Fix transaction pruning in tx-pool (#6276)

The `tree_route` generated by the import notification is only from the
old best block to the new best parent. This means, it does not contain
the new best block in `enacted()`. We need to prune the transactions of
the new best block "manually" to fix this bug.

Besides that, this pr also changed the `id` parameter of the `NewBlock`
chain event to `hash`. The hash of a block is unique in contrast to the
block number. (Block id can either be number or hash)

substrate/Cargo.lock

@@ -6745,10 +6745,12 @@ dependencies = [
  "parity-scale-codec",
  "parity-util-mem",
  "parking_lot 0.10.2",
+ "sc-block-builder",
  "sc-client-api",
  "sc-transaction-graph",
  "sp-api",
  "sp-blockchain",
+ "sp-consensus",
  "sp-core",
  "sp-keyring",
  "sp-runtime",

substrate/bin/node/cli/src/service.rs

@@ -490,7 +490,7 @@ mod tests {
 					service.transaction_pool().maintain(
 						ChainEvent::NewBlock {
 							is_new_best: true,
-							id: parent_id.clone(),
+							hash: parent_header.hash(),
 							tree_route: None,
 							header: parent_header.clone(),
 						},

substrate/client/api/src/client.rs

@@ -234,7 +234,7 @@ pub struct BlockImportNotification<Block: BlockT> {
 	pub header: Block::Header,
 	/// Is this the new best block.
 	pub is_new_best: bool,
-	/// Tree route from old best to new best.
+	/// Tree route from old best to new best parent.
 	///
 	/// If `None`, there was no re-org while importing.
 	pub tree_route: Option<Arc<sp_blockchain::TreeRoute<Block>>>,
@@ -248,3 +248,22 @@ pub struct FinalityNotification<Block: BlockT> {
 	/// Imported block header.
 	pub header: Block::Header,
 }
+
+impl<B: BlockT> From<BlockImportNotification<B>> for sp_transaction_pool::ChainEvent<B> {
+	fn from(n: BlockImportNotification<B>) -> Self {
+		Self::NewBlock {
+			is_new_best: n.is_new_best,
+			hash: n.hash,
+			header: n.header,
+			tree_route: n.tree_route,
+		}
+	}
+}
+
+impl<B: BlockT> From<FinalityNotification<B>> for sp_transaction_pool::ChainEvent<B> {
+	fn from(n: FinalityNotification<B>) -> Self {
+		Self::Finalized {
+			hash: n.hash,
+		}
+	}
+}

substrate/client/basic-authorship/src/basic_authorship.rs

@@ -351,11 +351,11 @@ mod tests {
 		}.into_signed_tx()
 	}
 
-	fn chain_event<B: BlockT>(block_number: u64, header: B::Header) -> ChainEvent<B>
+	fn chain_event<B: BlockT>(header: B::Header) -> ChainEvent<B>
 		where NumberFor<B>: From<u64>
 	{
 		ChainEvent::NewBlock {
-			id: BlockId::Number(block_number.into()),
+			hash: header.hash(),
 			tree_route: None,
 			is_new_best: true,
 			header,
@@ -380,8 +380,9 @@ mod tests {
 
 		futures::executor::block_on(
 			txpool.maintain(chain_event(
-				0,
-				client.header(&BlockId::Number(0u64)).expect("header get error").expect("there should be header")
+				client.header(&BlockId::Number(0u64))
+					.expect("header get error")
+					.expect("there should be header")
 			))
 		);
 
@@ -470,7 +471,6 @@ mod tests {
 
 		futures::executor::block_on(
 			txpool.maintain(chain_event(
-				0,
 				client.header(&BlockId::Number(0u64))
 					.expect("header get error")
 					.expect("there should be header"),
@@ -574,8 +574,9 @@ mod tests {
 
 		futures::executor::block_on(
 			txpool.maintain(chain_event(
-				0,
-				client.header(&BlockId::Number(0u64)).expect("header get error").expect("there should be header")
+				client.header(&BlockId::Number(0u64))
+					.expect("header get error")
+					.expect("there should be header")
 			))
 		);
 
@@ -585,8 +586,9 @@ mod tests {
 
 		futures::executor::block_on(
 			txpool.maintain(chain_event(
-				1,
-				client.header(&BlockId::Number(1)).expect("header get error").expect("there should be header")
+				client.header(&BlockId::Number(1))
+					.expect("header get error")
+					.expect("there should be header")
 			))
 		);
 

substrate/client/consensus/manual-seal/src/lib.rs

@@ -413,9 +413,10 @@ mod tests {
 		assert!(client.header(&BlockId::Number(0)).unwrap().is_some());
 		assert!(pool.submit_one(&BlockId::Number(1), SOURCE, uxt(Alice, 1)).await.is_ok());
 
+		let header = client.header(&BlockId::Number(1)).expect("db error").expect("imported above");
 		pool.maintain(sp_transaction_pool::ChainEvent::NewBlock {
-			id: BlockId::Number(1),
-			header: client.header(&BlockId::Number(1)).expect("db error").expect("imported above"),
+			hash: header.hash(),
+			header,
 			is_new_best: true,
 			tree_route: None,
 		}).await;

substrate/client/service/src/builder.rs

@@ -55,7 +55,7 @@ use std::{
 };
 use wasm_timer::SystemTime;
 use sc_telemetry::{telemetry, SUBSTRATE_INFO};
-use sp_transaction_pool::{MaintainedTransactionPool, ChainEvent};
+use sp_transaction_pool::MaintainedTransactionPool;
 use prometheus_endpoint::Registry;
 use sc_client_db::{Backend, DatabaseSettings};
 use sp_core::traits::CodeExecutor;
@@ -1042,14 +1042,9 @@ ServiceBuilder<
 		{
 			let txpool = Arc::downgrade(&transaction_pool);
 
-			let mut import_stream = client.import_notification_stream().map(|n| ChainEvent::NewBlock {
-				id: BlockId::Hash(n.hash),
-				header: n.header,
-				tree_route: n.tree_route,
-				is_new_best: n.is_new_best,
-			}).fuse();
+			let mut import_stream = client.import_notification_stream().map(Into::into).fuse();
 			let mut finality_stream = client.finality_notification_stream()
-				.map(|n| ChainEvent::Finalized::<TBl> { hash: n.hash })
+				.map(Into::into)
 				.fuse();
 
 			let events = async move {

substrate/client/service/src/client/client.rs

@@ -786,7 +786,7 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 			NewBlockState::Normal
 		};
 
-		let tree_route = if is_new_best {
+		let tree_route = if is_new_best && info.best_hash != parent_hash {
 			let route_from_best = sp_blockchain::tree_route(
 				self.backend.blockchain(),
 				info.best_hash,

substrate/client/transaction-pool/Cargo.toml

@@ -36,5 +36,7 @@ wasm-timer = "0.2"
 assert_matches = "1.3.0"
 hex = "0.4"
 sp-keyring = { version = "2.0.0-rc2", path = "../../primitives/keyring" }
+sp-consensus = { version = "0.8.0-rc2", path = "../../primitives/consensus/common" }
 substrate-test-runtime-transaction-pool = { version = "2.0.0-rc2", path = "../../test-utils/runtime/transaction-pool" }
 substrate-test-runtime-client = { version = "2.0.0-rc2", path = "../../test-utils/runtime/client" }
+sc-block-builder = { version = "0.8.0-rc2", path = "../block-builder" }

substrate/client/transaction-pool/src/lib.rs

@@ -468,10 +468,11 @@ impl<PoolApi, Block> MaintainedTransactionPool for BasicPool<PoolApi, Block>
 {
 	fn maintain(&self, event: ChainEvent<Self::Block>) -> Pin<Box<dyn Future<Output=()> + Send>> {
 		match event {
-			ChainEvent::NewBlock { id, tree_route, is_new_best, .. } => {
+			ChainEvent::NewBlock { hash, tree_route, is_new_best, .. } => {
 				let pool = self.pool.clone();
 				let api = self.api.clone();
 
+				let id = BlockId::hash(hash);
 				let block_number = match api.block_id_to_number(&id) {
 					Ok(Some(number)) => number,
 					_ => {
@@ -495,13 +496,13 @@ impl<PoolApi, Block> MaintainedTransactionPool for BasicPool<PoolApi, Block>
 
 				async move {
 					// If there is a tree route, we use this to prune known tx based on the enacted
-					// blocks and otherwise we only prune known txs if the block is
-					// the new best block.
+					// blocks.
 					if let Some(ref tree_route) = tree_route {
 						future::join_all(
 							tree_route
 								.enacted()
-								.iter().map(|h|
+								.iter()
+								.map(|h|
 									prune_known_txs_for_block(
 										BlockId::Hash(h.hash.clone()),
 										&*api,
@@ -509,7 +510,10 @@ impl<PoolApi, Block> MaintainedTransactionPool for BasicPool<PoolApi, Block>
 									),
 								),
 						).await;
-					} else if is_new_best {
+					}
+
+					// If this is a new best block, we need to prune its transactions from the pool.
+					if is_new_best {
 						prune_known_txs_for_block(id.clone(), &*api, &*pool).await;
 					}
 

substrate/client/transaction-pool/src/testing/pool.rs

@@ -18,7 +18,7 @@
 
 use crate::*;
 use sp_transaction_pool::TransactionStatus;
-use futures::executor::block_on;
+use futures::executor::{block_on, block_on_stream};
 use txpool::{self, Pool};
 use sp_runtime::{
 	generic::BlockId,
@@ -26,11 +26,15 @@ use sp_runtime::{
 };
 use substrate_test_runtime_client::{
 	runtime::{Block, Hash, Index, Header, Extrinsic, Transfer}, AccountKeyring::*,
+	ClientBlockImportExt,
 };
 use substrate_test_runtime_transaction_pool::{TestApi, uxt};
 use futures::{prelude::*, task::Poll};
 use codec::Encode;
 use std::collections::BTreeSet;
+use sc_client_api::client::BlockchainEvents;
+use sc_block_builder::BlockBuilderProvider;
+use sp_consensus::BlockOrigin;
 
 fn pool() -> Pool<TestApi> {
 	Pool::new(Default::default(), TestApi::with_alice_nonce(209).into())
@@ -50,16 +54,6 @@ fn maintained_pool() -> (
 	(pool, thread_pool, notifier)
 }
 
-fn header(number: u64) -> Header {
-	Header {
-		number,
-		digest: Default::default(),
-		extrinsics_root:  Default::default(),
-		parent_hash: Default::default(),
-		state_root: Default::default(),
-	}
-}
-
 const SOURCE: TransactionSource = TransactionSource::External;
 
 #[test]
@@ -153,7 +147,7 @@ fn only_prune_on_new_best() {
 	assert_eq!(pool.status().ready, 1);
 
 	let event = ChainEvent::NewBlock {
-		id: BlockId::Number(1),
+		hash: header.hash(),
 		is_new_best: false,
 		header: header.clone(),
 		tree_route: None,
@@ -163,7 +157,7 @@ fn only_prune_on_new_best() {
 
 	let header = pool.api.push_block(2, vec![uxt]);
 	let event = ChainEvent::NewBlock {
-		id: BlockId::Number(2),
+		hash: header.hash(),
 		is_new_best: true,
 		header: header.clone(),
 		tree_route: None,
@@ -209,12 +203,12 @@ fn should_correctly_prune_transactions_providing_more_than_one_tag() {
 	assert_eq!(pool.validated_pool().status().future, 2);
 }
 
-fn block_event(id: u64) -> ChainEvent<Block> {
+fn block_event(header: Header) -> ChainEvent<Block> {
 	ChainEvent::NewBlock {
-		id: BlockId::number(id),
+		hash: header.hash(),
 		is_new_best: true,
 		tree_route: None,
-		header: header(id),
+		header,
 	}
 }
 
@@ -223,10 +217,10 @@ fn block_event_with_retracted(
 	retracted_start: Hash,
 	api: &TestApi,
 ) -> ChainEvent<Block> {
-	let tree_route = api.tree_route(retracted_start, header.hash()).expect("Tree route exists");
+	let tree_route = api.tree_route(retracted_start, header.parent_hash).expect("Tree route exists");
 
 	ChainEvent::NewBlock {
-		id: BlockId::hash(header.hash()),
+		hash: header.hash(),
 		is_new_best: true,
 		tree_route: Some(Arc::new(tree_route)),
 		header,
@@ -242,9 +236,9 @@ fn should_prune_old_during_maintenance() {
 	block_on(pool.submit_one(&BlockId::number(0), SOURCE, xt.clone())).expect("1. Imported");
 	assert_eq!(pool.status().ready, 1);
 
-	pool.api.push_block(1, vec![xt.clone()]);
+	let header = pool.api.push_block(1, vec![xt.clone()]);
 
-	block_on(pool.maintain(block_event(1)));
+	block_on(pool.maintain(block_event(header)));
 	assert_eq!(pool.status().ready, 0);
 }
 
@@ -259,9 +253,9 @@ fn should_revalidate_during_maintenance() {
 	assert_eq!(pool.status().ready, 2);
 	assert_eq!(pool.api.validation_requests().len(), 2);
 
-	pool.api.push_block(1, vec![xt1.clone()]);
+	let header = pool.api.push_block(1, vec![xt1.clone()]);
 
-	block_on(pool.maintain(block_event(1)));
+	block_on(pool.maintain(block_event(header)));
 	assert_eq!(pool.status().ready, 1);
 	block_on(notifier.next());
 
@@ -317,17 +311,17 @@ fn should_revalidate_transaction_multiple_times() {
 	block_on(pool.submit_one(&BlockId::number(0), SOURCE, xt.clone())).expect("1. Imported");
 	assert_eq!(pool.status().ready, 1);
 
-	pool.api.push_block(1, vec![xt.clone()]);
+	let header = pool.api.push_block(1, vec![xt.clone()]);
 
-	block_on(pool.maintain(block_event(1)));
+	block_on(pool.maintain(block_event(header)));
 
 	block_on(pool.submit_one(&BlockId::number(0), SOURCE, xt.clone())).expect("1. Imported");
 	assert_eq!(pool.status().ready, 1);
 
-	pool.api.push_block(2, vec![]);
+	let header = pool.api.push_block(2, vec![]);
 	pool.api.add_invalid(&xt);
 
-	block_on(pool.maintain(block_event(2)));
+	block_on(pool.maintain(block_event(header)));
 	block_on(notifier.next());
 
 	assert_eq!(pool.status().ready, 0);
@@ -345,15 +339,15 @@ fn should_revalidate_across_many_blocks() {
 	block_on(pool.submit_one(&BlockId::number(1), SOURCE, xt2.clone())).expect("1. Imported");
 	assert_eq!(pool.status().ready, 2);
 
-	pool.api.push_block(1, vec![]);
-	block_on(pool.maintain(block_event(1)));
+	let header = pool.api.push_block(1, vec![]);
+	block_on(pool.maintain(block_event(header)));
 	block_on(notifier.next());
 
 	block_on(pool.submit_one(&BlockId::number(2), SOURCE, xt3.clone())).expect("1. Imported");
 	assert_eq!(pool.status().ready, 3);
 
-	pool.api.push_block(2, vec![xt1.clone()]);
-	block_on(pool.maintain(block_event(2)));
+	let header = pool.api.push_block(2, vec![xt1.clone()]);
+	block_on(pool.maintain(block_event(header)));
 	block_on(notifier.next());
 
 	assert_eq!(pool.status().ready, 2);
@@ -398,7 +392,8 @@ fn should_push_watchers_during_maintaince() {
 	pool.api.add_invalid(&tx4);
 
 	// clear timer events if any
-	block_on(pool.maintain(block_event(0)));
+	let header = pool.api.push_block(1, vec![]);
+	block_on(pool.maintain(block_event(header)));
 	block_on(notifier.next());
 
 	// then
@@ -415,8 +410,9 @@ fn should_push_watchers_during_maintaince() {
 	);
 
 	// when
-	let header_hash = pool.api.push_block(1, vec![tx0, tx1, tx2]).hash();
-	block_on(pool.maintain(block_event(1)));
+	let header = pool.api.push_block(2, vec![tx0, tx1, tx2]);
+	let header_hash = header.hash();
+	block_on(pool.maintain(block_event(header)));
 
 	let event = ChainEvent::Finalized { hash: header_hash.clone() };
 	block_on(pool.maintain(event));
@@ -472,7 +468,7 @@ fn finalization() {
 
 	let header = pool.api.chain().read().block_by_number.get(&2).unwrap()[0].header().clone();
 	let event = ChainEvent::NewBlock {
-		id: BlockId::Hash(header.hash()),
+		hash: header.hash(),
 		is_new_best: true,
 		header: header.clone(),
 		tree_route: None,
@@ -524,7 +520,7 @@ fn fork_aware_finalization() {
 		assert_eq!(pool.status().ready, 1);
 
 		let event = ChainEvent::NewBlock {
-			id: BlockId::Number(2),
+			hash: header.hash(),
 			is_new_best: true,
 			header: header.clone(),
 			tree_route: None,
@@ -544,7 +540,7 @@ fn fork_aware_finalization() {
 		).expect("1. Imported");
 		assert_eq!(pool.status().ready, 1);
 		let event = ChainEvent::NewBlock {
-			id: BlockId::Hash(header.hash()),
+			hash: header.hash(),
 			is_new_best: true,
 			header: header.clone(),
 			tree_route: None,
@@ -563,7 +559,7 @@ fn fork_aware_finalization() {
 		let header = pool.api.push_block_with_parent(c2, vec![from_bob.clone()]);
 
 		let event = ChainEvent::NewBlock {
-			id: BlockId::Hash(header.hash()),
+			hash: header.hash(),
 			is_new_best: true,
 			header: header.clone(),
 			tree_route: None,
@@ -601,7 +597,7 @@ fn fork_aware_finalization() {
 		canon_watchers.push((w, header.hash()));
 
 		let event = ChainEvent::NewBlock {
-			id: BlockId::Hash(header.hash()),
+			hash: header.hash(),
 			is_new_best: true,
 			header: header.clone(),
 			tree_route: None,
@@ -620,7 +616,7 @@ fn fork_aware_finalization() {
 		let header = pool.api.push_block(5, vec![from_dave, from_bob]);
 		e1 = header.hash();
 		let event = ChainEvent::NewBlock {
-			id: BlockId::Hash(header.hash()),
+			hash: header.hash(),
 			is_new_best: true,
 			header: header.clone(),
 			tree_route: None,
@@ -702,7 +698,7 @@ fn resubmit_tx_of_fork_that_is_not_part_of_retracted() {
 		assert_eq!(pool.status().ready, 1);
 
 		let event = ChainEvent::NewBlock {
-			id: BlockId::Number(2),
+			hash: header.hash(),
 			is_new_best: true,
 			header: header.clone(),
 			tree_route: None,
@@ -720,7 +716,7 @@ fn resubmit_tx_of_fork_that_is_not_part_of_retracted() {
 		let header = pool.api.push_block(2, vec![tx1.clone()]);
 		assert_eq!(pool.status().ready, 1);
 		let event = ChainEvent::NewBlock {
-			id: BlockId::Hash(header.hash()),
+			hash: header.hash(),
 			is_new_best: false,
 			header: header.clone(),
 			tree_route: None,
@@ -773,7 +769,7 @@ fn resubmit_from_retracted_fork() {
 		assert_eq!(pool.status().ready, 1);
 
 		let event = ChainEvent::NewBlock {
-			id: BlockId::Number(2),
+			hash: header.hash(),
 			is_new_best: true,
 			header: header.clone(),
 			tree_route: None,
@@ -789,7 +785,7 @@ fn resubmit_from_retracted_fork() {
 		).expect("1. Imported");
 		let header = pool.api.push_block(3, vec![tx1.clone()]);
 		let event = ChainEvent::NewBlock {
-			id: BlockId::Hash(header.hash()),
+			hash: header.hash(),
 			is_new_best: true,
 			header: header.clone(),
 			tree_route: None,
@@ -805,7 +801,7 @@ fn resubmit_from_retracted_fork() {
 		).expect("1. Imported");
 		let header = pool.api.push_block(4, vec![tx2.clone()]);
 		let event = ChainEvent::NewBlock {
-			id: BlockId::Hash(header.hash()),
+			hash: header.hash(),
 			is_new_best: true,
 			header: header.clone(),
 			tree_route: None,
@@ -822,7 +818,7 @@ fn resubmit_from_retracted_fork() {
 		).expect("1. Imported");
 		let header = pool.api.push_block(2, vec![tx3.clone()]);
 		let event = ChainEvent::NewBlock {
-			id: BlockId::Hash(header.hash()),
+			hash: header.hash(),
 			is_new_best: false,
 			header: header.clone(),
 			tree_route: None,
@@ -839,7 +835,7 @@ fn resubmit_from_retracted_fork() {
 		).expect("1. Imported");
 		let header = pool.api.push_block_with_parent(d1.clone(), vec![tx4.clone()]);
 		let event = ChainEvent::NewBlock {
-			id: BlockId::Hash(header.hash()),
+			hash: header.hash(),
 			is_new_best: false,
 			header: header.clone(),
 			tree_route: None,
@@ -886,12 +882,12 @@ fn ready_set_should_not_resolve_before_block_update() {
 #[test]
 fn ready_set_should_resolve_after_block_update() {
 	let (pool, _guard, _notifier) = maintained_pool();
-	pool.api.push_block(1, vec![]);
+	let header = pool.api.push_block(1, vec![]);
 
 	let xt1 = uxt(Alice, 209);
 
 	block_on(pool.submit_one(&BlockId::number(1), SOURCE, xt1.clone())).expect("1. Imported");
-	block_on(pool.maintain(block_event(1)));
+	block_on(pool.maintain(block_event(header)));
 
 	assert!(pool.ready_at(1).now_or_never().is_some());
 }
@@ -899,7 +895,7 @@ fn ready_set_should_resolve_after_block_update() {
 #[test]
 fn ready_set_should_eventually_resolve_when_block_update_arrives() {
 	let (pool, _guard, _notifier) = maintained_pool();
-	pool.api.push_block(1, vec![]);
+	let header = pool.api.push_block(1, vec![]);
 
 	let xt1 = uxt(Alice, 209);
 
@@ -913,7 +909,7 @@ fn ready_set_should_eventually_resolve_when_block_update_arrives() {
 		panic!("Ready set should not be ready before block update!");
 	}
 
-	block_on(pool.maintain(block_event(1)));
+	block_on(pool.maintain(block_event(header)));
 
 	match ready_set_future.poll_unpin(&mut context)  {
 		Poll::Pending => {
@@ -949,7 +945,11 @@ fn should_not_accept_old_signatures() {
 		"c427eb672e8c441c86d31f1a81b22b43102058e9ce237cabe9897ea5099ffd426cd1c6a1f4f2869c3df57901d36bedcb295657adb3a4355add86ed234eb83108"
 	).expect("hex invalid")[..]).expect("signature construction failed");
 
-	let xt = Extrinsic::Transfer { transfer, signature: old_singature, exhaust_resources_when_not_first: false };
+	let xt = Extrinsic::Transfer {
+		transfer,
+		signature: old_singature,
+		exhaust_resources_when_not_first: false,
+	};
 
 	assert_matches::assert_matches!(
 		block_on(pool.submit_one(&BlockId::number(0), SOURCE, xt.clone())),
@@ -959,3 +959,31 @@ fn should_not_accept_old_signatures() {
 		"Should be invalid transaction with bad proof",
 	);
 }
+
+#[test]
+fn import_notification_to_pool_maintain_works() {
+	let mut client = Arc::new(substrate_test_runtime_client::new());
+
+	let pool = Arc::new(
+		BasicPool::new_test(Arc::new(FullChainApi::new(client.clone()))).0
+	);
+
+	// Prepare the extrisic, push it to the pool and check that it was added.
+	let xt = uxt(Alice, 0);
+	block_on(pool.submit_one(&BlockId::number(0), SOURCE, xt.clone())).expect("1. Imported");
+	assert_eq!(pool.status().ready, 1);
+
+	let mut import_stream = block_on_stream(client.import_notification_stream());
+
+	// Build the block with the transaction included
+	let mut block_builder = client.new_block(Default::default()).unwrap();
+	block_builder.push(xt).unwrap();
+	let block = block_builder.build().unwrap().block;
+	client.import(BlockOrigin::Own, block).unwrap();
+
+	// Get the notification of the block import and maintain the pool with it,
+	// Now, the pool should not contain any transactions.
+	let evt = import_stream.next().expect("Importing a block leads to an event");
+	block_on(pool.maintain(evt.into()));
+	assert_eq!(pool.status().ready, 0);
+}

substrate/primitives/transaction-pool/src/pool.rs

@@ -251,11 +251,11 @@ pub enum ChainEvent<B: BlockT> {
 	NewBlock {
 		/// Is this the new best block.
 		is_new_best: bool,
-		/// Id of the just imported block.
-		id: BlockId<B>,
+		/// Hash of the block.
+		hash: B::Hash,
 		/// Header of the just imported block
 		header: B::Header,
-		/// Tree route from old best to new best that was calculated on import.
+		/// Tree route from old best to new best parent that was calculated on import.
 		///
 		/// If `None`, no re-org happened on import.
 		tree_route: Option<Arc<sp_blockchain::TreeRoute<B>>>,