fdf_core/
dispatcher.rs

1// Copyright 2024 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5//! Safe bindings for the driver runtime dispatcher stable ABI
6
7use fdf_sys::*;
8
9use core::cell::{RefCell, UnsafeCell};
10use core::ffi;
11use core::future::Future;
12use core::marker::PhantomData;
13use core::mem::ManuallyDrop;
14use core::ptr::{addr_of_mut, null_mut, NonNull};
15use core::task::Context;
16use std::sync::{Arc, Mutex, Weak};
17
18use zx::Status;
19
20use futures::future::{BoxFuture, FutureExt};
21use futures::task::{waker_ref, ArcWake};
22
23pub use fdf_sys::fdf_dispatcher_t;
24
25/// A marker trait for a function type that can be used as a shutdown observer for [`Dispatcher`].
26pub trait ShutdownObserverFn: FnOnce(DispatcherRef<'_>) + Send + 'static {}
27impl<T> ShutdownObserverFn for T where T: FnOnce(DispatcherRef<'_>) + Send + 'static {}
28
29/// A builder for [`Dispatcher`]s
30#[derive(Default)]
31pub struct DispatcherBuilder {
32    #[doc(hidden)]
33    pub options: u32,
34    #[doc(hidden)]
35    pub name: String,
36    #[doc(hidden)]
37    pub scheduler_role: String,
38    #[doc(hidden)]
39    pub shutdown_observer: Option<ShutdownObserver>,
40}
41
42impl DispatcherBuilder {
43    /// See `FDF_DISPATCHER_OPTION_UNSYNCHRONIZED` in the C API
44    pub(crate) const UNSYNCHRONIZED: u32 = 0b01;
45    /// See `FDF_DISPATCHER_OPTION_ALLOW_SYNC_CALLS` in the C API
46    pub(crate) const ALLOW_THREAD_BLOCKING: u32 = 0b10;
47
48    /// Creates a new [`DispatcherBuilder`] that can be used to configure a new dispatcher.
49    /// For more information on the threading-related flags for the dispatcher, see
50    /// https://fuchsia.dev/fuchsia-src/concepts/drivers/driver-dispatcher-and-threads
51    pub fn new() -> Self {
52        Self::default()
53    }
54
55    /// Sets whether parallel callbacks in the callbacks set in the dispatcher are allowed. May
56    /// not be set with [`Self::allow_thread_blocking`].
57    ///
58    /// See https://fuchsia.dev/fuchsia-src/concepts/drivers/driver-dispatcher-and-threads
59    /// for more information on the threading model of driver dispatchers.
60    pub fn unsynchronized(mut self) -> Self {
61        assert!(
62            !self.allows_thread_blocking(),
63            "you may not create an unsynchronized dispatcher that allows synchronous calls"
64        );
65        self.options = self.options | Self::UNSYNCHRONIZED;
66        self
67    }
68
69    /// Whether or not this is an unsynchronized dispatcher
70    pub fn is_unsynchronized(&self) -> bool {
71        (self.options & Self::UNSYNCHRONIZED) == Self::UNSYNCHRONIZED
72    }
73
74    /// This dispatcher may not share zircon threads with other drivers. May not be set with
75    /// [`Self::unsynchronized`].
76    ///
77    /// See https://fuchsia.dev/fuchsia-src/concepts/drivers/driver-dispatcher-and-threads
78    /// for more information on the threading model of driver dispatchers.
79    pub fn allow_thread_blocking(mut self) -> Self {
80        assert!(
81            !self.is_unsynchronized(),
82            "you may not create an unsynchronized dispatcher that allows synchronous calls"
83        );
84        self.options = self.options | Self::ALLOW_THREAD_BLOCKING;
85        self
86    }
87
88    /// Whether or not this dispatcher allows synchronous calls
89    pub fn allows_thread_blocking(&self) -> bool {
90        (self.options & Self::ALLOW_THREAD_BLOCKING) == Self::ALLOW_THREAD_BLOCKING
91    }
92
93    /// A descriptive name for this dispatcher that is used in debug output and process
94    /// lists.
95    pub fn name(mut self, name: &str) -> Self {
96        self.name = name.to_string();
97        self
98    }
99
100    /// A hint string for the runtime that may or may not impact the priority the work scheduled
101    /// by this dispatcher is handled at. It may or may not impact the ability for other drivers
102    /// to share zircon threads with the dispatcher.
103    pub fn scheduler_role(mut self, role: &str) -> Self {
104        self.scheduler_role = role.to_string();
105        self
106    }
107
108    /// A callback to be called before after the dispatcher has completed asynchronous shutdown.
109    pub fn shutdown_observer<F: ShutdownObserverFn>(mut self, shutdown_observer: F) -> Self {
110        self.shutdown_observer = Some(ShutdownObserver::new(shutdown_observer));
111        self
112    }
113
114    /// Create the dispatcher as configured by this object. This must be called from a
115    /// thread managed by the driver runtime. The dispatcher returned is owned by the caller,
116    /// and will initiate asynchronous shutdown when the object is dropped unless
117    /// [`Dispatcher::release`] is called on it to convert it into an unowned [`DispatcherRef`].
118    pub fn create(self) -> Result<Dispatcher, Status> {
119        let mut out_dispatcher = null_mut();
120        let options = self.options;
121        let name = self.name.as_ptr() as *mut ffi::c_char;
122        let name_len = self.name.len();
123        let scheduler_role = self.scheduler_role.as_ptr() as *mut ffi::c_char;
124        let scheduler_role_len = self.scheduler_role.len();
125        let observer =
126            self.shutdown_observer.unwrap_or_else(|| ShutdownObserver::new(|_| {})).into_ptr();
127        // SAFETY: all arguments point to memory that will be available for the duration
128        // of the call, except `observer`, which will be available until it is unallocated
129        // by the dispatcher exit handler.
130        Status::ok(unsafe {
131            fdf_dispatcher_create(
132                options,
133                name,
134                name_len,
135                scheduler_role,
136                scheduler_role_len,
137                observer,
138                &mut out_dispatcher,
139            )
140        })?;
141        // SAFETY: `out_dispatcher` is valid by construction if `fdf_dispatcher_create` returns
142        // ZX_OK.
143        Ok(Dispatcher(unsafe { NonNull::new_unchecked(out_dispatcher) }))
144    }
145
146    /// As with [`Self::create`], this creates a new dispatcher as configured by this object, but
147    /// instead of returning an owned reference it immediately releases the reference to be
148    /// managed by the driver runtime.
149    pub fn create_released(self) -> Result<DispatcherRef<'static>, Status> {
150        self.create().map(Dispatcher::release)
151    }
152}
153
154/// An owned handle for a dispatcher managed by the driver runtime.
155#[derive(Debug)]
156pub struct Dispatcher(pub(crate) NonNull<fdf_dispatcher_t>);
157
158// SAFETY: The api of fdf_dispatcher_t is thread safe.
159unsafe impl Send for Dispatcher {}
160unsafe impl Sync for Dispatcher {}
161thread_local! {
162    static OVERRIDE_DISPATCHER: RefCell<Option<NonNull<fdf_dispatcher_t>>> = const { RefCell::new(None) };
163}
164
165impl Dispatcher {
166    /// Creates a dispatcher ref from a raw handle.
167    ///
168    /// # Safety
169    ///
170    /// Caller is responsible for ensuring that the given handle is valid and
171    /// not owned by any other wrapper that will free it at an arbitrary
172    /// time.
173    pub unsafe fn from_raw(handle: NonNull<fdf_dispatcher_t>) -> Self {
174        Self(handle)
175    }
176
177    #[doc(hidden)]
178    pub fn inner<'a>(&'a self) -> &'a NonNull<fdf_dispatcher_t> {
179        &self.0
180    }
181
182    fn get_raw_flags(&self) -> u32 {
183        // SAFETY: the inner fdf_dispatcher_t is valid by construction
184        unsafe { fdf_dispatcher_get_options(self.0.as_ptr()) }
185    }
186
187    /// Whether this dispatcher's tasks and futures can run on multiple threads at the same time.
188    pub fn is_unsynchronized(&self) -> bool {
189        (self.get_raw_flags() & DispatcherBuilder::UNSYNCHRONIZED) != 0
190    }
191
192    /// Whether this dispatcher is allowed to call blocking functions or not
193    pub fn allows_thread_blocking(&self) -> bool {
194        (self.get_raw_flags() & DispatcherBuilder::ALLOW_THREAD_BLOCKING) != 0
195    }
196
197    /// Schedules the callback [`p`] to be run on this dispatcher later.
198    pub fn post_task_sync(&self, p: impl TaskCallback) -> Result<(), Status> {
199        // SAFETY: the fdf dispatcher is valid by construction and can provide an async dispatcher.
200        let async_dispatcher = unsafe { fdf_dispatcher_get_async_dispatcher(self.0.as_ptr()) };
201        let task_arc = Arc::new(UnsafeCell::new(TaskFunc {
202            task: async_task { handler: Some(TaskFunc::call), ..Default::default() },
203            func: Box::new(p),
204        }));
205
206        let task_cell = Arc::into_raw(task_arc);
207        // SAFETY: we need a raw mut pointer to give to async_post_task. From
208        // when we call that function to when the task is cancelled or the
209        // callback is called, the driver runtime owns the contents of that
210        // object and we will not manipulate it. So even though the Arc only
211        // gives us a shared reference, it's fine to give the runtime a
212        // mutable pointer to it.
213        let res = unsafe {
214            let task_ptr = addr_of_mut!((*UnsafeCell::raw_get(task_cell)).task);
215            async_post_task(async_dispatcher, task_ptr)
216        };
217        if res != ZX_OK {
218            // SAFETY: `TaskFunc::call` will never be called now so dispose of
219            // the long-lived reference we just created.
220            unsafe { Arc::decrement_strong_count(task_cell) }
221            Err(Status::from_raw(res))
222        } else {
223            Ok(())
224        }
225    }
226
227    /// Releases ownership over this dispatcher and returns a [`DispatcherRef`]
228    /// that can be used to access it. The lifetime of this reference is static because it will
229    /// exist so long as this current driver is loaded, but the driver runtime will shut it down
230    /// when the driver is unloaded.
231    pub fn release(self) -> DispatcherRef<'static> {
232        DispatcherRef(ManuallyDrop::new(self), PhantomData)
233    }
234
235    /// Returns a [`DispatcherRef`] that references this dispatcher with a lifetime constrained by
236    /// `self`.
237    pub fn as_dispatcher_ref(&self) -> DispatcherRef<'_> {
238        DispatcherRef(ManuallyDrop::new(Dispatcher(self.0)), PhantomData)
239    }
240
241    /// Overrides the current dispatcher used by [`CurrentDispatcher::on_dispatcher`] while the
242    /// callback is being called.
243    #[doc(hidden)]
244    pub fn override_current<R>(dispatcher: DispatcherRef<'_>, f: impl FnOnce() -> R) -> R {
245        OVERRIDE_DISPATCHER.with(|global| {
246            let previous = global.replace(Some(dispatcher.0 .0));
247            let res = f();
248            global.replace(previous);
249            res
250        })
251    }
252}
253
254impl Drop for Dispatcher {
255    fn drop(&mut self) {
256        // SAFETY: we only ever provide an owned `Dispatcher` to one owner, so when
257        // that one is dropped we can invoke the shutdown of the dispatcher
258        unsafe { fdf_dispatcher_shutdown_async(self.0.as_mut()) }
259    }
260}
261
262/// An unowned reference to a driver runtime dispatcher such as is produced by calling
263/// [`Dispatcher::release`]. When this object goes out of scope it won't shut down the dispatcher,
264/// leaving that up to the driver runtime or another owner.
265#[derive(Debug)]
266pub struct DispatcherRef<'a>(ManuallyDrop<Dispatcher>, PhantomData<&'a Dispatcher>);
267
268impl<'a> DispatcherRef<'a> {
269    /// Creates a dispatcher ref from a raw handle.
270    ///
271    /// # Safety
272    ///
273    /// Caller is responsible for ensuring that the given handle is valid for
274    /// the lifetime `'a`.
275    pub unsafe fn from_raw(handle: NonNull<fdf_dispatcher_t>) -> Self {
276        // SAFETY: Caller promises the handle is valid.
277        Self(ManuallyDrop::new(unsafe { Dispatcher::from_raw(handle) }), PhantomData)
278    }
279}
280
281impl<'a> Clone for DispatcherRef<'a> {
282    fn clone(&self) -> Self {
283        Self(ManuallyDrop::new(Dispatcher(self.0 .0)), PhantomData)
284    }
285}
286
287impl<'a> core::ops::Deref for DispatcherRef<'a> {
288    type Target = Dispatcher;
289    fn deref(&self) -> &Self::Target {
290        &self.0
291    }
292}
293
294impl<'a> core::ops::DerefMut for DispatcherRef<'a> {
295    fn deref_mut(&mut self) -> &mut Self::Target {
296        &mut self.0
297    }
298}
299
300/// A trait that can be used to access a lifetime-constrained dispatcher in a generic way.
301pub trait OnDispatcher: Clone + Send + Sync + Unpin {
302    /// Runs the function `f` with a lifetime-bound [`DispatcherRef`] for this object's dispatcher.
303    /// If the dispatcher is no longer valid, the callback will be given [`None`].
304    fn on_dispatcher<R>(&self, f: impl FnOnce(Option<DispatcherRef<'_>>) -> R) -> R;
305
306    /// Helper version of [`OnDispatcher::on_dispatcher`] that translates an invalidated dispatcher
307    /// handle into a [`Status::BAD_STATE`] error instead of giving the callback [`None`].
308    fn on_maybe_dispatcher<R, E: From<Status>>(
309        &self,
310        f: impl FnOnce(DispatcherRef<'_>) -> Result<R, E>,
311    ) -> Result<R, E> {
312        self.on_dispatcher(|dispatcher| {
313            let dispatcher = dispatcher.ok_or(Status::BAD_STATE)?;
314            f(dispatcher)
315        })
316    }
317
318    /// Spawn an asynchronous task on this dispatcher. If this returns [`Ok`] then the task
319    /// has successfully been scheduled and will run or be cancelled and dropped when the dispatcher
320    /// shuts down.
321    fn spawn_task(&self, future: impl Future<Output = ()> + Send + 'static) -> Result<(), Status>
322    where
323        Self: 'static,
324    {
325        let task =
326            Arc::new(Task { future: Mutex::new(Some(future.boxed())), dispatcher: self.clone() });
327        task.queue()
328    }
329}
330
331impl<'a, D: OnDispatcher> OnDispatcher for &'a D {
332    fn on_dispatcher<R>(&self, f: impl FnOnce(Option<DispatcherRef<'_>>) -> R) -> R {
333        D::on_dispatcher(*self, f)
334    }
335}
336
337impl<'a> OnDispatcher for &'a Dispatcher {
338    fn on_dispatcher<R>(&self, f: impl FnOnce(Option<DispatcherRef<'_>>) -> R) -> R {
339        f(Some(self.as_dispatcher_ref()))
340    }
341}
342
343impl<'a> OnDispatcher for DispatcherRef<'a> {
344    fn on_dispatcher<R>(&self, f: impl FnOnce(Option<DispatcherRef<'_>>) -> R) -> R {
345        f(Some(self.as_dispatcher_ref()))
346    }
347}
348
349impl OnDispatcher for Arc<Dispatcher> {
350    fn on_dispatcher<R>(&self, f: impl FnOnce(Option<DispatcherRef<'_>>) -> R) -> R {
351        f(Some(self.as_dispatcher_ref()))
352    }
353}
354
355impl OnDispatcher for Weak<Dispatcher> {
356    fn on_dispatcher<R>(&self, f: impl FnOnce(Option<DispatcherRef<'_>>) -> R) -> R {
357        let dispatcher = Weak::upgrade(self);
358        match dispatcher {
359            Some(dispatcher) => f(Some(dispatcher.as_dispatcher_ref())),
360            None => f(None),
361        }
362    }
363}
364
365/// A placeholder for the currently active dispatcher. Use [`OnDispatcher::on_dispatcher`] to
366/// access it when needed.
367#[derive(Clone, Copy)]
368pub struct CurrentDispatcher;
369
370impl OnDispatcher for CurrentDispatcher {
371    fn on_dispatcher<R>(&self, f: impl FnOnce(Option<DispatcherRef<'_>>) -> R) -> R {
372        let dispatcher = OVERRIDE_DISPATCHER
373            .with(|global| global.borrow().clone())
374            .or_else(|| {
375                // SAFETY: NonNull::new will null-check that we have a current dispatcher.
376                NonNull::new(unsafe { fdf_dispatcher_get_current_dispatcher() })
377            })
378            .map(|dispatcher| {
379                // SAFETY: We constrain the lifetime of the `DispatcherRef` we provide to the
380                // function below to the span of the current function. Since we are running on
381                // the dispatcher, or another dispatcher that is bound to the same lifetime (through
382                // override_dispatcher), we can be sure that the dispatcher will not be shut
383                // down before that function completes.
384                DispatcherRef(
385                    ManuallyDrop::new(unsafe { Dispatcher::from_raw(dispatcher) }),
386                    Default::default(),
387                )
388            });
389        f(dispatcher)
390    }
391}
392
393/// A marker trait for a callback that can be used with [`Dispatcher::post_task_sync`].
394pub trait TaskCallback: FnOnce(Status) + 'static + Send {}
395impl<T> TaskCallback for T where T: FnOnce(Status) + 'static + Send {}
396
397struct Task<D> {
398    future: Mutex<Option<BoxFuture<'static, ()>>>,
399    dispatcher: D,
400}
401
402impl<D: OnDispatcher + 'static> ArcWake for Task<D> {
403    fn wake_by_ref(arc_self: &Arc<Self>) {
404        match arc_self.queue() {
405            Err(e) if e == Status::from_raw(ZX_ERR_BAD_STATE) => {
406                // the dispatcher is shutting down so drop the future, if there
407                // is one, to cancel it.
408                let future_slot = arc_self.future.lock().unwrap().take();
409                core::mem::drop(future_slot);
410            }
411            res => res.expect("Unexpected error waking dispatcher task"),
412        }
413    }
414}
415
416impl<D: OnDispatcher + 'static> Task<D> {
417    /// Posts a task to progress the currently stored future. The task will
418    /// consume the future if the future is ready after the next poll.
419    /// Otherwise, the future is kept to be polled again after being woken.
420    fn queue(self: &Arc<Self>) -> Result<(), Status> {
421        let arc_self = self.clone();
422        self.dispatcher.on_maybe_dispatcher(move |dispatcher| {
423            dispatcher
424                .post_task_sync(move |status| {
425                    let mut future_slot = arc_self.future.lock().unwrap();
426                    // if we're cancelled, drop the future we're waiting on.
427                    if status != Status::from_raw(ZX_OK) {
428                        core::mem::drop(future_slot.take());
429                        return;
430                    }
431
432                    let Some(mut future) = future_slot.take() else {
433                        return;
434                    };
435                    let waker = waker_ref(&arc_self);
436                    let context = &mut Context::from_waker(&waker);
437                    if future.as_mut().poll(context).is_pending() {
438                        *future_slot = Some(future);
439                    }
440                })
441                .map(|_| ())
442        })
443    }
444}
445
446#[repr(C)]
447struct TaskFunc {
448    task: async_task,
449    func: Box<dyn TaskCallback>,
450}
451
452impl TaskFunc {
453    extern "C" fn call(_dispatcher: *mut async_dispatcher, task: *mut async_task, status: i32) {
454        // SAFETY: the async api promises that this function will only be called
455        // up to once, so we can reconstitute the `Arc` and let it get dropped.
456        let task = unsafe { Arc::from_raw(task as *const UnsafeCell<Self>) };
457        // SAFETY: if we can't get a mut ref from the arc, then the task is already
458        // being cancelled, so we don't want to call it.
459        if let Some(task) = Arc::try_unwrap(task).ok() {
460            (task.into_inner().func)(Status::from_raw(status));
461        }
462    }
463}
464
465/// A shutdown observer for [`fdf_dispatcher_create`] that can call any kind of callback instead of
466/// just a C-compatible function when a dispatcher is shutdown.
467///
468/// # Safety
469///
470/// This object relies on a specific layout to allow it to be cast between a
471/// `*mut fdf_dispatcher_shutdown_observer` and a `*mut ShutdownObserver`. To that end,
472/// it is important that this struct stay both `#[repr(C)]` and that `observer` be its first member.
473#[repr(C)]
474#[doc(hidden)]
475pub struct ShutdownObserver {
476    observer: fdf_dispatcher_shutdown_observer,
477    shutdown_fn: Box<dyn ShutdownObserverFn>,
478}
479
480impl ShutdownObserver {
481    /// Creates a new [`ShutdownObserver`] with `f` as the callback to run when a dispatcher
482    /// finishes shutting down.
483    pub fn new<F: ShutdownObserverFn>(f: F) -> Self {
484        let shutdown_fn = Box::new(f);
485        Self {
486            observer: fdf_dispatcher_shutdown_observer { handler: Some(Self::handler) },
487            shutdown_fn,
488        }
489    }
490
491    /// Turns this object into a stable pointer suitable for passing to [`fdf_dispatcher_create`]
492    /// by wrapping it in a [`Box`] and leaking it to be reconstituded by [`Self::handler`] when
493    /// the dispatcher is shut down.
494    pub fn into_ptr(self) -> *mut fdf_dispatcher_shutdown_observer {
495        // Note: this relies on the assumption that `self.observer` is at the beginning of the
496        // struct.
497        Box::leak(Box::new(self)) as *mut _ as *mut _
498    }
499
500    /// The callback that is registered with the dispatcher that will be called when the dispatcher
501    /// is shut down.
502    ///
503    /// # Safety
504    ///
505    /// This function should only ever be called by the driver runtime at dispatcher shutdown
506    /// time, must only ever be called once for any given [`ShutdownObserver`] object, and
507    /// that [`ShutdownObserver`] object must have previously been made into a pointer by
508    /// [`Self::into_ptr`].
509    unsafe extern "C" fn handler(
510        dispatcher: *mut fdf_dispatcher_t,
511        observer: *mut fdf_dispatcher_shutdown_observer_t,
512    ) {
513        // SAFETY: The driver framework promises to only call this function once, so we can
514        // safely take ownership of the [`Box`] and deallocate it when this function ends.
515        let observer = unsafe { Box::from_raw(observer as *mut ShutdownObserver) };
516        // SAFETY: `dispatcher` is the dispatcher being shut down, so it can't be non-null.
517        let dispatcher_ref = DispatcherRef(
518            ManuallyDrop::new(Dispatcher(unsafe { NonNull::new_unchecked(dispatcher) })),
519            PhantomData,
520        );
521        (observer.shutdown_fn)(dispatcher_ref);
522        // SAFETY: we only shutdown the dispatcher when the dispatcher is dropped, and we only ever
523        // instantiate one owned copy of `Dispatcher` for a given dispatcher.
524        unsafe { fdf_dispatcher_destroy(dispatcher) };
525    }
526}
527
528#[cfg(test)]
529mod tests {
530    use super::*;
531
532    use std::sync::{mpsc, Once};
533
534    use futures::channel::mpsc as async_mpsc;
535    use futures::{SinkExt, StreamExt};
536
537    use core::ffi::{c_char, c_void};
538    use core::ptr::null_mut;
539
540    static GLOBAL_DRIVER_ENV: Once = Once::new();
541
542    pub fn ensure_driver_env() {
543        GLOBAL_DRIVER_ENV.call_once(|| {
544            // SAFETY: calling fdf_env_start, which does not have any soundness
545            // concerns for rust code, and this is only used in tests.
546            unsafe {
547                assert_eq!(fdf_env_start(0), ZX_OK);
548            }
549        });
550    }
551    pub fn with_raw_dispatcher<T>(name: &str, p: impl for<'a> FnOnce(Weak<Dispatcher>) -> T) -> T {
552        with_raw_dispatcher_flags(name, DispatcherBuilder::ALLOW_THREAD_BLOCKING, p)
553    }
554
555    pub(crate) fn with_raw_dispatcher_flags<T>(
556        name: &str,
557        flags: u32,
558        p: impl for<'a> FnOnce(Weak<Dispatcher>) -> T,
559    ) -> T {
560        ensure_driver_env();
561
562        let (shutdown_tx, shutdown_rx) = mpsc::channel();
563        let mut dispatcher = null_mut();
564        let mut observer = ShutdownObserver::new(move |dispatcher| {
565            // SAFETY: we verify that the dispatcher has no tasks left queued in it,
566            // just because this is testing code.
567            assert!(!unsafe { fdf_env_dispatcher_has_queued_tasks(dispatcher.0 .0.as_ptr()) });
568            shutdown_tx.send(()).unwrap();
569        })
570        .into_ptr();
571        let driver_ptr = &mut observer as *mut _ as *mut c_void;
572        // SAFETY: The pointers we pass to this function are all stable for the
573        // duration of this function, and are not available to copy or clone to
574        // client code (only through a ref to the non-`Clone`` `Dispatcher`
575        // wrapper).
576        let res = unsafe {
577            fdf_env_dispatcher_create_with_owner(
578                driver_ptr,
579                flags,
580                name.as_ptr() as *const c_char,
581                name.len(),
582                "".as_ptr() as *const c_char,
583                0 as usize,
584                observer,
585                &mut dispatcher,
586            )
587        };
588        assert_eq!(res, ZX_OK);
589        let dispatcher = Arc::new(Dispatcher(NonNull::new(dispatcher).unwrap()));
590
591        let res = p(Arc::downgrade(&dispatcher));
592
593        // this initiates the dispatcher shutdown on a driver runtime
594        // thread. When all tasks on the dispatcher have completed, the wait
595        // on the shutdown_rx below will end and we can tear it down.
596        let weak_dispatcher = Arc::downgrade(&dispatcher);
597        drop(dispatcher);
598        shutdown_rx.recv().unwrap();
599        assert_eq!(
600            0,
601            weak_dispatcher.strong_count(),
602            "a dispatcher reference escaped the test body"
603        );
604
605        res
606    }
607
608    #[test]
609    fn start_test_dispatcher() {
610        with_raw_dispatcher("testing", |dispatcher| {
611            println!("hello {dispatcher:?}");
612        })
613    }
614
615    #[test]
616    fn post_task_on_dispatcher() {
617        with_raw_dispatcher("testing task", |dispatcher| {
618            let (tx, rx) = mpsc::channel();
619            let dispatcher = Weak::upgrade(&dispatcher).unwrap();
620            dispatcher
621                .post_task_sync(move |status| {
622                    assert_eq!(status, Status::from_raw(ZX_OK));
623                    tx.send(status).unwrap();
624                })
625                .unwrap();
626            assert_eq!(rx.recv().unwrap(), Status::from_raw(ZX_OK));
627        });
628    }
629
630    #[test]
631    fn post_task_on_subdispatcher() {
632        let (shutdown_tx, shutdown_rx) = mpsc::channel();
633        with_raw_dispatcher("testing task top level", move |dispatcher| {
634            let (tx, rx) = mpsc::channel();
635            let (inner_tx, inner_rx) = mpsc::channel();
636            let dispatcher = Weak::upgrade(&dispatcher).unwrap();
637            dispatcher
638                .post_task_sync(move |status| {
639                    assert_eq!(status, Status::from_raw(ZX_OK));
640                    let inner = DispatcherBuilder::new()
641                        .name("testing task second level")
642                        .scheduler_role("")
643                        .allow_thread_blocking()
644                        .shutdown_observer(move |_dispatcher| {
645                            println!("shutdown observer called");
646                            shutdown_tx.send(1).unwrap();
647                        })
648                        .create()
649                        .unwrap();
650                    inner
651                        .post_task_sync(move |status| {
652                            assert_eq!(status, Status::from_raw(ZX_OK));
653                            tx.send(status).unwrap();
654                        })
655                        .unwrap();
656                    // we want to make sure the inner dispatcher lives long
657                    // enough to run the task, so we sent it out to the outer
658                    // closure.
659                    inner_tx.send(inner).unwrap();
660                })
661                .unwrap();
662            assert_eq!(rx.recv().unwrap(), Status::from_raw(ZX_OK));
663            inner_rx.recv().unwrap();
664        });
665        assert_eq!(shutdown_rx.recv().unwrap(), 1);
666    }
667
668    async fn ping(mut tx: async_mpsc::Sender<u8>, mut rx: async_mpsc::Receiver<u8>) {
669        println!("starting ping!");
670        tx.send(0).await.unwrap();
671        while let Some(next) = rx.next().await {
672            println!("ping! {next}");
673            tx.send(next + 1).await.unwrap();
674        }
675    }
676
677    async fn pong(
678        fin_tx: std::sync::mpsc::Sender<()>,
679        mut tx: async_mpsc::Sender<u8>,
680        mut rx: async_mpsc::Receiver<u8>,
681    ) {
682        println!("starting pong!");
683        while let Some(next) = rx.next().await {
684            println!("pong! {next}");
685            if next > 10 {
686                println!("bye!");
687                break;
688            }
689            tx.send(next + 1).await.unwrap();
690        }
691        fin_tx.send(()).unwrap();
692    }
693
694    #[test]
695    fn async_ping_pong() {
696        with_raw_dispatcher("async ping pong", |dispatcher| {
697            let (fin_tx, fin_rx) = mpsc::channel();
698            let (ping_tx, pong_rx) = async_mpsc::channel(10);
699            let (pong_tx, ping_rx) = async_mpsc::channel(10);
700            dispatcher.spawn_task(ping(ping_tx, ping_rx)).unwrap();
701            dispatcher.spawn_task(pong(fin_tx, pong_tx, pong_rx)).unwrap();
702
703            fin_rx.recv().expect("to receive final value");
704        });
705    }
706
707    async fn slow_pong(
708        fin_tx: std::sync::mpsc::Sender<()>,
709        mut tx: async_mpsc::Sender<u8>,
710        mut rx: async_mpsc::Receiver<u8>,
711    ) {
712        use zx::MonotonicDuration;
713        println!("starting pong!");
714        while let Some(next) = rx.next().await {
715            println!("pong! {next}");
716            fuchsia_async::Timer::new(fuchsia_async::MonotonicInstant::after(
717                MonotonicDuration::from_seconds(1),
718            ))
719            .await;
720            if next > 10 {
721                println!("bye!");
722                break;
723            }
724            tx.send(next + 1).await.unwrap();
725        }
726        fin_tx.send(()).unwrap();
727    }
728
729    #[test]
730    fn mixed_executor_async_ping_pong() {
731        with_raw_dispatcher("async ping pong", |dispatcher| {
732            let (fin_tx, fin_rx) = mpsc::channel();
733            let (ping_tx, pong_rx) = async_mpsc::channel(10);
734            let (pong_tx, ping_rx) = async_mpsc::channel(10);
735
736            // spawn ping on the driver dispatcher
737            dispatcher.spawn_task(ping(ping_tx, ping_rx)).unwrap();
738
739            // and run pong on the fuchsia_async executor
740            let mut executor = fuchsia_async::LocalExecutor::new();
741            executor.run_singlethreaded(slow_pong(fin_tx, pong_tx, pong_rx));
742
743            fin_rx.recv().expect("to receive final value");
744        });
745    }
746}
fdf_core/dispatcher.rs

fdf_core/
dispatcher.rs
