Make communication_for exit when we end a round (#313)

* Make `communication_for` exit when we end a round

* Fix compilation

polkadot/validation/src/lib.rs

@@ -147,6 +147,7 @@ pub trait Network {
 		&self,
 		table: Arc<SharedTable>,
 		authorities: &[SessionKey],
+		exit: exit_future::Exit,
 	) -> Self::BuildTableRouter;
 }
 
@@ -313,11 +314,14 @@ impl<C, N, P> ParachainValidation<C, N, P> where
 		let (group_info, local_duty) = make_group_info(
 			duty_roster,
 			&authorities,
-			sign_with.public().into(),
+			sign_with.public(),
 		)?;
 
-		info!("Starting parachain attestation session on top of parent {:?}. Local parachain duty is {:?}",
-			parent_hash, local_duty.validation);
+		info!(
+			"Starting parachain attestation session on top of parent {:?}. Local parachain duty is {:?}",
+			parent_hash,
+			local_duty.validation,
+		);
 
 		let active_parachains = self.client.runtime_api().active_parachains(&id)?;
 
@@ -331,25 +335,23 @@ impl<C, N, P> ParachainValidation<C, N, P> where
 			self.extrinsic_store.clone(),
 			max_block_data_size,
 		));
+
+		let (_drop_signal, exit) = exit_future::signal();
+
 		let router = self.network.communication_for(
 			table.clone(),
 			&authorities,
+			exit.clone(),
 		);
 
-		let drop_signal = match local_duty.validation {
-			Chain::Parachain(id) => Some(self.launch_work(
-				parent_hash,
-				id,
-				router,
-				max_block_data_size,
-			)),
-			Chain::Relay => None,
-		};
+		if let Chain::Parachain(id) = local_duty.validation {
+			self.launch_work(parent_hash, id, router, max_block_data_size, exit);
+		}
 
 		let tracker = Arc::new(AttestationTracker {
 			table,
 			started: Instant::now(),
-			_drop_signal: drop_signal
+			_drop_signal,
 		});
 
 		live_instances.insert(parent_hash, tracker.clone());
@@ -369,10 +371,10 @@ impl<C, N, P> ParachainValidation<C, N, P> where
 		validation_para: ParaId,
 		build_router: N::BuildTableRouter,
 		max_block_data_size: Option<u64>,
-	) -> exit_future::Signal {
+		exit: exit_future::Exit,
+	) {
 		use extrinsic_store::Data;
 
-		let (signal, exit) = exit_future::signal();
 		let (collators, client) = (self.collators.clone(), self.client.clone());
 		let extrinsic_store = self.extrinsic_store.clone();
 
@@ -428,16 +430,15 @@ impl<C, N, P> ParachainValidation<C, N, P> where
 			.then(|_| Ok(()));
 
 		// spawn onto thread pool.
-		if let Err(_) = self.handle.execute(Box::new(cancellable_work)) {
+		if self.handle.execute(Box::new(cancellable_work)).is_err() {
 			error!("Failed to spawn cancellable work task");
 		}
-		signal
 	}
 }
 
 /// Parachain validation for a single block.
 struct AttestationTracker {
-	_drop_signal: Option<exit_future::Signal>,
+	_drop_signal: exit_future::Signal,
 	table: Arc<SharedTable>,
 	started: Instant,
 }
@@ -544,7 +545,7 @@ impl<C, N, P, SC, TxApi> consensus::Environment<Block> for ProposerFactory<C, N,
 			parent_id,
 			parent_number: parent_header.number,
 			transaction_pool: self.transaction_pool.clone(),
-			slot_duration: self.aura_slot_duration.clone(),
+			slot_duration: self.aura_slot_duration,
 		})
 	}
 }