Add a helper for pausing a Stream on errors#50
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Based on kube-rs/kube#720, but with generalizations for runtime-agnosticity, and and pin-project-lite.
| pub(crate) fn rt_sleeper() -> impl Sleeper { | ||
| AsyncStdSleeper | ||
| } | ||
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| #[cfg(feature = "tokio")] | ||
| fn rt_sleeper() -> impl Sleeper { | ||
| pub(crate) fn rt_sleeper() -> impl Sleeper { | ||
| TokioSleeper | ||
| } | ||
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| #[cfg(feature = "tokio")] | ||
| #[cfg_attr(docsrs, doc(cfg(feature = "tokio")))] | ||
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| struct TokioSleeper; | ||
| pub(crate) struct TokioSleeper; |
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Need to use this in stream
| #[cfg(feature = "futures")] | ||
| #[cfg_attr(docsrs, doc(cfg(feature = "futures")))] | ||
| pub mod future; | ||
| #[cfg(feature = "futures")] |
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Didn't create a new feature here, since this doesn't bring in any new (runtime) dependencies, but happy to change if prefer
| tokio::time::pause(); | ||
| let tick = Duration::from_secs(1); | ||
| let rx = stream::iter([Ok(0), Ok(1), Err(2), Ok(3), Ok(4)]); | ||
| let rx = StreamBackoff::new(rx, crate::backoff::Constant::new(tick), TokioSleeper); |
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Need to use Tokio specifically for these marble tests, since async-std doesn't support time travel (and, regardless, Sleeper doesn't and probably shouldn't support that).
| match this.state.as_mut().project() { | ||
| StateProj::BackingOff { mut backoff_sleep } => match backoff_sleep.as_mut().poll(cx) { | ||
| Poll::Ready(()) => { | ||
| // tracing::debug!(deadline = ?backoff_sleep.deadline(), "Backoff complete, waking up"); |
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I think these trace messages can be valuable for debugging (since backoff is bound to look weird to the user), but I didn't want to bring in new dependencies for this. On the other hand, Tokio already brings in the dependency so I'm not sure it'd be a huge problem to add.
| use tokio_1 as tokio; | ||
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| #[tokio::test] | ||
| async fn stream_should_back_off() { |
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These tests depend on TokioSleeper which requires the tokio feature, so they'll fail to build with the feature set futures,!tokio. Do we want to always build TokioSleeper in tests?
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| /// Dynamic backoff policy that is still deterministic and testable | ||
| struct LinearBackoff { |
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Might be worth promoting this to crate::backoff? Not sure I'd use it in production, but it's pretty nice to have a predictable and deterministic variant of ExponentialBackoff when writing marble tests.
| /// | ||
| /// If [`Backoff::next_backoff`] returns [`None`] then the backing stream is given up on, and closed. | ||
| #[cfg(any(feature = "tokio", feature = "async-std"))] | ||
| pub fn backoff<S: TryStream, B: Backoff>( |
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Ideally this'd be an extension method on TryStream, but that isn't allowed for impl Trait return values.
Even when neither tokio nor async-std are enabled.
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Based on kube-rs/kube#720, but with generalizations for runtime-agnosticity, and and pin-project-lite.
Not sure about whether this ultimately belongs here or in a utility crate, but figured it was worth raising the question regardless.