1use anyhow::{anyhow, Result};
2use async_task::Runnable;
3use futures::channel::mpsc;
4use smol::{channel, prelude::*, Executor};
5use std::{
6 any::Any,
7 fmt::{self, Display},
8 marker::PhantomData,
9 mem,
10 pin::Pin,
11 rc::Rc,
12 sync::Arc,
13 task::{Context, Poll},
14 thread,
15 time::Duration,
16};
17
18use crate::{
19 platform::{self, Dispatcher},
20 util, MutableAppContext,
21};
22
23pub enum Foreground {
24 Platform {
25 dispatcher: Arc<dyn platform::Dispatcher>,
26 _not_send_or_sync: PhantomData<Rc<()>>,
27 },
28 #[cfg(any(test, feature = "test-support"))]
29 Deterministic {
30 cx_id: usize,
31 executor: Arc<Deterministic>,
32 },
33}
34
35pub enum Background {
36 #[cfg(any(test, feature = "test-support"))]
37 Deterministic { executor: Arc<Deterministic> },
38 Production {
39 executor: Arc<smol::Executor<'static>>,
40 _stop: channel::Sender<()>,
41 },
42}
43
44type AnyLocalFuture = Pin<Box<dyn 'static + Future<Output = Box<dyn Any + 'static>>>>;
45type AnyFuture = Pin<Box<dyn 'static + Send + Future<Output = Box<dyn Any + Send + 'static>>>>;
46type AnyTask = async_task::Task<Box<dyn Any + Send + 'static>>;
47type AnyLocalTask = async_task::Task<Box<dyn Any + 'static>>;
48
49#[must_use]
50pub enum Task<T> {
51 Ready(Option<T>),
52 Local {
53 any_task: AnyLocalTask,
54 result_type: PhantomData<T>,
55 },
56 Send {
57 any_task: AnyTask,
58 result_type: PhantomData<T>,
59 },
60}
61
62unsafe impl<T: Send> Send for Task<T> {}
63
64#[cfg(any(test, feature = "test-support"))]
65struct DeterministicState {
66 rng: rand::prelude::StdRng,
67 seed: u64,
68 scheduled_from_foreground: collections::HashMap<usize, Vec<ForegroundRunnable>>,
69 scheduled_from_background: Vec<Runnable>,
70 forbid_parking: bool,
71 block_on_ticks: std::ops::RangeInclusive<usize>,
72 now: std::time::Instant,
73 next_timer_id: usize,
74 pending_timers: Vec<(usize, std::time::Instant, postage::barrier::Sender)>,
75 waiting_backtrace: Option<backtrace::Backtrace>,
76}
77
78#[cfg(any(test, feature = "test-support"))]
79struct ForegroundRunnable {
80 runnable: Runnable,
81 main: bool,
82}
83
84#[cfg(any(test, feature = "test-support"))]
85pub struct Deterministic {
86 state: Arc<parking_lot::Mutex<DeterministicState>>,
87 parker: parking_lot::Mutex<parking::Parker>,
88}
89
90pub enum Timer {
91 Production(smol::Timer),
92 #[cfg(any(test, feature = "test-support"))]
93 Deterministic(DeterministicTimer),
94}
95
96#[cfg(any(test, feature = "test-support"))]
97pub struct DeterministicTimer {
98 rx: postage::barrier::Receiver,
99 id: usize,
100 state: Arc<parking_lot::Mutex<DeterministicState>>,
101}
102
103#[cfg(any(test, feature = "test-support"))]
104impl Deterministic {
105 pub fn new(seed: u64) -> Arc<Self> {
106 use rand::prelude::*;
107
108 Arc::new(Self {
109 state: Arc::new(parking_lot::Mutex::new(DeterministicState {
110 rng: StdRng::seed_from_u64(seed),
111 seed,
112 scheduled_from_foreground: Default::default(),
113 scheduled_from_background: Default::default(),
114 forbid_parking: false,
115 block_on_ticks: 0..=1000,
116 now: std::time::Instant::now(),
117 next_timer_id: Default::default(),
118 pending_timers: Default::default(),
119 waiting_backtrace: None,
120 })),
121 parker: Default::default(),
122 })
123 }
124
125 pub fn build_background(self: &Arc<Self>) -> Arc<Background> {
126 Arc::new(Background::Deterministic {
127 executor: self.clone(),
128 })
129 }
130
131 pub fn build_foreground(self: &Arc<Self>, id: usize) -> Rc<Foreground> {
132 Rc::new(Foreground::Deterministic {
133 cx_id: id,
134 executor: self.clone(),
135 })
136 }
137
138 fn spawn_from_foreground(
139 &self,
140 cx_id: usize,
141 future: AnyLocalFuture,
142 main: bool,
143 ) -> AnyLocalTask {
144 let state = self.state.clone();
145 let unparker = self.parker.lock().unparker();
146 let (runnable, task) = async_task::spawn_local(future, move |runnable| {
147 let mut state = state.lock();
148 state
149 .scheduled_from_foreground
150 .entry(cx_id)
151 .or_default()
152 .push(ForegroundRunnable { runnable, main });
153 unparker.unpark();
154 });
155 runnable.schedule();
156 task
157 }
158
159 fn spawn(&self, future: AnyFuture) -> AnyTask {
160 let state = self.state.clone();
161 let unparker = self.parker.lock().unparker();
162 let (runnable, task) = async_task::spawn(future, move |runnable| {
163 let mut state = state.lock();
164 state.scheduled_from_background.push(runnable);
165 unparker.unpark();
166 });
167 runnable.schedule();
168 task
169 }
170
171 fn run<'a>(
172 &self,
173 cx_id: usize,
174 main_future: Pin<Box<dyn 'a + Future<Output = Box<dyn Any>>>>,
175 ) -> Box<dyn Any> {
176 use std::sync::atomic::{AtomicBool, Ordering::SeqCst};
177
178 let woken = Arc::new(AtomicBool::new(false));
179
180 let state = self.state.clone();
181 let unparker = self.parker.lock().unparker();
182 let (runnable, mut main_task) = unsafe {
183 async_task::spawn_unchecked(main_future, move |runnable| {
184 let mut state = state.lock();
185 state
186 .scheduled_from_foreground
187 .entry(cx_id)
188 .or_default()
189 .push(ForegroundRunnable {
190 runnable,
191 main: true,
192 });
193 unparker.unpark();
194 })
195 };
196 runnable.schedule();
197
198 loop {
199 if let Some(result) = self.run_internal(woken.clone(), Some(&mut main_task)) {
200 return result;
201 }
202
203 if !woken.load(SeqCst) {
204 self.state.lock().will_park();
205 }
206
207 woken.store(false, SeqCst);
208 self.parker.lock().park();
209 }
210 }
211
212 pub fn run_until_parked(&self) {
213 use std::sync::atomic::AtomicBool;
214 let woken = Arc::new(AtomicBool::new(false));
215 self.run_internal(woken, None);
216 }
217
218 fn run_internal(
219 &self,
220 woken: Arc<std::sync::atomic::AtomicBool>,
221 mut main_task: Option<&mut AnyLocalTask>,
222 ) -> Option<Box<dyn Any>> {
223 use rand::prelude::*;
224 use std::sync::atomic::Ordering::SeqCst;
225
226 let unparker = self.parker.lock().unparker();
227 let waker = waker_fn::waker_fn(move || {
228 woken.store(true, SeqCst);
229 unparker.unpark();
230 });
231
232 let mut cx = Context::from_waker(&waker);
233 loop {
234 let mut state = self.state.lock();
235
236 if state.scheduled_from_foreground.is_empty()
237 && state.scheduled_from_background.is_empty()
238 {
239 if let Some(main_task) = main_task {
240 if let Poll::Ready(result) = main_task.poll(&mut cx) {
241 return Some(result);
242 }
243 }
244
245 return None;
246 }
247
248 if !state.scheduled_from_background.is_empty() && state.rng.gen() {
249 let background_len = state.scheduled_from_background.len();
250 let ix = state.rng.gen_range(0..background_len);
251 let runnable = state.scheduled_from_background.remove(ix);
252 drop(state);
253 runnable.run();
254 } else if !state.scheduled_from_foreground.is_empty() {
255 let available_cx_ids = state
256 .scheduled_from_foreground
257 .keys()
258 .copied()
259 .collect::<Vec<_>>();
260 let cx_id_to_run = *available_cx_ids.iter().choose(&mut state.rng).unwrap();
261 let scheduled_from_cx = state
262 .scheduled_from_foreground
263 .get_mut(&cx_id_to_run)
264 .unwrap();
265 let foreground_runnable = scheduled_from_cx.remove(0);
266 if scheduled_from_cx.is_empty() {
267 state.scheduled_from_foreground.remove(&cx_id_to_run);
268 }
269
270 drop(state);
271
272 foreground_runnable.runnable.run();
273 if let Some(main_task) = main_task.as_mut() {
274 if foreground_runnable.main {
275 if let Poll::Ready(result) = main_task.poll(&mut cx) {
276 return Some(result);
277 }
278 }
279 }
280 }
281 }
282 }
283
284 fn block<F, T>(&self, future: &mut F, max_ticks: usize) -> Option<T>
285 where
286 F: Unpin + Future<Output = T>,
287 {
288 use rand::prelude::*;
289
290 let unparker = self.parker.lock().unparker();
291 let waker = waker_fn::waker_fn(move || {
292 unparker.unpark();
293 });
294
295 let mut cx = Context::from_waker(&waker);
296 for _ in 0..max_ticks {
297 let mut state = self.state.lock();
298 let runnable_count = state.scheduled_from_background.len();
299 let ix = state.rng.gen_range(0..=runnable_count);
300 if ix < state.scheduled_from_background.len() {
301 let runnable = state.scheduled_from_background.remove(ix);
302 drop(state);
303 runnable.run();
304 } else {
305 drop(state);
306 if let Poll::Ready(result) = future.poll(&mut cx) {
307 return Some(result);
308 }
309 let mut state = self.state.lock();
310 if state.scheduled_from_background.is_empty() {
311 state.will_park();
312 drop(state);
313 self.parker.lock().park();
314 }
315
316 continue;
317 }
318 }
319
320 None
321 }
322
323 pub fn timer(&self, duration: Duration) -> Timer {
324 let (tx, rx) = postage::barrier::channel();
325 let mut state = self.state.lock();
326 let wakeup_at = state.now + duration;
327 let id = util::post_inc(&mut state.next_timer_id);
328 state.pending_timers.push((id, wakeup_at, tx));
329 let state = self.state.clone();
330 Timer::Deterministic(DeterministicTimer { rx, id, state })
331 }
332
333 pub fn advance_clock(&self, duration: Duration) {
334 let new_now = self.state.lock().now + duration;
335 loop {
336 self.run_until_parked();
337 let mut state = self.state.lock();
338
339 if let Some((_, wakeup_time, _)) = state.pending_timers.first() {
340 let wakeup_time = *wakeup_time;
341 if wakeup_time <= new_now {
342 let timer_count = state
343 .pending_timers
344 .iter()
345 .take_while(|(_, t, _)| *t == wakeup_time)
346 .count();
347 state.now = wakeup_time;
348 let timers_to_wake = state
349 .pending_timers
350 .drain(0..timer_count)
351 .collect::<Vec<_>>();
352 drop(state);
353 drop(timers_to_wake);
354 continue;
355 }
356 }
357
358 break;
359 }
360
361 self.state.lock().now = new_now;
362 }
363
364 pub fn forbid_parking(&self) {
365 use rand::prelude::*;
366
367 let mut state = self.state.lock();
368 state.forbid_parking = true;
369 state.rng = StdRng::seed_from_u64(state.seed);
370 }
371}
372
373impl Drop for Timer {
374 fn drop(&mut self) {
375 #[cfg(any(test, feature = "test-support"))]
376 if let Timer::Deterministic(DeterministicTimer { state, id, .. }) = self {
377 state
378 .lock()
379 .pending_timers
380 .retain(|(timer_id, _, _)| timer_id != id)
381 }
382 }
383}
384
385impl Future for Timer {
386 type Output = ();
387
388 fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
389 match &mut *self {
390 #[cfg(any(test, feature = "test-support"))]
391 Self::Deterministic(DeterministicTimer { rx, .. }) => {
392 use postage::stream::{PollRecv, Stream as _};
393 smol::pin!(rx);
394 match rx.poll_recv(&mut postage::Context::from_waker(cx.waker())) {
395 PollRecv::Ready(()) | PollRecv::Closed => Poll::Ready(()),
396 PollRecv::Pending => Poll::Pending,
397 }
398 }
399 Self::Production(timer) => {
400 smol::pin!(timer);
401 match timer.poll(cx) {
402 Poll::Ready(_) => Poll::Ready(()),
403 Poll::Pending => Poll::Pending,
404 }
405 }
406 }
407 }
408}
409
410#[cfg(any(test, feature = "test-support"))]
411impl DeterministicState {
412 fn will_park(&mut self) {
413 if self.forbid_parking {
414 let mut backtrace_message = String::new();
415 #[cfg(any(test, feature = "test-support"))]
416 if let Some(backtrace) = self.waiting_backtrace.as_mut() {
417 backtrace.resolve();
418 backtrace_message = format!(
419 "\nbacktrace of waiting future:\n{:?}",
420 util::CwdBacktrace(backtrace)
421 );
422 }
423
424 panic!(
425 "deterministic executor parked after a call to forbid_parking{}",
426 backtrace_message
427 );
428 }
429 }
430}
431
432impl Foreground {
433 pub fn platform(dispatcher: Arc<dyn platform::Dispatcher>) -> Result<Self> {
434 if dispatcher.is_main_thread() {
435 Ok(Self::Platform {
436 dispatcher,
437 _not_send_or_sync: PhantomData,
438 })
439 } else {
440 Err(anyhow!("must be constructed on main thread"))
441 }
442 }
443
444 pub fn spawn<T: 'static>(&self, future: impl Future<Output = T> + 'static) -> Task<T> {
445 let future = any_local_future(future);
446 let any_task = match self {
447 #[cfg(any(test, feature = "test-support"))]
448 Self::Deterministic { cx_id, executor } => {
449 executor.spawn_from_foreground(*cx_id, future, false)
450 }
451 Self::Platform { dispatcher, .. } => {
452 fn spawn_inner(
453 future: AnyLocalFuture,
454 dispatcher: &Arc<dyn Dispatcher>,
455 ) -> AnyLocalTask {
456 let dispatcher = dispatcher.clone();
457 let schedule =
458 move |runnable: Runnable| dispatcher.run_on_main_thread(runnable);
459 let (runnable, task) = async_task::spawn_local(future, schedule);
460 runnable.schedule();
461 task
462 }
463 spawn_inner(future, dispatcher)
464 }
465 };
466 Task::local(any_task)
467 }
468
469 #[cfg(any(test, feature = "test-support"))]
470 pub fn run<T: 'static>(&self, future: impl Future<Output = T>) -> T {
471 let future = async move { Box::new(future.await) as Box<dyn Any> }.boxed_local();
472 let result = match self {
473 Self::Deterministic { cx_id, executor } => executor.run(*cx_id, future),
474 Self::Platform { .. } => panic!("you can't call run on a platform foreground executor"),
475 };
476 *result.downcast().unwrap()
477 }
478
479 #[cfg(any(test, feature = "test-support"))]
480 pub fn run_until_parked(&self) {
481 match self {
482 Self::Deterministic { executor, .. } => executor.run_until_parked(),
483 _ => panic!("this method can only be called on a deterministic executor"),
484 }
485 }
486
487 #[cfg(any(test, feature = "test-support"))]
488 pub fn parking_forbidden(&self) -> bool {
489 match self {
490 Self::Deterministic { executor, .. } => executor.state.lock().forbid_parking,
491 _ => panic!("this method can only be called on a deterministic executor"),
492 }
493 }
494
495 #[cfg(any(test, feature = "test-support"))]
496 pub fn start_waiting(&self) {
497 match self {
498 Self::Deterministic { executor, .. } => {
499 executor.state.lock().waiting_backtrace =
500 Some(backtrace::Backtrace::new_unresolved());
501 }
502 _ => panic!("this method can only be called on a deterministic executor"),
503 }
504 }
505
506 #[cfg(any(test, feature = "test-support"))]
507 pub fn finish_waiting(&self) {
508 match self {
509 Self::Deterministic { executor, .. } => {
510 executor.state.lock().waiting_backtrace.take();
511 }
512 _ => panic!("this method can only be called on a deterministic executor"),
513 }
514 }
515
516 #[cfg(any(test, feature = "test-support"))]
517 pub fn forbid_parking(&self) {
518 match self {
519 Self::Deterministic { executor, .. } => executor.forbid_parking(),
520 _ => panic!("this method can only be called on a deterministic executor"),
521 }
522 }
523
524 #[cfg(any(test, feature = "test-support"))]
525 pub fn advance_clock(&self, duration: Duration) {
526 match self {
527 Self::Deterministic { executor, .. } => {
528 executor.run_until_parked();
529 executor.advance_clock(duration);
530 }
531 _ => panic!("this method can only be called on a deterministic executor"),
532 }
533 }
534
535 #[cfg(any(test, feature = "test-support"))]
536 pub fn set_block_on_ticks(&self, range: std::ops::RangeInclusive<usize>) {
537 match self {
538 Self::Deterministic { executor, .. } => executor.state.lock().block_on_ticks = range,
539 _ => panic!("this method can only be called on a deterministic executor"),
540 }
541 }
542}
543
544impl Background {
545 pub fn new() -> Self {
546 let executor = Arc::new(Executor::new());
547 let stop = channel::unbounded::<()>();
548
549 for i in 0..2 * num_cpus::get() {
550 let executor = executor.clone();
551 let stop = stop.1.clone();
552 thread::Builder::new()
553 .name(format!("background-executor-{}", i))
554 .spawn(move || smol::block_on(executor.run(stop.recv())))
555 .unwrap();
556 }
557
558 Self::Production {
559 executor,
560 _stop: stop.0,
561 }
562 }
563
564 pub fn num_cpus(&self) -> usize {
565 num_cpus::get()
566 }
567
568 pub fn spawn<T, F>(&self, future: F) -> Task<T>
569 where
570 T: 'static + Send,
571 F: Send + Future<Output = T> + 'static,
572 {
573 let future = any_future(future);
574 let any_task = match self {
575 Self::Production { executor, .. } => executor.spawn(future),
576 #[cfg(any(test, feature = "test-support"))]
577 Self::Deterministic { executor } => executor.spawn(future),
578 };
579 Task::send(any_task)
580 }
581
582 pub fn block<F, T>(&self, future: F) -> T
583 where
584 F: Future<Output = T>,
585 {
586 smol::pin!(future);
587 match self {
588 Self::Production { .. } => smol::block_on(&mut future),
589 #[cfg(any(test, feature = "test-support"))]
590 Self::Deterministic { executor, .. } => {
591 executor.block(&mut future, usize::MAX).unwrap()
592 }
593 }
594 }
595
596 pub fn block_with_timeout<F, T>(
597 &self,
598 timeout: Duration,
599 future: F,
600 ) -> Result<T, impl Future<Output = T>>
601 where
602 T: 'static,
603 F: 'static + Unpin + Future<Output = T>,
604 {
605 let mut future = any_local_future(future);
606 if !timeout.is_zero() {
607 let output = match self {
608 Self::Production { .. } => smol::block_on(util::timeout(timeout, &mut future)).ok(),
609 #[cfg(any(test, feature = "test-support"))]
610 Self::Deterministic { executor, .. } => {
611 use rand::prelude::*;
612 let max_ticks = {
613 let mut state = executor.state.lock();
614 let range = state.block_on_ticks.clone();
615 state.rng.gen_range(range)
616 };
617 executor.block(&mut future, max_ticks)
618 }
619 };
620 if let Some(output) = output {
621 return Ok(*output.downcast().unwrap());
622 }
623 }
624 Err(async { *future.await.downcast().unwrap() })
625 }
626
627 pub async fn scoped<'scope, F>(self: &Arc<Self>, scheduler: F)
628 where
629 F: FnOnce(&mut Scope<'scope>),
630 {
631 let mut scope = Scope::new(self.clone());
632 (scheduler)(&mut scope);
633 let spawned = mem::take(&mut scope.futures)
634 .into_iter()
635 .map(|f| self.spawn(f))
636 .collect::<Vec<_>>();
637 for task in spawned {
638 task.await;
639 }
640 }
641
642 pub fn timer(&self, duration: Duration) -> Timer {
643 match self {
644 Background::Production { .. } => Timer::Production(smol::Timer::after(duration)),
645 #[cfg(any(test, feature = "test-support"))]
646 Background::Deterministic { executor } => executor.timer(duration),
647 }
648 }
649
650 #[cfg(any(test, feature = "test-support"))]
651 pub async fn simulate_random_delay(&self) {
652 use rand::prelude::*;
653 use smol::future::yield_now;
654
655 match self {
656 Self::Deterministic { executor, .. } => {
657 if executor.state.lock().rng.gen_bool(0.2) {
658 let yields = executor.state.lock().rng.gen_range(1..=10);
659 for _ in 0..yields {
660 yield_now().await;
661 }
662 }
663 }
664 _ => {
665 log::info!("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
666
667 // panic!("this method can only be called on a deterministic executor")
668 }
669 }
670 }
671}
672
673pub struct Scope<'a> {
674 executor: Arc<Background>,
675 futures: Vec<Pin<Box<dyn Future<Output = ()> + Send + 'static>>>,
676 tx: Option<mpsc::Sender<()>>,
677 rx: mpsc::Receiver<()>,
678 _phantom: PhantomData<&'a ()>,
679}
680
681impl<'a> Scope<'a> {
682 fn new(executor: Arc<Background>) -> Self {
683 let (tx, rx) = mpsc::channel(1);
684 Self {
685 executor,
686 tx: Some(tx),
687 rx,
688 futures: Default::default(),
689 _phantom: PhantomData,
690 }
691 }
692
693 pub fn spawn<F>(&mut self, f: F)
694 where
695 F: Future<Output = ()> + Send + 'a,
696 {
697 let tx = self.tx.clone().unwrap();
698
699 // Safety: The 'a lifetime is guaranteed to outlive any of these futures because
700 // dropping this `Scope` blocks until all of the futures have resolved.
701 let f = unsafe {
702 mem::transmute::<
703 Pin<Box<dyn Future<Output = ()> + Send + 'a>>,
704 Pin<Box<dyn Future<Output = ()> + Send + 'static>>,
705 >(Box::pin(async move {
706 f.await;
707 drop(tx);
708 }))
709 };
710 self.futures.push(f);
711 }
712}
713
714impl<'a> Drop for Scope<'a> {
715 fn drop(&mut self) {
716 self.tx.take().unwrap();
717
718 // Wait until the channel is closed, which means that all of the spawned
719 // futures have resolved.
720 self.executor.block(self.rx.next());
721 }
722}
723
724impl<T> Task<T> {
725 pub fn ready(value: T) -> Self {
726 Self::Ready(Some(value))
727 }
728
729 fn local(any_task: AnyLocalTask) -> Self {
730 Self::Local {
731 any_task,
732 result_type: PhantomData,
733 }
734 }
735
736 pub fn detach(self) {
737 match self {
738 Task::Ready(_) => {}
739 Task::Local { any_task, .. } => any_task.detach(),
740 Task::Send { any_task, .. } => any_task.detach(),
741 }
742 }
743}
744
745impl<T: 'static, E: 'static + Display> Task<Result<T, E>> {
746 pub fn detach_and_log_err(self, cx: &mut MutableAppContext) {
747 cx.spawn(|_| async move {
748 if let Err(err) = self.await {
749 log::error!("{}", err);
750 }
751 })
752 .detach();
753 }
754}
755
756impl<T: Send> Task<T> {
757 fn send(any_task: AnyTask) -> Self {
758 Self::Send {
759 any_task,
760 result_type: PhantomData,
761 }
762 }
763}
764
765impl<T: fmt::Debug> fmt::Debug for Task<T> {
766 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
767 match self {
768 Task::Ready(value) => value.fmt(f),
769 Task::Local { any_task, .. } => any_task.fmt(f),
770 Task::Send { any_task, .. } => any_task.fmt(f),
771 }
772 }
773}
774
775impl<T: 'static> Future for Task<T> {
776 type Output = T;
777
778 fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
779 match unsafe { self.get_unchecked_mut() } {
780 Task::Ready(value) => Poll::Ready(value.take().unwrap()),
781 Task::Local { any_task, .. } => {
782 any_task.poll(cx).map(|value| *value.downcast().unwrap())
783 }
784 Task::Send { any_task, .. } => {
785 any_task.poll(cx).map(|value| *value.downcast().unwrap())
786 }
787 }
788 }
789}
790
791fn any_future<T, F>(future: F) -> AnyFuture
792where
793 T: 'static + Send,
794 F: Future<Output = T> + Send + 'static,
795{
796 async { Box::new(future.await) as Box<dyn Any + Send> }.boxed()
797}
798
799fn any_local_future<T, F>(future: F) -> AnyLocalFuture
800where
801 T: 'static,
802 F: Future<Output = T> + 'static,
803{
804 async { Box::new(future.await) as Box<dyn Any> }.boxed_local()
805}