Use best block state to craft message relay transactions (#499)

* use best block state to craft message relay transactions

* removed obsolete TODO

* Update relays/messages-relay/src/message_race_loop.rs

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

bridges/relays/messages-relay/src/message_lane_loop.rs

@@ -169,8 +169,10 @@ pub trait TargetClient<P: MessageLane>: Clone + Send + Sync {
 pub struct ClientState<SelfHeaderId, PeerHeaderId> {
 	/// Best header id of this chain.
 	pub best_self: SelfHeaderId,
-	/// Best header id of the peer chain.
-	pub best_peer: PeerHeaderId,
+	/// Best finalized header id of this chain.
+	pub best_finalized_self: SelfHeaderId,
+	/// Best finalized header id of the peer chain read at the best block of this chain (at `best_finalized_self`).
+	pub best_finalized_peer_at_best_self: PeerHeaderId,
 }
 
 /// State of source client in one-way message lane.
@@ -746,12 +748,14 @@ pub(crate) mod tests {
 				is_source_fails: true,
 				source_state: ClientState {
 					best_self: HeaderId(0, 0),
-					best_peer: HeaderId(0, 0),
+					best_finalized_self: HeaderId(0, 0),
+					best_finalized_peer_at_best_self: HeaderId(0, 0),
 				},
 				source_latest_generated_nonce: 1,
 				target_state: ClientState {
 					best_self: HeaderId(0, 0),
-					best_peer: HeaderId(0, 0),
+					best_finalized_self: HeaderId(0, 0),
+					best_finalized_peer_at_best_self: HeaderId(0, 0),
 				},
 				target_latest_received_nonce: 0,
 				..Default::default()
@@ -766,9 +770,11 @@ pub(crate) mod tests {
 				if data.is_target_reconnected {
 					data.is_target_fails = false;
 				}
-				if data.target_state.best_peer.0 < 10 {
-					data.target_state.best_peer =
-						HeaderId(data.target_state.best_peer.0 + 1, data.target_state.best_peer.0 + 1);
+				if data.target_state.best_finalized_peer_at_best_self.0 < 10 {
+					data.target_state.best_finalized_peer_at_best_self = HeaderId(
+						data.target_state.best_finalized_peer_at_best_self.0 + 1,
+						data.target_state.best_finalized_peer_at_best_self.0 + 1,
+					);
 				}
 				if !data.submitted_messages_proofs.is_empty() {
 					exit_sender.unbounded_send(()).unwrap();
@@ -787,12 +793,14 @@ pub(crate) mod tests {
 			TestClientData {
 				source_state: ClientState {
 					best_self: HeaderId(10, 10),
-					best_peer: HeaderId(0, 0),
+					best_finalized_self: HeaderId(10, 10),
+					best_finalized_peer_at_best_self: HeaderId(0, 0),
 				},
 				source_latest_generated_nonce: 10,
 				target_state: ClientState {
 					best_self: HeaderId(0, 0),
-					best_peer: HeaderId(0, 0),
+					best_finalized_self: HeaderId(0, 0),
+					best_finalized_peer_at_best_self: HeaderId(0, 0),
 				},
 				target_latest_received_nonce: 0,
 				..Default::default()
@@ -800,12 +808,12 @@ pub(crate) mod tests {
 			Arc::new(|_: &mut TestClientData| {}),
 			Arc::new(move |data: &mut TestClientData| {
 				// syncing source headers -> target chain (all at once)
-				if data.target_state.best_peer.0 < data.source_state.best_self.0 {
-					data.target_state.best_peer = data.source_state.best_self;
+				if data.target_state.best_finalized_peer_at_best_self.0 < data.source_state.best_finalized_self.0 {
+					data.target_state.best_finalized_peer_at_best_self = data.source_state.best_finalized_self;
 				}
-				// syncing target headers -> source chain (all at once)
-				if data.source_state.best_peer.0 < data.target_state.best_self.0 {
-					data.source_state.best_peer = data.target_state.best_self;
+				// syncing source headers -> target chain (all at once)
+				if data.source_state.best_finalized_peer_at_best_self.0 < data.target_state.best_finalized_self.0 {
+					data.source_state.best_finalized_peer_at_best_self = data.target_state.best_finalized_self;
 				}
 				// if target has received messages batch => increase blocks so that confirmations may be sent
 				if data.target_latest_received_nonce == 4
@@ -814,8 +822,10 @@ pub(crate) mod tests {
 				{
 					data.target_state.best_self =
 						HeaderId(data.target_state.best_self.0 + 1, data.target_state.best_self.0 + 1);
+					data.target_state.best_finalized_self = data.target_state.best_self;
 					data.source_state.best_self =
 						HeaderId(data.source_state.best_self.0 + 1, data.source_state.best_self.0 + 1);
+					data.source_state.best_finalized_self = data.source_state.best_self;
 				}
 				// if source has received all messages receiving confirmations => increase source block so that confirmations may be sent
 				if data.source_latest_confirmed_received_nonce == 10 {

bridges/relays/messages-relay/src/message_race_delivery.rs

@@ -264,11 +264,6 @@ impl<P: MessageLane> RaceStrategy<SourceHeaderIdOf<P>, TargetHeaderIdOf<P>, P::M
 		// There's additional condition in the message delivery race: target would reject messages
 		// if there are too much unconfirmed messages at the inbound lane.
 
-		// https://github.com/paritytech/parity-bridges-common/issues/432
-		// TODO: message lane loop works with finalized blocks only, but we're submitting transactions that
-		// are updating best block (which may not be finalized yet). So all decisions that are made below
-		// may be outdated. This needs to be changed - all logic here must be built on top of best blocks.
-
 		// The receiving race is responsible to deliver confirmations back to the source chain. So if
 		// there's a lot of unconfirmed messages, let's wait until it'll be able to do its job.
 		let latest_received_nonce_at_target = target_nonces.latest_nonce;
@@ -388,9 +383,8 @@ impl NoncesRange for MessageWeightsMap {
 #[cfg(test)]
 mod tests {
 	use super::*;
-	use crate::message_lane_loop::{
-		tests::{header_id, TestMessageLane, TestMessagesProof, TestSourceHeaderId, TestTargetHeaderId},
-		ClientState,
+	use crate::message_lane_loop::tests::{
+		header_id, TestMessageLane, TestMessagesProof, TestSourceHeaderId, TestTargetHeaderId,
 	};
 
 	type TestRaceState = RaceState<TestSourceHeaderId, TestTargetHeaderId, TestMessagesProof>;
@@ -398,14 +392,9 @@ mod tests {
 
 	fn prepare_strategy() -> (TestRaceState, TestStrategy) {
 		let mut race_state = RaceState {
-			source_state: Some(ClientState {
-				best_self: header_id(1),
-				best_peer: header_id(1),
-			}),
-			target_state: Some(ClientState {
-				best_self: header_id(1),
-				best_peer: header_id(1),
-			}),
+			best_finalized_source_header_id_at_source: Some(header_id(1)),
+			best_finalized_source_header_id_at_best_target: Some(header_id(1)),
+			best_target_header_id: Some(header_id(1)),
 			nonces_to_submit: None,
 			nonces_submitted: None,
 		};

bridges/relays/messages-relay/src/message_race_loop.rs

@@ -168,10 +168,13 @@ pub trait RaceStrategy<SourceHeaderId, TargetHeaderId, Proof> {
 /// State of the race.
 #[derive(Debug)]
 pub struct RaceState<SourceHeaderId, TargetHeaderId, Proof> {
-	/// Source state, if known.
-	pub source_state: Option<ClientState<SourceHeaderId, TargetHeaderId>>,
-	/// Target state, if known.
-	pub target_state: Option<ClientState<TargetHeaderId, SourceHeaderId>>,
+	/// Best finalized source header id at the source client.
+	pub best_finalized_source_header_id_at_source: Option<SourceHeaderId>,
+	/// Best finalized source header id at the best block on the target
+	/// client (at the `best_finalized_source_header_id_at_best_target`).
+	pub best_finalized_source_header_id_at_best_target: Option<SourceHeaderId>,
+	/// Best header id at the target client.
+	pub best_target_header_id: Option<TargetHeaderId>,
 	/// Range of nonces that we have selected to submit.
 	pub nonces_to_submit: Option<(SourceHeaderId, RangeInclusive<MessageNonce>, Proof)>,
 	/// Range of nonces that is currently submitted.
@@ -227,17 +230,23 @@ pub async fn run<P: MessageRace, SC: SourceClient<P>>(
 			// when headers ids are updated
 			source_state = race_source_updated.next() => {
 				if let Some(source_state) = source_state {
-					if race_state.source_state.as_ref() != Some(&source_state) {
+					let is_source_state_updated = race_state.best_finalized_source_header_id_at_source.as_ref()
+						!= Some(&source_state.best_finalized_self);
+					if is_source_state_updated {
 						source_nonces_required = true;
-						race_state.source_state = Some(source_state);
+						race_state.best_finalized_source_header_id_at_source = Some(source_state.best_finalized_self);
 					}
 				}
 			},
 			target_state = race_target_updated.next() => {
 				if let Some(target_state) = target_state {
-					if race_state.target_state.as_ref() != Some(&target_state) {
+					let is_target_state_updated = race_state.best_target_header_id.as_ref()
+						!= Some(&target_state.best_self);
+					if is_target_state_updated {
 						target_nonces_required = true;
-						race_state.target_state = Some(target_state);
+						race_state.best_target_header_id = Some(target_state.best_self);
+						race_state.best_finalized_source_header_id_at_best_target
+							= Some(target_state.best_finalized_peer_at_best_self);
 					}
 				}
 			},
@@ -358,10 +367,12 @@ pub async fn run<P: MessageRace, SC: SourceClient<P>>(
 			} else if source_nonces_required {
 				log::debug!(target: "bridge", "Asking {} about message nonces", P::source_name());
 				let at_block = race_state
-					.source_state
+					.best_finalized_source_header_id_at_source
 					.as_ref()
-					.expect("source_nonces_required is only true when source_state is Some; qed")
-					.best_self
+					.expect(
+						"source_nonces_required is only true when\
+						best_finalized_source_header_id_at_source is Some; qed",
+					)
 					.clone();
 				source_nonces.set(race_source.nonces(at_block, strategy.best_at_source()).fuse());
 			} else {
@@ -388,10 +399,9 @@ pub async fn run<P: MessageRace, SC: SourceClient<P>>(
 			if target_nonces_required {
 				log::debug!(target: "bridge", "Asking {} about message nonces", P::target_name());
 				let at_block = race_state
-					.target_state
+					.best_target_header_id
 					.as_ref()
-					.expect("target_nonces_required is only true when target_state is Some; qed")
-					.best_self
+					.expect("target_nonces_required is only true when best_target_header_id is Some; qed")
 					.clone();
 				target_nonces.set(race_target.nonces(at_block).fuse());
 			} else {
@@ -404,8 +414,9 @@ pub async fn run<P: MessageRace, SC: SourceClient<P>>(
 impl<SourceHeaderId, TargetHeaderId, Proof> Default for RaceState<SourceHeaderId, TargetHeaderId, Proof> {
 	fn default() -> Self {
 		RaceState {
-			source_state: None,
-			target_state: None,
+			best_finalized_source_header_id_at_source: None,
+			best_finalized_source_header_id_at_best_target: None,
+			best_target_header_id: None,
 			nonces_to_submit: None,
 			nonces_submitted: None,
 		}
@@ -446,11 +457,20 @@ where
 	SourceHeaderId: Clone,
 	Strategy: RaceStrategy<SourceHeaderId, TargetHeaderId, Proof>,
 {
-	race_state.target_state.as_ref().and_then(|target_state| {
-		strategy
-			.select_nonces_to_deliver(&race_state)
-			.map(|(nonces_range, proof_parameters)| (target_state.best_peer.clone(), nonces_range, proof_parameters))
-	})
+	race_state
+		.best_finalized_source_header_id_at_best_target
+		.as_ref()
+		.and_then(|best_finalized_source_header_id_at_best_target| {
+			strategy
+				.select_nonces_to_deliver(&race_state)
+				.map(|(nonces_range, proof_parameters)| {
+					(
+						best_finalized_source_header_id_at_best_target.clone(),
+						nonces_range,
+						proof_parameters,
+					)
+				})
+		})
 }
 
 #[cfg(test)]
@@ -468,14 +488,9 @@ mod tests {
 		// target node only knows about source' BEST_AT_TARGET block
 		// source node has BEST_AT_SOURCE > BEST_AT_TARGET block
 		let mut race_state = RaceState::<_, _, ()> {
-			source_state: Some(ClientState {
-				best_self: HeaderId(BEST_AT_SOURCE, BEST_AT_SOURCE),
-				best_peer: HeaderId(0, 0),
-			}),
-			target_state: Some(ClientState {
-				best_self: HeaderId(0, 0),
-				best_peer: HeaderId(BEST_AT_TARGET, BEST_AT_TARGET),
-			}),
+			best_finalized_source_header_id_at_source: Some(HeaderId(BEST_AT_SOURCE, BEST_AT_SOURCE)),
+			best_finalized_source_header_id_at_best_target: Some(HeaderId(BEST_AT_TARGET, BEST_AT_TARGET)),
+			best_target_header_id: Some(HeaderId(0, 0)),
 			nonces_to_submit: None,
 			nonces_submitted: None,
 		};

bridges/relays/messages-relay/src/message_race_strategy.rs

@@ -88,9 +88,8 @@ where
 		// 2) we can't deliver new nonce until header, that has emitted this nonce, is finalized
 		// by target client
 		// 3) selector is used for more complicated logic
-		let best_header_at_target = &race_state.target_state.as_ref()?.best_peer;
+		let best_header_at_target = &race_state.best_finalized_source_header_id_at_best_target.as_ref()?;
 		let mut nonces_end = None;
-
 		while let Some((queued_at, queued_range)) = self.source_queue.pop_front() {
 			// select (sub) range to deliver
 			let queued_range_begin = queued_range.begin();
@@ -241,10 +240,7 @@ where
 mod tests {
 	use super::*;
 	use crate::message_lane::MessageLane;
-	use crate::message_lane_loop::{
-		tests::{header_id, TestMessageLane, TestMessagesProof},
-		ClientState,
-	};
+	use crate::message_lane_loop::tests::{header_id, TestMessageLane, TestMessagesProof};
 
 	type SourceNoncesRange = RangeInclusive<MessageNonce>;
 
@@ -374,21 +370,15 @@ mod tests {
 		let mut strategy = BasicStrategy::<TestMessageLane>::new();
 		strategy.source_nonces_updated(header_id(1), source_nonces(1..=1));
 		strategy.source_nonces_updated(header_id(2), source_nonces(2..=2));
-		strategy.source_nonces_updated(header_id(3), source_nonces(6..=6));
-		strategy.source_nonces_updated(header_id(5), source_nonces(8..=8));
+		strategy.source_nonces_updated(header_id(3), source_nonces(3..=6));
+		strategy.source_nonces_updated(header_id(5), source_nonces(7..=8));
 
-		state.target_state = Some(ClientState {
-			best_self: header_id(0),
-			best_peer: header_id(4),
-		});
+		state.best_finalized_source_header_id_at_best_target = Some(header_id(4));
 		assert_eq!(strategy.select_nonces_to_deliver(&state), Some((1..=6, ())));
 		strategy.target_nonces_updated(target_nonces(6), &mut state);
 		assert_eq!(strategy.select_nonces_to_deliver(&state), None);
 
-		state.target_state = Some(ClientState {
-			best_self: header_id(0),
-			best_peer: header_id(5),
-		});
+		state.best_finalized_source_header_id_at_best_target = Some(header_id(5));
 		assert_eq!(strategy.select_nonces_to_deliver(&state), Some((7..=8, ())));
 		strategy.target_nonces_updated(target_nonces(8), &mut state);
 		assert_eq!(strategy.select_nonces_to_deliver(&state), None);
@@ -400,10 +390,10 @@ mod tests {
 		let mut strategy = BasicStrategy::<TestMessageLane>::new();
 		strategy.source_nonces_updated(header_id(1), source_nonces(1..=100));
 
-		state.target_state = Some(ClientState {
-			best_self: header_id(0),
-			best_peer: header_id(1),
-		});
+		state.best_finalized_source_header_id_at_source = Some(header_id(1));
+		state.best_finalized_source_header_id_at_best_target = Some(header_id(1));
+		state.best_target_header_id = Some(header_id(1));
+
 		assert_eq!(
 			strategy.select_nonces_to_deliver_with_selector(&state, |_| Some(50..=100)),
 			Some(1..=49),
@@ -417,11 +407,9 @@ mod tests {
 		let mut strategy = BasicStrategy::<TestMessageLane>::new();
 		strategy.source_nonces_updated(header_id(1), source_nonces(1..=100));
 		strategy.target_nonces_updated(target_nonces(50), &mut state);
-		state.target_state = Some(ClientState {
-			best_self: header_id(0),
-			best_peer: header_id(1),
-		});
-
+		state.best_finalized_source_header_id_at_source = Some(header_id(1));
+		state.best_finalized_source_header_id_at_best_target = Some(header_id(1));
+		state.best_target_header_id = Some(header_id(1));
 		strategy.select_nonces_to_deliver_with_selector(&state, invalid_selector);
 	}
 

bridges/relays/messages-relay/src/metrics.rs

@@ -64,7 +64,7 @@ impl MessageLaneLoopMetrics {
 			.set(source_client_state.best_self.0.into());
 		self.best_block_numbers
 			.with_label_values(&["target_at_source"])
-			.set(source_client_state.best_peer.0.into());
+			.set(source_client_state.best_finalized_peer_at_best_self.0.into());
 	}
 
 	/// Update target client state metrics.
@@ -74,7 +74,7 @@ impl MessageLaneLoopMetrics {
 			.set(target_client_state.best_self.0.into());
 		self.best_block_numbers
 			.with_label_values(&["source_at_target"])
-			.set(target_client_state.best_peer.0.into());
+			.set(target_client_state.best_finalized_peer_at_best_self.0.into());
 	}
 
 	/// Update latest generated nonce at source.

bridges/relays/substrate/src/messages_source.rs

@@ -234,13 +234,18 @@ where
 	let self_best_finalized_header = self_client.header_by_hash(self_best_finalized_header_hash).await?;
 	let self_best_finalized_id = HeaderId(*self_best_finalized_header.number(), self_best_finalized_header_hash);
 
+	// now let's read our best header on **this** chain
+	let self_best_header = self_client.best_header().await?;
+	let self_best_hash = self_best_header.hash();
+	let self_best_id = HeaderId(*self_best_header.number(), self_best_hash);
+
 	// now let's read id of best finalized peer header at our best finalized block
 	let best_finalized_peer_on_self_method = format!("{}HeaderApi_finalized_block", bridged_chain_name);
 	let encoded_best_finalized_peer_on_self = self_client
 		.state_call(
 			best_finalized_peer_on_self_method,
 			Bytes(Vec::new()),
-			Some(self_best_finalized_header_hash),
+			Some(self_best_hash),
 		)
 		.await?;
 	let decoded_best_finalized_peer_on_self: (BridgedHeaderNumber, BridgedHeaderHash) =
@@ -251,7 +256,8 @@ where
 	);
 
 	Ok(ClientState {
-		best_self: self_best_finalized_id,
-		best_peer: peer_on_self_best_finalized_id,
+		best_self: self_best_id,
+		best_finalized_self: self_best_finalized_id,
+		best_finalized_peer_at_best_self: peer_on_self_best_finalized_id,
 	})
 }