Use the user-provided `SleepFuture` for interval checks in BP

`background-processor` does a number of jobs on various timers.
Instead of doing those by interrogating `std::time::Instant`, this
change swaps to using the existing user-provided sleep future.

Fixes #1864.

diff --git a/lightning-background-processor/src/lib.rs b/lightning-background-processor/src/lib.rs
index e93139bf0c2b0bf51fceeed432236d84a504498c..b2ee865471c89f3ca1d537088c8e3425c9d4cbf8 100644 (file)
--- a/lightning-background-processor/src/lib.rs
+++ b/lightning-background-processor/src/lib.rs
@@ -36,7 +36,7 @@ use std::time::{Duration, Instant};
 use std::ops::Deref;
 
 #[cfg(feature = "futures")]
-use futures_util::{select_biased, future::FutureExt};
+use futures_util::{select_biased, future::FutureExt, task};
 
 /// `BackgroundProcessor` takes care of tasks that (1) need to happen periodically to keep
 /// Rust-Lightning running properly, and (2) either can or should be run in the background. Its
@@ -364,7 +364,7 @@ pub async fn process_events_async<
        PM: 'static + Deref<Target = PeerManager<Descriptor, CMH, RMH, OMH, L, UMH>> + Send + Sync,
        S: 'static + Deref<Target = SC> + Send + Sync,
        SC: WriteableScore<'a>,
-       SleepFuture: core::future::Future<Output = bool>,
+       SleepFuture: core::future::Future<Output = bool> + core::marker::Unpin,
        Sleeper: Fn(Duration) -> SleepFuture
 >(
        persister: PS, event_handler: EventHandler, chain_monitor: M, channel_manager: CM,
@@ -411,7 +411,12 @@ where
                                        false
                                }
                        }
-               }, |_| Instant::now(), |time: &Instant, dur| time.elapsed().as_secs() > dur)
+               }, |t| sleeper(Duration::from_secs(t)),
+               |fut: &mut SleepFuture, _| {
+                       let mut waker = task::noop_waker();
+                       let mut ctx = task::Context::from_waker(&mut waker);
+                       core::pin::Pin::new(fut).poll(&mut ctx).is_ready()
+               })
 }
 
 impl BackgroundProcessor {