57 lines
1.2 KiB
Rust
57 lines
1.2 KiB
Rust
use std::fmt::{Debug, Formatter};
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use {
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crate::utils::numcell::NumCell,
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std::{
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cell::Cell,
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future::Future,
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pin::Pin,
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task::{Context, Poll, Waker},
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},
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};
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#[derive(Default)]
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pub struct AsyncEvent {
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triggers: NumCell<u32>,
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waker: Cell<Option<Waker>>,
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}
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impl Debug for AsyncEvent {
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fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
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f.debug_struct("AsyncEvent").field("triggers", &self.triggers.get()).finish_non_exhaustive()
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}
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}
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impl AsyncEvent {
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pub fn clear(&self) {
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self.waker.take();
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}
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pub fn trigger(&self) {
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if self.triggers.fetch_add(1) == 0 {
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if let Some(waker) = self.waker.take() {
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waker.wake();
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}
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}
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}
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pub fn triggered(&self) -> AsyncEventTriggered {
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AsyncEventTriggered { ae: self }
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}
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}
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pub struct AsyncEventTriggered<'a> {
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ae: &'a AsyncEvent,
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}
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impl<'a> Future for AsyncEventTriggered<'a> {
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type Output = ();
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fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
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if self.ae.triggers.replace(0) == 0 {
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self.ae.waker.set(Some(cx.waker().clone()));
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Poll::Pending
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} else {
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Poll::Ready(())
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}
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}
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}
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