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/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>>