embassy_sync/waitqueue/
atomic_waker.rs

1use core::cell::Cell;
2use core::task::Waker;
3
4use crate::blocking_mutex::raw::{CriticalSectionRawMutex, RawMutex};
5use crate::blocking_mutex::Mutex;
6
7/// Utility struct to register and wake a waker.
8/// If a waker is registered, registering another waker will replace the previous one without waking it.
9/// Intended to wake a task from an interrupt. Therefore, it is generally not expected,
10/// that multiple tasks register try to register a waker simultaneously.
11pub struct GenericAtomicWaker<M: RawMutex> {
12    waker: Mutex<M, Cell<Option<Waker>>>,
13}
14
15impl<M: RawMutex> GenericAtomicWaker<M> {
16    /// Create a new `AtomicWaker`.
17    pub const fn new(mutex: M) -> Self {
18        Self {
19            waker: Mutex::const_new(mutex, Cell::new(None)),
20        }
21    }
22
23    /// Register a waker. Overwrites the previous waker, if any.
24    pub fn register(&self, w: &Waker) {
25        self.waker.lock(|cell| {
26            cell.set(match cell.replace(None) {
27                Some(w2) if (w2.will_wake(w)) => Some(w2),
28                _ => Some(w.clone()),
29            })
30        })
31    }
32
33    /// Wake the registered waker, if any.
34    pub fn wake(&self) {
35        self.waker.lock(|cell| {
36            if let Some(w) = cell.replace(None) {
37                w.wake_by_ref();
38                cell.set(Some(w));
39            }
40        })
41    }
42}
43
44/// Utility struct to register and wake a waker.
45pub struct AtomicWaker {
46    waker: GenericAtomicWaker<CriticalSectionRawMutex>,
47}
48
49impl AtomicWaker {
50    /// Create a new `AtomicWaker`.
51    pub const fn new() -> Self {
52        Self {
53            waker: GenericAtomicWaker::new(CriticalSectionRawMutex::new()),
54        }
55    }
56
57    /// Register a waker. Overwrites the previous waker, if any.
58    pub fn register(&self, w: &Waker) {
59        self.waker.register(w);
60    }
61
62    /// Wake the registered waker, if any.
63    pub fn wake(&self) {
64        self.waker.wake();
65    }
66}
embassy_sync/waitqueue/atomic_waker.rs

embassy_sync/waitqueue/
atomic_waker.rs
