kube_runtime/utils/
event_decode.rs

1use crate::watcher::{Error, Event};
2use core::{
3    pin::Pin,
4    task::{ready, Context, Poll},
5};
6use futures::{Stream, TryStream};
7use pin_project::pin_project;
8
9#[pin_project]
10/// Stream returned by the [`applied_objects`](super::WatchStreamExt::applied_objects) and [`touched_objects`](super::WatchStreamExt::touched_objects) method.
11#[must_use = "streams do nothing unless polled"]
12pub struct EventDecode<St> {
13    #[pin]
14    stream: St,
15    emit_deleted: bool,
16}
17impl<St: TryStream<Ok = Event<K>>, K> EventDecode<St> {
18    pub(super) fn new(stream: St, emit_deleted: bool) -> Self {
19        Self { stream, emit_deleted }
20    }
21}
22impl<St, K> Stream for EventDecode<St>
23where
24    St: Stream<Item = Result<Event<K>, Error>>,
25{
26    type Item = Result<K, Error>;
27
28    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
29        let mut me = self.project();
30        Poll::Ready(loop {
31            let var_name = match ready!(me.stream.as_mut().poll_next(cx)) {
32                Some(Ok(Event::Apply(obj) | Event::InitApply(obj))) => Some(Ok(obj)),
33                Some(Ok(Event::Delete(obj))) => {
34                    if *me.emit_deleted {
35                        Some(Ok(obj))
36                    } else {
37                        continue;
38                    }
39                }
40                Some(Ok(Event::Init | Event::InitDone)) => continue,
41                Some(Err(err)) => Some(Err(err)),
42                None => return Poll::Ready(None),
43            };
44            break var_name;
45        })
46    }
47}
48
49#[cfg(test)]
50pub(crate) mod tests {
51    use std::{pin::pin, task::Poll};
52
53    use super::{Error, Event, EventDecode};
54    use futures::{poll, stream, StreamExt};
55
56    #[tokio::test]
57    async fn watches_applies_uses_correct_stream() {
58        let data = stream::iter([
59            Ok(Event::Apply(0)),
60            Ok(Event::Apply(1)),
61            Ok(Event::Delete(0)),
62            Ok(Event::Apply(2)),
63            Ok(Event::InitApply(1)),
64            Ok(Event::InitApply(2)),
65            Err(Error::NoResourceVersion),
66            Ok(Event::Apply(2)),
67        ]);
68        let mut rx = pin!(EventDecode::new(data, false));
69        assert!(matches!(poll!(rx.next()), Poll::Ready(Some(Ok(0)))));
70        assert!(matches!(poll!(rx.next()), Poll::Ready(Some(Ok(1)))));
71        // NB: no Deleted events here
72        assert!(matches!(poll!(rx.next()), Poll::Ready(Some(Ok(2)))));
73        // Restart comes through, currently in reverse order
74        // (normally on restart they just come in alphabetical order by name)
75        // this is fine though, alphabetical event order has no functional meaning in watchers
76        assert!(matches!(poll!(rx.next()), Poll::Ready(Some(Ok(1)))));
77        assert!(matches!(poll!(rx.next()), Poll::Ready(Some(Ok(2)))));
78        // Error passed through
79        assert!(matches!(
80            poll!(rx.next()),
81            Poll::Ready(Some(Err(Error::NoResourceVersion)))
82        ));
83        assert!(matches!(poll!(rx.next()), Poll::Ready(Some(Ok(2)))));
84        assert!(matches!(poll!(rx.next()), Poll::Ready(None)));
85    }
86}
kube_runtime/utils/event_decode.rs

kube_runtime/utils/
event_decode.rs
