Cache and Broadcast channel update later

- Cache the force-close channel update message, and broadcast them
  later.
- Update get_and_clear_pending_msg_events to broadcast the
  pending_broadcast_events along with other messages.

Author: shaavan

lightning/src/ln/channelmanager.rs

@@ -1381,6 +1381,10 @@ where
 
 	pending_offers_messages: Mutex<Vec<PendingOnionMessage<OffersMessage>>>,
 
+	/// Tracks the channel_update message that were not broadcasted because
+	/// we were not connected to any peers.
+	pending_broadcast_messages: Mutex<Vec<MessageSendEvent>>,
+
 	entropy_source: ES,
 	node_signer: NS,
 	signer_provider: SP,
@@ -2455,6 +2459,7 @@ where
 			funding_batch_states: Mutex::new(BTreeMap::new()),
 
 			pending_offers_messages: Mutex::new(Vec::new()),
+			pending_broadcast_messages: Mutex::new(Vec::new()),
 
 			entropy_source,
 			node_signer,
@@ -2946,17 +2951,12 @@ where
 			}
 		};
 		if let Some(update) = update_opt {
-			// Try to send the `BroadcastChannelUpdate` to the peer we just force-closed on, but if
-			// not try to broadcast it via whatever peer we have.
-			let per_peer_state = self.per_peer_state.read().unwrap();
-			let a_peer_state_opt = per_peer_state.get(peer_node_id)
-				.ok_or(per_peer_state.values().next());
-			if let Ok(a_peer_state_mutex) = a_peer_state_opt {
-				let mut a_peer_state = a_peer_state_mutex.lock().unwrap();
-				a_peer_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
-					msg: update
-				});
-			}
+			// If we have some Channel Update to broadcast, we cache it and broadcast it later.
+			let mut pending_broadcast_messages = self.pending_broadcast_messages.lock().unwrap();
+			pending_broadcast_messages.push(events::MessageSendEvent::BroadcastChannelUpdate {
+				msg: update
+			});
+			log_trace!(self.logger, "Caching the channel_updates of force-closed channel. We will them broadcast later.");
 		}
 
 		Ok(counterparty_node_id)
@@ -8203,6 +8203,8 @@ where
 					pending_events.append(&mut peer_state.pending_msg_events);
 				}
 			}
+			let mut broadcast_msgs = self.pending_broadcast_messages.lock().unwrap();
+			pending_events.append(&mut broadcast_msgs);
 
 			if !pending_events.is_empty() {
 				events.replace(pending_events);
@@ -11099,6 +11101,8 @@ where
 
 			pending_offers_messages: Mutex::new(Vec::new()),
 
+			pending_broadcast_messages: Mutex::new(Vec::new()),
+
 			entropy_source: args.entropy_source,
 			node_signer: args.node_signer,
 			signer_provider: args.signer_provider,