enable disputes (#3478)

* initial integration and migration code

* fix tests

* fix counting test

* assume the current version on missing file

* use SelectRelayChain

* remove duplicate metric

* Update node/service/src/lib.rs

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

* remove ApprovalCheckingVotingRule

* address my concern

* never mode for StagnantCheckInterval

* REVERTME: some logs

* w00t

* it's ugly but it works

* Revert "REVERTME: some logs"

This reverts commit e210505a

.

* it's handle, not handler

* fix a few typos

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

Cargo.lock

@@ -6631,6 +6631,7 @@ dependencies = [
  "kv-log-macro",
  "lru",
  "metered-channel",
+ "parking_lot 0.11.1",
  "polkadot-node-metrics",
  "polkadot-node-network-protocol",
  "polkadot-node-primitives",
@@ -6976,6 +6977,9 @@ dependencies = [
  "polkadot-node-core-bitfield-signing",
  "polkadot-node-core-candidate-validation",
  "polkadot-node-core-chain-api",
+ "polkadot-node-core-chain-selection",
+ "polkadot-node-core-dispute-coordinator",
+ "polkadot-node-core-dispute-participation",
  "polkadot-node-core-parachains-inherent",
  "polkadot-node-core-provisioner",
  "polkadot-node-core-runtime-api",

node/core/chain-selection/src/lib.rs

@@ -28,6 +28,7 @@ use polkadot_node_subsystem::{
 use kvdb::KeyValueDB;
 use parity_scale_codec::Error as CodecError;
 use futures::channel::oneshot;
+use futures::future::Either;
 use futures::prelude::*;
 
 use std::time::{UNIX_EPOCH, Duration,SystemTime};
@@ -244,7 +245,7 @@ impl Clock for SystemClock {
 
 /// The interval, in seconds to check for stagnant blocks.
 #[derive(Debug, Clone)]
-pub struct StagnantCheckInterval(Duration);
+pub struct StagnantCheckInterval(Option<Duration>);
 
 impl Default for StagnantCheckInterval {
 	fn default() -> Self {
@@ -255,28 +256,37 @@ impl Default for StagnantCheckInterval {
 		// between 2 validators is D + 5s.
 		const DEFAULT_STAGNANT_CHECK_INTERVAL: Duration = Duration::from_secs(5);
 
-		StagnantCheckInterval(DEFAULT_STAGNANT_CHECK_INTERVAL)
+		StagnantCheckInterval(Some(DEFAULT_STAGNANT_CHECK_INTERVAL))
 	}
 }
 
 impl StagnantCheckInterval {
 	/// Create a new stagnant-check interval wrapping the given duration.
 	pub fn new(interval: Duration) -> Self {
-		StagnantCheckInterval(interval)
+		StagnantCheckInterval(Some(interval))
 	}
 
-	fn timeout_stream(&self) -> impl Stream<Item = ()> {
-		let interval = self.0;
-		let mut delay = futures_timer::Delay::new(interval);
+	/// Create a `StagnantCheckInterval` which never triggers.
+	pub fn never() -> Self {
+		StagnantCheckInterval(None)
+	}
 
-		futures::stream::poll_fn(move |cx| {
-			let poll = delay.poll_unpin(cx);
-			if poll.is_ready() {
-				delay.reset(interval)
-			}
+	fn timeout_stream(&self) -> impl Stream<Item = ()> {
+		match self.0 {
+			Some(interval) => Either::Left({
+				let mut delay = futures_timer::Delay::new(interval);
+
+				futures::stream::poll_fn(move |cx| {
+					let poll = delay.poll_unpin(cx);
+					if poll.is_ready() {
+						delay.reset(interval)
+					}
 
-			poll.map(Some)
-		})
+					poll.map(Some)
+				})
+			}),
+			None => Either::Right(futures::stream::pending()),
+		}
 	}
 }
 

node/malus/src/variant-a.rs

@@ -27,7 +27,7 @@ use polkadot_cli::{
 	create_default_subsystems,
 	service::{
 		AuthorityDiscoveryApi, AuxStore, BabeApi, Block, Error, HeaderBackend, Overseer,
-		OverseerGen, OverseerGenArgs, Handle, ParachainHost, ProvideRuntimeApi,
+		OverseerGen, OverseerGenArgs, OverseerHandle, ParachainHost, ProvideRuntimeApi,
 		SpawnNamed,
 	},
 	Cli,
@@ -73,7 +73,7 @@ impl OverseerGen for BehaveMaleficient {
 	fn generate<'a, Spawner, RuntimeClient>(
 		&self,
 		args: OverseerGenArgs<'a, Spawner, RuntimeClient>,
-	) -> Result<(Overseer<Spawner, Arc<RuntimeClient>>, Handle), Error>
+	) -> Result<(Overseer<Spawner, Arc<RuntimeClient>>, OverseerHandle), Error>
 	where
 		RuntimeClient: 'static + ProvideRuntimeApi<Block> + HeaderBackend<Block> + AuxStore,
 		RuntimeClient::Api: ParachainHost<Block> + BabeApi<Block> + AuthorityDiscoveryApi<Block>,

node/overseer/Cargo.toml

@@ -10,6 +10,7 @@ client = { package = "sc-client-api", git = "https://github.com/paritytech/subst
 sp-api = { git = "https://github.com/paritytech/substrate", branch = "master" }
 futures = "0.3.15"
 futures-timer = "3.0.2"
+parking_lot = "0.11.1"
 polkadot-node-network-protocol = { path = "../network/protocol" }
 polkadot-node-primitives = { path = "../primitives" }
 polkadot-node-subsystem-types = { path = "../subsystem-types" }

node/overseer/examples/minimal-example.rs

@@ -174,7 +174,7 @@ fn main() {
 			.replace_candidate_backing(Subsystem1)
 			;
 
-		let (overseer, _handler) = Overseer::new(
+		let (overseer, _handle) = Overseer::new(
 			vec![],
 			all_subsystems,
 			None,

node/overseer/overseer-gen/examples/dummy.rs

@@ -123,7 +123,7 @@ impl SpawnNamed for DummySpawner{
 struct DummyCtx;
 
 fn main() {
-	let (overseer, _handler): (Xxx<_>, _) = Xxx::builder()
+	let (overseer, _handle): (Xxx<_>, _) = Xxx::builder()
 		.sub0(AwesomeSubSys::default())
 		.plinkos(GoblinTower::default())
 		.i_like_pi(::std::f64::consts::PI)

node/overseer/src/lib.rs

@@ -73,6 +73,7 @@ use futures::{
 	Future, FutureExt, StreamExt,
 };
 use lru::LruCache;
+use parking_lot::RwLock;
 
 use polkadot_primitives::v1::{Block, BlockId,BlockNumber, Hash, ParachainHost};
 use client::{BlockImportNotification, BlockchainEvents, FinalityNotification};
@@ -159,13 +160,24 @@ impl<Client> HeadSupportsParachains for Arc<Client> where
 }
 
 
-/// A handler used to communicate with the [`Overseer`].
+/// A handle used to communicate with the [`Overseer`].
 ///
 /// [`Overseer`]: struct.Overseer.html
 #[derive(Clone)]
-pub struct Handle(pub OverseerHandle);
+pub enum Handle {
+	/// Used only at initialization to break the cyclic dependency.
+	// TODO: refactor in https://github.com/paritytech/polkadot/issues/3427
+	Disconnected(Arc<RwLock<Option<OverseerHandle>>>),
+	/// A handle to the overseer.
+	Connected(OverseerHandle),
+}
 
 impl Handle {
+	/// Create a new disconnected [`Handle`].
+	pub fn new_disconnected() -> Self {
+		Self::Disconnected(Arc::new(RwLock::new(None)))
+	}
+
 	/// Inform the `Overseer` that that some block was imported.
 	pub async fn block_imported(&mut self, block: BlockInfo) {
 		self.send_and_log_error(Event::BlockImported(block)).await
@@ -207,25 +219,59 @@ impl Handle {
 
 	/// Most basic operation, to stop a server.
 	async fn send_and_log_error(&mut self, event: Event) {
-		if self.0.send(event).await.is_err() {
-			tracing::info!(target: LOG_TARGET, "Failed to send an event to Overseer");
+		self.try_connect();
+		if let Self::Connected(ref mut handle) = self {
+			if handle.send(event).await.is_err() {
+				tracing::info!(target: LOG_TARGET, "Failed to send an event to Overseer");
+			}
+		} else {
+			tracing::warn!(target: LOG_TARGET, "Using a disconnected Handle to send to Overseer");
 		}
 	}
 
-	/// Whether the overseer handler is connected to an overseer.
-	pub fn is_connected(&self) -> bool {
-		true
+	/// Whether the handle is disconnected.
+	pub fn is_disconnected(&self) -> bool {
+		match self {
+			Self::Disconnected(ref x) => x.read().is_none(),
+			_ => false,
+		}
 	}
 
-	/// Whether the handler is disconnected.
-	pub fn is_disconnected(&self) -> bool {
-		false
+	/// Connect this handle and all disconnected clones of it to the overseer.
+	pub fn connect_to_overseer(&mut self, handle: OverseerHandle) {
+		match self {
+			Self::Disconnected(ref mut x) => {
+				let mut maybe_handle = x.write();
+				if maybe_handle.is_none() {
+					tracing::info!(target: LOG_TARGET, "🖇️ Connecting all Handles to Overseer");
+					*maybe_handle = Some(handle);
+				} else {
+					tracing::warn!(
+						target: LOG_TARGET,
+						"Attempting to connect a clone of a connected Handle",
+					);
+				}
+			},
+			_ => {
+				tracing::warn!(
+					target: LOG_TARGET,
+					"Attempting to connect an already connected Handle",
+				);
+			},
+		}
 	}
 
-	/// Using this handler, connect another handler to the same
-	/// overseer, if any.
-	pub fn connect_other(&self, other: &mut Handle) {
-		*other = self.clone();
+	/// Try upgrading from `Self::Disconnected` to `Self::Connected` state
+	/// after calling `connect_to_overseer` on `self` or a clone of `self`.
+	fn try_connect(&mut self) {
+		if let Self::Disconnected(ref mut x) = self {
+			let guard = x.write();
+			if let Some(ref h) = *guard {
+				let handle = h.clone();
+				drop(guard);
+				*self = Self::Connected(handle);
+			}
+		}
 	}
 }
 
@@ -301,7 +347,7 @@ pub enum ExternalRequest {
 /// import and finality notifications into the [`OverseerHandle`].
 pub async fn forward_events<P: BlockchainEvents<Block>>(
 	client: Arc<P>,
-	mut handler: Handle,
+	mut handle: Handle,
 ) {
 	let mut finality = client.finality_notification_stream();
 	let mut imports = client.import_notification_stream();
@@ -311,7 +357,7 @@ pub async fn forward_events<P: BlockchainEvents<Block>>(
 			f = finality.next() => {
 				match f {
 					Some(block) => {
-						handler.block_finalized(block.into()).await;
+						handle.block_finalized(block.into()).await;
 					}
 					None => break,
 				}
@@ -319,7 +365,7 @@ pub async fn forward_events<P: BlockchainEvents<Block>>(
 			i = imports.next() => {
 				match i {
 					Some(block) => {
-						handler.block_imported(block.into()).await;
+						handle.block_imported(block.into()).await;
 					}
 					None => break,
 				}
@@ -338,7 +384,6 @@ pub async fn forward_events<P: BlockchainEvents<Block>>(
 	network=NetworkBridgeEvent<protocol_v1::ValidationProtocol>,
 )]
 pub struct Overseer<SupportsParachains> {
-
 	#[subsystem(no_dispatch, CandidateValidationMessage)]
 	candidate_validation: CandidateValidation,
 
@@ -390,16 +435,16 @@ pub struct Overseer<SupportsParachains> {
 	#[subsystem(no_dispatch, GossipSupportMessage)]
 	gossip_support: GossipSupport,
 
-	#[subsystem(no_dispatch, wip, DisputeCoordinatorMessage)]
-	dipute_coordinator: DisputeCoordinator,
+	#[subsystem(no_dispatch, DisputeCoordinatorMessage)]
+	dispute_coordinator: DisputeCoordinator,
 
-	#[subsystem(no_dispatch, wip, DisputeParticipationMessage)]
+	#[subsystem(no_dispatch, DisputeParticipationMessage)]
 	dispute_participation: DisputeParticipation,
 
-	#[subsystem(no_dispatch, wip, DisputeDistributionMessage)]
-	dipute_distribution: DisputeDistribution,
+	#[subsystem(no_dispatch, DisputeDistributionMessage)]
+	dispute_distribution: DisputeDistribution,
 
-	#[subsystem(no_dispatch, wip, ChainSelectionMessage)]
+	#[subsystem(no_dispatch, ChainSelectionMessage)]
 	chain_selection: ChainSelection,
 
 	/// External listeners waiting for a hash to be in the active-leave set.
@@ -436,7 +481,7 @@ where
 	/// This returns the overseer along with an [`OverseerHandle`] which can
 	/// be used to send messages from external parts of the codebase.
 	///
-	/// The [`OverseerHandler`] returned from this function is connected to
+	/// The [`OverseerHandle`] returned from this function is connected to
 	/// the returned [`Overseer`].
 	///
 	/// ```text
@@ -527,7 +572,7 @@ where
 	/// let spawner = sp_core::testing::TaskExecutor::new();
 	/// let all_subsystems = AllSubsystems::<()>::dummy()
 	///		.replace_candidate_validation(ValidationSubsystem);
-	/// let (overseer, _handler) = Overseer::new(
+	/// let (overseer, _handle) = Overseer::new(
 	///     vec![],
 	///     all_subsystems,
 	///     None,
@@ -549,13 +594,13 @@ where
 	/// # 	});
 	/// # }
 	/// ```
-	pub fn new<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS>(
+	pub fn new<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS, DC, DP, DD, CS>(
 		leaves: impl IntoIterator<Item = BlockInfo>,
-		all_subsystems: AllSubsystems<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS>,
+		all_subsystems: AllSubsystems<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS, DC, DP, DD, CS>,
 		prometheus_registry: Option<&prometheus::Registry>,
 		supports_parachains: SupportsParachains,
 		s: S,
-	) -> SubsystemResult<(Self, Handle)>
+	) -> SubsystemResult<(Self, OverseerHandle)>
 	where
 		CV: Subsystem<OverseerSubsystemContext<CandidateValidationMessage>, SubsystemError> + Send,
 		CB: Subsystem<OverseerSubsystemContext<CandidateBackingMessage>, SubsystemError> + Send,
@@ -574,11 +619,15 @@ where
 		ApD: Subsystem<OverseerSubsystemContext<ApprovalDistributionMessage>, SubsystemError> + Send,
 		ApV: Subsystem<OverseerSubsystemContext<ApprovalVotingMessage>, SubsystemError> + Send,
 		GS: Subsystem<OverseerSubsystemContext<GossipSupportMessage>, SubsystemError> + Send,
+		DC: Subsystem<OverseerSubsystemContext<DisputeCoordinatorMessage>, SubsystemError> + Send,
+		DP: Subsystem<OverseerSubsystemContext<DisputeParticipationMessage>, SubsystemError> + Send,
+		DD: Subsystem<OverseerSubsystemContext<DisputeDistributionMessage>, SubsystemError> + Send,
+		CS: Subsystem<OverseerSubsystemContext<ChainSelectionMessage>, SubsystemError> + Send,
 		S: SpawnNamed,
 	{
 		let metrics: Metrics = <Metrics as MetricsTrait>::register(prometheus_registry)?;
 
-		let (mut overseer, handler) = Self::builder()
+		let (mut overseer, handle) = Self::builder()
 			.candidate_validation(all_subsystems.candidate_validation)
 			.candidate_backing(all_subsystems.candidate_backing)
 			.statement_distribution(all_subsystems.statement_distribution)
@@ -596,6 +645,10 @@ where
 			.approval_distribution(all_subsystems.approval_distribution)
 			.approval_voting(all_subsystems.approval_voting)
 			.gossip_support(all_subsystems.gossip_support)
+			.dispute_coordinator(all_subsystems.dispute_coordinator)
+			.dispute_participation(all_subsystems.dispute_participation)
+			.dispute_distribution(all_subsystems.dispute_distribution)
+			.chain_selection(all_subsystems.chain_selection)
 			.leaves(Vec::from_iter(
 				leaves.into_iter().map(|BlockInfo { hash, parent_hash: _, number }| (hash, number))
 			))
@@ -647,7 +700,7 @@ where
 			overseer.spawner().spawn("metrics_metronome", Box::pin(metronome));
 		}
 
-		Ok((overseer, Handle(handler)))
+		Ok((overseer, handle))
 	}
 
 	/// Stop the overseer.

node/overseer/src/subsystems.rs

@@ -77,7 +77,7 @@ where
 pub struct AllSubsystems<
 	CV = (), CB = (), SD = (), AD = (), AR = (), BS = (), BD = (), P = (),
 	RA = (), AS = (), NB = (), CA = (), CG = (), CP = (), ApD = (), ApV = (),
-	GS = (),
+	GS = (), DC = (), DP = (), DD = (), CS = (),
 > {
 	/// A candidate validation subsystem.
 	pub candidate_validation: CV,
@@ -113,10 +113,18 @@ pub struct AllSubsystems<
 	pub approval_voting: ApV,
 	/// A Connection Request Issuer subsystem.
 	pub gossip_support: GS,
+	/// A Dispute Coordinator subsystem.
+	pub dispute_coordinator: DC,
+	/// A Dispute Participation subsystem.
+	pub dispute_participation: DP,
+	/// A Dispute Distribution subsystem.
+	pub dispute_distribution: DD,
+	/// A Chain Selection subsystem.
+	pub chain_selection: CS,
 }
 
-impl<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS>
-	AllSubsystems<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS>
+impl<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS, DC, DP, DD, CS>
+	AllSubsystems<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS, DC, DP, DD, CS>
 {
 	/// Create a new instance of [`AllSubsystems`].
 	///
@@ -148,6 +156,10 @@ impl<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS>
 		DummySubsystem,
 		DummySubsystem,
 		DummySubsystem,
+		DummySubsystem,
+		DummySubsystem,
+		DummySubsystem,
+		DummySubsystem,
 	> {
 		AllSubsystems {
 			candidate_validation: DummySubsystem,
@@ -167,11 +179,15 @@ impl<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS>
 			approval_distribution: DummySubsystem,
 			approval_voting: DummySubsystem,
 			gossip_support: DummySubsystem,
+			dispute_coordinator: DummySubsystem,
+			dispute_participation: DummySubsystem,
+			dispute_distribution: DummySubsystem,
+			chain_selection: DummySubsystem,
 		}
 	}
 
 	/// Reference every individual subsystem.
-	pub fn as_ref(&self) -> AllSubsystems<&'_ CV, &'_ CB, &'_ SD, &'_ AD, &'_ AR, &'_ BS, &'_ BD, &'_ P, &'_ RA, &'_ AS, &'_ NB, &'_ CA, &'_ CG, &'_ CP, &'_ ApD, &'_ ApV, &'_ GS> {
+	pub fn as_ref(&self) -> AllSubsystems<&'_ CV, &'_ CB, &'_ SD, &'_ AD, &'_ AR, &'_ BS, &'_ BD, &'_ P, &'_ RA, &'_ AS, &'_ NB, &'_ CA, &'_ CG, &'_ CP, &'_ ApD, &'_ ApV, &'_ GS, &'_ DC, &'_ DP, &'_ DD, &'_ CS> {
 		AllSubsystems {
 			candidate_validation: &self.candidate_validation,
 			candidate_backing: &self.candidate_backing,
@@ -190,6 +206,10 @@ impl<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS>
 			approval_distribution: &self.approval_distribution,
 			approval_voting: &self.approval_voting,
 			gossip_support: &self.gossip_support,
+			dispute_coordinator: &self.dispute_coordinator,
+			dispute_participation: &self.dispute_participation,
+			dispute_distribution: &self.dispute_distribution,
+			chain_selection: &self.chain_selection,
 		}
 	}
 
@@ -213,6 +233,10 @@ impl<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS>
 			<Mapper as MapSubsystem<ApD>>::Output,
 			<Mapper as MapSubsystem<ApV>>::Output,
 			<Mapper as MapSubsystem<GS>>::Output,
+			<Mapper as MapSubsystem<DC>>::Output,
+			<Mapper as MapSubsystem<DP>>::Output,
+			<Mapper as MapSubsystem<DD>>::Output,
+			<Mapper as MapSubsystem<CS>>::Output,
 		>
 	where
 		Mapper: MapSubsystem<CV>,
@@ -232,6 +256,10 @@ impl<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS>
 		Mapper: MapSubsystem<ApD>,
 		Mapper: MapSubsystem<ApV>,
 		Mapper: MapSubsystem<GS>,
+		Mapper: MapSubsystem<DC>,
+		Mapper: MapSubsystem<DP>,
+		Mapper: MapSubsystem<DD>,
+		Mapper: MapSubsystem<CS>,
 	{
 		AllSubsystems {
 			candidate_validation: <Mapper as MapSubsystem<CV>>::map_subsystem(&mapper, self.candidate_validation),
@@ -251,6 +279,10 @@ impl<CV, CB, SD, AD, AR, BS, BD, P, RA, AS, NB, CA, CG, CP, ApD, ApV, GS>
 			approval_distribution: <Mapper as MapSubsystem<ApD>>::map_subsystem(&mapper, self.approval_distribution),
 			approval_voting: <Mapper as MapSubsystem<ApV>>::map_subsystem(&mapper, self.approval_voting),
 			gossip_support: <Mapper as MapSubsystem<GS>>::map_subsystem(&mapper, self.gossip_support),
+			dispute_coordinator: <Mapper as MapSubsystem<DC>>::map_subsystem(&mapper, self.dispute_coordinator),
+			dispute_participation: <Mapper as MapSubsystem<DP>>::map_subsystem(&mapper, self.dispute_participation),
+			dispute_distribution: <Mapper as MapSubsystem<DD>>::map_subsystem(&mapper, self.dispute_distribution),
+			chain_selection: <Mapper as MapSubsystem<CS>>::map_subsystem(&mapper, self.chain_selection),
 		}
 	}
 }

node/overseer/src/tests.rs

@@ -18,6 +18,7 @@ use std::sync::atomic;
 use std::collections::HashMap;
 use std::task::{Poll};
 use futures::{executor, pin_mut, select, FutureExt, pending, poll, stream};
+use futures::channel::mpsc;
 
 use polkadot_primitives::v1::{CollatorPair, CandidateHash};
 use polkadot_node_primitives::{CollationResult, CollationGenerationConfig, PoV, BlockData};
@@ -166,13 +167,14 @@ fn overseer_works() {
 			.replace_candidate_validation(TestSubsystem1(s1_tx))
 			.replace_candidate_backing(TestSubsystem2(s2_tx));
 
-		let (overseer, mut handler) = Overseer::new(
+		let (overseer, handle) = Overseer::new(
 			vec![],
 			all_subsystems,
 			None,
 			MockSupportsParachains,
 			spawner,
 		).unwrap();
+		let mut handle = Handle::Connected(handle);
 		let overseer_fut = overseer.run().fuse();
 
 		pin_mut!(overseer_fut);
@@ -188,7 +190,7 @@ fn overseer_works() {
 						Some(msg) => {
 							s1_results.push(msg);
 							if s1_results.len() == 10 {
-								handler.stop().await;
+								handle.stop().await;
 							}
 						}
 						None => break,
@@ -236,21 +238,22 @@ fn overseer_metrics_work() {
 
 		let all_subsystems = AllSubsystems::<()>::dummy();
 		let registry = prometheus::Registry::new();
-		let (overseer, mut handler) = Overseer::new(
+		let (overseer, handle) = Overseer::new(
 			vec![first_block],
 			all_subsystems,
 			Some(&registry),
 			MockSupportsParachains,
 			spawner,
 		).unwrap();
+		let mut handle = Handle::Connected(handle);
 		let overseer_fut = overseer.run().fuse();
 
 		pin_mut!(overseer_fut);
 
-		handler.block_imported(second_block).await;
-		handler.block_imported(third_block).await;
-		handler.send_msg_anon(AllMessages::CandidateValidation(test_candidate_validation_msg())).await;
-		handler.stop().await;
+		handle.block_imported(second_block).await;
+		handle.block_imported(third_block).await;
+		handle.send_msg_anon(AllMessages::CandidateValidation(test_candidate_validation_msg())).await;
+		handle.stop().await;
 
 		select! {
 			res = overseer_fut => {
@@ -398,13 +401,14 @@ fn overseer_start_stop_works() {
 		let all_subsystems = AllSubsystems::<()>::dummy()
 			.replace_candidate_validation(TestSubsystem5(tx_5))
 			.replace_candidate_backing(TestSubsystem6(tx_6));
-		let (overseer, mut handler) = Overseer::new(
+		let (overseer, handle) = Overseer::new(
 			vec![first_block],
 			all_subsystems,
 			None,
 			MockSupportsParachains,
 			spawner,
 		).unwrap();
+		let mut handle = Handle::Connected(handle);
 
 		let overseer_fut = overseer.run().fuse();
 		pin_mut!(overseer_fut);
@@ -412,8 +416,8 @@ fn overseer_start_stop_works() {
 		let mut ss5_results = Vec::new();
 		let mut ss6_results = Vec::new();
 
-		handler.block_imported(second_block).await;
-		handler.block_imported(third_block).await;
+		handle.block_imported(second_block).await;
+		handle.block_imported(third_block).await;
 
 		let expected_heartbeats = vec![
 			OverseerSignal::ActiveLeaves(ActiveLeavesUpdate::start_work(ActivatedLeaf {
@@ -463,7 +467,7 @@ fn overseer_start_stop_works() {
 
 			if ss5_results.len() == expected_heartbeats.len() &&
 				ss6_results.len() == expected_heartbeats.len() {
-					handler.stop().await;
+					handle.stop().await;
 			}
 		}
 
@@ -507,13 +511,14 @@ fn overseer_finalize_works() {
 			.replace_candidate_backing(TestSubsystem6(tx_6));
 
 		// start with two forks of different height.
-		let (overseer, mut handler) = Overseer::new(
+		let (overseer, handle) = Overseer::new(
 			vec![first_block, second_block],
 			all_subsystems,
 			None,
 			MockSupportsParachains,
 			spawner,
 		).unwrap();
+		let mut handle = Handle::Connected(handle);
 
 		let overseer_fut = overseer.run().fuse();
 		pin_mut!(overseer_fut);
@@ -522,7 +527,7 @@ fn overseer_finalize_works() {
 		let mut ss6_results = Vec::new();
 
 		// this should stop work on both forks we started with earlier.
-		handler.block_finalized(third_block).await;
+		handle.block_finalized(third_block).await;
 
 		let expected_heartbeats = vec![
 			OverseerSignal::ActiveLeaves(ActiveLeavesUpdate {
@@ -569,7 +574,7 @@ fn overseer_finalize_works() {
 			}
 
 			if ss5_results.len() == expected_heartbeats.len() && ss6_results.len() == expected_heartbeats.len() {
-				handler.stop().await;
+				handle.stop().await;
 			}
 		}
 
@@ -607,21 +612,22 @@ fn do_not_send_empty_leaves_update_on_block_finalization() {
 		let all_subsystems = AllSubsystems::<()>::dummy()
 			.replace_candidate_backing(TestSubsystem6(tx_5));
 
-		let (overseer, mut handler) = Overseer::new(
+		let (overseer, handle) = Overseer::new(
 			Vec::new(),
 			all_subsystems,
 			None,
 			MockSupportsParachains,
 			spawner,
 		).unwrap();
+		let mut handle = Handle::Connected(handle);
 
 		let overseer_fut = overseer.run().fuse();