Asyncify launch_work a bit more (#777)

* Asyncify launch_work a bit more

* An error message misword

* A bit more async in collator

polkadot/collator/src/lib.rs

@@ -363,13 +363,15 @@ fn run_collator_node<S, E, P, Extrinsic>(
 	};
 
 	let inner_exit = exit.clone();
-	let work = client.import_notification_stream()
-		.for_each(move |notification| {
+	let work = async move {
+		let mut notification_stream = client.import_notification_stream();
+
+		while let Some(notification) = notification_stream.next().await {
 			macro_rules! try_fr {
 				($e:expr) => {
 					match $e {
 						Ok(x) => x,
-						Err(e) => return future::Either::Left(future::err(Error::Polkadot(
+						Err(e) => return (future::err(Error::Polkadot(
 							format!("{:?}", e)
 						))),
 					}
@@ -386,11 +388,11 @@ fn run_collator_node<S, E, P, Extrinsic>(
 			let validation_network = validation_network.clone();
 			let inner_exit_2 = inner_exit.clone();
 
-			let work = future::lazy(move |_| {
+			let work = future::lazy(move |_| async move {
 				let api = client.runtime_api();
 				let status = match try_fr!(api.parachain_status(&id, para_id)) {
 					Some(status) => status,
-					None => return future::Either::Left(future::ok(())),
+					None => return future::ok(()),
 				};
 
 				let validators = try_fr!(api.validators(&id));
@@ -407,14 +409,14 @@ fn run_collator_node<S, E, P, Extrinsic>(
 					validators,
 				};
 
-				let collation_work = collate(
+				if let Ok((collation, outgoing)) = collate(
 					relay_parent,
 					para_id,
 					status,
 					context,
 					parachain_context,
 					key,
-				).map_ok(move |(collation, outgoing)| {
+				).await {
 					network.with_spec(move |spec, ctx| {
 						let res = spec.add_local_collation(
 							ctx,
@@ -426,10 +428,9 @@ fn run_collator_node<S, E, P, Extrinsic>(
 
 						let exit = inner_exit_2.clone();
 						tokio::spawn(future::select(res.boxed(), exit).map(drop).map(|_| Ok(())).compat());
-					})
 					});
-
-				future::Either::Right(collation_work)
+				}
+				future::ok(())
 			});
 
 			let deadlined = future::select(
@@ -450,8 +451,8 @@ fn run_collator_node<S, E, P, Extrinsic>(
 				).map(drop);
 
 			tokio::spawn(future.map(|_| Ok(())).compat());
-			future::ready(())
-		});
+		}
+	}.boxed();
 
 	service.spawn_essential_task(work);
 

polkadot/validation/src/validation_service/mod.rs

@@ -34,7 +34,7 @@ use sp_blockchain::HeaderBackend;
 use block_builder::BlockBuilderApi;
 use consensus::SelectChain;
 use futures::prelude::*;
-use futures::{future::{ready, select}, task::{Spawn, SpawnExt}};
+use futures::{future::select, task::{Spawn, SpawnExt}};
 use polkadot_primitives::{Block, Hash, BlockId};
 use polkadot_primitives::parachain::{
 	Chain, ParachainHost, Id as ParaId, ValidatorIndex, ValidatorId, ValidatorPair,
@@ -384,18 +384,18 @@ impl<C, N, P> ParachainValidationInstances<C, N, P> where
 		let (collators, client) = (self.collators.clone(), self.client.clone());
 		let availability_store = self.availability_store.clone();
 
-		let with_router = move |router: N::TableRouter| {
+		let with_router = move |router: N::TableRouter| async move {
 			// fetch a local collation from connected collators.
-			let collation_work = crate::collation::collation_fetch(
+			match crate::collation::collation_fetch(
 				validation_para,
 				relay_parent,
 				collators,
 				client.clone(),
 				max_block_data_size,
-			);
+			).await {
+				Ok(collation_work) => {
+					let (collation, outgoing_targeted, fees_charged) = collation_work;
 
-			collation_work.map(move |result| match result {
-				Ok((collation, outgoing_targeted, fees_charged)) => {
 					match crate::collation::produce_receipt_and_chunks(
 						authorities_num,
 						&collation.pov,
@@ -410,41 +410,33 @@ impl<C, N, P> ParachainValidationInstances<C, N, P> where
 							let chunks_clone = chunks.clone();
 							let receipt_clone = receipt.clone();
 
-							let res = async move {
 							if let Err(e) = av_clone.clone().add_erasure_chunks(
 								relay_parent.clone(),
 								receipt_clone,
 								chunks_clone,
 							).await {
-									warn!(target: "validation", "Failed to add erasure chunks: {}", e);
-								}
-							}
-							.unit_error()
-							.boxed()
-							.then(move |_| {
+								warn!(
+									target: "validation",
+									"Failed to add erasure chunks: {}", e
+								);
+							} else {
 								router.local_collation(
 									collation,
 									receipt,
 									outgoing_targeted,
 									(local_id, &chunks),
 								);
-								ready(())
-							});
-
-
-							Some(res)
+							}
 						}
 						Err(e) => {
 							warn!(target: "validation", "Failed to produce a receipt: {:?}", e);
-							None
-						}
 						}
+					};
 				}
 				Err(e) => {
-					warn!(target: "validation", "Failed to collate candidate: {:?}", e);
-					None
+					warn!(target: "validation", "Failed to fetch a candidate: {:?}", e);
+				}
 			}
-			})
 		};
 
 		let router = build_router