.slot("busy-slot").expect("busy slot remains");
    let slot = slot.lock().await;
    assert_eq!(slot.owner_id(), Some(owner));
    assert!(slot.queue.is_empty());
    drop(slot);
    let drained = drain_events(&mut events);
    let rejections: Vec<_> = drained
        .iter()
        .filter(|event| event.kind == EventKind::ControllerRejected)
        .collect();
    assert_eq!(rejections.len(), 1);
    assert_rejection_parity(rejections[0], id, &outcome);
    assert!(
        drained
            .iter()
            .all(|event| event.kind != EventKind::RuntimeFailure)
    );
}

#[tokio::test]
async fn explicit_slot_queue_full_rejects_before_pending_ownership() {
    let supervisor = Supervisor::new(crate::SupervisorConfig::default(), vec![]);
    let bus = Bus::new(64);
    let config = ControllerConfig::new(NonZeroUsize::new(16).unwrap(), 1);
    let ctrl = Controller::new(config, supervisor.core(), bus.clone());
    let mut events = bus.subscribe();
    let owner = TaskId::next();
    let queued = TaskId::next();
    let mut state = running_slot(owner);
    state
        .queue
        .push_back(pending(queued, waiting_spec("existing-head")));
    ctrl.state()
        .slots
        .insert(Arc::from("full-slot"), Arc::new(Mutex::new(state)));
    let id = TaskId::next();
    let (done, outcome) = oneshot::channel();
    let mut operations = tracked_operations(&ctrl);

    ctrl.handle_submission(
        Submission {
            id,
            owned: owned_controller_spec(
                ControllerSpec::queue(TaskSpec::once("full-slot-task", Arc::new(SpawnBombTask)))
                    .with_slot("full-slot"),
            ),
            done: Some(done),
        },
        &mut operations,
    )
    .await;

    let outcome = receive_oneshot(outcome, "queue-full watcher").await;
    assert!(matches!(
        outcome,
        TaskOutcome::Rejected {
            kind: crate::RejectionKind::QueueFull,
            ..
        }
    ));
    let slot = ctrl.slot("full-slot").expect("full slot remains");
    let slot = slot.lock().await;
    assert_eq!(slot.owner_id(), Some(owner));
    assert_eq!(slot.queue.len(), 1);
    assert_eq!(slot.queue.front().map(|pending| pending.id), Some(queued));
    drop(slot);
    let drained = drain_events(&mut events);
    let rejections: Vec<_> = drained
        .iter()
        .filter(|event| event.kind == EventKind::ControllerRejected)
        .collect();
    assert_eq!(rejections.len(), 1);
    assert_rejection_parity(rejections[0], id, &outcome);
    assert!(
        drained
            .iter()
            .all(|event| event.kind != EventKind::RuntimeFailure)
    );
}

#[tokio::test]
async fn controller_slot_limit_rejects_submission_without_retaining_ownership() {
    let supervisor = Supervisor::new(crate::SupervisorConfig::default(), vec![]);
    let bus = Bus::new(64);
    let config = ControllerConfig::default().with_max_controller_slots(NonZeroUsize::new(1));
    let ctrl = Controller::new(config, supervisor.core(), bus.clone());
    let mut events = bus.subscribe();
    let existing_owner = TaskId::next();
    ctrl.state().slots.insert(
        Arc::from("existing-slot"),
        Arc::new(Mutex::new(running_slot(existing_owner))),
    );
    let id = TaskId::next();
    let (done, outcome) = oneshot::channel();
    let mut operations = tracked_operations(&ctrl);

    ctrl.handle_submission(
        Submission {
            id,
            owned: owned_controller_spec(
                ControllerSpec::queue(TaskSpec::once("slot-limit-task", Arc::new(SpawnBombTask)))
                    .with_slot("new-slot"),
            ),
            done: Some(done),
        },
        &mut operations,
    )
    .await;

    let outcome = receive_oneshot(outcome, "slot-limit watcher").await;
    assert!(matches!(
        outcome,
        TaskOutcome::Rejected {
            kind: crate::RejectionKind::ResourceLimit,
            ..
        }
    ));
    {
        let state = ctrl.state();
        assert_eq!(state.slots.len(), 1);
        assert!(state.slots.contains_key("existing-slot"));
        assert!(!state.slots.contains_key("new-slot"));
        assert!(state.watchers.is_empty());
        assert!(state.queued_slots.is_empty());
        assert!(state.capacity_pending.is_empty());
    }
    assert!(operations.capacity.is_empty());
    assert!(operations.admissions.is_empty());
    assert!(operations.removals.is_empty());

    let drained = drain_events(&mut events);
    let rejection = drained
        .iter()
        .find(|event| event.kind == EventKind::ControllerRejected && event.id == Some(id))
        .expect("slot-limit rejection event");
    assert_rejection_parity(rejection, id, &outcome);
    assert_eq!(
        rejection.rejection_kind,
        Some(crate::RejectionKind::ResourceLimit)
    );
}

#[tokio::test]
async fn controller_registry_commit_uses_stored_task_name() {
    let supervisor = Supervisor::new(crate::SupervisorConfig::default(), vec![]);
    let ctrl = Controller::new(ControllerConfig::default(), supervisor.core(), Bus::new(64));
    let task: TaskRef = TaskFn::arc(|_ctx: TaskContext| async { Ok(()) });
    let task_name: Arc<str> = Arc::from("stored-task-name");
    let id = TaskId::next();
    let (done, outcome) = oneshot::channel();
    let mut operations = tracked_operations(&ctrl);

    handle_submission_fully(
        &ctrl,
        Submission {
            id,
            owned: owned_controller_spec(ControllerSpec::queue(TaskSpec::once(
                Arc::clone(&task_name),
                task,
            ))),
            done: Some(done),
        },
        &mut operations,
    )
    .await;

    assert_eq!(operations.admissions.len(), 1);
    assert!(operations.removals.is_empty());
    assert!(ctrl.state().watchers.is_empty());
    {
        let state = ctrl.state();
        let stored_name = state
            .slots
            .keys()
            .find(|name| name.as_ref() == task_name.as_ref())
            .expect("the implicit slot must retain the task name");
        assert!(Arc::ptr_eq(&task_name, stored_name));
    }
    let slot = ctrl
        .slot("stored-task-name")
        .expect("the stored task name must become the fallback slot");
    assert!(matches!(
        slot.lock().await.phase(),
        SlotPhase::Admitting { owner, .. } if owner == id
    ));

    drop(outcome);
    abort_and_drain(&mut operations.admissions).await;
    abort_and_drain(&mut operations.removals).await;
}

#[tokio::test]
async fn stored_names_apply_cross_slot_submissions_inline_in_fifo_order() {
    let supervisor = Supervisor::new(crate::SupervisorConfig::default(), vec![]);
    let bus = Bus::new(64);
    let ctrl = Controller::new(ControllerConfig::default(), supervisor.core(), bus.clone());
    let mut events = bus.subscribe();
    let mut operations = tracked_operations(&ctrl);
    let first = TaskId::next();
    let second = TaskId::next();

    for (id, name) in [(first, "inline-first"), (second, "inline-second")] {
        ctrl.handle_submission(
            Submission {
                id,
                owned: owned_controller_spec(ControllerSpec::queue(make_spec(name))),
                done: None,
            },
            &mut operations,
        )
        .await;
    }

    for (id, name) in [(first, "inline-first"), (second, "inline-second")] {
        let slot = ctrl
            .slot(name)
            .expect("the stored task name must create its implicit slot inline");
        assert!(matches!(
            slot.lock().await.phase(),
            SlotPhase::Admitting { owner, .. } if owner == id
        ));
    }
    assert_eq!(
        operations.admissions.len(),
        2,
        "one pending registry reply must not prevent the next slot from starting admission"
    );
    let submitted: Vec<_> = drain_events(&mut events)
        .into_iter()
        .filter(|event| event.kind == EventKind::ControllerSubmitted)
        .filter_map(|event| event.id)
        .collect();
    assert_eq!(submitted, vec![first, second]);

    abort_and_drain(&mut operations.admissions).await;
}

#[tokio::test]
async fn registry_precommit_shutdown_drop_panic_preserves_watcher_and_controller_state() {
    let supervisor = Supervisor::new(
        crate::SupervisorConfig::default()
            .with_registry_queue_capacity(NonZeroUsize::new(1).unwrap()),
        vec![],
    );
    let filler_id = TaskId::next();
    let (_reply, _completion) = supervisor
        .core()
        .add_task_with_id_watched(
            filler_id,
            Arc::from("drop-panic-filler"),
            owned_task_spec(waiting_spec("drop-panic-filler")),
            None,
        )
        .expect("the filler must occupy the registry queue");
    assert_eq!(supervisor.core().registry_command_capacity(), 0);
    supervisor.core().close_registry_admission_for_test();

    let bus = Bus::new(64);
    let ctrl = Controller::new(ControllerConfig::default(), supervisor.core(), bus.clone());
    let mut events = bus.subscribe();
    let drops = Arc::new(AtomicUsize::new(0));
    let id = TaskId::next();
    let (done, outcome) = oneshot::channel();
    let mut operations = tracked_operations(&ctrl);

    handle_submission_fully(
        &ctrl,
        Submission {
            id,
            owned: with_controller_panic_reporter(
                isolated_owned_controller_spec(
                    ControllerSpec::queue(TaskSpec::once(
                        "drop-panic-uncommitted",
                        Arc::new(PanickingDropTask {
                            drops: Arc::clone(&drops),
                        }),
                    ))
                    .with_slot("drop-panic-slot"),
                ),
                &ctrl.bus,
            ),
            done: Some(done),
        },
        &mut operations,
    )
    .await;

    assert!(
        poll_until(Duration::from_secs(2), || async {
            drops.load(Ordering::Acquire) == 1
        })
        .await,
        "deferred task destruction must complete"
    );
    let outcome = receive_oneshot(outcome, "pre-commit failure watcher").await;
    assert!(matches!(
        outcome,
        TaskOutcome::Rejected {
            kind: crate::RejectionKind::AdmissionFailed,
            ..
        }
    ));
    assert!(ctrl.state().watchers.is_empty());
    assert!(ctrl.slot("drop-panic-slot").is_none());
    assert!(operations.admissions.is_empty());
    assert!(operations.removals.is_empty());

    let drained = drain_until_runtime_failure(&mut events, "injected task drop panic").await;
    let rejection = drained
        .iter()
        .find(|event| event.kind == EventKind::ControllerRejected)
        .expect("pre-commit failure must publish a rejection");
    assert_rejection_parity(rejection, id, &outcome);
    let drop_failure = drained
        .iter()
        .find(|event| {
            event.kind == EventKind::RuntimeFailure
                && event
                    .reason
                    .as_deref()
                    .is_some_and(|reason| reason.contains("injected task drop panic"))
        })
        .expect("panicking destructor must be isolated and diagnosed");
    assert_eq!(drop_failure.task.as_deref(), Some("controller"));
}

#[tokio::test]
async fn queued_precommit_failures_finish_before_panicking_task_drop() {
    let supervisor = Supervisor::new(
        crate::SupervisorConfig::default()
            .with_registry_queue_capacity(NonZeroUsize::new(1).unwrap()),
        vec![],
    );
    let filler_id = TaskId::next();
    let (_reply, _completion) = supervisor
        .core()
        .add_task_with_id_watched(
            filler_id,
            Arc::from("queued-drop-filler"),
            owned_task_spec(waiting_spec("queued-drop-filler")),
            None,
        )
        .expect("the filler must occupy the registry queue");
    supervisor.core().close_registry_admission_for_test();

    let ctrl = Controller::new(ControllerConfig::default(), supervisor.core(), Bus::new(64));
    let drops = Arc::new(AtomicUsize::new(0));
    let first = TaskId::next();
    let second = TaskId::next();
    let (first_done, first_outcome) = oneshot::channel();
    let (second_done, second_outcome) = oneshot::channel();
    {
        let mut state = ctrl.state();
        state.watchers.insert(first, first_done);
        state.watchers.insert(second, second_done);
    }
    let mut slot = SlotState::new();
    slot.queue.push_back(PendingSubmission::new(
        first,
        Arc::from("queued-drop-panic"),
        with_controller_panic_reporter(
            isolated_owned_task_spec(TaskSpec::once(
                "queued-drop-panic",
                Arc::new(PanickingDropTask {
                    drops: Arc::clone(&drops),
                }),
            )),
            &ctrl.bus,
        ),
    ));
    slot.queue
        .push_back(pending(second, waiting_spec("queued-after-drop-panic")));
    let slot_name = Arc::from("queued-drop-slot");
    let mut operations = tracked_operations(&ctrl);

    let deferred =
        ctrl.start_next_from_queue(supervisor.core(), &mut slot, &slot_name, &mut operations);

    assert!(slot.is_idle());
    assert!(slot.queue.is_empty());
    assert!(operations.admissions.is_empty());
    assert_eq!(deferred.len(), 2);
    assert!(matches!(
        receive_oneshot(first_outcome, "first queued pre-commit watcher").await,
        TaskOutcome::Rejected {
            kind: crate::RejectionKind::AdmissionFailed,
            ..
        }
    ));
    assert!(matches!(
        receive_oneshot(second_outcome, "second queued pre-commit watcher").await,
        TaskOutcome::Rejected {
            kind: crate::RejectionKind::AdmissionFailed,
            ..
        }
    ));
    assert!(ctrl.state().watchers.is_empty());
    assert_eq!(drops.load(Ordering::Acquire), 0);

    ctrl.drop_pending_submissions(deferred);
    assert!(
        poll_until(Duration::from_secs(2), || async {
            drops.load(Ordering::Acquire) == 1
        })
        .await,
        "deferred task destruction must complete"
    );
}

#[tokio::test(flavor = "current_thread")]
async fn registry_reply_marks_slot_running_without_task_added() {
    let sup = Supervisor::new(crate::SupervisorConfig::default(), vec![]);
    let handle = sup.serve().expect("runtime startup");
    let controller_bus = Bus::new(1);
    let ctrl = Controller::new(
        ControllerConfig::default(),
        sup.core(),
        controller_bus.clone(),
    );
    let token = CancellationToken::new();
    let runner = start_controller_loop(&ctrl, &token).await;

    let id = ctrl
        .handle()
        .submit(ControllerSpec::queue(waiting_spec("reply-admitted")).with_slot("s"))
        .await
        .expect("controller intake must accept the submission");
    for _ in 0..16 {
        controller_bus.publish(Event::new(EventKind::AttemptStarting).with_task("noise"));
    }

    let reached_running = poll_until(Duration::from_secs(2), || async {
        let Some(slot) = ctrl.slot("s") else {
            return false;
        };
        let slot = slot.lock().await;
        slot.owner_id() == Some(id) && matches!(slot.phase(), SlotPhase::Running { .. })
    })
    .await;

    assert!(
        reached_running,
        "the direct registry reply must confirm admission without TaskAdded"
    );
    stop_controller_loop(token, runner).await;
    assert!(ctrl.state().slots.is_empty());

    let _ = handle.shutdown().await;
}

#[tokio::test(flavor = "current_thread")]
async fn duplicate_reply_frees_slot_without_task_add_failed() {
    let sup = Supervisor::new(crate::SupervisorConfig::default(), vec![]);
    let handle = sup.serve().expect("runtime startup");
    handle
        .add(waiting_spec("duplicate-reply"))
        .await
        .expect("the existing task must register");

    let ctrl = Controller::new(ControllerConfig::default(), sup.core(), Bus::new(1));
    let token = CancellationToken::new();
    let runner = start_controller_loop(&ctrl, &token).await;
    let (id, outcome) = ctrl
        .handle()
        .submit_and_watch(ControllerSpec::queue(waiting_spec("duplicate-reply")).with_slot("s"))
        .await
        .expect("controller intake must accept the duplicate");

    let outcome = tokio::time::timeout(Duration::from_secs(2), outcome)
        .await
        .expect("registry rejection must resolve the watcher")
        .expect("registry must send a rejected outcome");
    assert!(matches!(outcome, TaskOutcome::Rejected {
            kind: crate::RejectionKind::AlreadyExists,
            reason,
            ..
        } if reason.as_ref() == crate::reasons::ALREADY_EXISTS));
    assert!(
        poll_until(Duration::from_secs(2), || async {
            ctrl.slot("s").is_none() && !ctrl.state().watchers.contains_key(&id)
        })
        .await,
        "the rejected admission must release its slot ownership"
    );
    assert!(
        ctrl.slot("s").is_none(),
        "an idle empty slot should be collected after registry rejection"
    );

    stop_controller_loop(token, runner).await;
    let _ = handle.shutdown().await;
}

#[tokio::test(flavor = "current_thread")]
async fn queued_admission_skips_registry_rejected_head() {
    let sup = Supervisor::new(crate::SupervisorConfig::default(), vec![]);
    let handle = sup.serve().expect("runtime startup");
    handle
        .add(waiting_spec("queued-duplicate"))
        .await
        .expect("the existing task must register");
    let ctrl = Controller::new(ControllerConfig::default(), sup.core(), Bus::new(1));
    let slot_name: Arc<str> = Arc::from("s");
    let slot_arc = ctrl.get_or_create_slot(&slot_name);
    let duplicate_id = TaskId::next();
    let accepted_id = TaskId::next();
    let (duplicate_done, duplicate_outcome) = oneshot::channel();
    let (accepted_done, _accepted_outcome) = oneshot::channel();
    {
        let mut state = ctrl.state();
        state.watchers.insert(duplicate_id, duplicate_done);
        state.watchers.insert(accepted_id, accepted_done);
    }

    let mut operations = tracked_operations(&ctrl);
    {
        let mut slot = slot_arc.lock().await;
        slot.queue
            .push_back(pending(duplicate_id, waiting_spec("queued-duplicate")));
        slot.queue
            .push_back(pending(accepted_id, waiting_spec("queued-accepted")));
        let deferred =
            ctrl.start_next_from_queue(sup.core(), &mut slot, &slot_name, &mut operations);
        assert!(deferred.is_empty());
    }

    for _ in 0..2 {
        let result = tokio::time::timeout(Duration::from_secs(2), operations.admissions.next())
            .await
            .expect("registry admission reply must arrive")
            .expect("one admission must be in flight")
            .expect("admission waiter must not fail");
        ctrl.handle_admission_result(result, &mut operations).await;
    }

    let duplicate_outcome = duplicate_outcome
        .await
        .expect("registry must resolve the duplicate watcher");
    assert!(matches!(duplicate_outcome, TaskOutcome::Rejected {
            kind: crate::RejectionKind::AlreadyExists,
            reason,
            ..
        } if reason.as_ref() == crate::reasons::ALREADY_EXISTS));
    let slot = slot_arc.lock().await;
    assert_eq!(slot.owner_id(), Some(accepted_id));
    assert!(matches!(slot.phase(), SlotPhase::Running { .. }));
    assert!(slot.queue.is_empty());
    assert_ne!(slot.owner_id(), Some(duplicate_id));

    let _ = handle.shutdown().await;
}