Add Notifier to OnionMessenger

Author: tnull

lightning-background-processor/src/lib.rs

@@ -492,23 +492,28 @@ pub(crate) mod futures_util {
 	pub(crate) struct Selector<
 		A: Future<Output = ()> + Unpin,
 		B: Future<Output = ()> + Unpin,
-		C: Future<Output = bool> + Unpin,
+		C: Future<Output = ()> + Unpin,
+		D: Future<Output = bool> + Unpin,
 	> {
 		pub a: A,
 		pub b: B,
 		pub c: C,
+		pub d: D,
 	}
+
 	pub(crate) enum SelectorOutput {
 		A,
 		B,
-		C(bool),
+		C,
+		D(bool),
 	}
 
 	impl<
 			A: Future<Output = ()> + Unpin,
 			B: Future<Output = ()> + Unpin,
-			C: Future<Output = bool> + Unpin,
-		> Future for Selector<A, B, C>
+			C: Future<Output = ()> + Unpin,
+			D: Future<Output = bool> + Unpin,
+		> Future for Selector<A, B, C, D>
 	{
 		type Output = SelectorOutput;
 		fn poll(
@@ -527,15 +532,41 @@ pub(crate) mod futures_util {
 				Poll::Pending => {},
 			}
 			match Pin::new(&mut self.c).poll(ctx) {
+				Poll::Ready(()) => {
+					return Poll::Ready(SelectorOutput::C);
+				},
+				Poll::Pending => {},
+			}
+			match Pin::new(&mut self.d).poll(ctx) {
 				Poll::Ready(res) => {
-					return Poll::Ready(SelectorOutput::C(res));
+					return Poll::Ready(SelectorOutput::D(res));
 				},
 				Poll::Pending => {},
 			}
 			Poll::Pending
 		}
 	}
 
+	pub(crate) struct OptionalSelector<F: Future<Output = ()> + Unpin> {
+		pub optional_future: Option<F>,
+	}
+
+	impl<F: Future<Output = ()> + Unpin> Future for OptionalSelector<F> {
+		type Output = ();
+		fn poll(mut self: Pin<&mut Self>, ctx: &mut core::task::Context<'_>) -> Poll<Self::Output> {
+			match self.optional_future.as_mut() {
+				Some(f) => match core::pin::pin!(f).poll(ctx) {
+					Poll::Ready(()) => {
+						self.optional_future.take();
+						Poll::Ready(())
+					},
+					Poll::Pending => Poll::Pending,
+				},
+				None => Poll::Pending,
+			}
+		}
+	}
+
 	// If we want to poll a future without an async context to figure out if it has completed or
 	// not without awaiting, we need a Waker, which needs a vtable...we fill it with dummy values
 	// but sadly there's a good bit of boilerplate here.
@@ -557,7 +588,7 @@ pub(crate) mod futures_util {
 #[cfg(feature = "futures")]
 use core::task;
 #[cfg(feature = "futures")]
-use futures_util::{dummy_waker, Selector, SelectorOutput};
+use futures_util::{dummy_waker, OptionalSelector, Selector, SelectorOutput};
 
 /// Processes background events in a future.
 ///
@@ -782,18 +813,25 @@ where
 		scorer,
 		should_break,
 		{
+			let om_fut = if let Some(om) = onion_messenger.as_ref() {
+				let fut = om.get_om().get_update_future();
+				OptionalSelector { optional_future: Some(fut) }
+			} else {
+				OptionalSelector { optional_future: None }
+			};
 			let fut = Selector {
 				a: channel_manager.get_cm().get_event_or_persistence_needed_future(),
 				b: chain_monitor.get_update_future(),
-				c: sleeper(if mobile_interruptable_platform {
+				c: om_fut,
+				d: sleeper(if mobile_interruptable_platform {
 					Duration::from_millis(100)
 				} else {
 					Duration::from_secs(FASTEST_TIMER)
 				}),
 			};
 			match fut.await {
-				SelectorOutput::A | SelectorOutput::B => {},
-				SelectorOutput::C(exit) => {
+				SelectorOutput::A | SelectorOutput::B | SelectorOutput::C => {},
+				SelectorOutput::D(exit) => {
 					should_break = exit;
 				},
 			}

lightning/src/onion_message/messenger.rs

@@ -34,6 +34,7 @@ use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload
 use crate::util::async_poll::{MultiResultFuturePoller, ResultFuture};
 use crate::util::logger::{Logger, WithContext};
 use crate::util::ser::Writeable;
+use crate::util::wakers::{Future, Notifier};
 
 use core::fmt;
 use core::ops::Deref;
@@ -266,6 +267,9 @@ pub struct OnionMessenger<
 	pending_intercepted_msgs_events: Mutex<Vec<Event>>,
 	pending_peer_connected_events: Mutex<Vec<Event>>,
 	pending_events_processor: AtomicBool,
+	/// A [`Notifier`] used to wake up the background processor in case we have any [`Event`]s for
+	/// it to give to users.
+	event_notifier: Notifier,
 }
 
 /// [`OnionMessage`]s buffered to be sent.
@@ -290,13 +294,19 @@ impl OnionMessageRecipient {
 		}
 	}
 
-	fn enqueue_message(&mut self, message: OnionMessage) {
+	// Returns whether changes were made that are pending event processing
+	fn enqueue_message(&mut self, message: OnionMessage) -> bool {
+		let mut pending_event_processing = false;
 		let pending_messages = match self {
 			OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
-			OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
+			OnionMessageRecipient::PendingConnection(pending_messages, _, _) => {
+				pending_event_processing = true;
+				pending_messages
+			}
 		};
 
 		pending_messages.push_back(message);
+		pending_event_processing
 	}
 
 	fn dequeue_message(&mut self) -> Option<OnionMessage> {
@@ -1037,6 +1047,7 @@ macro_rules! drop_handled_events_and_abort { ($self: expr, $res: expr, $offset:
 		if $res.iter().any(|r| r.is_err()) {
 			// We failed handling some events. Return to have them eventually replayed.
 			$self.pending_events_processor.store(false, Ordering::Release);
+			$self.event_notifier.notify();
 			return;
 		}
 	}
@@ -1119,6 +1130,7 @@ where
 			pending_intercepted_msgs_events: Mutex::new(Vec::new()),
 			pending_peer_connected_events: Mutex::new(Vec::new()),
 			pending_events_processor: AtomicBool::new(false),
+			event_notifier: Notifier::new(),
 		}
 	}
 
@@ -1228,13 +1240,19 @@ where
 			hash_map::Entry::Vacant(e) => match addresses {
 				None => Err(SendError::InvalidFirstHop(first_node_id)),
 				Some(addresses) => {
-					e.insert(OnionMessageRecipient::pending_connection(addresses))
+					let notify = e.insert(OnionMessageRecipient::pending_connection(addresses))
 						.enqueue_message(onion_message);
+					if notify {
+						self.event_notifier.notify();
+					}
 					Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 				},
 			},
 			hash_map::Entry::Occupied(mut e) => {
-				e.get_mut().enqueue_message(onion_message);
+				let notify = e.get_mut().enqueue_message(onion_message);
+				if notify {
+					self.event_notifier.notify();
+				}
 				if e.get().is_connected() {
 					Ok(SendSuccess::Buffered)
 				} else {
@@ -1345,6 +1363,18 @@ where
 			return
 		}
 		pending_intercepted_msgs_events.push(event);
+		self.event_notifier.notify();
+	}
+
+	/// Gets a [`Future`] that completes when an event is available via
+	/// [`EventsProvider::process_pending_events`] or [`Self::process_pending_events_async`].
+	///
+	/// Note that callbacks registered on the [`Future`] MUST NOT call back into this
+	/// [`OnionMessenger`] and should instead register actions to be taken later.
+	///
+	/// [`EventsProvider::process_pending_events`]: crate::events::EventsProvider::process_pending_events
+	pub fn get_update_future(&self) -> Future {
+		self.event_notifier.get_future()
 	}
 
 	/// Processes any events asynchronously using the given handler.
@@ -1616,6 +1646,7 @@ where
 				pending_peer_connected_events.push(
 					Event::OnionMessagePeerConnected { peer_node_id: *their_node_id }
 				);
+				self.event_notifier.notify();
 			}
 		} else {
 			self.message_recipients.lock().unwrap().remove(their_node_id);

lightning/src/util/wakers.rs

@@ -154,6 +154,25 @@ pub struct Future {
 }
 
 impl Future {
+	/// Constructs a new `Future` with empty state.
+	///
+	/// The returned `Future` will never complete, similar to [`core::future::Pending`].
+	pub fn new_pending() -> Self {
+		let state = FutureState {
+			callbacks: Vec::new(),
+			std_future_callbacks: Vec::new(),
+			callbacks_with_state: Vec::new(),
+			complete: false,
+			callbacks_made: false,
+			next_idx: 1,
+		};
+
+		Self {
+			state: Arc::new(Mutex::new(state)),
+			self_idx: 0
+		}
+	}
+
 	/// Registers a callback to be called upon completion of this future. If the future has already
 	/// completed, the callback will be called immediately.
 	///