Jędrzej Stuczyński
98 lines
3.0 KiB
Rust
98 lines
3.0 KiB
Rust
// Copyright 2021 - Nym Technologies SA <contact@nymtech.net>
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// SPDX-License-Identifier: Apache-2.0
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use std::pin::Pin;
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use std::task::{Context, Poll, Waker};
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use std::time::Duration;
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use tokio_stream::Stream;
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// this is a copy of tokio-util delay_queue with `Sleep` and `Instant` being replaced with
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// `wasm_timer` equivalents
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#[cfg(not(target_arch = "wasm32"))]
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type DelayQueue<T> = tokio_util::time::DelayQueue<T>;
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#[cfg(not(target_arch = "wasm32"))]
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pub use tokio_util::time::delay_queue::Expired;
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#[cfg(not(target_arch = "wasm32"))]
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pub type QueueKey = tokio_util::time::delay_queue::Key;
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#[cfg(not(target_arch = "wasm32"))]
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use tokio::time::Instant;
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#[cfg(target_arch = "wasm32")]
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type DelayQueue<T> = wasmtimer::tokio_util::DelayQueue<T>;
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#[cfg(target_arch = "wasm32")]
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pub use wasmtimer::tokio_util::delay_queue::Expired;
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#[cfg(target_arch = "wasm32")]
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pub type QueueKey = wasmtimer::tokio_util::delay_queue::Key;
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#[cfg(target_arch = "wasm32")]
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use wasmtimer::std::Instant;
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/// A variant of tokio's `DelayQueue`, such that its `Stream` implementation will never return a 'None'.
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pub struct NonExhaustiveDelayQueue<T> {
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inner: DelayQueue<T>,
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waker: Option<Waker>,
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}
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// more methods of underlying DelayQueue will get exposed as we need them
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impl<T> NonExhaustiveDelayQueue<T> {
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pub fn new() -> Self {
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NonExhaustiveDelayQueue {
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inner: DelayQueue::new(),
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waker: None,
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}
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}
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pub fn insert(&mut self, value: T, timeout: Duration) -> QueueKey {
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let key = self.inner.insert(value, timeout);
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if let Some(waker) = self.waker.take() {
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// we were waiting for an item - wake the executor!
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waker.wake()
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}
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key
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}
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pub fn insert_at(&mut self, value: T, when: Instant) -> QueueKey {
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let key = self.inner.insert_at(value, when);
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if let Some(waker) = self.waker.take() {
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// we were waiting for an item - wake the executor!
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waker.wake()
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}
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key
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}
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// TODO: it seems like this one can cause panic in very rare edge cases, however,
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// I can't seem to be able to reproduce it at all.
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pub fn remove(&mut self, key: &QueueKey) -> Expired<T> {
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self.inner.remove(key)
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}
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}
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impl<T> Default for NonExhaustiveDelayQueue<T> {
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fn default() -> Self {
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NonExhaustiveDelayQueue::new()
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}
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}
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impl<T> Stream for NonExhaustiveDelayQueue<T> {
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type Item = <DelayQueue<T> as Stream>::Item;
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fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
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match Pin::new(&mut self.inner).poll_next(cx) {
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Poll::Pending => Poll::Pending,
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Poll::Ready(Some(item)) => Poll::Ready(Some(item)),
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Poll::Ready(None) => {
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// we'll need to keep the waker to notify the executor once we get new item
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self.waker = Some(cx.waker().clone());
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Poll::Pending
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}
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}
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}
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}
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// #[cfg(test)]
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// mod tests {
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// use super::*;
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//
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//
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// }
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