Cli option for greedy relayer + run no-losses relayer by default (#1042)

* cli option for greedy relayer + run no-losses relayer by default

* trigger build

* Revert "trigger build"

This reverts commit f77ae3a634b909bb4dc915941a4c1011a86019f0.

* NoLosses -> Rational

bridges/relays/messages/src/message_lane.rs

@@ -21,7 +21,7 @@
 
 use num_traits::{SaturatingAdd, Zero};
 use relay_utils::{BlockNumberBase, HeaderId};
-use std::fmt::Debug;
+use std::{fmt::Debug, ops::Sub};
 
 /// One-way message lane.
 pub trait MessageLane: 'static + Clone + Send + Sync {
@@ -40,7 +40,15 @@ pub trait MessageLane: 'static + Clone + Send + Sync {
 	/// 1) pay transaction fees;
 	/// 2) pay message delivery and dispatch fee;
 	/// 3) pay relayer rewards.
-	type SourceChainBalance: Clone + Copy + Debug + PartialOrd + SaturatingAdd + Zero + Send + Sync;
+	type SourceChainBalance: Clone
+		+ Copy
+		+ Debug
+		+ PartialOrd
+		+ Sub<Output = Self::SourceChainBalance>
+		+ SaturatingAdd
+		+ Zero
+		+ Send
+		+ Sync;
 	/// Number of the source header.
 	type SourceHeaderNumber: BlockNumberBase;
 	/// Hash of the source header.

bridges/relays/messages/src/message_lane_loop.rs

@@ -65,7 +65,7 @@ pub enum RelayerMode {
 	/// The relayer doesn't care about rewards.
 	Altruistic,
 	/// The relayer will deliver all messages and confirmations as long as he's not losing any funds.
-	NoLosses,
+	Rational,
 }
 
 /// Message delivery race parameters.

bridges/relays/messages/src/message_race_delivery.rs

@@ -540,8 +540,7 @@ where
 /// From given set of source nonces, that are ready to be delivered, select nonces
 /// to fit into single delivery transaction.
 ///
-/// The function returns nonces that are NOT selected for current batch and will be
-/// delivered later.
+/// The function returns last nonce that must be delivered to the target chain.
 #[allow(clippy::too_many_arguments)]
 async fn select_nonces_for_delivery_transaction<P: MessageLane>(
 	relayer_mode: RelayerMode,
@@ -564,6 +563,8 @@ async fn select_nonces_for_delivery_transaction<P: MessageLane>(
 	let mut selected_unpaid_weight: Weight = 0;
 	let mut selected_size: u32 = 0;
 	let mut selected_count: MessageNonce = 0;
+	let mut selected_reward = P::SourceChainBalance::zero();
+	let mut selected_cost = P::SourceChainBalance::zero();
 
 	let mut total_reward = P::SourceChainBalance::zero();
 	let mut total_confirmations_cost = P::SourceChainBalance::zero();
@@ -647,7 +648,7 @@ async fn select_nonces_for_delivery_transaction<P: MessageLane>(
 			RelayerMode::Altruistic => {
 				soft_selected_count = index + 1;
 			}
-			RelayerMode::NoLosses => {
+			RelayerMode::Rational => {
 				let delivery_transaction_cost = lane_target_client
 					.estimate_delivery_transaction_in_source_tokens(
 						0..=(new_selected_count as MessageNonce - 1),
@@ -698,9 +699,11 @@ async fn select_nonces_for_delivery_transaction<P: MessageLane>(
 					);
 				}
 
-				// NoLosses relayer never want to lose his funds
+				// Rational relayer never want to lose his funds
 				if total_reward >= total_cost {
 					soft_selected_count = index + 1;
+					selected_reward = total_reward;
+					selected_cost = total_cost;
 				}
 			}
 		}
@@ -732,6 +735,18 @@ async fn select_nonces_for_delivery_transaction<P: MessageLane>(
 	}
 
 	if hard_selected_count != 0 {
+		if relayer_mode != RelayerMode::Altruistic {
+			log::trace!(
+				target: "bridge",
+				"Expected reward from delivering nonces [{:?}; {:?}] is: {:?} - {:?} = {:?}",
+				hard_selected_begin_nonce,
+				hard_selected_begin_nonce + hard_selected_count as MessageNonce - 1,
+				selected_reward,
+				selected_cost,
+				selected_reward - selected_cost,
+			);
+		}
+
 		Some(hard_selected_begin_nonce + hard_selected_count as MessageNonce - 1)
 	} else {
 		None
@@ -1151,9 +1166,9 @@ mod tests {
 	}
 
 	#[async_std::test]
-	async fn no_losses_relayer_is_delivering_messages_if_cost_is_equal_to_reward() {
+	async fn rational_relayer_is_delivering_messages_if_cost_is_equal_to_reward() {
 		let (state, mut strategy) = prepare_strategy();
-		strategy.relayer_mode = RelayerMode::NoLosses;
+		strategy.relayer_mode = RelayerMode::Rational;
 
 		// so now we have:
 		// - 20..=23 with reward = cost
@@ -1165,7 +1180,7 @@ mod tests {
 	}
 
 	#[async_std::test]
-	async fn no_losses_relayer_is_not_delivering_messages_if_cost_is_larger_than_reward() {
+	async fn rational_relayer_is_not_delivering_messages_if_cost_is_larger_than_reward() {
 		let (mut state, mut strategy) = prepare_strategy();
 		let nonces = source_nonces(
 			24..=25,
@@ -1175,7 +1190,7 @@ mod tests {
 		);
 		strategy.strategy.source_nonces_updated(header_id(2), nonces);
 		state.best_finalized_source_header_id_at_best_target = Some(header_id(2));
-		strategy.relayer_mode = RelayerMode::NoLosses;
+		strategy.relayer_mode = RelayerMode::Rational;
 
 		// so now we have:
 		// - 20..=23 with reward = cost
@@ -1188,7 +1203,7 @@ mod tests {
 	}
 
 	#[async_std::test]
-	async fn no_losses_relayer_is_delivering_unpaid_messages() {
+	async fn rational_relayer_is_delivering_unpaid_messages() {
 		async fn test_with_dispatch_fee_payment(
 			dispatch_fee_payment: DispatchFeePayment,
 		) -> Option<(RangeInclusive<MessageNonce>, MessageProofParameters)> {
@@ -1206,7 +1221,7 @@ mod tests {
 			strategy.max_messages_in_single_batch = 100;
 			strategy.max_messages_weight_in_single_batch = 100;
 			strategy.max_messages_size_in_single_batch = 100;
-			strategy.relayer_mode = RelayerMode::NoLosses;
+			strategy.relayer_mode = RelayerMode::Rational;
 
 			// so now we have:
 			// - 20..=23 with reward = cost