Fuzz reloading with a stale monitor in chanmon_consistency

Now that we are gearing up to support fully async monitor storage,
we really need to fuzz monitor updates not completing before a
reload, which we do here in the `chanmon_consistency` fuzzer.

While there are more parts to async monitor updating that we need
to fuzz, this at least gets us started by having basic async
restart cases handled. In the future, we should extend this to make
sure some basic properties (eg claim/balance consistency) remain
true through `chanmon_consistency` runs.

Author: TheBlueMatt

fuzz/src/chanmon_consistency.rs

@@ -142,6 +142,12 @@ impl Writer for VecWriter {
 	}
 }
 
+struct LatestMonitorState {
+	persisted_monitor_id: u64,
+	persisted_monitor: Vec<u8>,
+	pending_monitor_updates: Vec<(u64, Vec<u8>)>,
+}
+
 struct TestChainMonitor {
 	pub logger: Arc<dyn Logger>,
 	pub keys: Arc<KeyProvider>,
@@ -152,7 +158,10 @@ struct TestChainMonitor {
 	// monitor implying we are not able to punish misbehaving counterparties). Because this test
 	// "fails" if we ever force-close a channel, we avoid doing so, always saving the latest
 	// fully-serialized monitor state here, as well as the corresponding update_id.
-	pub latest_monitors: Mutex<HashMap<OutPoint, (u64, Vec<u8>)>>,
+	//
+	// Note that this doesn't apply to monitors which are pending persistence, so we store the
+	// latest pending monitor separately.
+	pub latest_monitors: Mutex<HashMap<OutPoint, LatestMonitorState>>,
 }
 impl TestChainMonitor {
 	pub fn new(broadcaster: Arc<TestBroadcaster>, logger: Arc<dyn Logger>, feeest: Arc<FuzzEstimator>, persister: Arc<TestPersister>, keys: Arc<KeyProvider>) -> Self {
@@ -169,22 +178,47 @@ impl chain::Watch<TestChannelSigner> for TestChainMonitor {
 	fn watch_channel(&self, funding_txo: OutPoint, monitor: channelmonitor::ChannelMonitor<TestChannelSigner>) -> Result<chain::ChannelMonitorUpdateStatus, ()> {
 		let mut ser = VecWriter(Vec::new());
 		monitor.write(&mut ser).unwrap();
-		if let Some(_) = self.latest_monitors.lock().unwrap().insert(funding_txo, (monitor.get_latest_update_id(), ser.0)) {
+		let monitor_id = monitor.get_latest_update_id();
+		let res = self.chain_monitor.watch_channel(funding_txo, monitor);
+		let state = match res {
+			Ok(chain::ChannelMonitorUpdateStatus::Completed) => {
+				LatestMonitorState {
+					persisted_monitor_id: monitor_id, persisted_monitor: ser.0,
+					pending_monitor_updates: Vec::new(),
+				}
+			},
+			Ok(chain::ChannelMonitorUpdateStatus::InProgress) =>
+				panic!("The test currently doesn't test initial-persistence via the async pipeline"),
+			Ok(chain::ChannelMonitorUpdateStatus::UnrecoverableError) => panic!(),
+			Err(()) => panic!(),
+		};
+		if self.latest_monitors.lock().unwrap().insert(funding_txo, state).is_some() {
 			panic!("Already had monitor pre-watch_channel");
 		}
-		self.chain_monitor.watch_channel(funding_txo, monitor)
+		res
 	}
 
 	fn update_channel(&self, funding_txo: OutPoint, update: &channelmonitor::ChannelMonitorUpdate) -> chain::ChannelMonitorUpdateStatus {
 		let mut map_lock = self.latest_monitors.lock().unwrap();
 		let map_entry = map_lock.get_mut(&funding_txo).expect("Didn't have monitor on update call");
+		let latest_monitor_data = map_entry.pending_monitor_updates.last().as_ref().map(|(_, data)| data).unwrap_or(&map_entry.persisted_monitor);
 		let deserialized_monitor = <(BlockHash, channelmonitor::ChannelMonitor<TestChannelSigner>)>::
-			read(&mut Cursor::new(&map_entry.1), (&*self.keys, &*self.keys)).unwrap().1;
+			read(&mut Cursor::new(&latest_monitor_data), (&*self.keys, &*self.keys)).unwrap().1;
 		deserialized_monitor.update_monitor(update, &&TestBroadcaster{}, &&FuzzEstimator { ret_val: atomic::AtomicU32::new(253) }, &self.logger).unwrap();
 		let mut ser = VecWriter(Vec::new());
 		deserialized_monitor.write(&mut ser).unwrap();
-		*map_entry = (update.update_id, ser.0);
-		self.chain_monitor.update_channel(funding_txo, update)
+		let res = self.chain_monitor.update_channel(funding_txo, update);
+		match res {
+			chain::ChannelMonitorUpdateStatus::Completed => {
+				map_entry.persisted_monitor_id = update.update_id;
+				map_entry.persisted_monitor = ser.0;
+			},
+			chain::ChannelMonitorUpdateStatus::InProgress => {
+				map_entry.pending_monitor_updates.push((update.update_id, ser.0));
+			},
+			chain::ChannelMonitorUpdateStatus::UnrecoverableError => panic!(),
+		}
+		res
 	}
 
 	fn release_pending_monitor_events(&self) -> Vec<(OutPoint, ChannelId, Vec<MonitorEvent>, Option<PublicKey>)> {
@@ -511,9 +545,12 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
 
 			let mut monitors = new_hash_map();
 			let mut old_monitors = $old_monitors.latest_monitors.lock().unwrap();
-			for (outpoint, (update_id, monitor_ser)) in old_monitors.drain() {
-				monitors.insert(outpoint, <(BlockHash, ChannelMonitor<TestChannelSigner>)>::read(&mut Cursor::new(&monitor_ser), (&*$keys_manager, &*$keys_manager)).expect("Failed to read monitor").1);
-				chain_monitor.latest_monitors.lock().unwrap().insert(outpoint, (update_id, monitor_ser));
+			for (outpoint, mut prev_state) in old_monitors.drain() {
+				monitors.insert(outpoint, <(BlockHash, ChannelMonitor<TestChannelSigner>)>::read(
+					&mut Cursor::new(&prev_state.persisted_monitor), (&*$keys_manager, &*$keys_manager)
+				).expect("Failed to read monitor").1);
+				prev_state.pending_monitor_updates.clear();
+				chain_monitor.latest_monitors.lock().unwrap().insert(outpoint, prev_state);
 			}
 			let mut monitor_refs = new_hash_map();
 			for (outpoint, monitor) in monitors.iter_mut() {
@@ -1040,6 +1077,41 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
 			} }
 		}
 
+		let complete_monitor_update = |
+			monitor: &Arc<TestChainMonitor>, chan_funding,
+			compl_selector: &dyn Fn(&mut Vec<(u64, Vec<u8>)>) -> Option<(u64, Vec<u8>)>,
+		| {
+			if let Some(state) = monitor.latest_monitors.lock().unwrap().get_mut(chan_funding) {
+				assert!(
+					state.pending_monitor_updates.windows(2).all(|pair| pair[0].0 < pair[1].0),
+					"updates should be sorted by id"
+				);
+				if let Some((id, data)) = compl_selector(&mut state.pending_monitor_updates) {
+					monitor.chain_monitor.channel_monitor_updated(*chan_funding, id).unwrap();
+					if id > state.persisted_monitor_id {
+						state.persisted_monitor_id = id;
+						state.persisted_monitor = data;
+					}
+				}
+			}
+		};
+
+		let complete_all_monitor_updates = |monitor: &Arc<TestChainMonitor>, chan_funding| {
+			if let Some(state) = monitor.latest_monitors.lock().unwrap().get_mut(chan_funding) {
+				assert!(
+					state.pending_monitor_updates.windows(2).all(|pair| pair[0].0 < pair[1].0),
+					"updates should be sorted by id"
+				);
+				for (id, data) in state.pending_monitor_updates.drain(..) {
+					monitor.chain_monitor.channel_monitor_updated(*chan_funding, id).unwrap();
+					if id > state.persisted_monitor_id {
+						state.persisted_monitor_id = id;
+						state.persisted_monitor = data;
+					}
+				}
+			}
+		};
+
 		let v = get_slice!(1)[0];
 		out.locked_write(format!("READ A BYTE! HANDLING INPUT {:x}...........\n", v).as_bytes());
 		match v {
@@ -1054,30 +1126,10 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
 			0x05 => *monitor_b.persister.update_ret.lock().unwrap() = ChannelMonitorUpdateStatus::Completed,
 			0x06 => *monitor_c.persister.update_ret.lock().unwrap() = ChannelMonitorUpdateStatus::Completed,
 
-			0x08 => {
-				if let Some((id, _)) = monitor_a.latest_monitors.lock().unwrap().get(&chan_1_funding) {
-					monitor_a.chain_monitor.force_channel_monitor_updated(chan_1_funding, *id);
-					nodes[0].process_monitor_events();
-				}
-			},
-			0x09 => {
-				if let Some((id, _)) = monitor_b.latest_monitors.lock().unwrap().get(&chan_1_funding) {
-					monitor_b.chain_monitor.force_channel_monitor_updated(chan_1_funding, *id);
-					nodes[1].process_monitor_events();
-				}
-			},
-			0x0a => {
-				if let Some((id, _)) = monitor_b.latest_monitors.lock().unwrap().get(&chan_2_funding) {
-					monitor_b.chain_monitor.force_channel_monitor_updated(chan_2_funding, *id);
-					nodes[1].process_monitor_events();
-				}
-			},
-			0x0b => {
-				if let Some((id, _)) = monitor_c.latest_monitors.lock().unwrap().get(&chan_2_funding) {
-					monitor_c.chain_monitor.force_channel_monitor_updated(chan_2_funding, *id);
-					nodes[2].process_monitor_events();
-				}
-			},
+			0x08 => complete_all_monitor_updates(&monitor_a, &chan_1_funding),
+			0x09 => complete_all_monitor_updates(&monitor_b, &chan_1_funding),
+			0x0a => complete_all_monitor_updates(&monitor_b, &chan_2_funding),
+			0x0b => complete_all_monitor_updates(&monitor_c, &chan_2_funding),
 
 			0x0c => {
 				if !chan_a_disconnected {
@@ -1285,119 +1337,59 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
 			},
 			0x89 => { fee_est_c.ret_val.store(253, atomic::Ordering::Release); nodes[2].maybe_update_chan_fees(); },
 
-			0xf0 => {
-				let pending_updates = monitor_a.chain_monitor.list_pending_monitor_updates().remove(&chan_1_funding).unwrap();
-				if let Some(id) = pending_updates.get(0) {
-					monitor_a.chain_monitor.channel_monitor_updated(chan_1_funding, *id).unwrap();
-				}
-				nodes[0].process_monitor_events();
-			}
-			0xf1 => {
-				let pending_updates = monitor_a.chain_monitor.list_pending_monitor_updates().remove(&chan_1_funding).unwrap();
-				if let Some(id) = pending_updates.get(1) {
-					monitor_a.chain_monitor.channel_monitor_updated(chan_1_funding, *id).unwrap();
-				}
-				nodes[0].process_monitor_events();
-			}
-			0xf2 => {
-				let pending_updates = monitor_a.chain_monitor.list_pending_monitor_updates().remove(&chan_1_funding).unwrap();
-				if let Some(id) = pending_updates.last() {
-					monitor_a.chain_monitor.channel_monitor_updated(chan_1_funding, *id).unwrap();
-				}
-				nodes[0].process_monitor_events();
-			}
-
-			0xf4 => {
-				let pending_updates = monitor_b.chain_monitor.list_pending_monitor_updates().remove(&chan_1_funding).unwrap();
-				if let Some(id) = pending_updates.get(0) {
-					monitor_b.chain_monitor.channel_monitor_updated(chan_1_funding, *id).unwrap();
-				}
-				nodes[1].process_monitor_events();
-			}
-			0xf5 => {
-				let pending_updates = monitor_b.chain_monitor.list_pending_monitor_updates().remove(&chan_1_funding).unwrap();
-				if let Some(id) = pending_updates.get(1) {
-					monitor_b.chain_monitor.channel_monitor_updated(chan_1_funding, *id).unwrap();
-				}
-				nodes[1].process_monitor_events();
-			}
-			0xf6 => {
-				let pending_updates = monitor_b.chain_monitor.list_pending_monitor_updates().remove(&chan_1_funding).unwrap();
-				if let Some(id) = pending_updates.last() {
-					monitor_b.chain_monitor.channel_monitor_updated(chan_1_funding, *id).unwrap();
-				}
-				nodes[1].process_monitor_events();
-			}
-
-			0xf8 => {
-				let pending_updates = monitor_b.chain_monitor.list_pending_monitor_updates().remove(&chan_2_funding).unwrap();
-				if let Some(id) = pending_updates.get(0) {
-					monitor_b.chain_monitor.channel_monitor_updated(chan_2_funding, *id).unwrap();
-				}
-				nodes[1].process_monitor_events();
-			}
-			0xf9 => {
-				let pending_updates = monitor_b.chain_monitor.list_pending_monitor_updates().remove(&chan_2_funding).unwrap();
-				if let Some(id) = pending_updates.get(1) {
-					monitor_b.chain_monitor.channel_monitor_updated(chan_2_funding, *id).unwrap();
-				}
-				nodes[1].process_monitor_events();
-			}
-			0xfa => {
-				let pending_updates = monitor_b.chain_monitor.list_pending_monitor_updates().remove(&chan_2_funding).unwrap();
-				if let Some(id) = pending_updates.last() {
-					monitor_b.chain_monitor.channel_monitor_updated(chan_2_funding, *id).unwrap();
-				}
-				nodes[1].process_monitor_events();
-			}
-
-			0xfc => {
-				let pending_updates = monitor_c.chain_monitor.list_pending_monitor_updates().remove(&chan_2_funding).unwrap();
-				if let Some(id) = pending_updates.get(0) {
-					monitor_c.chain_monitor.channel_monitor_updated(chan_2_funding, *id).unwrap();
-				}
-				nodes[2].process_monitor_events();
-			}
-			0xfd => {
-				let pending_updates = monitor_c.chain_monitor.list_pending_monitor_updates().remove(&chan_2_funding).unwrap();
-				if let Some(id) = pending_updates.get(1) {
-					monitor_c.chain_monitor.channel_monitor_updated(chan_2_funding, *id).unwrap();
-				}
-				nodes[2].process_monitor_events();
-			}
-			0xfe => {
-				let pending_updates = monitor_c.chain_monitor.list_pending_monitor_updates().remove(&chan_2_funding).unwrap();
-				if let Some(id) = pending_updates.last() {
-					monitor_c.chain_monitor.channel_monitor_updated(chan_2_funding, *id).unwrap();
-				}
-				nodes[2].process_monitor_events();
-			}
+			0xf0 =>
+				complete_monitor_update(&monitor_a, &chan_1_funding,
+					&|v: &mut Vec<_>| if !v.is_empty() { Some(v.remove(0)) } else { None }),
+			0xf1 =>
+				complete_monitor_update(&monitor_a, &chan_1_funding,
+					&|v: &mut Vec<_>| if v.len() > 1 { Some(v.remove(1)) } else { None }),
+			0xf2 =>
+				complete_monitor_update(&monitor_a, &chan_1_funding,
+					&|v: &mut Vec<_>| v.pop()),
+
+			0xf4 =>
+				complete_monitor_update(&monitor_b, &chan_1_funding,
+					&|v: &mut Vec<_>| if !v.is_empty() { Some(v.remove(0)) } else { None }),
+			0xf5 =>
+				complete_monitor_update(&monitor_b, &chan_1_funding,
+					&|v: &mut Vec<_>| if v.len() > 1 { Some(v.remove(1)) } else { None }),
+			0xf6 =>
+				complete_monitor_update(&monitor_b, &chan_1_funding,
+					&|v: &mut Vec<_>| v.pop()),
+
+			0xf8 =>
+				complete_monitor_update(&monitor_b, &chan_2_funding,
+					&|v: &mut Vec<_>| if !v.is_empty() { Some(v.remove(0)) } else { None }),
+			0xf9 =>
+				complete_monitor_update(&monitor_b, &chan_2_funding,
+					&|v: &mut Vec<_>| if v.len() > 1 { Some(v.remove(1)) } else { None }),
+			0xfa =>
+				complete_monitor_update(&monitor_b, &chan_2_funding,
+					&|v: &mut Vec<_>| v.pop()),
+
+			0xfc =>
+				complete_monitor_update(&monitor_c, &chan_2_funding,
+					&|v: &mut Vec<_>| if !v.is_empty() { Some(v.remove(0)) } else { None }),
+			0xfd =>
+				complete_monitor_update(&monitor_c, &chan_2_funding,
+					&|v: &mut Vec<_>| if v.len() > 1 { Some(v.remove(1)) } else { None }),
+			0xfe =>
+				complete_monitor_update(&monitor_c, &chan_2_funding,
+					&|v: &mut Vec<_>| v.pop()),
 
 			0xff => {
 				// Test that no channel is in a stuck state where neither party can send funds even
 				// after we resolve all pending events.
-				// First make sure there are no pending monitor updates, resetting the error state
-				// and calling force_channel_monitor_updated for each monitor.
+				// First make sure there are no pending monitor updates and further update
+				// operations complete.
 				*monitor_a.persister.update_ret.lock().unwrap() = ChannelMonitorUpdateStatus::Completed;
 				*monitor_b.persister.update_ret.lock().unwrap() = ChannelMonitorUpdateStatus::Completed;
 				*monitor_c.persister.update_ret.lock().unwrap() = ChannelMonitorUpdateStatus::Completed;
 
-				if let Some((id, _)) = monitor_a.latest_monitors.lock().unwrap().get(&chan_1_funding) {
-					monitor_a.chain_monitor.force_channel_monitor_updated(chan_1_funding, *id);
-					nodes[0].process_monitor_events();
-				}
-				if let Some((id, _)) = monitor_b.latest_monitors.lock().unwrap().get(&chan_1_funding) {
-					monitor_b.chain_monitor.force_channel_monitor_updated(chan_1_funding, *id);
-					nodes[1].process_monitor_events();
-				}
-				if let Some((id, _)) = monitor_b.latest_monitors.lock().unwrap().get(&chan_2_funding) {
-					monitor_b.chain_monitor.force_channel_monitor_updated(chan_2_funding, *id);
-					nodes[1].process_monitor_events();
-				}
-				if let Some((id, _)) = monitor_c.latest_monitors.lock().unwrap().get(&chan_2_funding) {
-					monitor_c.chain_monitor.force_channel_monitor_updated(chan_2_funding, *id);
-					nodes[2].process_monitor_events();
-				}
+				complete_all_monitor_updates(&monitor_a, &chan_1_funding);
+				complete_all_monitor_updates(&monitor_b, &chan_1_funding);
+				complete_all_monitor_updates(&monitor_b, &chan_2_funding);
+				complete_all_monitor_updates(&monitor_c, &chan_2_funding);
 
 				// Next, make sure peers are all connected to each other
 				if chan_a_disconnected {