Use real conversion rate in greedy relayer strategy (#1035)

* use real conversion rate in greedy relayer strategy

* only accept positive, normal numbers in FloatJsonValueMetric

bridges/relays/messages/src/message_lane_loop.rs

@@ -212,7 +212,7 @@ pub trait TargetClient<P: MessageLane>: RelayClient {
 		nonces: RangeInclusive<MessageNonce>,
 		total_dispatch_weight: Weight,
 		total_size: u32,
-	) -> P::SourceChainBalance;
+	) -> Result<P::SourceChainBalance, Self::Error>;
 }
 
 /// State of the client.
@@ -775,10 +775,12 @@ pub(crate) mod tests {
 			nonces: RangeInclusive<MessageNonce>,
 			total_dispatch_weight: Weight,
 			total_size: u32,
-		) -> TestSourceChainBalance {
-			BASE_MESSAGE_DELIVERY_TRANSACTION_COST * (nonces.end() - nonces.start() + 1)
-				+ total_dispatch_weight
-				+ total_size as TestSourceChainBalance
+		) -> Result<TestSourceChainBalance, TestError> {
+			Ok(
+				BASE_MESSAGE_DELIVERY_TRANSACTION_COST * (nonces.end() - nonces.start() + 1)
+					+ total_dispatch_weight
+					+ total_size as TestSourceChainBalance,
+			)
 		}
 	}
 

bridges/relays/messages/src/message_race_delivery.rs

@@ -654,7 +654,15 @@ async fn select_nonces_for_delivery_transaction<P: MessageLane>(
 						new_selected_unpaid_weight,
 						new_selected_size as u32,
 					)
-					.await;
+					.await
+					.map_err(|err| {
+						log::debug!(
+							target: "bridge",
+							"Failed to estimate delivery transaction cost: {:?}. No nonces selected for delivery",
+							err,
+						);
+					})
+					.ok()?;
 
 				// if it is the first message that makes reward less than cost, let's log it
 				// if this message makes batch profitable again, let's log it