f use wait_while, rather than wait

Author: TheBlueMatt

lightning/src/util/wakers.rs

@@ -240,12 +240,8 @@ impl Sleeper {
 	/// Wait until one of the [`Future`]s registered with this [`Sleeper`] has completed.
 	pub fn wait(&self) {
 		let (cv, notified_fut_mtx) = self.setup_wait();
-		let notified_fut = loop {
-			let mut notified_fut_lck = cv.wait(notified_fut_mtx.lock().unwrap()).unwrap();
-			if let Some(notified_fut) = notified_fut_lck.take() {
-				break notified_fut;
-			}
-		};
+		let notified_fut = cv.wait_while(notified_fut_mtx.lock().unwrap(), |fut_opt| fut_opt.is_none())
+			.unwrap().take().expect("CV wait shouldn't have returned until the notifying future was set");
 		notified_fut.lock().unwrap().callbacks_made = true;
 	}
 
@@ -254,18 +250,14 @@ impl Sleeper {
 	/// elapsed.
 	#[cfg(any(test, feature = "std"))]
 	pub fn wait_timeout(&self, max_wait: Duration) -> bool {
-		let start_time = Instant::now();
 		let (cv, notified_fut_mtx) = self.setup_wait();
-		let notified_fut = loop {
-			let wait_duration = max_wait.saturating_sub(start_time.elapsed());
-			if wait_duration == Duration::from_secs(0) { return false; }
-			match cv.wait_timeout(notified_fut_mtx.lock().unwrap(), wait_duration) {
-				Ok((mut notified_fut, _)) if notified_fut.is_some() =>
-					break notified_fut.take().unwrap(),
-				Ok((notified_fut_lck, _)) => continue,
+		let notified_fut =
+			match cv.wait_timeout_while(notified_fut_mtx.lock().unwrap(), max_wait, |fut_opt| fut_opt.is_none()) {
+				Ok((_, e)) if e.timed_out() => return false,
+				Ok((mut notified_fut, _)) =>
+					notified_fut.take().expect("CV wait shouldn't have returned until the notifying future was set"),
 				Err(_) => panic!("Previous panic while a lock was held led to a lock panic"),
 			};
-		};
 		notified_fut.lock().unwrap().callbacks_made = true;
 		true
 	}