Pick from paritytech/parity-bridges-common#1328 (#13)

relays/messages/src/message_race_delivery.rs

@@ -72,6 +72,7 @@ pub async fn run<P: MessageLane, Strategy: RelayStrategy>(
 			max_messages_size_in_single_batch: params.max_messages_size_in_single_batch,
 			relay_strategy: params.relay_strategy,
 			latest_confirmed_nonces_at_source: VecDeque::new(),
+			latest_updated_confirm_nonce_at_source: None,
 			target_nonces: None,
 			strategy: BasicStrategy::new(),
 		},
@@ -251,6 +252,8 @@ struct MessageDeliveryStrategy<P: MessageLane, Strategy: RelayStrategy, SC, TC>
 	/// Latest confirmed nonces at the source client + the header id where we have first met this
 	/// nonce.
 	latest_confirmed_nonces_at_source: VecDeque<(SourceHeaderIdOf<P>, MessageNonce)>,
+	/// latest updated confirm nonce at source chain
+	latest_updated_confirm_nonce_at_source: Option<MessageNonce>,
 	/// Target nonces from the source client.
 	target_nonces: Option<TargetClientNonces<DeliveryRaceTargetNoncesData>>,
 	/// Basic delivery strategy.
@@ -280,6 +283,10 @@ impl<P: MessageLane, Strategy: RelayStrategy, SC, TC> std::fmt::Debug
 			.field("max_messages_weight_in_single_batch", &self.max_messages_weight_in_single_batch)
 			.field("max_messages_size_in_single_batch", &self.max_messages_size_in_single_batch)
 			.field("latest_confirmed_nonces_at_source", &self.latest_confirmed_nonces_at_source)
+			.field(
+				"latest_updated_confirm_nonce_at_source",
+				&self.latest_updated_confirm_nonce_at_source,
+			)
 			.field("target_nonces", &self.target_nonces)
 			.field("strategy", &self.strategy)
 			.finish()
@@ -346,13 +353,13 @@ where
 	) {
 		if let Some(confirmed_nonce) = nonces.confirmed_nonce {
 			let is_confirmed_nonce_updated = self
-				.latest_confirmed_nonces_at_source
-				.back()
-				.map(|(_, prev_nonce)| *prev_nonce != confirmed_nonce)
+				.latest_updated_confirm_nonce_at_source
+				.map(|nonce| nonce != confirmed_nonce)
 				.unwrap_or(true);
 			if is_confirmed_nonce_updated {
 				self.latest_confirmed_nonces_at_source
 					.push_back((at_block.clone(), confirmed_nonce));
+				self.latest_updated_confirm_nonce_at_source = Some(confirmed_nonce);
 			}
 		}
 		self.strategy.source_nonces_updated(at_block, nonces)
@@ -392,6 +399,13 @@ where
 			{
 				self.latest_confirmed_nonces_at_source.pop_front();
 			}
+			let latest = self.latest_confirmed_nonces_at_source.back();
+			log::debug!(
+				target: "bridge",
+				"Pop front latest_confirmed_nonces_at_source. the oldest_header_number_to_keep is {:?}. after pop the latest value is {:?}",
+				oldest_header_number_to_keep,
+				latest
+			);
 		}
 
 		if let Some(ref mut target_nonces) = self.target_nonces {