Merge commit 71475c85 (no conflict)

.github/ISSUE_TEMPLATE/bug_report.md

@@ -9,5 +9,5 @@ assignees: ''
 
 - It would help if you submit info about the system you are running, e.g.: operating system, kernel version, amount of available memory and swap, etc.
 - Logs could be very helpful. If possible, submit the whole log. Please format it as ```code blocks```.
-- Describe the role your node plays, e.g. validator, sentry, full node or light client.
+- Describe the role your node plays, e.g. validator, full node or light client.
 - Any command-line options were passed?

docker/sentry-docker-compose.yml

-# Docker compose file to simulate a sentry node setup.
-#
-#
-# Setup:
-#
-# Validator A is not supposed to be connected to the public internet. Instead it
-# connects to a sentry node (sentry-a) which connects to the public internet.
-#
-#
-# Usage:
-#
-# 1. Build `target/release/substrate` binary: `cargo build --release`
-#
-# 2. Start networks and containers: `sudo docker-compose -f scripts/sentry-node/docker-compose.yml up`
-#
-# 3. Reach:
-#   - validator-a: localhost:9944
-#   - sentry-a: localhost:9946
-
-version: "3.7"
-services:
-  validator:
-    ports:
-      - "9944:9944"
-#    volumes:
-#      - ../../target/release/substrate:/usr/local/bin/substrate
-    image: parity/polkadot
-    networks:
-      - network-a
-    environment:
-        - VALIDATOR_NODE_KEY
-        - VALIDATOR_BASE_PATH
-        - VALIDATOR_CHAIN
-        - VALIDATOR_PORT
-        - VALIDATOR_NAME
-        - VALIDATOR_RESERVED_NODES
-    command:
-      # Local node id: QmRpheLN4JWdAnY7HGJfWFNbfkQCb6tFf4vvA6hgjMZKrR
-      - "--node-key"
-      - "${VALIDATOR_NODE_KEY:-0000000000000000000000000000000000000000000000000000000000000001}"
-      - "--base-path"
-      - "${VALIDATOR_BASE_PATH:-/tmp/alice}"
-      - "--chain=${VALIDATOR_CHAIN:-local}"
-      - "--port"
-      - "${VALIDATOR_PORT:-30333}"
-      - "--validator"
-      - "--name"
-      - "${VALIDATOR_NANE:-AlicesNode}"
-      - "--reserved-nodes"
-      - "${VALIDATOR_RESERVED_NODES:-/dns/sentry/tcp/30333/p2p/QmV7EhW6J6KgmNdr558RH1mPx2xGGznW7At4BhXzntRFsi}"
-      # Not only bind to localhost.
-      - "--ws-external"
-      - "--rpc-external"
-      # - "--log"
-      # - "sub-libp2p=trace"
-      # - "--log"
-      # - "afg=trace"
-      - "--no-telemetry"
-      - "--rpc-cors"
-      - "all"
-
-  sentry:
-    image: parity/polkadot
-    ports:
-      - "9946:9944"
-#    volumes:
-#      - ../../target/release/substrate:/usr/local/bin/substrate
-    networks:
-      - network-a
-      - internet
-    environment:
-        - SENTRY_NODE_KEY
-        - SENTRY_BASE_PATH
-        - SENTRY_CHAIN
-        - SENTRY_PORT
-        - SENTRY_NAME
-        - SENTRY_BOOTNODES
-    command:
-      # Local node id: QmV7EhW6J6KgmNdr558RH1mPx2xGGznW7At4BhXzntRFsi
-      - "--node-key"
-      - "${SENTRY_NODE_KEY:-0000000000000000000000000000000000000000000000000000000000000003}"
-      - "--base-path"
-      - "${SENTRY_BASE_PATH:-/tmp/charlies}"
-      - "--chain=${SENTRY_CHAIN:-local}"
-      # Don't configure a key, as sentry is not a validator.
-      - "--port"
-      - "${SENTRY_PORT:-30333}"
-      # sentry-a is not a validator.
-      # - "--validator"
-      - "--name"
-      - "${SENTRY_NAME:-CharliesNode}"
-      - "--bootnodes"
-      - "${SENTRY_BOOTNODES:-/dns/validator-a/tcp/30333/p2p/QmRpheLN4JWdAnY7HGJfWFNbfkQCb6tFf4vvA6hgjMZKrR}"
-      - "--no-telemetry"
-      - "--rpc-cors"
-      - "all"
-      # Not only bind to localhost.
-      - "--ws-external"
-      - "--rpc-external"
-
-networks:
-  network-a:
-  internet:

node/core/approval-voting/src/import.rs

@@ -121,13 +121,13 @@ async fn determine_new_blocks(
 		return Ok(ancestry);
 	}
 
-	loop {
+	'outer: loop {
 		let &(ref last_hash, ref last_header) = ancestry.last()
 			.expect("ancestry has length 1 at initialization and is only added to; qed");
 
 		// If we iterated back to genesis, which can happen at the beginning of chains.
 		if last_header.number <= 1 {
-			break
+			break 'outer
 		}
 
 		let (tx, rx) = oneshot::channel();
@@ -139,7 +139,7 @@ async fn determine_new_blocks(
 
 		// Continue past these errors.
 		let batch_hashes = match rx.await {
-			Err(_) | Ok(Err(_)) => break,
+			Err(_) | Ok(Err(_)) => break 'outer,
 			Ok(Ok(ancestors)) => ancestors,
 		};
 
@@ -179,14 +179,13 @@ async fn determine_new_blocks(
 			let is_relevant = header.number > finalized_number;
 
 			if is_known || !is_relevant {
-				break
+				break 'outer
 			}
 
 			ancestry.push((hash, header));
 		}
 	}
 
-	ancestry.reverse();
 	Ok(ancestry)
 }
 
@@ -313,7 +312,8 @@ async fn cache_session_info_for_head(
 					return Ok(Err(SessionsUnavailable));
 				}
 				Some(s) => {
-					session_window.session_info.drain(..overlap_start as usize);
+					let outdated = std::cmp::min(overlap_start as usize, session_window.session_info.len());
+					session_window.session_info.drain(..outdated);
 					session_window.session_info.extend(s);
 					session_window.earliest_session = Some(window_start);
 				}
@@ -813,7 +813,7 @@ mod tests {
 
 		// Finalized block should be omitted. The head provided to `determine_new_blocks`
 		// should be included.
-		let expected_ancestry = (13..18)
+		let expected_ancestry = (13..=18)
 			.map(|n| chain.header_by_number(n).map(|h| (h.hash(), h.clone())).unwrap())
 			.rev()
 			.collect::<Vec<_>>();
@@ -880,7 +880,7 @@ mod tests {
 
 		});
 
-		futures::executor::block_on(futures::future::select(test_fut, aux_fut));
+		futures::executor::block_on(futures::future::join(test_fut, aux_fut));
 	}
 
 	#[test]
@@ -913,7 +913,7 @@ mod tests {
 
 		// Known block should be omitted. The head provided to `determine_new_blocks`
 		// should be included.
-		let expected_ancestry = (16..18)
+		let expected_ancestry = (16..=18)
 			.map(|n| chain.header_by_number(n).map(|h| (h.hash(), h.clone())).unwrap())
 			.rev()
 			.collect::<Vec<_>>();
@@ -957,7 +957,7 @@ mod tests {
 			}
 		});
 
-		futures::executor::block_on(futures::future::select(test_fut, aux_fut));
+		futures::executor::block_on(futures::future::join(test_fut, aux_fut));
 	}
 
 	#[test]
@@ -1266,7 +1266,7 @@ mod tests {
 			);
 		});
 
-		futures::executor::block_on(futures::future::select(test_fut, aux_fut));
+		futures::executor::block_on(futures::future::join(test_fut, aux_fut));
 	}
 
 	#[test]
@@ -1371,7 +1371,7 @@ mod tests {
 			);
 		});
 
-		futures::executor::block_on(futures::future::select(test_fut, aux_fut));
+		futures::executor::block_on(futures::future::join(test_fut, aux_fut));
 	}
 
 	#[test]
@@ -1451,7 +1451,7 @@ mod tests {
 			);
 		});
 
-		futures::executor::block_on(futures::future::select(test_fut, aux_fut));
+		futures::executor::block_on(futures::future::join(test_fut, aux_fut));
 	}
 
 	fn cache_session_info_test(
@@ -1484,7 +1484,7 @@ mod tests {
 					&header,
 				).await.unwrap().unwrap();
 
-				assert_eq!(window.earliest_session, Some(0));
+				assert_eq!(window.earliest_session, Some(start_session));
 				assert_eq!(
 					window.session_info,
 					(start_session..=session).map(dummy_session_info).collect::<Vec<_>>(),
@@ -1519,7 +1519,7 @@ mod tests {
 			}
 		});
 
-		futures::executor::block_on(futures::future::select(test_fut, aux_fut));
+		futures::executor::block_on(futures::future::join(test_fut, aux_fut));
 	}
 
 	#[test]
@@ -1679,7 +1679,7 @@ mod tests {
 			}
 		});
 
-		futures::executor::block_on(futures::future::select(test_fut, aux_fut));
+		futures::executor::block_on(futures::future::join(test_fut, aux_fut));
 	}
 
 	#[test]
@@ -1744,6 +1744,6 @@ mod tests {
 			);
 		});
 
-		futures::executor::block_on(futures::future::select(test_fut, aux_fut));
+		futures::executor::block_on(futures::future::join(test_fut, aux_fut));
 	}
 }

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

@@ -76,11 +76,23 @@ const LOG_TARGET: &str = "approval_voting";
 
 /// The approval voting subsystem.
 pub struct ApprovalVotingSubsystem<T> {
-	keystore: LocalKeystore,
+	keystore: Arc<LocalKeystore>,
 	slot_duration_millis: u64,
 	db: Arc<T>,
 }
 
+impl<T> ApprovalVotingSubsystem<T> {
+	/// Create a new approval voting subsystem with the given keystore, slot duration,
+	/// and underlying DB.
+	pub fn new(keystore: Arc<LocalKeystore>, slot_duration_millis: u64, db: Arc<T>) -> Self {
+		ApprovalVotingSubsystem {
+			keystore,
+			slot_duration_millis,
+			db,
+		}
+	}
+}
+
 impl<T, C> Subsystem<C> for ApprovalVotingSubsystem<T>
 	where T: AuxStore + Send + Sync + 'static, C: SubsystemContext<Message = ApprovalVotingMessage> {
 	fn start(self, ctx: C) -> SpawnedSubsystem {
@@ -229,7 +241,7 @@ use approval_db_v1_reader::ApprovalDBV1Reader;
 
 struct State<T> {
 	session_window: import::RollingSessionWindow,
-	keystore: LocalKeystore,
+	keystore: Arc<LocalKeystore>,
 	slot_duration_millis: u64,
 	db: T,
 	clock: Box<dyn Clock + Send + Sync>,
@@ -529,10 +541,10 @@ async fn handle_approved_ancestor(
 	db: &impl DBReader,
 	target: Hash,
 	lower_bound: BlockNumber,
-) -> SubsystemResult<Option<Hash>> {
+) -> SubsystemResult<Option<(Hash, BlockNumber)>> {
 	let mut all_approved_max = None;
 
-	let block_number = {
+	let target_number = {
 		let (tx, rx) = oneshot::channel();
 
 		ctx.send_message(ChainApiMessage::BlockNumber(target, tx).into()).await;
@@ -544,17 +556,17 @@ async fn handle_approved_ancestor(
 		}
 	};
 
-	if block_number <= lower_bound { return Ok(None) }
+	if target_number <= lower_bound { return Ok(None) }
 
 	// request ancestors up to but not including the lower bound,
 	// as a vote on the lower bound is implied if we cannot find
 	// anything else.
-	let ancestry = if block_number > lower_bound + 1 {
+	let ancestry = if target_number > lower_bound + 1 {
 		let (tx, rx) = oneshot::channel();
 
 		ctx.send_message(ChainApiMessage::Ancestors {
 			hash: target,
-			k: (block_number - (lower_bound + 1)) as usize,
+			k: (target_number - (lower_bound + 1)) as usize,
 			response_channel: tx,
 		}.into()).await;
 
@@ -566,7 +578,7 @@ async fn handle_approved_ancestor(
 		Vec::new()
 	};
 
-	for block_hash in std::iter::once(target).chain(ancestry) {
+	for (i, block_hash) in std::iter::once(target).chain(ancestry).enumerate() {
 		// Block entries should be present as the assumption is that
 		// nothing here is finalized. If we encounter any missing block
 		// entries we can fail.
@@ -577,7 +589,9 @@ async fn handle_approved_ancestor(
 
 		if entry.is_fully_approved() {
 			if all_approved_max.is_none() {
-				all_approved_max = Some(block_hash);
+				// First iteration of the loop is target, i = 0. After that,
+				// ancestry is moving backwards.
+				all_approved_max = Some((block_hash, target_number - i as BlockNumber));
 			}
 		} else {
 			all_approved_max = None;

node/core/approval-voting/src/tests.rs

@@ -184,7 +184,7 @@ impl DBReader for TestStore {
 fn blank_state() -> State<TestStore> {
 	State {
 		session_window: import::RollingSessionWindow::default(),
-		keystore: LocalKeystore::in_memory(),
+		keystore: Arc::new(LocalKeystore::in_memory()),
 		slot_duration_millis: SLOT_DURATION_MILLIS,
 		db: TestStore::default(),
 		clock: Box::new(MockClock::default()),
@@ -1490,7 +1490,7 @@ fn approved_ancestor_all_approved() {
 	let test_fut = Box::pin(async move {
 		assert_eq!(
 			handle_approved_ancestor(&mut ctx, &state.db, block_hash_4, 0).await.unwrap(),
-			Some(block_hash_4),
+			Some((block_hash_4, 4)),
 		)
 	});
 
@@ -1572,7 +1572,7 @@ fn approved_ancestor_missing_approval() {
 	let test_fut = Box::pin(async move {
 		assert_eq!(
 			handle_approved_ancestor(&mut ctx, &state.db, block_hash_4, 0).await.unwrap(),
-			Some(block_hash_2),
+			Some((block_hash_2, 2)),
 		)
 	});
 

node/core/candidate-validation/src/lib.rs

@@ -445,9 +445,9 @@ fn validate_candidate_exhaustive<B: ValidationBackend, S: SpawnNamed + 'static>(
 	match B::validate(backend_arg, &validation_code, params, spawn) {
 		Err(ValidationError::InvalidCandidate(WasmInvalidCandidate::Timeout)) =>
 			Ok(ValidationResult::Invalid(InvalidCandidate::Timeout)),
-		Err(ValidationError::InvalidCandidate(WasmInvalidCandidate::ParamsTooLarge(l))) =>
+		Err(ValidationError::InvalidCandidate(WasmInvalidCandidate::ParamsTooLarge(l, _))) =>
 			Ok(ValidationResult::Invalid(InvalidCandidate::ParamsTooLarge(l as u64))),
-		Err(ValidationError::InvalidCandidate(WasmInvalidCandidate::CodeTooLarge(l))) =>
+		Err(ValidationError::InvalidCandidate(WasmInvalidCandidate::CodeTooLarge(l, _))) =>
 			Ok(ValidationResult::Invalid(InvalidCandidate::CodeTooLarge(l as u64))),
 		Err(ValidationError::InvalidCandidate(WasmInvalidCandidate::BadReturn)) =>
 			Ok(ValidationResult::Invalid(InvalidCandidate::BadReturn)),

node/core/proposer/src/lib.rs

@@ -79,7 +79,7 @@ where
 		+ Send
 		+ Sync,
 	Client::Api:
-		BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
+		BlockBuilderApi<Block> + ApiExt<Block>,
 	Backend:
 		'static + sc_client_api::Backend<Block, State = sp_api::StateBackendFor<Client, Block>>,
 	// Rust bug: https://github.com/rust-lang/rust/issues/24159
@@ -133,7 +133,7 @@ where
 		+ Send
 		+ Sync,
 	Client::Api:
-		BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
+		BlockBuilderApi<Block> + ApiExt<Block>,
 	Backend:
 		'static + sc_client_api::Backend<Block, State = sp_api::StateBackendFor<Client, Block>>,
 	// Rust bug: https://github.com/rust-lang/rust/issues/24159
@@ -179,7 +179,7 @@ where
 		+ Send
 		+ Sync,
 	Client::Api:
-		BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
+		BlockBuilderApi<Block> + ApiExt<Block>,
 	Backend:
 		'static + sc_client_api::Backend<Block, State = sp_api::StateBackendFor<Client, Block>>,
 	// Rust bug: https://github.com/rust-lang/rust/issues/24159

node/core/runtime-api/src/lib.rs

@@ -453,8 +453,6 @@ mod tests {
 
 	sp_api::mock_impl_runtime_apis! {
 		impl ParachainHost<Block> for MockRuntimeApi {
-			type Error = sp_api::ApiError;
-
 			fn validators(&self) -> Vec<ValidatorId> {
 				self.validators.clone()
 			}

node/network/protocol/src/lib.rs

@@ -70,10 +70,7 @@ impl From<sc_network::ObservedRole> for ObservedRole {
 		match role {
 			sc_network::ObservedRole::Light => ObservedRole::Light,
 			sc_network::ObservedRole::Authority => ObservedRole::Authority,
-			sc_network::ObservedRole::Full
-				| sc_network::ObservedRole::OurSentry
-				| sc_network::ObservedRole::OurGuardedAuthority
-				=> ObservedRole::Full,
+			sc_network::ObservedRole::Full => ObservedRole::Full,
 		}
 	}
 }

node/service/Cargo.toml

@@ -19,6 +19,7 @@ sc-executor = { git = "https://github.com/paritytech/substrate", branch = "maste
 sc-finality-grandpa-warp-sync = { git = "https://github.com/paritytech/substrate", branch = "master", optional = true }
 sc-network = { git = "https://github.com/paritytech/substrate", branch = "master" }
 sc-transaction-pool = { git = "https://github.com/paritytech/substrate", branch = "master" }
+sc-keystore = { git = "https://github.com/paritytech/substrate", branch = "master" }
 service = { package = "sc-service", git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
 telemetry = { package = "sc-telemetry", git = "https://github.com/paritytech/substrate", branch = "master" }
 
@@ -95,6 +96,7 @@ polkadot-node-core-runtime-api = { path = "../core/runtime-api", optional = true
 polkadot-pov-distribution = { path = "../network/pov-distribution", optional = true }
 polkadot-statement-distribution = { path = "../network/statement-distribution", optional = true }
 polkadot-approval-distribution = { path = "../network/approval-distribution", optional = true }
+polkadot-node-core-approval-voting = { path = "../core/approval-voting", optional = true }
 
 [dev-dependencies]
 polkadot-test-client = { path = "../test/client" }
@@ -132,4 +134,5 @@ real-overseer = [
 	"polkadot-pov-distribution",
 	"polkadot-statement-distribution",
 	"polkadot-approval-distribution",
+	"polkadot-node-core-approval-voting",
 ]

node/service/src/chain_spec.rs

@@ -870,7 +870,6 @@ fn rococo_staging_testnet_config_genesis(wasm_binary: &[u8]) -> rococo_runtime::
 				group_rotation_frequency: 20,
 				chain_availability_period: 4,
 				thread_availability_period: 4,
-				no_show_slots: 10,
 				max_upward_queue_count: 8,
 				max_upward_queue_size: 8 * 1024,
 				max_downward_message_size: 1024,
@@ -893,6 +892,11 @@ fn rococo_staging_testnet_config_genesis(wasm_binary: &[u8]) -> rococo_runtime::
 				hrmp_max_parachain_outbound_channels: 4,
 				hrmp_max_parathread_outbound_channels: 4,
 				hrmp_max_message_num_per_candidate: 5,
+				no_show_slots: 2,
+				n_delay_tranches: 25,
+				needed_approvals: 2,
+				relay_vrf_modulo_samples: 10,
+				zeroth_delay_tranche_width: 0,
 				..Default::default()
 			},
 		}),
@@ -1376,7 +1380,6 @@ pub fn rococo_testnet_genesis(
 				group_rotation_frequency: 20,
 				chain_availability_period: 4,
 				thread_availability_period: 4,
-				no_show_slots: 10,
 				max_upward_queue_count: 8,
 				max_upward_queue_size: 8 * 1024,
 				max_downward_message_size: 1024,
@@ -1399,6 +1402,11 @@ pub fn rococo_testnet_genesis(
 				hrmp_max_parachain_outbound_channels: 4,
 				hrmp_max_parathread_outbound_channels: 4,
 				hrmp_max_message_num_per_candidate: 5,
+				no_show_slots: 2,
+				n_delay_tranches: 25,
+				needed_approvals: 2,
+				relay_vrf_modulo_samples: 10,
+				zeroth_delay_tranche_width: 0,
 				..Default::default()
 			},
 		}),

node/service/src/client.rs

@@ -30,7 +30,7 @@ use consensus_common::BlockStatus;
 /// A set of APIs that polkadot-like runtimes must implement.
 pub trait RuntimeApiCollection:
 	sp_transaction_pool::runtime_api::TaggedTransactionQueue<Block>
-	+ sp_api::ApiExt<Block, Error = sp_blockchain::Error>
+	+ sp_api::ApiExt<Block>
 	+ babe_primitives::BabeApi<Block>
 	+ grandpa_primitives::GrandpaApi<Block>
 	+ ParachainHost<Block>
@@ -48,7 +48,7 @@ where
 impl<Api> RuntimeApiCollection for Api
 where
 	Api: sp_transaction_pool::runtime_api::TaggedTransactionQueue<Block>
-		+ sp_api::ApiExt<Block, Error = sp_blockchain::Error>
+		+ sp_api::ApiExt<Block>
 		+ babe_primitives::BabeApi<Block>
 		+ grandpa_primitives::GrandpaApi<Block>
 		+ ParachainHost<Block>
@@ -71,7 +71,6 @@ pub trait AbstractClient<Block, Backend>:
 	+ HeaderBackend<Block>
 	+ CallApiAt<
 		Block,
-		Error = sp_blockchain::Error,
 		StateBackend = Backend::State
 	>
 	where
@@ -90,7 +89,6 @@ impl<Block, Backend, Client> AbstractClient<Block, Backend> for Client
 			+ Sized + Send + Sync
 			+ CallApiAt<
 				Block,
-				Error = sp_blockchain::Error,
 				StateBackend = Backend::State
 			>,
 		Client::Api: RuntimeApiCollection<StateBackend = Backend::State>,

node/service/src/grandpa_support.rs

@@ -16,14 +16,146 @@
 
 //! Polkadot-specific GRANDPA integration utilities.
 
-#[cfg(feature = "full-node")]
-use polkadot_primitives::v1::Hash;
+use std::sync::Arc;
+
+use polkadot_primitives::v1::{Block as PolkadotBlock, Header as PolkadotHeader, BlockNumber, Hash};
+use polkadot_subsystem::messages::ApprovalVotingMessage;
+
 use sp_runtime::traits::{Block as BlockT, NumberFor};
+use sp_runtime::generic::BlockId;
+use sp_runtime::traits::Header as _;
+
+use prometheus_endpoint::{self, Registry};
+use polkadot_overseer::OverseerHandler;
+
+use futures::channel::oneshot;
+
+/// A custom GRANDPA voting rule that acts as a diagnostic for the approval
+/// voting subsystem's desired votes.
+///
+/// The practical effect of this voting rule is to implement a fixed delay of
+/// blocks and to issue a prometheus metric on the lag behind the head that
+/// approval checking would indicate.
+#[cfg(feature = "full-node")]
+#[derive(Clone)]
+pub(crate) struct ApprovalCheckingDiagnostic {
+	checking_lag: Option<prometheus_endpoint::Histogram>,
+	overseer: OverseerHandler,
+}
+
+#[cfg(feature = "full-node")]
+impl ApprovalCheckingDiagnostic {
+	/// Create a new approval checking diagnostic voting rule.
+	pub fn new(overseer: OverseerHandler, registry: Option<&Registry>)
+		-> Result<Self, prometheus_endpoint::PrometheusError>
+	{
+		Ok(ApprovalCheckingDiagnostic {
+			checking_lag: if let Some(registry) = registry {
+				Some(prometheus_endpoint::register(
+					prometheus_endpoint::Histogram::with_opts(
+						prometheus_endpoint::HistogramOpts::new(
+							"approval_checking_finality_lag",
+							"How far behind the head of the chain the Approval Checking protocol wants to vote",
+						).buckets(vec![1.0, 2.0, 3.0, 4.0, 5.0, 10.0, 20.0, 30.0, 40.0, 50.0])
+					)?,
+					registry,
+				)?)
+			} else {
+				None
+			},
+			overseer,
+		})
+	}
+}
+
+#[cfg(feature = "full-node")]
+impl<B> grandpa::VotingRule<PolkadotBlock, B> for ApprovalCheckingDiagnostic
+	where B: sp_blockchain::HeaderBackend<PolkadotBlock>
+{
+	fn restrict_vote(
+		&self,
+		backend: Arc<B>,
+		base: &PolkadotHeader,
+		_best_target: &PolkadotHeader,
+		current_target: &PolkadotHeader,
+	) -> grandpa::VotingRuleResult<PolkadotBlock> {
+		// always wait 50 blocks behind the head to finalize.
+		const DIAGNOSTIC_GRANDPA_DELAY: BlockNumber = 50;
+
+		let aux = || {
+			let find_target = |target_number: BlockNumber, current_header: &PolkadotHeader| {
+				let mut target_hash = current_header.hash();
+				let mut target_header = current_header.clone();
+
+				loop {
+					if *target_header.number() < target_number {
+						unreachable!(
+							"we are traversing backwards from a known block; \