Reintroduce msg dispatch status reporting (#2027)

* Use an actual Result inside MessageDispatchResult

We need this in order to distinguish between Ok and Err

* Revert #1660

* Fixes + simplifications

* Implement review suggestions

bridges/bin/millau/runtime/src/xcm_config.rs

@@ -242,7 +242,7 @@ mod tests {
 		target_chain::{DispatchMessage, DispatchMessageData, MessageDispatch},
 		LaneId, MessageKey,
 	};
-	use bridge_runtime_common::messages_xcm_extension::XcmBlobMessageDispatchResult;
+	use bridge_runtime_common::messages_xcm_extension::XcmBlobMessageDispatchError;
 	use codec::Encode;
 	use pallet_bridge_messages::OutboundLanes;
 	use xcm_executor::XcmExecutor;
@@ -352,8 +352,8 @@ mod tests {
 		let dispatch_result =
 			FromRialtoMessageDispatch::dispatch(&AccountId::from([0u8; 32]), incoming_message);
 		assert!(matches!(
-			dispatch_result.dispatch_level_result,
+			dispatch_result.dispatch_result,
-			XcmBlobMessageDispatchResult::NotDispatched(_),
+			Err(XcmBlobMessageDispatchError::NotDispatched(_)),
 		));
 	}
 
@@ -366,8 +366,8 @@ mod tests {
 		let dispatch_result =
 			FromRialtoMessageDispatch::dispatch(&AccountId::from([0u8; 32]), incoming_message);
 		assert!(matches!(
-			dispatch_result.dispatch_level_result,
+			dispatch_result.dispatch_result,
-			XcmBlobMessageDispatchResult::NotDispatched(_),
+			Err(XcmBlobMessageDispatchError::NotDispatched(_)),
 		));
 	}
 }

bridges/bin/rialto-parachain/runtime/src/lib.rs

@@ -853,7 +853,7 @@ mod tests {
 		LaneId, MessageKey,
 	};
 	use bridge_runtime_common::{
-		integrity::check_additional_signed, messages_xcm_extension::XcmBlobMessageDispatchResult,
+		integrity::check_additional_signed, messages_xcm_extension::XcmBlobMessageDispatchError,
 	};
 	use codec::Encode;
 	use pallet_bridge_messages::OutboundLanes;
@@ -928,8 +928,8 @@ mod tests {
 			let dispatch_result =
 				FromMillauMessageDispatch::dispatch(&AccountId::from([0u8; 32]), incoming_message);
 			assert!(matches!(
-				dispatch_result.dispatch_level_result,
+				dispatch_result.dispatch_result,
-				XcmBlobMessageDispatchResult::NotDispatched(_),
+				Err(XcmBlobMessageDispatchError::NotDispatched(_)),
 			));
 		});
 	}

bridges/bin/rialto/runtime/src/xcm_config.rs

@@ -197,7 +197,7 @@ mod tests {
 		target_chain::{DispatchMessage, DispatchMessageData, MessageDispatch},
 		LaneId, MessageKey,
 	};
-	use bridge_runtime_common::messages_xcm_extension::XcmBlobMessageDispatchResult;
+	use bridge_runtime_common::messages_xcm_extension::XcmBlobMessageDispatchError;
 	use codec::Encode;
 	use pallet_bridge_messages::OutboundLanes;
 	use xcm_executor::XcmExecutor;
@@ -269,8 +269,8 @@ mod tests {
 		let dispatch_result =
 			FromMillauMessageDispatch::dispatch(&AccountId::from([0u8; 32]), incoming_message);
 		assert!(matches!(
-			dispatch_result.dispatch_level_result,
+			dispatch_result.dispatch_result,
-			XcmBlobMessageDispatchResult::NotDispatched(_),
+			Err(XcmBlobMessageDispatchError::NotDispatched(_)),
 		));
 	}
 }

bridges/bin/runtime-common/src/integrity.rs

@@ -307,8 +307,10 @@ pub fn check_message_lane_weights<C: Chain, T: frame_system::Config>(
 		messages::target::maximal_incoming_message_dispatch_weight(C::max_extrinsic_weight()),
 	);
 
-	let max_incoming_inbound_lane_data_proof_size =
+	let max_incoming_inbound_lane_data_proof_size = InboundLaneData::<()>::encoded_size_hint_u32(
-		InboundLaneData::<()>::encoded_size_hint_u32(this_chain_max_unrewarded_relayers as _);
+		this_chain_max_unrewarded_relayers as _,
+		this_chain_max_unconfirmed_messages as _,
+	);
 	pallet_bridge_messages::ensure_able_to_receive_confirmation::<Weights<T>>(
 		C::max_extrinsic_size(),
 		C::max_extrinsic_weight(),

bridges/bin/runtime-common/src/messages_xcm_extension.rs

@@ -39,9 +39,8 @@ pub type XcmAsPlainPayload = sp_std::prelude::Vec<u8>;
 
 /// Message dispatch result type for single message
 #[derive(CloneNoBound, EqNoBound, PartialEqNoBound, Encode, Decode, Debug, TypeInfo)]
-pub enum XcmBlobMessageDispatchResult {
+pub enum XcmBlobMessageDispatchError {
 	InvalidPayload,
-	Dispatched,
 	NotDispatched(#[codec(skip)] Option<DispatchBlobError>),
 }
 
@@ -65,7 +64,7 @@ impl<
 	for XcmBlobMessageDispatch<SourceBridgeHubChain, TargetBridgeHubChain, BlobDispatcher, Weights>
 {
 	type DispatchPayload = XcmAsPlainPayload;
-	type DispatchLevelResult = XcmBlobMessageDispatchResult;
+	type DispatchError = XcmBlobMessageDispatchError;
 
 	fn dispatch_weight(message: &mut DispatchMessage<Self::DispatchPayload>) -> Weight {
 		match message.data.payload {
@@ -80,7 +79,7 @@ impl<
 	fn dispatch(
 		_relayer_account: &AccountIdOf<SourceBridgeHubChain>,
 		message: DispatchMessage<Self::DispatchPayload>,
-	) -> MessageDispatchResult<Self::DispatchLevelResult> {
+	) -> MessageDispatchResult<Self::DispatchError> {
 		let payload = match message.data.payload {
 			Ok(payload) => payload,
 			Err(e) => {
@@ -92,7 +91,7 @@ impl<
 				);
 				return MessageDispatchResult {
 					unspent_weight: Weight::zero(),
-					dispatch_level_result: XcmBlobMessageDispatchResult::InvalidPayload,
+					dispatch_result: Err(XcmBlobMessageDispatchError::InvalidPayload),
 				}
 			},
 		};
@@ -103,7 +102,7 @@ impl<
 					"[XcmBlobMessageDispatch] DispatchBlob::dispatch_blob was ok - message_nonce: {:?}",
 					message.key.nonce
 				);
-				XcmBlobMessageDispatchResult::Dispatched
+				Ok(())
 			},
 			Err(e) => {
 				log::error!(
@@ -111,10 +110,13 @@ impl<
 					"[XcmBlobMessageDispatch] DispatchBlob::dispatch_blob failed, error: {:?} - message_nonce: {:?}",
 					e, message.key.nonce
 				);
-				XcmBlobMessageDispatchResult::NotDispatched(Some(e))
+				Err(XcmBlobMessageDispatchError::NotDispatched(Some(e)))
 			},
 		};
-		MessageDispatchResult { unspent_weight: Weight::zero(), dispatch_level_result }
+		MessageDispatchResult {
+			unspent_weight: Weight::zero(),
+			dispatch_result: dispatch_level_result,
+		}
 	}
 }
 

bridges/modules/messages/Cargo.toml

@@ -7,6 +7,7 @@ edition = "2021"
 license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 
 [dependencies]
+bitvec = { version = "1", default-features = false, features = ["alloc"] }
 codec = { package = "parity-scale-codec", version = "3.1.5", default-features = false }
 log = { version = "0.4.17", default-features = false }
 num-traits = { version = "0.2", default-features = false }

bridges/modules/messages/src/benchmarking.rs

@@ -301,7 +301,7 @@ benchmarks_instance_pallet! {
 			inbound_lane_data: InboundLaneData {
 				relayers: vec![UnrewardedRelayer {
 					relayer: relayer_id.clone(),
-					messages: DeliveredMessages::new(1),
+					messages: DeliveredMessages::new(1, true),
 				}].into_iter().collect(),
 				last_confirmed_nonce: 0,
 			},
@@ -333,8 +333,8 @@ benchmarks_instance_pallet! {
 			total_messages: 2,
 			last_delivered_nonce: 2,
 		};
-		let mut delivered_messages = DeliveredMessages::new(1);
+		let mut delivered_messages = DeliveredMessages::new(1, true);
-		delivered_messages.note_dispatched_message();
+		delivered_messages.note_dispatched_message(true);
 		let proof = T::prepare_message_delivery_proof(MessageDeliveryProofParams {
 			lane: T::bench_lane_id(),
 			inbound_lane_data: InboundLaneData {
@@ -379,11 +379,11 @@ benchmarks_instance_pallet! {
 				relayers: vec![
 					UnrewardedRelayer {
 						relayer: relayer1_id.clone(),
-						messages: DeliveredMessages::new(1),
+						messages: DeliveredMessages::new(1, true),
 					},
 					UnrewardedRelayer {
 						relayer: relayer2_id.clone(),
-						messages: DeliveredMessages::new(2),
+						messages: DeliveredMessages::new(2, true),
 					},
 				].into_iter().collect(),
 				last_confirmed_nonce: 0,
@@ -451,7 +451,7 @@ fn receive_messages<T: Config<I>, I: 'static>(nonce: MessageNonce) {
 	inbound_lane_storage.set_data(InboundLaneData {
 		relayers: vec![UnrewardedRelayer {
 			relayer: T::bridged_relayer_id(),
-			messages: DeliveredMessages::new(nonce),
+			messages: DeliveredMessages::new(nonce, true),
 		}]
 		.into_iter()
 		.collect(),

bridges/modules/messages/src/inbound_lane.rs

@@ -101,6 +101,7 @@ impl<T: Config<I>, I: 'static> MaxEncodedLen for StoredInboundLaneData<T, I> {
 	fn max_encoded_len() -> usize {
 		InboundLaneData::<T::InboundRelayer>::encoded_size_hint(
 			T::MaxUnrewardedRelayerEntriesAtInboundLane::get() as usize,
+			T::MaxUnconfirmedMessagesAtInboundLane::get() as usize,
 		)
 		.unwrap_or(usize::MAX)
 	}
@@ -154,6 +155,9 @@ impl<S: InboundLaneStorage> InboundLane<S> {
 		// overlap.
 		match data.relayers.front_mut() {
 			Some(entry) if entry.messages.begin < new_confirmed_nonce => {
+				entry.messages.dispatch_results = entry.messages.dispatch_results
+					[(new_confirmed_nonce + 1 - entry.messages.begin) as usize..]
+					.to_bitvec();
 				entry.messages.begin = new_confirmed_nonce + 1;
 			},
 			_ => {},
@@ -170,7 +174,7 @@ impl<S: InboundLaneStorage> InboundLane<S> {
 		relayer_at_this_chain: &AccountId,
 		nonce: MessageNonce,
 		message_data: DispatchMessageData<Dispatch::DispatchPayload>,
-	) -> ReceivalResult<Dispatch::DispatchLevelResult> {
+	) -> ReceivalResult<Dispatch::DispatchError> {
 		let mut data = self.storage.data();
 		let is_correct_message = nonce == data.last_delivered_nonce() + 1;
 		if !is_correct_message {
@@ -198,19 +202,20 @@ impl<S: InboundLaneStorage> InboundLane<S> {
 		);
 
 		// now let's update inbound lane storage
-		let push_new = match data.relayers.back_mut() {
+		match data.relayers.back_mut() {
 			Some(entry) if entry.relayer == *relayer_at_bridged_chain => {
-				entry.messages.note_dispatched_message();
+				entry.messages.note_dispatched_message(dispatch_result.dispatch_result.is_ok());
-				false
+			},
+			_ => {
+				data.relayers.push_back(UnrewardedRelayer {
+					relayer: relayer_at_bridged_chain.clone(),
+					messages: DeliveredMessages::new(
+						nonce,
+						dispatch_result.dispatch_result.is_ok(),
+					),
+				});
 			},
-			_ => true,
 		};
-		if push_new {
-			data.relayers.push_back(UnrewardedRelayer {
-				relayer: (*relayer_at_bridged_chain).clone(),
-				messages: DeliveredMessages::new(nonce),
-			});
-		}
 		self.storage.set_data(data);
 
 		ReceivalResult::Dispatched(dispatch_result)

bridges/modules/messages/src/lib.rs

@@ -66,7 +66,7 @@ use bp_messages::{
 use bp_runtime::{BasicOperatingMode, ChainId, OwnedBridgeModule, Size};
 use codec::{Decode, Encode, MaxEncodedLen};
 use frame_support::{dispatch::PostDispatchInfo, ensure, fail, traits::Get};
-use sp_runtime::traits::UniqueSaturatedFrom;
+use sp_runtime::{traits::UniqueSaturatedFrom, SaturatedConversion};
 use sp_std::{cell::RefCell, marker::PhantomData, prelude::*};
 
 mod inbound_lane;
@@ -527,7 +527,7 @@ pub mod pallet {
 		MessagesReceived(
 			Vec<
 				ReceivedMessages<
-					<T::MessageDispatch as MessageDispatch<T::AccountId>>::DispatchLevelResult,
+					<T::MessageDispatch as MessageDispatch<T::AccountId>>::DispatchError,
 				>,
 			>,
 		),
@@ -807,15 +807,19 @@ impl<T: Config<I>, I: 'static> RuntimeInboundLaneStorage<T, I> {
 	/// `receive_messages_proof` call, because the actual inbound lane state is smaller than the
 	/// maximal configured.
 	///
-	/// Maximal inbound lane state set size is configured by the
+	/// Maximal inbound lane state size is computed using the
-	/// `MaxUnrewardedRelayerEntriesAtInboundLane` constant from the pallet configuration. The PoV
+	/// `MaxUnrewardedRelayerEntriesAtInboundLane` and `MaxUnconfirmedMessagesAtInboundLane`
-	/// of the call includes the maximal size of inbound lane state. If the actual size is smaller,
+	/// constants from the pallet configuration. The PoV of the call includes the maximal size
-	/// we may subtract extra bytes from this component.
+	/// of the inbound lane state. If the actual size is smaller, we may subtract extra bytes
+	/// from this component.
 	pub fn extra_proof_size_bytes(&self) -> u64 {
 		let max_encoded_len = StoredInboundLaneData::<T, I>::max_encoded_len();
 		let relayers_count = self.data().relayers.len();
+		let messages_count = self.data().relayers.iter().fold(0usize, |sum, relayer| {
+			sum.saturating_add(relayer.messages.total_messages().saturated_into::<usize>())
+		});
 		let actual_encoded_len =
-			InboundLaneData::<T::InboundRelayer>::encoded_size_hint(relayers_count)
+			InboundLaneData::<T::InboundRelayer>::encoded_size_hint(relayers_count, messages_count)
 				.unwrap_or(usize::MAX);
 		max_encoded_len.saturating_sub(actual_encoded_len) as _
 	}
@@ -946,6 +950,7 @@ mod tests {
 	};
 	use frame_system::{EventRecord, Pallet as System, Phase};
 	use sp_runtime::DispatchError;
+	use std::collections::VecDeque;
 
 	fn get_ready_for_events() {
 		System::<TestRuntime>::set_block_number(1);
@@ -1003,7 +1008,7 @@ mod tests {
 					last_confirmed_nonce: 1,
 					relayers: vec![UnrewardedRelayer {
 						relayer: 0,
-						messages: DeliveredMessages::new(1),
+						messages: DeliveredMessages::new(1, true),
 					}]
 					.into_iter()
 					.collect(),
@@ -1023,13 +1028,44 @@ mod tests {
 				phase: Phase::Initialization,
 				event: TestEvent::Messages(Event::MessagesDelivered {
 					lane_id: TEST_LANE_ID,
-					messages: DeliveredMessages::new(1),
+					messages: DeliveredMessages::new(1, true),
 				}),
 				topics: vec![],
 			}],
 		);
 	}
 
+	fn unrewarded_relayer_entry(msg_count: usize) -> UnrewardedRelayer<TestRelayer> {
+		UnrewardedRelayer {
+			relayer: 42u64,
+			messages: DeliveredMessages {
+				begin: 0,
+				end: msg_count as MessageNonce - 1,
+				dispatch_results: FromIterator::from_iter(vec![true; msg_count]),
+			},
+		}
+	}
+
+	fn unrewarded_relayers_vec(
+		entry_count: usize,
+		msg_count: usize,
+	) -> VecDeque<UnrewardedRelayer<TestRelayer>> {
+		if entry_count > msg_count {
+			panic!("unrewarded_relayers_vec(): expecting msg_count to be >= entry_count");
+		}
+
+		let mut unrewarded_relayers = vec![];
+		let mut available_msg_count = msg_count;
+		for _ in 0..entry_count - 1 {
+			unrewarded_relayers
+				.push(unrewarded_relayer_entry(std::cmp::min(1, available_msg_count)));
+			available_msg_count -= 1
+		}
+		unrewarded_relayers.push(unrewarded_relayer_entry(available_msg_count));
+
+		unrewarded_relayers.into_iter().collect()
+	}
+
 	#[test]
 	fn pallet_rejects_transactions_if_halted() {
 		run_test(|| {
@@ -1634,6 +1670,7 @@ mod tests {
 	fn proof_size_refund_from_receive_messages_proof_works() {
 		run_test(|| {
 			let max_entries = crate::mock::MaxUnrewardedRelayerEntriesAtInboundLane::get() as usize;
+			let max_msgs = crate::mock::MaxUnconfirmedMessagesAtInboundLane::get() as usize;
 
 			// if there's maximal number of unrewarded relayer entries at the inbound lane, then
 			// `proof_size` is unchanged in post-dispatch weight
@@ -1648,15 +1685,7 @@ mod tests {
 			InboundLanes::<TestRuntime>::insert(
 				TEST_LANE_ID,
 				StoredInboundLaneData(InboundLaneData {
-					relayers: vec![
+					relayers: unrewarded_relayers_vec(max_entries, max_msgs),
-						UnrewardedRelayer {
-							relayer: 42,
-							messages: DeliveredMessages { begin: 0, end: 100 }
-						};
-						max_entries
-					]
-					.into_iter()
-					.collect(),
 					last_confirmed_nonce: 0,
 				}),
 			);
@@ -1677,15 +1706,7 @@ mod tests {
 			InboundLanes::<TestRuntime>::insert(
 				TEST_LANE_ID,
 				StoredInboundLaneData(InboundLaneData {
-					relayers: vec![
+					relayers: unrewarded_relayers_vec(max_entries - 1, max_msgs),
-						UnrewardedRelayer {
-							relayer: 42,
-							messages: DeliveredMessages { begin: 0, end: 100 }
-						};
-						max_entries - 1
-					]
-					.into_iter()
-					.collect(),
 					last_confirmed_nonce: 0,
 				}),
 			);
@@ -1701,7 +1722,7 @@ mod tests {
 			.unwrap();
 			assert!(
 				post_dispatch_weight.proof_size() < pre_dispatch_weight.proof_size(),
-				"Expected post-dispatch PoV {} to be less than pre-dispatch PoV {}",
+				"Expected post-dispatch PoV {} to be < than pre-dispatch PoV {}",
 				post_dispatch_weight.proof_size(),
 				pre_dispatch_weight.proof_size(),
 			);
@@ -1717,8 +1738,8 @@ mod tests {
 
 			// messages 1+2 are confirmed in 1 tx, message 3 in a separate tx
 			// dispatch of message 2 has failed
-			let mut delivered_messages_1_and_2 = DeliveredMessages::new(1);
+			let mut delivered_messages_1_and_2 = DeliveredMessages::new(1, true);
-			delivered_messages_1_and_2.note_dispatched_message();
+			delivered_messages_1_and_2.note_dispatched_message(true);
 			let messages_1_and_2_proof = Ok((
 				TEST_LANE_ID,
 				InboundLaneData {
@@ -1731,7 +1752,7 @@ mod tests {
 					.collect(),
 				},
 			));
-			let delivered_message_3 = DeliveredMessages::new(3);
+			let delivered_message_3 = DeliveredMessages::new(3, true);
 			let messages_3_proof = Ok((
 				TEST_LANE_ID,
 				InboundLaneData {
@@ -2022,7 +2043,7 @@ mod tests {
 				last_confirmed_nonce: 1,
 				relayers: vec![UnrewardedRelayer {
 					relayer: 0,
-					messages: DeliveredMessages::new(1),
+					messages: DeliveredMessages::new(1, true),
 				}]
 				.into_iter()
 				.collect(),
@@ -2082,39 +2103,39 @@ mod tests {
 
 	#[test]
 	fn inbound_storage_extra_proof_size_bytes_works() {
-		fn relayer_entry() -> UnrewardedRelayer<TestRelayer> {
+		let max_entries = crate::mock::MaxUnrewardedRelayerEntriesAtInboundLane::get() as usize;
-			UnrewardedRelayer { relayer: 42u64, messages: DeliveredMessages { begin: 0, end: 100 } }
+		let max_msgs = crate::mock::MaxUnconfirmedMessagesAtInboundLane::get() as usize;
-		}
 
-		fn storage(relayer_entries: usize) -> RuntimeInboundLaneStorage<TestRuntime, ()> {
+		fn storage(
+			entry_count: usize,
+			msg_count: usize,
+		) -> RuntimeInboundLaneStorage<TestRuntime, ()> {
 			RuntimeInboundLaneStorage {
 				lane_id: Default::default(),
 				cached_data: RefCell::new(Some(InboundLaneData {
-					relayers: vec![relayer_entry(); relayer_entries].into_iter().collect(),
+					relayers: unrewarded_relayers_vec(entry_count, msg_count),
 					last_confirmed_nonce: 0,
 				})),
 				_phantom: Default::default(),
 			}
 		}
 
-		let max_entries = crate::mock::MaxUnrewardedRelayerEntriesAtInboundLane::get() as usize;
-
 		// when we have exactly `MaxUnrewardedRelayerEntriesAtInboundLane` unrewarded relayers
-		assert_eq!(storage(max_entries).extra_proof_size_bytes(), 0);
+		assert_eq!(storage(max_entries, max_msgs).extra_proof_size_bytes(), 0);
 
 		// when we have less than `MaxUnrewardedRelayerEntriesAtInboundLane` unrewarded relayers
 		assert_eq!(
-			storage(max_entries - 1).extra_proof_size_bytes(),
+			storage(max_entries - 1, max_msgs).extra_proof_size_bytes(),
-			relayer_entry().encode().len() as u64
+			unrewarded_relayer_entry(1).encoded_size() as u64
 		);
 		assert_eq!(
-			storage(max_entries - 2).extra_proof_size_bytes(),
+			storage(max_entries - 2, max_msgs).extra_proof_size_bytes(),
-			2 * relayer_entry().encode().len() as u64
+			2 * unrewarded_relayer_entry(1).encoded_size() as u64
 		);
 
 		// when we have more than `MaxUnrewardedRelayerEntriesAtInboundLane` unrewarded relayers
 		// (shall not happen in practice)
-		assert_eq!(storage(max_entries + 1).extra_proof_size_bytes(), 0);
+		assert_eq!(storage(max_entries + 1, max_msgs).extra_proof_size_bytes(), 0);
 	}
 
 	#[test]

bridges/modules/messages/src/mock.rs

@@ -19,6 +19,7 @@
 
 use crate::Config;
 
+use bitvec::prelude::*;
 use bp_messages::{
 	calc_relayers_rewards,
 	source_chain::{DeliveryConfirmationPayments, LaneMessageVerifier, TargetHeaderChain},
@@ -62,13 +63,13 @@ pub struct TestPayload {
 	///
 	/// Note: in correct code `dispatch_result.unspent_weight` will always be <= `declared_weight`,
 	/// but for test purposes we'll be making it larger than `declared_weight` sometimes.
-	pub dispatch_result: MessageDispatchResult<TestDispatchLevelResult>,
+	pub dispatch_result: MessageDispatchResult<TestDispatchError>,
 	/// Extra bytes that affect payload size.
 	pub extra: Vec<u8>,
 }
 pub type TestMessageFee = u64;
 pub type TestRelayer = u64;
-pub type TestDispatchLevelResult = ();
+pub type TestDispatchError = ();
 
 type Block = frame_system::mocking::MockBlock<TestRuntime>;
 type UncheckedExtrinsic = frame_system::mocking::MockUncheckedExtrinsic<TestRuntime>;
@@ -412,7 +413,7 @@ pub struct TestMessageDispatch;
 
 impl MessageDispatch<AccountId> for TestMessageDispatch {
 	type DispatchPayload = TestPayload;
-	type DispatchLevelResult = TestDispatchLevelResult;
+	type DispatchError = TestDispatchError;
 
 	fn dispatch_weight(message: &mut DispatchMessage<TestPayload>) -> Weight {
 		match message.data.payload.as_ref() {
@@ -424,7 +425,7 @@ impl MessageDispatch<AccountId> for TestMessageDispatch {
 	fn dispatch(
 		_relayer_account: &AccountId,
 		message: DispatchMessage<TestPayload>,
-	) -> MessageDispatchResult<TestDispatchLevelResult> {
+	) -> MessageDispatchResult<TestDispatchError> {
 		match message.data.payload.as_ref() {
 			Ok(payload) => payload.dispatch_result.clone(),
 			Err(_) => dispatch_result(0),
@@ -459,12 +460,10 @@ pub const fn message_payload(id: u64, declared_weight: u64) -> TestPayload {
 }
 
 /// Returns message dispatch result with given unspent weight.
-pub const fn dispatch_result(
+pub const fn dispatch_result(unspent_weight: u64) -> MessageDispatchResult<TestDispatchError> {
-	unspent_weight: u64,
-) -> MessageDispatchResult<TestDispatchLevelResult> {
 	MessageDispatchResult {
 		unspent_weight: Weight::from_parts(unspent_weight, 0),
-		dispatch_level_result: (),
+		dispatch_result: Ok(()),
 	}
 }
 
@@ -474,7 +473,14 @@ pub fn unrewarded_relayer(
 	end: MessageNonce,
 	relayer: TestRelayer,
 ) -> UnrewardedRelayer<TestRelayer> {
-	UnrewardedRelayer { relayer, messages: DeliveredMessages { begin, end } }
+	UnrewardedRelayer {
+		relayer,
+		messages: DeliveredMessages {
+			begin,
+			end,
+			dispatch_results: bitvec![u8, Msb0; 1; (end + 1).saturating_sub(begin) as _],
+		},
+	}
 }
 
 /// Return test externalities to use in tests.

bridges/modules/messages/src/outbound_lane.rs

@@ -18,8 +18,10 @@
 
 use crate::Config;
 
+use bitvec::prelude::*;
 use bp_messages::{
-	DeliveredMessages, LaneId, MessageNonce, MessagePayload, OutboundLaneData, UnrewardedRelayer,
+	DeliveredMessages, DispatchResultsBitVec, LaneId, MessageNonce, MessagePayload,
+	OutboundLaneData, UnrewardedRelayer,
 };
 use frame_support::{
 	weights::{RuntimeDbWeight, Weight},
@@ -65,6 +67,9 @@ pub enum ReceivalConfirmationResult {
 	/// The unrewarded relayers vec contains non-consecutive entries. May be a result of invalid
 	/// bridged chain storage.
 	NonConsecutiveUnrewardedRelayerEntries,
+	/// The unrewarded relayers vec contains entry with mismatched number of dispatch results. May
+	/// be a result of invalid bridged chain storage.
+	InvalidNumberOfDispatchResults,
 	/// The chain has more messages that need to be confirmed than there is in the proof.
 	TryingToConfirmMoreMessagesThanExpected(MessageNonce),
 }
@@ -124,9 +129,14 @@ impl<S: OutboundLaneStorage> OutboundLane<S> {
 			)
 		}
 
-		if let Err(e) = ensure_unrewarded_relayers_are_correct(latest_delivered_nonce, relayers) {
+		let dispatch_results = match extract_dispatch_results(
-			return e
+			data.latest_received_nonce,
-		}
+			latest_delivered_nonce,
+			relayers,
+		) {
+			Ok(dispatch_results) => dispatch_results,
+			Err(extract_error) => return extract_error,
+		};
 
 		let prev_latest_received_nonce = data.latest_received_nonce;
 		data.latest_received_nonce = latest_delivered_nonce;
@@ -135,6 +145,7 @@ impl<S: OutboundLaneStorage> OutboundLane<S> {
 		ReceivalConfirmationResult::ConfirmedMessages(DeliveredMessages {
 			begin: prev_latest_received_nonce + 1,
 			end: latest_delivered_nonce,
+			dispatch_results,
 		})
 	}
 
@@ -169,30 +180,34 @@ impl<S: OutboundLaneStorage> OutboundLane<S> {
 	}
 }
 
-/// Verifies unrewarded relayers vec.
+/// Extract new dispatch results from the unrewarded relayers vec.
 ///
 /// Returns `Err(_)` if unrewarded relayers vec contains invalid data, meaning that the bridged
 /// chain has invalid runtime storage.
-fn ensure_unrewarded_relayers_are_correct<RelayerId>(
+fn extract_dispatch_results<RelayerId>(
+	prev_latest_received_nonce: MessageNonce,
 	latest_received_nonce: MessageNonce,
 	relayers: &VecDeque<UnrewardedRelayer<RelayerId>>,
-) -> Result<(), ReceivalConfirmationResult> {
+) -> Result<DispatchResultsBitVec, ReceivalConfirmationResult> {
-	let mut last_entry_end: Option<MessageNonce> = None;
+	// the only caller of this functions checks that the
+	// prev_latest_received_nonce..=latest_received_nonce is valid, so we're ready to accept
+	// messages in this range => with_capacity call must succeed here or we'll be unable to receive
+	// confirmations at all
+	let mut received_dispatch_result =
+		BitVec::with_capacity((latest_received_nonce - prev_latest_received_nonce + 1) as _);
+	let mut expected_entry_begin = relayers.front().map(|entry| entry.messages.begin);
 	for entry in relayers {
 		// unrewarded relayer entry must have at least 1 unconfirmed message
 		// (guaranteed by the `InboundLane::receive_message()`)
-		if entry.messages.end < entry.messages.begin {
+		if entry.messages.total_messages() == 0 {
 			return Err(ReceivalConfirmationResult::EmptyUnrewardedRelayerEntry)
 		}
 		// every entry must confirm range of messages that follows previous entry range
 		// (guaranteed by the `InboundLane::receive_message()`)
-		if let Some(last_entry_end) = last_entry_end {
+		if expected_entry_begin != Some(entry.messages.begin) {
-			let expected_entry_begin = last_entry_end.checked_add(1);
+			return Err(ReceivalConfirmationResult::NonConsecutiveUnrewardedRelayerEntries)
-			if expected_entry_begin != Some(entry.messages.begin) {
-				return Err(ReceivalConfirmationResult::NonConsecutiveUnrewardedRelayerEntries)
-			}
 		}
-		last_entry_end = Some(entry.messages.end);
+		expected_entry_begin = entry.messages.end.checked_add(1);
 		// entry can't confirm messages larger than `inbound_lane_data.latest_received_nonce()`
 		// (guaranteed by the `InboundLane::receive_message()`)
 		if entry.messages.end > latest_received_nonce {
@@ -201,9 +216,30 @@ fn ensure_unrewarded_relayers_are_correct<RelayerId>(
 			// this is detected now
 			return Err(ReceivalConfirmationResult::FailedToConfirmFutureMessages)
 		}
+		// entry must have single dispatch result for every message
+		// (guaranteed by the `InboundLane::receive_message()`)
+		if entry.messages.dispatch_results.len() as MessageNonce != entry.messages.total_messages()
+		{
+			return Err(ReceivalConfirmationResult::InvalidNumberOfDispatchResults)
+		}
+
+		// now we know that the entry is valid
+		// => let's check if it brings new confirmations
+		let new_messages_begin =
+			sp_std::cmp::max(entry.messages.begin, prev_latest_received_nonce + 1);
+		if entry.messages.end < new_messages_begin {
+			continue
+		}
+
+		// now we know that entry brings new confirmations
+		// => let's extract dispatch results
+		received_dispatch_result.extend_from_bitslice(
+			&entry.messages.dispatch_results
+				[(new_messages_begin - entry.messages.begin) as usize..],
+		);
 	}
 
-	Ok(())
+	Ok(received_dispatch_result)
 }
 
 #[cfg(test)]
@@ -228,7 +264,11 @@ mod tests {
 	}
 
 	fn delivered_messages(nonces: RangeInclusive<MessageNonce>) -> DeliveredMessages {
-		DeliveredMessages { begin: *nonces.start(), end: *nonces.end() }
+		DeliveredMessages {
+			begin: *nonces.start(),
+			end: *nonces.end(),
+			dispatch_results: bitvec![u8, Msb0; 1; (nonces.end() - nonces.start() + 1) as _],
+		}
 	}
 
 	fn assert_3_messages_confirmation_fails(
@@ -361,6 +401,20 @@ mod tests {
 		);
 	}
 
+	#[test]
+	fn confirm_delivery_fails_if_number_of_dispatch_results_in_entry_is_invalid() {
+		let mut relayers: VecDeque<_> = unrewarded_relayers(1..=1)
+			.into_iter()
+			.chain(unrewarded_relayers(2..=2).into_iter())
+			.chain(unrewarded_relayers(3..=3).into_iter())
+			.collect();
+		relayers[0].messages.dispatch_results.clear();
+		assert_eq!(
+			assert_3_messages_confirmation_fails(3, &relayers),
+			ReceivalConfirmationResult::InvalidNumberOfDispatchResults,
+		);
+	}
+
 	#[test]
 	fn prune_messages_works() {
 		run_test(|| {

bridges/primitives/messages/Cargo.toml

@@ -7,6 +7,7 @@ edition = "2021"
 license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 
 [dependencies]
+bitvec = { version = "1", default-features = false, features = ["alloc"] }
 codec = { package = "parity-scale-codec", version = "3.1.5", default-features = false, features = ["derive", "bit-vec"] }
 scale-info = { version = "2.5.0", default-features = false, features = ["bit-vec", "derive"] }
 serde = { version = "1.0", optional = true, features = ["derive"] }
@@ -28,6 +29,7 @@ hex-literal = "0.4"
 [features]
 default = ["std"]
 std = [
+	"bitvec/std",
 	"bp-runtime/std",
 	"codec/std",
 	"frame-support/std",

bridges/primitives/messages/src/lib.rs

@@ -20,6 +20,7 @@
 // RuntimeApi generated functions
 #![allow(clippy::too_many_arguments)]
 
+use bitvec::prelude::*;
 use bp_runtime::{BasicOperatingMode, OperatingMode};
 use codec::{Decode, Encode, MaxEncodedLen};
 use frame_support::RuntimeDebug;
@@ -156,18 +157,68 @@ impl<RelayerId> Default for InboundLaneData<RelayerId> {
 }
 
 impl<RelayerId> InboundLaneData<RelayerId> {
+	fn dispatch_results_encoded_size_hint(
+		relayers_entries: usize,
+		message_count: usize,
+	) -> Option<usize>
+	where
+		RelayerId: MaxEncodedLen,
+	{
+		// The worst-case scenario for the bitvecs size is the one in which we have as many relayer
+		// entries as possible taking an extra 1 byte slot with just 1 bit of actual information.
+		// For example:
+		// 11111111 1-------
+		// 11111111 1-------
+		// 1-------
+		// 1-------
+
+		// If there are less msgs than relayer entries, in the worst case, each dispatch result
+		// belongs to a different relayer slot. This means 1 byte for the len prefix and 1 byte
+		// for the actual data.
+		if relayers_entries >= message_count {
+			return relayers_entries.checked_add(message_count)
+		}
+
+		let msgs_per_byte = 8;
+		// At the begining each relayer slot has 1 message, using 1 byte
+		let mut num_result_bytes = relayers_entries;
+		// Then we add batches of 8 messages to some relayer slot until there are no more messages.
+		// Each batch takes up 1 more byte.
+		num_result_bytes =
+			num_result_bytes.checked_add((message_count - relayers_entries) / msgs_per_byte)?;
+
+		// The len is stored in a `Compact<u32>`. `Compact<u32>` can store a max value of
+		// 63 on 1 byte, 16383 on 2 bytes, etc.
+		let max_len_per_first_byte = 0b0011_1111;
+		// At the begining each relayer slot uses 1 byte for the len prefix
+		// (each relayer slot contains 1 message)
+		let mut num_len_bytes = relayers_entries;
+		// Then we add batches of 63 messages to as many relayer slots as possible, requiring 2
+		// bytes for the `len` prefix. It's hard to believe that we'll need more than 2 bytes
+		// (more than 16383 messages in 1 relayer slot).
+		num_len_bytes = num_len_bytes.checked_add(sp_std::cmp::min(
+			(message_count - relayers_entries) / max_len_per_first_byte,
+			relayers_entries,
+		))?;
+
+		num_result_bytes.checked_add(num_len_bytes)
+	}
+
 	/// Returns approximate size of the struct, given a number of entries in the `relayers` set and
 	/// size of each entry.
 	///
 	/// Returns `None` if size overflows `usize` limits.
-	pub fn encoded_size_hint(relayers_entries: usize) -> Option<usize>
+	pub fn encoded_size_hint(relayers_entries: usize, message_count: usize) -> Option<usize>
 	where
 		RelayerId: MaxEncodedLen,
 	{
 		let message_nonce_size = MessageNonce::max_encoded_len();
 		let relayer_id_encoded_size = RelayerId::max_encoded_len();
 		let relayers_entry_size = relayer_id_encoded_size.checked_add(2 * message_nonce_size)?;
-		let relayers_size = relayers_entries.checked_mul(relayers_entry_size)?;
+		let relayers_size = relayers_entries.checked_mul(relayers_entry_size)?.checked_add(
+			Self::dispatch_results_encoded_size_hint(relayers_entries, message_count)?,
+		)?;
+
 		relayers_size.checked_add(message_nonce_size)
 	}
 
@@ -175,11 +226,11 @@ impl<RelayerId> InboundLaneData<RelayerId> {
 	/// `relayers` set and the size of each entry.
 	///
 	/// Returns `u32::MAX` if size overflows `u32` limits.
-	pub fn encoded_size_hint_u32(relayers_entries: usize) -> u32
+	pub fn encoded_size_hint_u32(relayers_entries: usize, messages_count: usize) -> u32
 	where
 		RelayerId: MaxEncodedLen,
 	{
-		Self::encoded_size_hint(relayers_entries)
+		Self::encoded_size_hint(relayers_entries, messages_count)
 			.and_then(|x| u32::try_from(x).ok())
 			.unwrap_or(u32::MAX)
 	}
@@ -219,6 +270,9 @@ pub struct InboundMessageDetails {
 	pub dispatch_weight: Weight,
 }
 
+/// Bit vector of message dispatch results.
+pub type DispatchResultsBitVec = BitVec<u8, Msb0>;
+
 /// Unrewarded relayer entry stored in the inbound lane data.
 ///
 /// This struct represents a continuous range of messages that have been delivered by the same
@@ -276,13 +330,19 @@ pub struct DeliveredMessages {
 	pub begin: MessageNonce,
 	/// Nonce of the last message that has been delivered (inclusive).
 	pub end: MessageNonce,
+	/// Dispatch result (`false`/`true`), returned by the message dispatcher for every
+	/// message in the `[begin; end]` range. See `dispatch_result` field of the
+	/// `bp_runtime::messages::MessageDispatchResult` structure for more information.
+	pub dispatch_results: DispatchResultsBitVec,
 }
 
 impl DeliveredMessages {
 	/// Create new `DeliveredMessages` struct that confirms delivery of single nonce with given
 	/// dispatch result.
-	pub fn new(nonce: MessageNonce) -> Self {
+	pub fn new(nonce: MessageNonce, dispatch_result: bool) -> Self {
-		DeliveredMessages { begin: nonce, end: nonce }
+		let mut dispatch_results = BitVec::with_capacity(1);
+		dispatch_results.push(dispatch_result);
+		DeliveredMessages { begin: nonce, end: nonce, dispatch_results }
 	}
 
 	/// Return total count of delivered messages.
@@ -295,14 +355,25 @@ impl DeliveredMessages {
 	}
 
 	/// Note new dispatched message.
-	pub fn note_dispatched_message(&mut self) {
+	pub fn note_dispatched_message(&mut self, dispatch_result: bool) {
 		self.end += 1;
+		self.dispatch_results.push(dispatch_result);
 	}
 
 	/// Returns true if delivered messages contain message with given nonce.
 	pub fn contains_message(&self, nonce: MessageNonce) -> bool {
 		(self.begin..=self.end).contains(&nonce)
 	}
+
+	/// Get dispatch result flag by message nonce.
+	///
+	/// Dispatch result flag must be interpreted using the knowledge of dispatch mechanism
+	/// at the target chain. See `dispatch_result` field of the
+	/// `bp_runtime::messages::MessageDispatchResult` structure for more information.
+	pub fn message_dispatch_result(&self, nonce: MessageNonce) -> Option<bool> {
+		let index = nonce.checked_sub(self.begin)? as usize;
+		self.dispatch_results.get(index).map(|bit| *bit)
+	}
 }
 
 /// Gist of `InboundLaneData::relayers` field used by runtime APIs.
@@ -414,10 +485,10 @@ mod tests {
 		assert_eq!(
 			total_unrewarded_messages(
 				&vec![
-					UnrewardedRelayer { relayer: 1, messages: DeliveredMessages::new(0) },
+					UnrewardedRelayer { relayer: 1, messages: DeliveredMessages::new(0, true) },
 					UnrewardedRelayer {
 						relayer: 2,
-						messages: DeliveredMessages::new(MessageNonce::MAX)
+						messages: DeliveredMessages::new(MessageNonce::MAX, true)
 					},
 				]
 				.into_iter()
@@ -438,12 +509,21 @@ mod tests {
 			(13u8, 128u8),
 		];
 		for (relayer_entries, messages_count) in test_cases {
-			let expected_size = InboundLaneData::<u8>::encoded_size_hint(relayer_entries as _);
+			let expected_size =
+				InboundLaneData::<u8>::encoded_size_hint(relayer_entries as _, messages_count as _);
 			let actual_size = InboundLaneData {
 				relayers: (1u8..=relayer_entries)
-					.map(|i| UnrewardedRelayer {
+					.map(|i| {
-						relayer: i,
+						let mut entry = UnrewardedRelayer {
-						messages: DeliveredMessages::new(i as _),
+							relayer: i,
+							messages: DeliveredMessages::new(i as _, true),
+						};
+						entry.messages.dispatch_results = bitvec![
+							u8, Msb0;
+							1;
+							(messages_count / relayer_entries) as _
+						];
+						entry
 					})
 					.collect(),
 				last_confirmed_nonce: messages_count as _,
@@ -459,13 +539,16 @@ mod tests {
 	}
 
 	#[test]
-	fn contains_result_works() {
+	fn message_dispatch_result_works() {
-		let delivered_messages = DeliveredMessages { begin: 100, end: 150 };
+		let delivered_messages =
+			DeliveredMessages { begin: 100, end: 150, dispatch_results: bitvec![u8, Msb0; 1; 151] };
 
 		assert!(!delivered_messages.contains_message(99));
 		assert!(delivered_messages.contains_message(100));
 		assert!(delivered_messages.contains_message(150));
 		assert!(!delivered_messages.contains_message(151));
+
+		assert_eq!(delivered_messages.message_dispatch_result(125), Some(true));
 	}
 
 	#[test]

bridges/primitives/messages/src/target_chain.rs

@@ -90,7 +90,7 @@ pub trait MessageDispatch<AccountId> {
 	type DispatchPayload: Decode;
 
 	/// Fine-grained result of single message dispatch (for better diagnostic purposes)
-	type DispatchLevelResult: Clone + sp_std::fmt::Debug + Eq;
+	type DispatchError: Clone + sp_std::fmt::Debug + Eq;
 
 	/// Estimate dispatch weight.
 	///
@@ -109,7 +109,7 @@ pub trait MessageDispatch<AccountId> {
 	fn dispatch(
 		relayer_account: &AccountId,
 		message: DispatchMessage<Self::DispatchPayload>,
-	) -> MessageDispatchResult<Self::DispatchLevelResult>;
+	) -> MessageDispatchResult<Self::DispatchError>;
 }
 
 /// Manages payments that are happening at the target chain during message delivery transaction.
@@ -190,7 +190,7 @@ impl<MessagesProof, DispatchPayload: Decode, AccountId> MessageDispatch<AccountI
 	for ForbidInboundMessages<MessagesProof, DispatchPayload>
 {
 	type DispatchPayload = DispatchPayload;
-	type DispatchLevelResult = ();
+	type DispatchError = ();
 
 	fn dispatch_weight(_message: &mut DispatchMessage<Self::DispatchPayload>) -> Weight {
 		Weight::MAX
@@ -199,7 +199,7 @@ impl<MessagesProof, DispatchPayload: Decode, AccountId> MessageDispatch<AccountI
 	fn dispatch(
 		_: &AccountId,
 		_: DispatchMessage<Self::DispatchPayload>,
-	) -> MessageDispatchResult<Self::DispatchLevelResult> {
+	) -> MessageDispatchResult<Self::DispatchError> {
-		MessageDispatchResult { unspent_weight: Weight::zero(), dispatch_level_result: () }
+		MessageDispatchResult { unspent_weight: Weight::zero(), dispatch_result: Err(()) }
 	}
 }

bridges/primitives/runtime/src/messages.rs

@@ -22,7 +22,7 @@ use scale_info::TypeInfo;
 
 /// Message dispatch result.
 #[derive(Encode, Decode, RuntimeDebug, Clone, PartialEq, Eq, TypeInfo)]
-pub struct MessageDispatchResult<DispatchLevelResult> {
+pub struct MessageDispatchResult<DispatchError> {
 	/// Unspent dispatch weight. This weight that will be deducted from total delivery transaction
 	/// weight, thus reducing the transaction cost. This shall not be zero in (at least) two cases:
 	///
@@ -31,5 +31,5 @@ pub struct MessageDispatchResult<DispatchLevelResult> {
 	/// 2) if message has not been dispatched at all.
 	pub unspent_weight: Weight,
 	/// Fine-grained result of single message dispatch (for better diagnostic purposes)
-	pub dispatch_level_result: DispatchLevelResult,
+	pub dispatch_result: Result<(), DispatchError>,
 }