integrate dispute finality (#3484)

* finality_target adjustments

* fn finality_target

* partially address review comments

* fixins

* more rustic if condition

* fix tests

* fixins

* Update node/core/approval-voting/src/lib.rs

Co-authored-by: Andronik Ordian <write@reusable.software>

* Update node/core/approval-voting/src/lib.rs

Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

* review comments part one

* rename candidates -> block_descriptions

* testing outline (incomplete, WIP)

* test foo

* split RelayChainSelection into RelayChainSelection{,WithFallback}, introduce HeaderProvider{,Provider}

* make some stuff public (revert this soon™)

* some test improvements

* slips of pens

* test fixins

* add another trait abstraction

* pending edge case tests + warnings fixes

* more test cases

* fin

* chore fmt

* fix cargo.lock

* Undo obsolete changes

* // comments

* make mod pub(crate)

* fix

* minimize static bounds

* resolve number() as before

* fmt

* post merge fix

* address some nits

Co-authored-by: Andronik Ordian <write@reusable.software>
Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

polkadot/node/core/approval-voting/src/lib.rs

@@ -27,7 +27,7 @@ use polkadot_node_subsystem::{
 		ApprovalVotingMessage, RuntimeApiMessage, RuntimeApiRequest, ChainApiMessage,
 		ApprovalDistributionMessage, CandidateValidationMessage,
 		AvailabilityRecoveryMessage, ChainSelectionMessage, DisputeCoordinatorMessage,
-		ImportStatementsResult,
+		ImportStatementsResult, HighestApprovedAncestorBlock, BlockDescription,
 	},
 	errors::RecoveryError,
 	overseer::{self, SubsystemSender as _}, SubsystemContext, SubsystemError, SubsystemResult, SpawnedSubsystem,
@@ -1180,7 +1180,7 @@ async fn handle_approved_ancestor(
 	target: Hash,
 	lower_bound: BlockNumber,
 	wakeups: &Wakeups,
-) -> SubsystemResult<Option<(Hash, BlockNumber)>> {
+) -> SubsystemResult<Option<HighestApprovedAncestorBlock>> {
 	const MAX_TRACING_WINDOW: usize = 200;
 	const ABNORMAL_DEPTH_THRESHOLD: usize = 5;
 
@@ -1228,6 +1228,8 @@ async fn handle_approved_ancestor(
 		Vec::new()
 	};
 
+	let mut block_descriptions = Vec::new();
+
 	let mut bits: BitVec<Lsb0, u8> = Default::default();
 	for (i, block_hash) in std::iter::once(target).chain(ancestry).enumerate() {
 		// Block entries should be present as the assumption is that
@@ -1259,8 +1261,10 @@ async fn handle_approved_ancestor(
 			}
 		} else if bits.len() <= ABNORMAL_DEPTH_THRESHOLD {
 			all_approved_max = None;
+			block_descriptions.clear();
 		} else {
 			all_approved_max = None;
+			block_descriptions.clear();
 
 			let unapproved: Vec<_> = entry.unapproved_candidates().collect();
 			tracing::debug!(
@@ -1338,6 +1342,11 @@ async fn handle_approved_ancestor(
 				}
 			}
 		}
+		block_descriptions.push(BlockDescription {
+			block_hash,
+			session: entry.session(),
+			candidates: entry.candidates().iter().map(|(_idx, candidate_hash)| *candidate_hash ).collect(),
+		});
 	}
 
 	tracing::trace!(
@@ -1366,8 +1375,19 @@ async fn handle_approved_ancestor(
 		},
 	);
 
+	// `reverse()` to obtain the ascending order from lowest to highest
+	// block within the candidates, which is the expected order
+	block_descriptions.reverse();
+
+	let all_approved_max = all_approved_max.map(|(hash, block_number)| {
+		HighestApprovedAncestorBlock{
+			hash,
+			number: block_number,
+			descriptions: block_descriptions,
+		}
+	});
 	match all_approved_max {
-		Some((ref hash, ref number)) => {
+		Some(HighestApprovedAncestorBlock { ref hash, ref number, .. }) => {
 			span.add_uint_tag("approved-number", *number as u64);
 			span.add_string_fmt_debug_tag("approved-hash", hash);
 		}

polkadot/node/core/approval-voting/src/old_tests.rs

@@ -26,7 +26,7 @@ use polkadot_node_primitives::approval::{
 	RELAY_VRF_MODULO_CONTEXT, DelayTranche,
 };
 use polkadot_node_subsystem_test_helpers::make_subsystem_context;
-use polkadot_node_subsystem::messages::AllMessages;
+use polkadot_node_subsystem::messages::{AllMessages, HighestApprovedAncestorBlock};
 use sp_core::testing::TaskExecutor;
 
 use parking_lot::Mutex;
@@ -1612,10 +1612,12 @@ fn approved_ancestor_all_approved() {
 
 	let test_fut = Box::pin(async move {
 		let overlay_db = OverlayedBackend::new(&db);
-		assert_eq!(
+		assert_matches!(
 			handle_approved_ancestor(&mut ctx, &overlay_db, block_hash_4, 0, &Default::default())
-				.await.unwrap(),
-			Some((block_hash_4, 4)),
+				.await,
+			Ok(Some(HighestApprovedAncestorBlock { hash, number, .. } )) => {
+				assert_eq!((block_hash_4, 4), (hash, number));
+			}
 		)
 	});
 
@@ -1686,10 +1688,12 @@ fn approved_ancestor_missing_approval() {
 
 	let test_fut = Box::pin(async move {
 		let overlay_db = OverlayedBackend::new(&db);
-		assert_eq!(
+		assert_matches!(
 			handle_approved_ancestor(&mut ctx, &overlay_db, block_hash_4, 0, &Default::default())
-				.await.unwrap(),
-			Some((block_hash_2, 2)),
+				.await,
+			Ok(Some(HighestApprovedAncestorBlock { hash, number, .. })) => {
+				assert_eq!((block_hash_2, 2), (hash, number));
+			}
 		)
 	});