Add CondVar::wait_{timeout_,}while to debug_sync

These are useful, but we previously couldn't use them due to our
MSRV. Now that we can, we should use them, so we expose them via
our normal debug_sync wrappers.

lightning/src/sync/debug_sync.rs

@@ -12,6 +12,8 @@ use std::sync::RwLockReadGuard as StdRwLockReadGuard;
 use std::sync::RwLockWriteGuard as StdRwLockWriteGuard;
 use std::sync::Condvar as StdCondvar;
 
+pub use std::sync::WaitTimeoutResult;
+
 use crate::prelude::HashMap;
 
 use super::{LockTestExt, LockHeldState};
@@ -40,12 +42,27 @@ impl Condvar {
 		self.inner.wait(guard.into_inner()).map(|lock| MutexGuard { mutex, lock }).map_err(|_| ())
 	}
 
+	pub fn wait_while<'a, T, F: FnMut(&mut T) -> bool>(&'a self, guard: MutexGuard<'a, T>, condition: F)
+	-> LockResult<MutexGuard<'a, T>> {
+		let mutex: &'a Mutex<T> = guard.mutex;
+		self.inner.wait_while(guard.into_inner(), condition).map(|lock| MutexGuard { mutex, lock })
+			.map_err(|_| ())
+	}
+
 	#[allow(unused)]
 	pub fn wait_timeout<'a, T>(&'a self, guard: MutexGuard<'a, T>, dur: Duration) -> LockResult<(MutexGuard<'a, T>, ())> {
 		let mutex = guard.mutex;
 		self.inner.wait_timeout(guard.into_inner(), dur).map(|(lock, _)| (MutexGuard { mutex, lock }, ())).map_err(|_| ())
 	}
 
+	#[allow(unused)]
+	pub fn wait_timeout_while<'a, T, F: FnMut(&mut T) -> bool>(&'a self, guard: MutexGuard<'a, T>, dur: Duration, condition: F)
+	-> LockResult<(MutexGuard<'a, T>, WaitTimeoutResult)> {
+		let mutex = guard.mutex;
+		self.inner.wait_timeout_while(guard.into_inner(), dur, condition).map_err(|_| ())
+			.map(|(lock, e)| (MutexGuard { mutex, lock }, e))
+	}
+
 	pub fn notify_all(&self) { self.inner.notify_all(); }
 }
 

lightning/src/sync/nostd_sync.rs

@@ -8,6 +8,11 @@ pub type LockResult<Guard> = Result<Guard, ()>;
 
 pub struct Condvar {}
 
+pub struct WaitTimeoutResult(bool);
+impl WaitTimeoutResult {
+	pub fn timed_out(&self) -> bool { self.0 }
+}
+
 impl Condvar {
 	pub fn new() -> Condvar {
 		Condvar { }
@@ -22,6 +27,22 @@ impl Condvar {
 		Ok((guard, ()))
 	}
 
+	pub fn wait_while<'a, T, F: FnMut(&mut T) -> bool>(&'a self, mut guard: MutexGuard<'a, T>, mut condition: F)
+	-> LockResult<MutexGuard<'a, T>> {
+		assert!(!condition(&mut *guard));
+		Ok(guard)
+	}
+
+	#[allow(unused)]
+	pub fn wait_timeout_while<'a, T, F: FnMut(&mut T) -> bool>(&'a self, mut guard: MutexGuard<'a, T>, dur: Duration, mut condition: F)
+	-> LockResult<(MutexGuard<'a, T>, WaitTimeoutResult)> {
+		if condition(&mut *guard) {
+			Ok((guard, WaitTimeoutResult(true)))
+		} else {
+			Ok((guard, WaitTimeoutResult(false)))
+		}
+	}
+
 	pub fn notify_all(&self) {}
 }