diatomic_waker/
arc_waker.rs

1use alloc::sync::Arc;
2use core::task::Waker;
3
4use crate::DiatomicWaker;
5use crate::WaitUntil;
6
7/// An owned object that can await notifications from one or several
8/// [`WakeSource`]s.
9///
10/// See the [crate-level documentation](crate) for usage.
11#[derive(Debug, Default)]
12pub struct WakeSink {
13    /// The shared data.
14    inner: Arc<DiatomicWaker>,
15}
16
17impl WakeSink {
18    /// Creates a new sink.
19    pub fn new() -> Self {
20        Self {
21            inner: Arc::new(DiatomicWaker::new()),
22        }
23    }
24
25    /// Creates an owned source.
26    #[inline]
27    pub fn source(&self) -> WakeSource {
28        WakeSource {
29            inner: self.inner.clone(),
30        }
31    }
32
33    /// Registers a new waker.
34    ///
35    /// Registration is lazy: the waker is cloned only if it differs from the
36    /// last registered waker (note that the last registered waker is cached
37    /// even if it was unregistered).
38    #[inline]
39    pub fn register(&mut self, waker: &Waker) {
40        // Safety: `DiatomicWaker::register`, `DiatomicWaker::unregister` and
41        // `DiatomicWaker::wait_until` cannot be used concurrently from multiple
42        // thread since `WakeSink` does not implement `Clone` and the wrappers
43        // of the above methods require exclusive ownership to `WakeSink`.
44        unsafe { self.inner.register(waker) };
45    }
46
47    /// Unregisters the waker.
48    ///
49    /// After the waker is unregistered, subsequent calls to
50    /// `WakeSource::notify` will be ignored.
51    ///
52    /// Note that the previously-registered waker (if any) remains cached.
53    #[inline]
54    pub fn unregister(&mut self) {
55        // Safety: `DiatomicWaker::register`, `DiatomicWaker::unregister` and
56        // `DiatomicWaker::wait_until` cannot be used concurrently from multiple
57        // thread since `WakeSink` does not implement `Clone` and the wrappers
58        // of the above methods require exclusive ownership to `WakeSink`.
59        unsafe { self.inner.unregister() };
60    }
61
62    /// Returns a future that can be `await`ed until the provided predicate
63    /// returns a value.
64    ///
65    /// The predicate is checked each time a notification is received.
66    #[inline]
67    pub fn wait_until<P, T>(&mut self, predicate: P) -> WaitUntil<'_, P, T>
68    where
69        P: FnMut() -> Option<T>,
70    {
71        // Safety: `DiatomicWaker::register`, `DiatomicWaker::unregister` and
72        // `DiatomicWaker::wait_until` cannot be used concurrently from multiple
73        // thread since `WakeSink` does not implement `Clone` and the wrappers
74        // of the above methods require exclusive ownership to `WakeSink`.
75        unsafe { self.inner.wait_until(predicate) }
76    }
77}
78
79/// An owned object that can send notifications to a [`WakeSink`].
80///
81/// See the [crate-level documentation](crate) for usage.
82#[derive(Clone, Debug)]
83pub struct WakeSource {
84    /// The shared data.
85    inner: Arc<DiatomicWaker>,
86}
87
88impl WakeSource {
89    /// Notifies the sink if a waker is registered.
90    ///
91    /// This automatically unregisters any waker that may have been previously
92    /// registered.
93    #[inline]
94    pub fn notify(&self) {
95        self.inner.notify();
96    }
97}
diatomic_waker/arc_waker.rs

diatomic_waker/
arc_waker.rs
