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Bias Selector to first poll the sleeper future #4259

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Merged
TheBlueMatt merged 1 commit into from
Dec 5, 2025
+19 −17
Merged

Bias Selector to first poll the sleeper future #4259

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36 changes: 19 additions & 17 deletions lightning-background-processor/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -476,11 +476,11 @@ pub(crate) mod futures_util {
use core::pin::Pin;
use core::task::{Poll, RawWaker, RawWakerVTable, Waker};
pub(crate) struct Selector<
A: Future<Output = ()> + Unpin,
A: Future<Output = bool> + Unpin,
B: Future<Output = ()> + Unpin,
C: Future<Output = ()> + Unpin,
D: Future<Output = ()> + Unpin,
E: Future<Output = bool> + Unpin,
E: Future<Output = ()> + Unpin,
> {
pub a: A,
pub b: B,
Expand All @@ -490,28 +490,30 @@ pub(crate) mod futures_util {
}

pub(crate) enum SelectorOutput {
A,
A(bool),
B,
C,
D,
E(bool),
E,
}

impl<
A: Future<Output = ()> + Unpin,
A: Future<Output = bool> + Unpin,
B: Future<Output = ()> + Unpin,
C: Future<Output = ()> + Unpin,
D: Future<Output = ()> + Unpin,
E: Future<Output = bool> + Unpin,
E: Future<Output = ()> + Unpin,
> Future for Selector<A, B, C, D, E>
{
type Output = SelectorOutput;
fn poll(
mut self: Pin<&mut Self>, ctx: &mut core::task::Context<'_>,
) -> Poll<SelectorOutput> {
// Bias the selector so it first polls the sleeper future, allowing to exit immediately
// if the flag is set.
match Pin::new(&mut self.a).poll(ctx) {
Poll::Ready(()) => {
return Poll::Ready(SelectorOutput::A);
Poll::Ready(res) => {
return Poll::Ready(SelectorOutput::A(res));
},
Poll::Pending => {},
}
Expand All @@ -534,8 +536,8 @@ pub(crate) mod futures_util {
Poll::Pending => {},
}
match Pin::new(&mut self.e).poll(ctx) {
Poll::Ready(res) => {
return Poll::Ready(SelectorOutput::E(res));
Poll::Ready(()) => {
return Poll::Ready(SelectorOutput::E);
},
Poll::Pending => {},
}
Expand Down Expand Up @@ -1037,15 +1039,15 @@ where
(false, false) => FASTEST_TIMER,
};
let fut = Selector {
a: channel_manager.get_cm().get_event_or_persistence_needed_future(),
b: chain_monitor.get_update_future(),
c: om_fut,
d: lm_fut,
e: sleeper(sleep_delay),
a: sleeper(sleep_delay),
b: channel_manager.get_cm().get_event_or_persistence_needed_future(),
c: chain_monitor.get_update_future(),
d: om_fut,
e: lm_fut,
};
match fut.await {
SelectorOutput::A | SelectorOutput::B | SelectorOutput::C | SelectorOutput::D => {},
SelectorOutput::E(exit) => {
SelectorOutput::B | SelectorOutput::C | SelectorOutput::D | SelectorOutput::E => {},
SelectorOutput::A(exit) => {
if exit {
break;
}
Expand Down