| use core::task::Waker; |
| |
| /// Utility struct to register and wake a waker. |
| #[derive(Debug)] |
| pub struct WakerRegistration { |
| waker: Option<Waker>, |
| } |
| |
| impl WakerRegistration { |
| pub const fn new() -> Self { |
| Self { waker: None } |
| } |
| |
| /// Register a waker. Overwrites the previous waker, if any. |
| pub fn register(&mut self, w: &Waker) { |
| match self.waker { |
| // Optimization: If both the old and new Wakers wake the same task, we can simply |
| // keep the old waker, skipping the clone. (In most executor implementations, |
| // cloning a waker is somewhat expensive, comparable to cloning an Arc). |
| Some(ref w2) if (w2.will_wake(w)) => {} |
| // In all other cases |
| // - we have no waker registered |
| // - we have a waker registered but it's for a different task. |
| // then clone the new waker and store it |
| _ => self.waker = Some(w.clone()), |
| } |
| } |
| |
| /// Wake the registered waker, if any. |
| pub fn wake(&mut self) { |
| self.waker.take().map(|w| w.wake()); |
| } |
| } |