Don't serialize nodes which we have no channels to

Author: ViktorT-11

lightning/src/ln/channelmanager.rs

@@ -1749,6 +1749,12 @@ where
 			.collect()
 	}
 
+	// Indicates that a peer meets the criteria where we're ok to disconnect the peer and remove it
+	// from our storage
+	fn ok_to_disconnected(&self, peer: &PeerState<<SP::Target as SignerProvider>::Signer>) -> bool {
+		peer.channel_by_id.len() == 0
+	}
+
 	/// Helper function that issues the channel close events
 	fn issue_channel_close_events(&self, channel: &Channel<<SP::Target as SignerProvider>::Signer>, closure_reason: ClosureReason) {
 		let mut pending_events_lock = self.pending_events.lock().unwrap();
@@ -6965,13 +6971,17 @@ where
 			best_block.block_hash().write(writer)?;
 		}
 
+		let mut peers_to_searialize_count: u64 = 0;
 		{
 			let per_peer_state = self.per_peer_state.read().unwrap();
 			let mut unfunded_channels = 0;
 			let mut number_of_channels = 0;
 			for (_, peer_state_mutex) in per_peer_state.iter() {
 				let mut peer_state_lock = peer_state_mutex.lock().unwrap();
 				let peer_state = &mut *peer_state_lock;
+				if !self.ok_to_disconnected(peer_state) {
+					peers_to_searialize_count += 1;
+				}
 				number_of_channels += peer_state.channel_by_id.len();
 				for (_, channel) in peer_state.channel_by_id.iter() {
 					if !channel.is_funding_initiated() {
@@ -7022,11 +7032,14 @@ where
 			htlc_purposes.push(purpose);
 		}
 
-		(per_peer_state.len() as u64).write(writer)?;
+		(peers_to_searialize_count).write(writer)?;
 		for (peer_pubkey, peer_state_mutex) in per_peer_state.iter() {
-			peer_pubkey.write(writer)?;
-			let peer_state = peer_state_mutex.lock().unwrap();
-			peer_state.latest_features.write(writer)?;
+			let peer_state_lock= peer_state_mutex.lock().unwrap();
+			let peer_state = & *peer_state_lock;
+			if !self.ok_to_disconnected(peer_state) {
+				peer_pubkey.write(writer)?;
+				peer_state.latest_features.write(writer)?;
+			}
 		}
 
 		let events = self.pending_events.lock().unwrap();

lightning/src/ln/reorg_tests.rs

@@ -13,7 +13,7 @@ use crate::chain::channelmonitor::ANTI_REORG_DELAY;
 use crate::chain::transaction::OutPoint;
 use crate::chain::Confirm;
 use crate::ln::channelmanager::ChannelManager;
-use crate::ln::msgs::ChannelMessageHandler;
+use crate::ln::msgs::{ChannelMessageHandler, Init};
 use crate::util::events::{Event, MessageSendEventsProvider, ClosureReason, HTLCDestination};
 use crate::util::test_utils;
 use crate::util::ser::Writeable;
@@ -374,6 +374,12 @@ fn do_test_unconf_chan(reload_node: bool, reorg_after_reload: bool, use_funding_
 	nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().clear();
 
 	// Now check that we can create a new channel
+	if reload_node && nodes[0].node.per_peer_state.read().unwrap().len() == 0 {
+		// If we dropped the channel before reloading the node, nodes[1] was also dropped from
+		// nodes[0] storage, and hence not connected again on startup. We therefore need to
+		// reconnect to the node before attempting to create a new channel.
+		nodes[0].node.peer_connected(&nodes[1].node.get_our_node_id(), &Init { features: nodes[1].node.init_features(), remote_network_address: None }).unwrap();
+	}
 	create_announced_chan_between_nodes(&nodes, 0, 1);
 	send_payment(&nodes[0], &[&nodes[1]], 8000000);
 }