Use plain source_queue view when selecting nonces for delivery (#1010)

* use plain source_queue view when selecting nonces for delivery

* Revert "use plain source_queue view when selecting nonces for delivery"

This reverts commit f1fdc3fa9a0934271b125328e69e4f16014780d1.

* Revert "Revert "use plain source_queue view when selecting nonces for delivery""

This reverts commit ccefa5ece24c675649251ebc5c686ef972eed2f4.

* clippy

* fmt

bridges/relays/messages/src/message_race_delivery.rs

@@ -23,7 +23,7 @@ use crate::message_race_loop::{
 	MessageRace, NoncesRange, RaceState, RaceStrategy, SourceClient, SourceClientNonces, TargetClient,
 	TargetClientNonces,
 };
-use crate::message_race_strategy::BasicStrategy;
+use crate::message_race_strategy::{BasicStrategy, SourceRangesQueue};
 use crate::metrics::MessageLaneLoopMetrics;
 
 use async_trait::async_trait;
@@ -31,7 +31,12 @@ use bp_messages::{MessageNonce, UnrewardedRelayersState, Weight};
 use futures::stream::FusedStream;
 use num_traits::{SaturatingAdd, Zero};
 use relay_utils::FailedClient;
-use std::{collections::VecDeque, marker::PhantomData, ops::RangeInclusive, time::Duration};
+use std::{
+	collections::VecDeque,
+	marker::PhantomData,
+	ops::{Range, RangeInclusive},
+	time::Duration,
+};
 
 /// Run message delivery race.
 pub async fn run<P: MessageLane>(
@@ -499,22 +504,25 @@ where
 		let lane_source_client = self.lane_source_client.clone();
 		let lane_target_client = self.lane_target_client.clone();
 
+		let maximal_source_queue_index = self.strategy.maximal_available_source_queue_index(race_state)?;
 		let previous_total_dispatch_weight = self.total_queued_dispatch_weight();
-		let selected_nonces = self
-			.strategy
-			.select_nonces_to_deliver_with_selector(race_state.clone(), |range| async {
-				select_nonces_for_delivery_transaction(
-					relayer_mode,
-					max_nonces,
-					max_messages_weight_in_single_batch,
-					max_messages_size_in_single_batch,
-					lane_source_client.clone(),
-					lane_target_client.clone(),
-					range,
-				)
-				.await
-			})
-			.await?;
+		let source_queue = self.strategy.source_queue();
+		let range_end = select_nonces_for_delivery_transaction(
+			relayer_mode,
+			max_nonces,
+			max_messages_weight_in_single_batch,
+			max_messages_size_in_single_batch,
+			lane_source_client.clone(),
+			lane_target_client.clone(),
+			source_queue,
+			0..maximal_source_queue_index + 1,
+		)
+		.await?;
+
+		let range_begin = source_queue[0].1.begin();
+		let selected_nonces = range_begin..=range_end;
+		self.strategy.remove_le_nonces_from_source_queue(range_end);
+
 		let new_total_dispatch_weight = self.total_queued_dispatch_weight();
 		let dispatch_weight = previous_total_dispatch_weight - new_total_dispatch_weight;
 
@@ -533,6 +541,7 @@ where
 ///
 /// The function returns nonces that are NOT selected for current batch and will be
 /// delivered later.
+#[allow(clippy::too_many_arguments)]
 async fn select_nonces_for_delivery_transaction<P: MessageLane>(
 	relayer_mode: RelayerMode,
 	max_messages_in_this_batch: MessageNonce,
@@ -540,8 +549,13 @@ async fn select_nonces_for_delivery_transaction<P: MessageLane>(
 	max_messages_size_in_single_batch: u32,
 	lane_source_client: impl MessageLaneSourceClient<P>,
 	lane_target_client: impl MessageLaneTargetClient<P>,
-	ready_nonces: MessageDetailsMap<P::SourceChainBalance>,
-) -> Option<MessageDetailsMap<P::SourceChainBalance>> {
+	nonces_queue: &SourceRangesQueue<
+		P::SourceHeaderHash,
+		P::SourceHeaderNumber,
+		MessageDetailsMap<P::SourceChainBalance>,
+	>,
+	nonces_queue_range: Range<usize>,
+) -> Option<MessageNonce> {
 	let mut hard_selected_count = 0;
 	let mut soft_selected_count = 0;
 
@@ -563,7 +577,11 @@ async fn select_nonces_for_delivery_transaction<P: MessageLane>(
 		Zero::zero()
 	};
 
-	for (index, (nonce, details)) in ready_nonces.iter().enumerate() {
+	let all_ready_nonces = nonces_queue
+		.range(nonces_queue_range.clone())
+		.flat_map(|(_, ready_nonces)| ready_nonces.iter())
+		.enumerate();
+	for (index, (nonce, details)) in all_ready_nonces {
 		// Since we (hopefully) have some reserves in `max_messages_weight_in_single_batch`
 		// and `max_messages_size_in_single_batch`, we may still try to submit transaction
 		// with single message if message overflows these limits. The worst case would be if
@@ -671,23 +689,27 @@ async fn select_nonces_for_delivery_transaction<P: MessageLane>(
 		selected_count = new_selected_count;
 	}
 
+	let hard_selected_begin_nonce = nonces_queue[nonces_queue_range.start].1.begin();
 	if hard_selected_count != soft_selected_count {
+		let hard_selected_end_nonce = hard_selected_begin_nonce + hard_selected_count as MessageNonce - 1;
+		let soft_selected_begin_nonce = hard_selected_begin_nonce;
+		let soft_selected_end_nonce = soft_selected_begin_nonce + soft_selected_count as MessageNonce - 1;
 		log::warn!(
 			target: "bridge",
 			"Relayer may deliver nonces [{:?}; {:?}], but because of its strategy ({:?}) it has selected \
 			nonces [{:?}; {:?}].",
-			ready_nonces.keys().next(),
-			ready_nonces.keys().next().map(|begin| begin + (hard_selected_count as MessageNonce) - 1),
+			hard_selected_begin_nonce,
+			hard_selected_end_nonce,
 			relayer_mode,
-			ready_nonces.keys().next(),
-			ready_nonces.keys().next().map(|begin| begin + (soft_selected_count as MessageNonce) - 1),
-
+			soft_selected_begin_nonce,
+			soft_selected_end_nonce,
 		);
 
 		hard_selected_count = soft_selected_count;
 	}
-	if hard_selected_count != ready_nonces.len() {
-		Some(ready_nonces.into_iter().skip(hard_selected_count).collect())
+
+	if hard_selected_count != 0 {
+		Some(hard_selected_begin_nonce + hard_selected_count as MessageNonce - 1)
 	} else {
 		None
 	}
@@ -1127,4 +1149,30 @@ mod tests {
 			Some(((20..=23), proof_parameters(false, 4)))
 		);
 	}
+
+	#[async_std::test]
+	async fn relayer_uses_flattened_view_of_the_source_queue_to_select_nonces() {
+		// Real scenario that has happened on test deployments:
+		// 1) relayer witnessed M1 at block 1 => it has separate entry in the `source_queue`
+		// 2) relayer witnessed M2 at block 2 => it has separate entry in the `source_queue`
+		// 3) if block 2 is known to the target node, then both M1 and M2 are selected for single delivery,
+		//    even though weight(M1+M2) > larger than largest allowed weight
+		//
+		// This was happening because selector (`select_nonces_for_delivery_transaction`) has been called
+		// for every `source_queue` entry separately without preserving any context.
+		let (mut state, mut strategy) = prepare_strategy();
+		let nonces = source_nonces(24..=25, 19, DEFAULT_REWARD - DELIVERY_TRANSACTION_COST);
+		strategy.strategy.source_nonces_updated(header_id(2), nonces);
+		strategy.max_unrewarded_relayer_entries_at_target = 100;
+		strategy.max_unconfirmed_nonces_at_target = 100;
+		strategy.max_messages_in_single_batch = 5;
+		strategy.max_messages_weight_in_single_batch = 100;
+		strategy.max_messages_size_in_single_batch = 100;
+		state.best_finalized_source_header_id_at_best_target = Some(header_id(2));
+
+		assert_eq!(
+			strategy.select_nonces_to_deliver(state).await,
+			Some(((20..=24), proof_parameters(false, 5)))
+		);
+	}
 }