Request based PoV distribution (#2640)

* Indentation fix.

* Prepare request-response for PoV fetching.

* Drop old PoV distribution.

* WIP: Fetch PoV directly from backing.

* Backing compiles.

* Runtime access and connection management for PoV distribution.

* Get rid of seemingly dead code.

* Implement PoV fetching.

Backing does not yet use it.

* Don't send `ConnectToValidators` for empty list.

* Even better - no need to check over and over again.

* PoV fetching implemented.

+ Typechecks
+ Should work

Missing:

- Guide
- Tests
- Do fallback fetching in case fetching from seconding validator fails.

* Check PoV hash upon reception.

* Implement retry of PoV fetching in backing.

* Avoid pointless validation spawning.

* Add jaeger span to pov requesting.

* Add back tracing.

* Review remarks.

* Whitespace.

* Whitespace again.

* Cleanup + fix tests.

* Log to log target in overseer.

* Fix more tests.

* Don't fail if group cannot be found.

* Simple test for PoV fetcher.

* Handle missing group membership better.

* Add test for retry functionality.

* Fix flaky test.

* Spaces again.

* Guide updates.

* Spaces.

polkadot/node/network/bridge/src/lib.rs

@@ -696,7 +696,6 @@ mod tests {
 	use polkadot_subsystem::messages::{
 		ApprovalDistributionMessage,
 		BitfieldDistributionMessage,
-		PoVDistributionMessage,
 		StatementDistributionMessage
 	};
 	use polkadot_node_subsystem_test_helpers::{
@@ -897,13 +896,6 @@ mod tests {
 			) if e == event.focus().expect("could not focus message")
 		);
 
-		assert_matches!(
-			virtual_overseer.recv().await,
-			AllMessages::PoVDistribution(
-				PoVDistributionMessage::NetworkBridgeUpdateV1(e)
-			) if e == event.focus().expect("could not focus message")
-		);
-
 		assert_matches!(
 			virtual_overseer.recv().await,
 			AllMessages::ApprovalDistribution(
@@ -1166,13 +1158,12 @@ mod tests {
 				).await;
 			}
 
-			let pov_distribution_message = protocol_v1::PoVDistributionMessage::Awaiting(
-				[0; 32].into(),
-				vec![[1; 32].into()],
+			let approval_distribution_message = protocol_v1::ApprovalDistributionMessage::Approvals(
+				Vec::new()
 			);
 
-			let message = protocol_v1::ValidationProtocol::PoVDistribution(
-				pov_distribution_message.clone(),
+			let message = protocol_v1::ValidationProtocol::ApprovalDistribution(
+				approval_distribution_message.clone(),
 			);
 
 			network_handle.peer_message(
@@ -1183,18 +1174,18 @@ mod tests {
 
 			network_handle.disconnect_peer(peer.clone(), PeerSet::Validation).await;
 
-			// PoV distribution message comes first, and the message is only sent to that subsystem.
+			// Approval distribution message comes first, and the message is only sent to that subsystem.
 			// then a disconnection event arises that is sent to all validation networking subsystems.
 
 			assert_matches!(
 				virtual_overseer.recv().await,
-				AllMessages::PoVDistribution(
-					PoVDistributionMessage::NetworkBridgeUpdateV1(
+				AllMessages::ApprovalDistribution(
+					ApprovalDistributionMessage::NetworkBridgeUpdateV1(
 						NetworkBridgeEvent::PeerMessage(p, m)
 					)
 				) => {
 					assert_eq!(p, peer);
-					assert_eq!(m, pov_distribution_message);
+					assert_eq!(m, approval_distribution_message);
 				}
 			);
 
@@ -1563,13 +1554,12 @@ mod tests {
 			// send a validation protocol message.
 
 			{
-				let pov_distribution_message = protocol_v1::PoVDistributionMessage::Awaiting(
-					[0; 32].into(),
-					vec![[1; 32].into()],
+				let approval_distribution_message = protocol_v1::ApprovalDistributionMessage::Approvals(
+					Vec::new()
 				);
 
-				let message = protocol_v1::ValidationProtocol::PoVDistribution(
-					pov_distribution_message.clone(),
+				let message = protocol_v1::ValidationProtocol::ApprovalDistribution(
+					approval_distribution_message.clone(),
 				);
 
 				virtual_overseer.send(FromOverseer::Communication {
@@ -1624,7 +1614,7 @@ mod tests {
 	fn spread_event_to_subsystems_is_up_to_date() {
 		// Number of subsystems expected to be interested in a network event,
 		// and hence the network event broadcasted to.
-		const EXPECTED_COUNT: usize = 4;
+		const EXPECTED_COUNT: usize = 3;
 
 		let mut cnt = 0_usize;
 		for msg in AllMessages::dispatch_iter(NetworkBridgeEvent::PeerDisconnected(PeerId::random())) {
@@ -1640,7 +1630,6 @@ mod tests {
 				AllMessages::BitfieldDistribution(_) => { cnt += 1; }
 				AllMessages::BitfieldSigning(_) => unreachable!("Not interested in network events"),
 				AllMessages::Provisioner(_) => unreachable!("Not interested in network events"),
-				AllMessages::PoVDistribution(_) => { cnt += 1; }
 				AllMessages::RuntimeApi(_) => unreachable!("Not interested in network events"),
 				AllMessages::AvailabilityStore(_) => unreachable!("Not interested in network events"),
 				AllMessages::NetworkBridge(_) => unreachable!("Not interested in network events"),

polkadot/node/network/bridge/src/multiplexer.rs

@@ -141,6 +141,11 @@ fn multiplex_single(
 			decode_with_peer::<v1::CollationFetchingRequest>(peer, payload)?,
 			pending_response,
 		)),
+		Protocol::PoVFetching => From::from(IncomingRequest::new(
+			peer,
+			decode_with_peer::<v1::PoVFetchingRequest>(peer, payload)?,
+			pending_response,
+		)),
 		Protocol::AvailableDataFetching => From::from(IncomingRequest::new(
 			peer,
 			decode_with_peer::<v1::AvailableDataFetchingRequest>(peer, payload)?,

polkadot/node/network/bridge/src/network.rs

@@ -237,14 +237,14 @@ impl Network for Arc<NetworkService<Block, Hash>> {
 			Recipient::Peer(peer_id) =>  Some(peer_id),
 			Recipient::Authority(authority) =>
 				authority_discovery
-				.get_addresses_by_authority_id(authority)
-				.await
-				.and_then(|addrs| {
-					addrs
-						.into_iter()
-						.find_map(|addr| peer_id_from_multiaddr(&addr))
-				}),
-			};
+					.get_addresses_by_authority_id(authority)
+					.await
+					.and_then(|addrs| {
+						addrs
+							.into_iter()
+							.find_map(|addr| peer_id_from_multiaddr(&addr))
+					}),
+		};
 
 		let peer_id = match peer_id {
 			None => {