Use async/await instead of manual polling of NetworkWorker (#13219)

* Convert `NetworkWorker::poll()` into async `next_action()`

* Use `NetworkWorker::next_action` instead of `poll` in `sc-network-test`

* Revert "Use `NetworkWorker::next_action` instead of `poll` in `sc-network-test`"

This reverts commit 4b5d851ec864f78f9d083a18a618fbe117c896d2.

* Fix `sc-network-test` to poll `NetworkWorker::next_action`

* Fix `sc_network::service` tests to poll `NetworkWorker::next_action`

* Fix docs

* kick CI

* Factor out `next_worker_message()` & `next_swarm_event()`

* Error handling: replace `futures::pending!()` with `expect()`

* Simplify stream polling in `select!`

* Replace `NetworkWorker::next_action()` with `run()`

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <git@kchr.de>

* minor: comment

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <git@kchr.de>

* Print debug log when network future is shut down

* Evaluate `NetworkWorker::run()` future once before the loop

* Fix client code to match new `NetworkService` interfaces

* Make clippy happy

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <git@kchr.de>

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <git@kchr.de>

* Revert "Apply suggestions from code review"

This reverts commit 9fa646d0ed613e5f8623d3d37d1d59ec0a535850.

* Make `NetworkWorker::run()` consume `self`

* Terminate system RPC future if RPC rx stream has terminated.

* Rewrite with let-else

* Fix comments

* Get `best_seen_block` and call `on_block_finalized` via `ChainSync` instead of `NetworkService`

* rustfmt

* make clippy happy

* Tests: schedule wake if `next_action()` returned true

* minor: comment

* minor: fix `NetworkWorker` rustdoc

* minor: amend the rustdoc

* Fix bug that caused `on_demand_beefy_justification_sync` test to hang

* rustfmt

* Apply review suggestions

---------

Co-authored-by: Bastian Köcher <git@kchr.de>

substrate/client/authority-discovery/src/worker/tests.rs

@@ -184,6 +184,10 @@ impl NetworkStateInfo for TestNetwork {
 	fn external_addresses(&self) -> Vec<Multiaddr> {
 		self.external_addresses.clone()
 	}
+
+	fn listen_addresses(&self) -> Vec<Multiaddr> {
+		self.external_addresses.clone()
+	}
 }
 
 struct TestSigner<'a> {

substrate/client/network/common/src/service.rs

@@ -180,13 +180,13 @@ pub trait NetworkPeers {
 	/// purposes.
 	fn deny_unreserved_peers(&self);
 
-	/// Adds a `PeerId` and its `Multiaddr` as reserved.
+	/// Adds a `PeerId` and its `Multiaddr` as reserved for a sync protocol (default peer set).
 	///
 	/// Returns an `Err` if the given string is not a valid multiaddress
 	/// or contains an invalid peer ID (which includes the local peer ID).
 	fn add_reserved_peer(&self, peer: MultiaddrWithPeerId) -> Result<(), String>;
 
-	/// Removes a `PeerId` from the list of reserved peers.
+	/// Removes a `PeerId` from the list of reserved peers for a sync protocol (default peer set).
 	fn remove_reserved_peer(&self, peer_id: PeerId);
 
 	/// Sets the reserved set of a protocol to the given set of peers.
@@ -359,6 +359,9 @@ pub trait NetworkStateInfo {
 	/// Returns the local external addresses.
 	fn external_addresses(&self) -> Vec<Multiaddr>;
 
+	/// Returns the listening addresses (without trailing `/p2p/` with our `PeerId`).
+	fn listen_addresses(&self) -> Vec<Multiaddr>;
+
 	/// Returns the local Peer ID.
 	fn local_peer_id(&self) -> PeerId;
 }
@@ -372,6 +375,10 @@ where
 		T::external_addresses(self)
 	}
 
+	fn listen_addresses(&self) -> Vec<Multiaddr> {
+		T::listen_addresses(self)
+	}
+
 	fn local_peer_id(&self) -> PeerId {
 		T::local_peer_id(self)
 	}

substrate/client/network/src/service/tests/chain_sync.rs

@@ -75,12 +75,8 @@ async fn normal_network_poll_no_peers() {
 		.with_chain_sync((chain_sync, chain_sync_service))
 		.build();
 
-	// poll the network once
+	// perform one action on network
-	futures::future::poll_fn(|cx| {
+	let _ = network.network().next_action().await;
-		let _ = network.network().poll_unpin(cx);
-		Poll::Ready(())
-	})
-	.await;
 }
 
 #[tokio::test]
@@ -110,11 +106,8 @@ async fn request_justification() {
 	// send "request justifiction" message and poll the network
 	network.service().request_justification(&hash, number);
 
-	futures::future::poll_fn(|cx| {
+	// perform one action on network
-		let _ = network.network().poll_unpin(cx);
+	let _ = network.network().next_action().await;
-		Poll::Ready(())
-	})
-	.await;
 }
 
 #[tokio::test]
@@ -141,11 +134,8 @@ async fn clear_justification_requests() {
 	// send "request justifiction" message and poll the network
 	network.service().clear_justification_requests();
 
-	futures::future::poll_fn(|cx| {
+	// perform one action on network
-		let _ = network.network().poll_unpin(cx);
+	let _ = network.network().next_action().await;
-		Poll::Ready(())
-	})
-	.await;
 }
 
 #[tokio::test]
@@ -180,11 +170,8 @@ async fn set_sync_fork_request() {
 	// send "set sync fork request" message and poll the network
 	network.service().set_sync_fork_request(copy_peers, hash, number);
 
-	futures::future::poll_fn(|cx| {
+	// perform one action on network
-		let _ = network.network().poll_unpin(cx);
+	let _ = network.network().next_action().await;
-		Poll::Ready(())
-	})
-	.await;
 }
 
 #[tokio::test]
@@ -225,11 +212,8 @@ async fn on_block_finalized() {
 	// send "set sync fork request" message and poll the network
 	network.network().on_block_finalized(hash, header);
 
-	futures::future::poll_fn(|cx| {
+	// perform one action on network
-		let _ = network.network().poll_unpin(cx);
+	let _ = network.network().next_action().await;
-		Poll::Ready(())
-	})
-	.await;
 }
 
 // report from mock import queue that importing a justification was not successful

substrate/client/network/src/service/tests/mod.rs

@@ -80,10 +80,7 @@ impl TestNetwork {
 		let service = worker.service().clone();
 		let event_stream = service.event_stream("test");
 
-		tokio::spawn(async move {
+		tokio::spawn(worker.run());
-			futures::pin_mut!(worker);
-			let _ = worker.await;
-		});
 
 		(service, event_stream)
 	}

substrate/client/network/sync/src/lib.rs

@@ -1358,6 +1358,12 @@ where
 						);
 					}
 				},
+				ToServiceCommand::BlockFinalized(hash, number) => {
+					self.on_block_finalized(&hash, number);
+				},
+				ToServiceCommand::Status { pending_response } => {
+					let _ = pending_response.send(self.status());
+				},
 			}
 		}
 

substrate/client/network/sync/src/service/chain_sync.rs

@@ -16,9 +16,10 @@
 // You should have received a copy of the GNU General Public License
 // along with this program. If not, see <https://www.gnu.org/licenses/>.
 
+use futures::channel::oneshot;
 use libp2p::PeerId;
 use sc_consensus::{BlockImportError, BlockImportStatus, JustificationSyncLink, Link};
-use sc_network_common::service::NetworkSyncForkRequest;
+use sc_network_common::{service::NetworkSyncForkRequest, sync::SyncStatus};
 use sc_utils::mpsc::TracingUnboundedSender;
 use sp_runtime::traits::{Block as BlockT, NumberFor};
 
@@ -34,6 +35,10 @@ pub enum ToServiceCommand<B: BlockT> {
 		Vec<(Result<BlockImportStatus<NumberFor<B>>, BlockImportError>, B::Hash)>,
 	),
 	JustificationImported(PeerId, B::Hash, NumberFor<B>, bool),
+	BlockFinalized(B::Hash, NumberFor<B>),
+	Status {
+		pending_response: oneshot::Sender<SyncStatus<B>>,
+	},
 }
 
 /// Handle for communicating with `ChainSync` asynchronously
@@ -47,6 +52,21 @@ impl<B: BlockT> ChainSyncInterfaceHandle<B> {
 	pub fn new(tx: TracingUnboundedSender<ToServiceCommand<B>>) -> Self {
 		Self { tx }
 	}
+
+	/// Notify ChainSync about finalized block
+	pub fn on_block_finalized(&self, hash: B::Hash, number: NumberFor<B>) {
+		let _ = self.tx.unbounded_send(ToServiceCommand::BlockFinalized(hash, number));
+	}
+
+	/// Get sync status
+	///
+	/// Returns an error if `ChainSync` has terminated.
+	pub async fn status(&self) -> Result<SyncStatus<B>, ()> {
+		let (tx, rx) = oneshot::channel();
+		let _ = self.tx.unbounded_send(ToServiceCommand::Status { pending_response: tx });
+
+		rx.await.map_err(|_| ())
+	}
 }
 
 impl<B: BlockT + 'static> NetworkSyncForkRequest<B::Hash, NumberFor<B>>

substrate/client/network/test/src/lib.rs

@@ -31,7 +31,7 @@ use std::{
 	time::Duration,
 };
 
-use futures::{channel::oneshot, future::BoxFuture, prelude::*};
+use futures::{channel::oneshot, future::BoxFuture, pin_mut, prelude::*};
 use libp2p::{build_multiaddr, PeerId};
 use log::trace;
 use parking_lot::Mutex;
@@ -83,7 +83,7 @@ use sp_runtime::{
 };
 use substrate_test_runtime_client::AccountKeyring;
 pub use substrate_test_runtime_client::{
-	runtime::{Block, Extrinsic, Hash, Transfer},
+	runtime::{Block, Extrinsic, Hash, Header, Transfer},
 	TestClient, TestClientBuilder, TestClientBuilderExt,
 };
 use tokio::time::timeout;
@@ -1078,8 +1078,17 @@ where
 		self.mut_peers(|peers| {
 			for (i, peer) in peers.iter_mut().enumerate() {
 				trace!(target: "sync", "-- Polling {}: {}", i, peer.id());
-				if let Poll::Ready(()) = peer.network.poll_unpin(cx) {
+				loop {
-					panic!("NetworkWorker has terminated unexpectedly.")
+					// The code below is not quite correct, because we are polling a different
+					// instance of the future every time. But as long as
+					// `NetworkWorker::next_action()` contains just streams polling not interleaved
+					// with other `.await`s, dropping the future and recreating it works the same as
+					// polling a single instance.
+					let net_poll_future = peer.network.next_action();
+					pin_mut!(net_poll_future);
+					if let Poll::Pending = net_poll_future.poll(cx) {
+						break
+					}
 				}
 				trace!(target: "sync", "-- Polling complete {}: {}", i, peer.id());
 

substrate/client/offchain/src/api.rs

@@ -419,6 +419,10 @@ mod tests {
 		fn local_peer_id(&self) -> PeerId {
 			PeerId::random()
 		}
+
+		fn listen_addresses(&self) -> Vec<Multiaddr> {
+			Vec::new()
+		}
 	}
 
 	fn offchain_api() -> (Api, AsyncApi) {

substrate/client/offchain/src/lib.rs

@@ -270,6 +270,10 @@ mod tests {
 		fn local_peer_id(&self) -> PeerId {
 			PeerId::random()
 		}
+
+		fn listen_addresses(&self) -> Vec<Multiaddr> {
+			Vec::new()
+		}
 	}
 
 	impl NetworkPeers for TestNetwork {

substrate/client/service/src/builder.rs

@@ -17,7 +17,7 @@
 // along with this program. If not, see <https://www.gnu.org/licenses/>.
 
 use crate::{
-	build_network_future,
+	build_network_future, build_system_rpc_future,
 	client::{Client, ClientConfig},
 	config::{Configuration, KeystoreConfig, PrometheusConfig},
 	error::Error,
@@ -963,19 +963,29 @@ where
 		Some("networking"),
 		chain_sync_network_provider.run(network.clone()),
 	);
-	spawn_handle.spawn("import-queue", None, import_queue.run(Box::new(chain_sync_service)));
+	spawn_handle.spawn(
+		"import-queue",
+		None,
+		import_queue.run(Box::new(chain_sync_service.clone())),
+	);
 
 	let (system_rpc_tx, system_rpc_rx) = tracing_unbounded("mpsc_system_rpc", 10_000);
-
+	spawn_handle.spawn(
-	let future = build_network_future(
+		"system-rpc-handler",
-		config.role.clone(),
+		Some("networking"),
-		network_mut,
+		build_system_rpc_future(
-		client,
+			config.role.clone(),
-		system_rpc_rx,
+			network_mut.service().clone(),
-		has_bootnodes,
+			chain_sync_service.clone(),
-		config.announce_block,
+			client.clone(),
+			system_rpc_rx,
+			has_bootnodes,
+		),
 	);
 
+	let future =
+		build_network_future(network_mut, client, chain_sync_service, config.announce_block);
+
 	// TODO: Normally, one is supposed to pass a list of notifications protocols supported by the
 	// node through the `NetworkConfiguration` struct. But because this function doesn't know in
 	// advance which components, such as GrandPa or Polkadot, will be plugged on top of the

substrate/client/service/src/lib.rs

@@ -37,12 +37,16 @@ mod task_manager;
 use std::{collections::HashMap, net::SocketAddr};
 
 use codec::{Decode, Encode};
-use futures::{channel::mpsc, FutureExt, StreamExt};
+use futures::{channel::mpsc, pin_mut, FutureExt, StreamExt};
 use jsonrpsee::{core::Error as JsonRpseeError, RpcModule};
 use log::{debug, error, warn};
 use sc_client_api::{blockchain::HeaderBackend, BlockBackend, BlockchainEvents, ProofProvider};
-use sc_network::PeerId;
+use sc_network::{NetworkStateInfo, PeerId};
-use sc_network_common::{config::MultiaddrWithPeerId, service::NetworkBlock};
+use sc_network_common::{
+	config::MultiaddrWithPeerId,
+	service::{NetworkBlock, NetworkPeers},
+};
+use sc_network_sync::service::chain_sync::ChainSyncInterfaceHandle;
 use sc_utils::mpsc::TracingUnboundedReceiver;
 use sp_blockchain::HeaderMetadata;
 use sp_consensus::SyncOracle;
@@ -138,9 +142,7 @@ pub struct PartialComponents<Client, Backend, SelectChain, ImportQueue, Transact
 	pub other: Other,
 }
 
-/// Builds a never-ending future that continuously polls the network.
+/// Builds a future that continuously polls the network.
-///
-/// The `status_sink` contain a list of senders to send a periodic network status to.
 async fn build_network_future<
 	B: BlockT,
 	C: BlockchainEvents<B>
@@ -153,21 +155,21 @@ async fn build_network_future<
 		+ 'static,
 	H: sc_network_common::ExHashT,
 >(
-	role: Role,
+	network: sc_network::NetworkWorker<B, H, C>,
-	mut network: sc_network::NetworkWorker<B, H, C>,
 	client: Arc<C>,
-	mut rpc_rx: TracingUnboundedReceiver<sc_rpc::system::Request<B>>,
+	chain_sync_service: ChainSyncInterfaceHandle<B>,
-	should_have_peers: bool,
 	announce_imported_blocks: bool,
 ) {
 	let mut imported_blocks_stream = client.import_notification_stream().fuse();
 
-	// Current best block at initialization, to report to the RPC layer.
-	let starting_block = client.info().best_number;
-
 	// Stream of finalized blocks reported by the client.
 	let mut finality_notification_stream = client.finality_notification_stream().fuse();
 
+	let network_service = network.service().clone();
+
+	let network_run = network.run().fuse();
+	pin_mut!(network_run);
+
 	loop {
 		futures::select! {
 			// List of blocks that the client has imported.
@@ -176,15 +178,18 @@ async fn build_network_future<
 					Some(n) => n,
 					// If this stream is shut down, that means the client has shut down, and the
 					// most appropriate thing to do for the network future is to shut down too.
-					None => return,
+					None => {
+						debug!("Block import stream has terminated, shutting down the network future.");
+						return
+					},
 				};
 
 				if announce_imported_blocks {
-					network.service().announce_block(notification.hash, None);
+					network_service.announce_block(notification.hash, None);
 				}
 
 				if notification.is_new_best {
-					network.service().new_best_block_imported(
+					network_service.new_best_block_imported(
 						notification.hash,
 						*notification.header.number(),
 					);
@@ -193,106 +198,160 @@ async fn build_network_future<
 
 			// List of blocks that the client has finalized.
 			notification = finality_notification_stream.select_next_some() => {
-				network.on_block_finalized(notification.hash, notification.header);
+				chain_sync_service.on_block_finalized(notification.hash, *notification.header.number());
 			}
 
-			// Answer incoming RPC requests.
+			// Drive the network. Shut down the network future if `NetworkWorker` has terminated.
-			request = rpc_rx.select_next_some() => {
+			_ = network_run => {
-				match request {
+				debug!("`NetworkWorker` has terminated, shutting down the network future.");
-					sc_rpc::system::Request::Health(sender) => {
+				return
-						let _ = sender.send(sc_rpc::system::Health {
+			}
-							peers: network.peers_debug_info().len(),
+		}
-							is_syncing: network.service().is_major_syncing(),
+	}
-							should_have_peers,
+}
-						});
+
-					},
+/// Builds a future that processes system RPC requests.
-					sc_rpc::system::Request::LocalPeerId(sender) => {
+async fn build_system_rpc_future<
-						let _ = sender.send(network.local_peer_id().to_base58());
+	B: BlockT,
-					},
+	C: BlockchainEvents<B>
-					sc_rpc::system::Request::LocalListenAddresses(sender) => {
+		+ HeaderBackend<B>
-						let peer_id = (*network.local_peer_id()).into();
+		+ BlockBackend<B>
-						let p2p_proto_suffix = sc_network::multiaddr::Protocol::P2p(peer_id);
+		+ HeaderMetadata<B, Error = sp_blockchain::Error>
-						let addresses = network.listen_addresses()
+		+ ProofProvider<B>
-							.map(|addr| addr.clone().with(p2p_proto_suffix.clone()).to_string())
+		+ Send
-							.collect();
+		+ Sync
-						let _ = sender.send(addresses);
+		+ 'static,
-					},
+	H: sc_network_common::ExHashT,
-					sc_rpc::system::Request::Peers(sender) => {
+>(
-						let _ = sender.send(network.peers_debug_info().into_iter().map(|(peer_id, p)|
+	role: Role,
-							sc_rpc::system::PeerInfo {
+	network_service: Arc<sc_network::NetworkService<B, H>>,
+	chain_sync_service: ChainSyncInterfaceHandle<B>,
+	client: Arc<C>,
+	mut rpc_rx: TracingUnboundedReceiver<sc_rpc::system::Request<B>>,
+	should_have_peers: bool,
+) {
+	// Current best block at initialization, to report to the RPC layer.
+	let starting_block = client.info().best_number;
+
+	loop {
+		// Answer incoming RPC requests.
+		let Some(req) = rpc_rx.next().await else {
+			debug!("RPC requests stream has terminated, shutting down the system RPC future.");
+			return;
+		};
+
+		match req {
+			sc_rpc::system::Request::Health(sender) => {
+				let peers = network_service.peers_debug_info().await;
+				if let Ok(peers) = peers {
+					let _ = sender.send(sc_rpc::system::Health {
+						peers: peers.len(),
+						is_syncing: network_service.is_major_syncing(),
+						should_have_peers,
+					});
+				} else {
+					break
+				}
+			},
+			sc_rpc::system::Request::LocalPeerId(sender) => {
+				let _ = sender.send(network_service.local_peer_id().to_base58());
+			},
+			sc_rpc::system::Request::LocalListenAddresses(sender) => {
+				let peer_id = network_service.local_peer_id().into();
+				let p2p_proto_suffix = sc_network::multiaddr::Protocol::P2p(peer_id);
+				let addresses = network_service
+					.listen_addresses()
+					.iter()
+					.map(|addr| addr.clone().with(p2p_proto_suffix.clone()).to_string())
+					.collect();
+				let _ = sender.send(addresses);
+			},
+			sc_rpc::system::Request::Peers(sender) => {
+				let peers = network_service.peers_debug_info().await;
+				if let Ok(peers) = peers {
+					let _ = sender.send(
+						peers
+							.into_iter()
+							.map(|(peer_id, p)| sc_rpc::system::PeerInfo {
 								peer_id: peer_id.to_base58(),
 								roles: format!("{:?}", p.roles),
 								best_hash: p.best_hash,
 								best_number: p.best_number,
-							}
+							})
-						).collect());
+							.collect(),
-					}
+					);
-					sc_rpc::system::Request::NetworkState(sender) => {
+				} else {
-						if let Ok(network_state) = serde_json::to_value(&network.network_state()) {
+					break
-							let _ = sender.send(network_state);
-						}
-					}
-					sc_rpc::system::Request::NetworkAddReservedPeer(peer_addr, sender) => {
-						let result = match MultiaddrWithPeerId::try_from(peer_addr) {
-							Ok(peer) => {
-								network.add_reserved_peer(peer)
-							},
-							Err(err) => {
-								Err(err.to_string())
-							},
-						};
-						let x = result.map_err(sc_rpc::system::error::Error::MalformattedPeerArg);
-						let _ = sender.send(x);
-					}
-					sc_rpc::system::Request::NetworkRemoveReservedPeer(peer_id, sender) => {
-						let _ = match peer_id.parse::<PeerId>() {
-							Ok(peer_id) => {
-								network.remove_reserved_peer(peer_id);
-								sender.send(Ok(()))
-							}
-							Err(e) => sender.send(Err(sc_rpc::system::error::Error::MalformattedPeerArg(
-								e.to_string(),
-							))),
-						};
-					}
-					sc_rpc::system::Request::NetworkReservedPeers(sender) => {
-						let reserved_peers = network.reserved_peers();
-						let reserved_peers = reserved_peers
-							.map(|peer_id| peer_id.to_base58())
-							.collect();
-
-						let _ = sender.send(reserved_peers);
-					}
-					sc_rpc::system::Request::NodeRoles(sender) => {
-						use sc_rpc::system::NodeRole;
-
-						let node_role = match role {
-							Role::Authority { .. } => NodeRole::Authority,
-							Role::Full => NodeRole::Full,
-						};
-
-						let _ = sender.send(vec![node_role]);
-					}
-					sc_rpc::system::Request::SyncState(sender) => {
-						use sc_rpc::system::SyncState;
-
-						let best_number = client.info().best_number;
-
-						let _ = sender.send(SyncState {
-							starting_block,
-							current_block: best_number,
-							highest_block: network.best_seen_block().unwrap_or(best_number),
-						});
-					}
 				}
-			}
+			},
+			sc_rpc::system::Request::NetworkState(sender) => {
+				let network_state = network_service.network_state().await;
+				if let Ok(network_state) = network_state {
+					if let Ok(network_state) = serde_json::to_value(network_state) {
+						let _ = sender.send(network_state);
+					}
+				} else {
+					break
+				}
+			},
+			sc_rpc::system::Request::NetworkAddReservedPeer(peer_addr, sender) => {
+				let result = match MultiaddrWithPeerId::try_from(peer_addr) {
+					Ok(peer) => network_service.add_reserved_peer(peer),
+					Err(err) => Err(err.to_string()),
+				};
+				let x = result.map_err(sc_rpc::system::error::Error::MalformattedPeerArg);
+				let _ = sender.send(x);
+			},
+			sc_rpc::system::Request::NetworkRemoveReservedPeer(peer_id, sender) => {
+				let _ = match peer_id.parse::<PeerId>() {
+					Ok(peer_id) => {
+						network_service.remove_reserved_peer(peer_id);
+						sender.send(Ok(()))
+					},
+					Err(e) => sender.send(Err(sc_rpc::system::error::Error::MalformattedPeerArg(
+						e.to_string(),
+					))),
+				};
+			},
+			sc_rpc::system::Request::NetworkReservedPeers(sender) => {
+				let reserved_peers = network_service.reserved_peers().await;
+				if let Ok(reserved_peers) = reserved_peers {
+					let reserved_peers =
+						reserved_peers.iter().map(|peer_id| peer_id.to_base58()).collect();
+					let _ = sender.send(reserved_peers);
+				} else {
+					break
+				}
+			},
+			sc_rpc::system::Request::NodeRoles(sender) => {
+				use sc_rpc::system::NodeRole;
 
-			// The network worker has done something. Nothing special to do, but could be
+				let node_role = match role {
-			// used in the future to perform actions in response of things that happened on
+					Role::Authority { .. } => NodeRole::Authority,
-			// the network.
+					Role::Full => NodeRole::Full,
-			_ = (&mut network).fuse() => {}
+				};
+
+				let _ = sender.send(vec![node_role]);
+			},
+			sc_rpc::system::Request::SyncState(sender) => {
+				use sc_rpc::system::SyncState;
+
+				let best_number = client.info().best_number;
+
+				let Ok(status) = chain_sync_service.status().await else {
+					debug!("`ChainSync` has terminated, shutting down the system RPC future.");
+					return
+				};
+
+				let _ = sender.send(SyncState {
+					starting_block,
+					current_block: best_number,
+					highest_block: status.best_seen_block.unwrap_or(best_number),
+				});
+			},
 		}
 	}
+	debug!("`NetworkWorker` has terminated, shutting down the system RPC future.");
 }
 
 // Wrapper for HTTP and WS servers that makes sure they are properly shut down.