Rewrite some Future structs as async functions (#679)

* Squashed commit of the following: commit e97a17157ae0887320994661e2f816275fc75b76 Author: Ashley <ashley.ruglys@gmail.com> Date: Tue Dec 10 15:06:28 2019 +0100 Rewrite some functions as async commit 970e485179f1e087cf0a51c6a4e71f923e87df45 Merge: f98966ac df3ea965 Author: Ashley <ashley.ruglys@gmail.com> Date: Tue Dec 10 11:19:37 2019 +0100 Merge remote-tracking branch 'parity/master' into ashley-futures-update commit f98966ac188067158071d1e3e243c34ea5738f56 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 23:40:20 2019 +0100 Add async blocks back in commit 7fa88af0271db659de9274c94cb8e7eead0e4289 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 23:17:02 2019 +0100 Revert "Asyncify network functions" This reverts commit f20ae6548dc482cb1e75bc80641cfe55c6131a53. commit 82413550cdac40bd14a09f62df12de49dd7e55af Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 19:09:55 2019 +0100 Fix validation test again commit 47e002b08369c9c775b92aea9b6f6ed81b30241b Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 19:07:43 2019 +0100 Switch favicon commit 0c5c1409078fc57120a39e40ec5cb1763d67d593 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 18:54:10 2019 +0100 Fix validation test commit 8bb6a0189fe824da09054cbf5b06f11a0f87072d Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 18:53:54 2019 +0100 Nits commit 33410f3a4910d3e688956cecfcca02cc2dfa6a7a Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 18:43:09 2019 +0100 Fix av store test commit f0c517eb240c42848cdb3305e0b554ef407bdfaa Merge: 938f411a 60e72111 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 18:21:39 2019 +0100 Merge branch 'ashley-futures-updates' into ashley-futures-update commit 60e72111651f2b366592c1e56756c6bf5d8ce2f1 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 18:19:40 2019 +0100 Clean up browser validation worker error commit f20ae6548dc482cb1e75bc80641cfe55c6131a53 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 18:16:40 2019 +0100 Asyncify network functions commit b22758d0a3852d701923bd238484e1c9eabec5e2 Merge: 2e8b05ed ef562cd7 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 17:47:26 2019 +0100 Merge remote-tracking branch 'parity/master' into ashley-futures-updates commit 2e8b05edf1a1fadd6943f967c27b6d34675ba06a Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 17:45:52 2019 +0100 Box pin changes commit 08bfdf7f2d27721abffee49221213304ebc4fd47 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 17:15:38 2019 +0100 Update network/src/lib.rs Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com> commit d8be456c508d5e5a03178db45d9f272b302a8a65 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 17:15:32 2019 +0100 Update network/src/lib.rs Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com> commit ec7367276fdd374b19f41555fd5985454c559600 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 17:14:36 2019 +0100 Update availability-store/src/worker.rs Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com> commit 938f411a9365e9c5fb16bfedb62aacac4403d063 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 17:05:05 2019 +0100 Revert "Revert removal of tokio_executor that causes tokio version mismatch panic" This reverts commit cfeb50c01d8df5e209483406a711e64761b44ae9. commit f92f58044b4fe04bde73a60820d154080dd64b16 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 15:47:35 2019 +0100 Fix adder test parachain commit cfeb50c01d8df5e209483406a711e64761b44ae9 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 15:31:36 2019 +0100 Revert removal of tokio_executor that causes tokio version mismatch panic commit 5bcb83a122b9a30f240a238ca670c6b658f4ddf1 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 15:17:55 2019 +0100 Fix typo commit fc02b1dc16e277649677396833a8d70e8588a56c Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 15:02:50 2019 +0100 Fix collator commit 6c4ff5b3bf1084a618ffec2d864090c9c8077f0f Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 14:35:37 2019 +0100 Small changes commit e1338cb4450df5377d8c911da56445914d667472 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 14:24:42 2019 +0100 Fix network tests commit 4e458f7a91c1ed5c986795f40ed55e596d176c4b Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 12:25:26 2019 +0100 Remove futures01 from availability-store commit 5729f6cd6b53f061ff155320c815509feb02309e Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 12:22:33 2019 +0100 Fix validation tests commit a820612565b42780f8b6c09c9c1c30f06a9985ba Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 12:01:48 2019 +0100 Fix availability store tests commit 112344faeee5f8f03b3b87c6baf7036a7fcbe415 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 11:36:03 2019 +0100 Update tokio version commit d2de6d8b3f0c3682679fe437d5459ac50a3c3895 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 11:33:25 2019 +0100 Revert cli tokio version to avoid libp2p panic commit 0c5f24e0c1131ac58a947448456e7fb62c869702 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 9 11:27:13 2019 +0100 Switch to polkadot-master commit 2e2311e33a4af87c2c545094ea8cb595cd6cfe2d Author: Ashley <ashley.ruglys@gmail.com> Date: Fri Dec 6 15:07:21 2019 +0100 Re-add release flag commit 6adc1b6114e154a590acf82acfaf0c1265409518 Merge: 9767f832 533c80ad Author: Ashley <ashley.ruglys@gmail.com> Date: Fri Dec 6 13:36:35 2019 +0100 Merge remote-tracking branch 'parity/master' into ashley-compile-to-wasm commit 9767f8325c33211065ef6830becdac0e3cf852de Merge: c528dc6d 0bf7d294 Author: Ashley <ashley.ruglys@gmail.com> Date: Wed Dec 4 17:11:39 2019 +0100 Merge remote-tracking branch 'parity/master' into ashley-compile-to-wasm commit c528dc6df8fc31cdcbc10889636355241398debd Author: Ashley <ashley.ruglys@gmail.com> Date: Wed Dec 4 17:07:00 2019 +0100 Fix wasm build commit da233a122c678dc7767dac7cc6e2564575b15cc8 Author: Ashley <ashley.ruglys@gmail.com> Date: Wed Dec 4 16:25:49 2019 +0100 tidy commit 832f8054df78afbcef1903e0f9e7e246b348c10d Merge: 4e1da888 121c917d Author: Ashley <ashley.ruglys@gmail.com> Date: Wed Dec 4 15:56:56 2019 +0100 Merge remote-tracking branch 'parity/master' into ashley-compile-to-wasm commit 4e1da8888dd2160064dd453782fb05513c65ade4 Author: Ashley <ashley.ruglys@gmail.com> Date: Tue Dec 3 16:47:02 2019 +0100 Temp switch back to substrate/master commit af88a87338688797bbc52315fdd0fc22cf23c6cf Merge: a03a980c 7832ad93 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 2 19:33:14 2019 +0100 Merge remote-tracking branch 'parity/master' into ashley-compile-to-wasm commit a03a980ce417ec7b446bfcbe7a66ec0ed6458135 Merge: 31a88a93 0c1ef335 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 2 13:52:37 2019 +0100 Merge remote-tracking branch 'parity/master' into ashley-compile-to-wasm commit 31a88a930ffdf5da72b3e587ec8c0e6b00922e3e Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 2 13:52:35 2019 +0100 Tidy commit 5b33b7a7af08d7a3aa3853b8e4995484fb640d52 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 2 11:55:51 2019 +0100 Add browser-demo commit 868f6e51dfdc0a64252acd9adabe7b9ba436b1f4 Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 2 10:51:57 2019 +0100 Add initial browser file commit e5e399c20f1dc4e1023ee57773dcdd9ab2a0a14b Author: Ashley <ashley.ruglys@gmail.com> Date: Mon Dec 2 10:45:02 2019 +0100 Add browser-demo commit 408288b05292d952944a6b8e1f2bcf9cf259a040 Author: Ashley <ashley.ruglys@gmail.com> Date: Sun Dec 1 19:28:33 2019 +0100 Get polkadot to compile via wasm! commit 04ffe72e868be57841d31f01eec1b90423a595d6 Author: Ashley <ashley.ruglys@gmail.com> Date: Sun Dec 1 19:28:16 2019 +0100 Migrate service commit 119f0829a53b825a3ebc9efdefa76ae7eabb04aa Merge: 93fb6428 37fec553 Author: Ashley <ashley.ruglys@gmail.com> Date: Sun Dec 1 17:43:49 2019 +0100 Merge remote-tracking branch 'parity/master' into ashley-compile-to-wasm commit 93fb6428501bac612a1675cf3b6e3d26f5bbc7c2 Author: Ashley <ashley.ruglys@gmail.com> Date: Sun Dec 1 12:21:25 2019 +0100 Switch branch commit 0c4fe8331bdc9665ac2427eb8c795112ac728d70 Author: Ashley <ashley.ruglys@gmail.com> Date: Sat Nov 30 11:45:59 2019 +0100 Tidy up validation commit 73563253d95962657108820ae130a8d3f3093ee8 Author: Ashley <ashley.ruglys@gmail.com> Date: Sat Nov 30 11:39:09 2019 +0100 Tidy up network commit 1c9cf0427c0e2d15c4b6d52b91d67d4a3963e30d Author: Ashley <ashley.ruglys@gmail.com> Date: Sat Nov 30 01:16:35 2019 +0100 Final changes to validation commit 322cca5224fdca0a29d88ff91700ef704a9d0c2a Author: Ashley <ashley.ruglys@gmail.com> Date: Sat Nov 30 00:31:55 2019 +0100 Migrate network to std futures commit 96f1a99491f5ae2957effa58cc1e385014575a32 Author: Ashley <ashley.ruglys@gmail.com> Date: Fri Nov 29 23:31:04 2019 +0100 Migrate validation to std futures commit aaf5e55fffd1367c05687eb34f4365a24e3a34c0 Author: Ashley <ashley.ruglys@gmail.com> Date: Fri Nov 29 17:10:11 2019 +0100 Switch to Spawn trait commit 2ab282f57e8b9a55cf8d285b283cf009216511d2 Merge: cceb6b72 ed7ee572 Author: Ashley <ashley.ruglys@gmail.com> Date: Fri Nov 29 16:31:24 2019 +0100 Merge remote-tracking branch 'parity/master' into ashley-compile-to-wasm commit cceb6b72f5677a1c43d2cd61bd525539054f0c01 Author: Ashley <ashley.ruglys@gmail.com> Date: Fri Nov 29 15:47:14 2019 +0100 Make validation work on wasm! commit b45a95cf7d829a916bf2ad6936d1e7f4b6f3ef77 Merge: 4ec635ee db7eaa6b Author: Ashley <ashley.ruglys@gmail.com> Date: Fri Nov 29 13:57:23 2019 +0100 Merge remote-tracking branch 'tomaka/wasm-start' into HEAD commit db7eaa6bd5d3bbcea829570fb47ab4d06f3558ce Merge: 6f97dbb7 f826ce53 Author: Pierre Krieger <pierre.krieger1708@gmail.com> Date: Thu Nov 28 13:58:15 2019 +0100 Merge branch 'master' into wasm-start commit 6f97dbb786750d854cf8f7a56c6a336ea5979228 Author: Pierre Krieger <pierre.krieger1708@gmail.com> Date: Thu Nov 28 12:47:45 2019 +0100 Use --manifest-path instead commit 20104e98ff1713b6c81b0251b43d060d4e672d55 Author: Pierre Krieger <pierre.krieger1708@gmail.com> Date: Thu Nov 28 10:44:51 2019 +0100 Make availability-store compile for WASM * Fix build * Fix futures blocking panic in validators (again) * Deindent
2026-05-30 21:01:02 +00:00 · 2019-12-13 18:37:34 +01:00
parent 68132e3fd3
commit 10ecc32c55
10 changed files with 178 additions and 448 deletions
@@ -48,6 +48,7 @@ use std::collections::HashSet;
 use std::fmt;
 use std::sync::Arc;
 use std::time::Duration;
+use std::pin::Pin;

 use futures::{future, Future, Stream, FutureExt, TryFutureExt, StreamExt, task::Spawn};
 use log::{warn, error};
@@ -242,20 +243,26 @@ impl<P: 'static, E: 'static, SP: 'static> RelayChainContext for ApiContext<P, E,
 	SP: Spawn + Clone + Send + Sync
 {
 	type Error = String;
-	type FutureEgress = Box<dyn Future<Output=Result<ConsolidatedIngress, String>> + Unpin + Send>;
+	type FutureEgress = Pin<Box<dyn Future<Output=Result<ConsolidatedIngress, String>> + Send>>;

 	fn unrouted_egress(&self, _id: ParaId) -> Self::FutureEgress {
-		// TODO: https://github.com/paritytech/polkadot/issues/253
-		//
-		// Fetch ingress and accumulate all unrounted egress
-		let _session = self.network.instantiate_leaf_work(LeafWorkParams {
-			local_session_key: None,
-			parent_hash: self.parent_hash,
-			authorities: self.validators.clone(),
-		})
-			.map_err(|e| format!("unable to instantiate validation session: {:?}", e));
+		let network = self.network.clone();
+		let parent_hash = self.parent_hash;
+		let authorities = self.validators.clone();

-		Box::new(future::ok(ConsolidatedIngress(Vec::new())))
+		async move {
+			// TODO: https://github.com/paritytech/polkadot/issues/253
+			//
+			// Fetch ingress and accumulate all unrounted egress
+			let _session = network.instantiate_leaf_work(LeafWorkParams {
+				local_session_key: None,
+				parent_hash,
+				authorities,
+			})
+				.map_err(|e| format!("unable to instantiate validation session: {:?}", e));
+
+			Ok(ConsolidatedIngress(Vec::new()))
+		}.boxed()
 	}
 }

@@ -425,7 +432,7 @@ impl<P, E> Worker for CollationNode<P, E> where
 							);

 							let exit = inner_exit_2.clone();
-							tokio::spawn(future::select(res, exit).map(drop));
+							tokio::spawn(future::select(res.boxed(), exit).map(drop));
 						})
 					});

@@ -28,7 +28,6 @@ pub mod gossip;
 use codec::{Decode, Encode};
 use futures::channel::{oneshot, mpsc};
 use futures::prelude::*;
-use futures::future::Either;
 use polkadot_primitives::{Block, Hash, Header};
 use polkadot_primitives::parachain::{
 	Id as ParaId, CollatorId, CandidateReceipt, Collation, PoVBlock,
@@ -837,25 +836,6 @@ impl PolkadotProtocol {
 		debug!(target: "p_net", "Importing local collation on relay parent {:?} and parachain {:?}",
 			relay_parent, collation.info.parachain_index);

-		let res = match self.availability_store {
-			Some(ref availability_store) => {
-				let availability_store_cloned = availability_store.clone();
-				let collation_cloned = collation.clone();
-				Either::Left((async move {
-						let _ = availability_store_cloned.make_available(av_store::Data {
-							relay_parent,
-							parachain_id: collation_cloned.info.parachain_index,
-							block_data: collation_cloned.pov.block_data.clone(),
-							outgoing_queues: Some(outgoing_targeted.clone().into()),
-						}).await;
-					}
-				)
-					.boxed()
-				)
-			}
-			None => Either::Right(futures::future::ready(())),
-		};
-
 		for (primary, cloned_collation) in self.local_collations.add_collation(relay_parent, targets, collation.clone()) {
 			match self.validators.get(&primary) {
 				Some(who) => {
@@ -871,7 +851,19 @@ impl PolkadotProtocol {
 			}
 		}

-		res
+		let availability_store = self.availability_store.clone();
+		let collation_cloned = collation.clone();
+
+		async move {
+			if let Some(availability_store) = availability_store {
+				let _ = availability_store.make_available(av_store::Data {
+					relay_parent,
+					parachain_id: collation_cloned.info.parachain_index,
+					block_data: collation_cloned.pov.block_data.clone(),
+					outgoing_queues: Some(outgoing_targeted.clone().into()),
+				}).await;
+			}
+		}
 	}

 	/// Give the network protocol a handle to an availability store, used for
@@ -41,8 +41,9 @@ use log::{debug, trace};
 use std::collections::{HashMap, HashSet};
 use std::io;
 use std::sync::Arc;
+use std::pin::Pin;

-use crate::validation::{self, LeafWorkDataFetcher, Executor};
+use crate::validation::{LeafWorkDataFetcher, Executor};
 use crate::NetworkService;

 /// Compute the gossip topic for attestations on the given parent hash.
@@ -232,7 +233,7 @@ impl<P: ProvideRuntimeApi + Send, E, N, T> TableRouter for Router<P, E, N, T> wh
 	E: Future<Output=()> + Clone + Send + 'static,
 {
 	type Error = io::Error;
-	type FetchValidationProof = validation::PoVReceiver;
+	type FetchValidationProof = Pin<Box<dyn Future<Output = Result<PoVBlock, io::Error>> + Send>>;

 	// We have fetched from a collator and here the receipt should have been already formed.
 	fn local_collation(
@@ -41,7 +41,7 @@ use std::collections::HashMap;
 use std::sync::Arc;
 use std::pin::Pin;
 use std::task::{Poll, Context};
-use futures::{prelude::*, channel::mpsc};
+use futures::{prelude::*, channel::mpsc, future::{select, Either}};
 use codec::Encode;

 use super::{TestContext, TestChainContext};
@@ -66,77 +66,48 @@ fn clone_gossip(n: &TopicNotification) -> TopicNotification {
 	}
 }

-struct GossipRouter {
-	incoming_messages: mpsc::UnboundedReceiver<(Hash, TopicNotification)>,
-	incoming_streams: mpsc::UnboundedReceiver<(Hash, mpsc::UnboundedSender<TopicNotification>)>,
-	outgoing: Vec<(Hash, mpsc::UnboundedSender<TopicNotification>)>,
-	messages: Vec<(Hash, TopicNotification)>,
-}
+async fn gossip_router(
+	mut incoming_messages: mpsc::UnboundedReceiver<(Hash, TopicNotification)>,
+	mut incoming_streams: mpsc::UnboundedReceiver<(Hash, mpsc::UnboundedSender<TopicNotification>)>
+) {
+	let mut outgoing: Vec<(Hash, mpsc::UnboundedSender<TopicNotification>)> = Vec::new();
+	let mut messages = Vec::new();

-impl GossipRouter {
-	fn add_message(&mut self, topic: Hash, message: TopicNotification) {
-		self.outgoing.retain(|&(ref o_topic, ref sender)| {
-			o_topic != &topic || sender.unbounded_send(clone_gossip(&message)).is_ok()
-		});
-		self.messages.push((topic, message));
-	}
+	loop {
+		match select(incoming_messages.next(), incoming_streams.next()).await {
+			Either::Left((Some((topic, message)), _)) => {
+				outgoing.retain(|&(ref o_topic, ref sender)| {
+					o_topic != &topic || sender.unbounded_send(clone_gossip(&message)).is_ok()
+				});
+				messages.push((topic, message));
+			},
+			Either::Right((Some((topic, sender)), _)) => {
+				for message in messages.iter()
+					.filter(|&&(ref t, _)| t == &topic)
+					.map(|&(_, ref msg)| clone_gossip(msg))
+				{
+					if let Err(_) = sender.unbounded_send(message) { return }
+				}

-	fn add_outgoing(&mut self, topic: Hash, sender: mpsc::UnboundedSender<TopicNotification>) {
-		for message in self.messages.iter()
-			.filter(|&&(ref t, _)| t == &topic)
-			.map(|&(_, ref msg)| clone_gossip(msg))
-		{
-			if let Err(_) = sender.unbounded_send(message) { return }
+				outgoing.push((topic, sender));
+			},
+			Either::Left((None, _)) | Either::Right((None, _)) =>  panic!("ended early.")
 		}
-
-		self.outgoing.push((topic, sender));
 	}
 }

-impl Future for GossipRouter {
-	type Output = ();
-
-	fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
-		let this = Pin::into_inner(self);
-
-		loop {
-			match Pin::new(&mut this.incoming_messages).poll_next(cx) {
-				Poll::Ready(Some((topic, message))) => this.add_message(topic, message),
-				Poll::Ready(None) => panic!("ended early."),
-				Poll::Pending => break,
-			}
-		}
-
-		loop {
-			match Pin::new(&mut this.incoming_streams).poll_next(cx) {
-				Poll::Ready(Some((topic, sender))) => this.add_outgoing(topic, sender),
-				Poll::Ready(None) => panic!("ended early."),
-				Poll::Pending => break,
-			}
-		}
-
-		Poll::Pending
-	}
-}
-
-
 #[derive(Clone)]
 struct GossipHandle {
 	send_message: mpsc::UnboundedSender<(Hash, TopicNotification)>,
 	send_listener: mpsc::UnboundedSender<(Hash, mpsc::UnboundedSender<TopicNotification>)>,
 }

-fn make_gossip() -> (GossipRouter, GossipHandle) {
+fn make_gossip() -> (impl Future<Output = ()>, GossipHandle) {
 	let (message_tx, message_rx) = mpsc::unbounded();
 	let (listener_tx, listener_rx) = mpsc::unbounded();

 	(
-		GossipRouter {
-			incoming_messages: message_rx,
-			incoming_streams: listener_rx,
-			outgoing: Vec::new(),
-			messages: Vec::new(),
-		},
+		gossip_router(message_rx, listener_rx),
 		GossipHandle { send_message: message_tx, send_listener: listener_tx },
 	)
 }
@@ -344,7 +315,7 @@ type TestValidationNetwork = crate::validation::ValidationNetwork<
 >;

 struct Built {
-	gossip: GossipRouter,
+	gossip: Pin<Box<dyn Future<Output = ()>>>,
 	api_handle: Arc<Mutex<ApiData>>,
 	networks: Vec<TestValidationNetwork>,
 }
@@ -377,7 +348,7 @@ fn build_network(n: usize, executor: TaskExecutor) -> Built {
 	let networks: Vec<_> = networks.collect();

 	Built {
-		gossip: gossip_router,
+		gossip: gossip_router.boxed(),
 		api_handle,
 		networks,
 	}
@@ -33,14 +33,13 @@ use polkadot_primitives::parachain::{
 use futures::prelude::*;
 use futures::task::SpawnExt;
 pub use futures::task::Spawn as Executor;
-use futures::channel::oneshot::{self, Receiver};
+use futures::channel::oneshot;
 use futures::future::{ready, select};

 use std::collections::hash_map::{HashMap, Entry};
 use std::io;
 use std::sync::Arc;
 use std::pin::Pin;
-use std::task::{Poll, Context};

 use arrayvec::ArrayVec;
 use parking_lot::Mutex;
@@ -242,47 +241,30 @@ impl<P, E, N, T> ParachainNetwork for ValidationNetwork<P, E, N, T> where
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub struct NetworkDown;

-/// A future that resolves when a collation is received.
-pub struct AwaitingCollation {
-	outer: oneshot::Receiver<oneshot::Receiver<Collation>>,
-	inner: Option<oneshot::Receiver<Collation>>
-}
-
-impl Future for AwaitingCollation {
-	type Output = Result<Collation, NetworkDown>;
-
-	fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
-		let this = Pin::into_inner(self);
-
-		if let Some(ref mut inner) = this.inner {
-			return Pin::new(inner).poll(cx).map_err(|_| NetworkDown)
-		}
-		match Pin::new(&mut this.outer).poll(cx) {
-			Poll::Ready(Ok(inner)) => {
-				this.inner = Some(inner);
-				Pin::new(this).poll(cx)
-			},
-			Poll::Ready(Err(_)) => Poll::Ready(Err(NetworkDown)),
-			Poll::Pending => Poll::Pending,
-		}
-	}
-}
-
 impl<P, E: Clone, N, T: Clone> Collators for ValidationNetwork<P, E, N, T> where
 	P: ProvideRuntimeApi + Send + Sync + 'static,
 	P::Api: ParachainHost<Block>,
 	N: NetworkService,
 {
 	type Error = NetworkDown;
-	type Collation = AwaitingCollation;
+	type Collation = Pin<Box<dyn Future<Output = Result<Collation, NetworkDown>> + Send>>;

 	fn collate(&self, parachain: ParaId, relay_parent: Hash) -> Self::Collation {
 		let (tx, rx) = oneshot::channel();
-		self.network.with_spec(move |spec, _| {
-			let collation = spec.await_collation(relay_parent, parachain);
-			let _ = tx.send(collation);
-		});
-		AwaitingCollation{outer: rx, inner: None}
+		let network = self.network.clone();
+
+		// A future that resolves when a collation is received.
+		async move {
+			network.with_spec(move |spec, _| {
+				let collation = spec.await_collation(relay_parent, parachain);
+				let _ = tx.send(collation);
+			});
+
+			rx.await
+				.map_err(|_| NetworkDown)?
+				.await
+				.map_err(|_| NetworkDown)
+		}.boxed()
 	}


@@ -348,27 +330,6 @@ impl Knowledge {
 	}
 }

-/// receiver for incoming data.
-#[derive(Clone)]
-pub struct IncomingReceiver {
-	inner: future::Shared<Receiver<Incoming>>
-}
-
-impl Future for IncomingReceiver {
-	type Output = Result<Incoming, io::Error>;
-
-	fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
-		match Pin::new(&mut Pin::into_inner(self).inner).poll(cx) {
-			Poll::Ready(Ok(i)) => Poll::Ready(Ok(Incoming::clone(&i))),
-			Poll::Ready(Err(_)) => Poll::Ready(Err(io::Error::new(
-				io::ErrorKind::Other,
-				"Sending end of channel hung up",
-			))),
-			Poll::Pending => Poll::Pending,
-		}
-	}
-}
-
 /// A current validation leaf-work instance
 #[derive(Clone)]
 pub(crate) struct LiveValidationLeaf {
@@ -564,36 +525,6 @@ impl LiveValidationLeaves {
 	}
 }

-/// Receiver for block data.
-pub struct PoVReceiver {
-	outer: Receiver<Receiver<PoVBlock>>,
-	inner: Option<Receiver<PoVBlock>>
-}
-
-impl Future for PoVReceiver {
-	type Output = Result<PoVBlock, io::Error>;
-
-	fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
-		let this = Pin::into_inner(self);
-
-		let map_err = |_| io::Error::new(
-			io::ErrorKind::Other,
-			"Sending end of channel hung up",
-		);
-
-		if let Some(ref mut inner) = this.inner {
-			return Pin::new(inner).poll(cx).map_err(map_err);
-		}
-		match Pin::new(&mut this.outer).poll(cx).map_err(map_err)? {
-			Poll::Ready(inner) => {
-				this.inner = Some(inner);
-				Pin::new(this).poll(cx)
-			}
-			Poll::Pending => Poll::Pending,
-		}
-	}
-}
-
 /// Can fetch data for a given validation leaf-work instance.
 pub struct LeafWorkDataFetcher<P, E, N: NetworkService, T> {
 	network: Arc<N>,
@@ -658,9 +589,14 @@ impl<P: ProvideRuntimeApi + Send, E, N, T> LeafWorkDataFetcher<P, E, N, T> where
 	E: Future<Output=()> + Clone + Send + 'static,
 {
 	/// Fetch PoV block for the given candidate receipt.
-	pub fn fetch_pov_block(&self, candidate: &CandidateReceipt) -> PoVReceiver {
+	pub fn fetch_pov_block(&self, candidate: &CandidateReceipt)
+		-> Pin<Box<dyn Future<Output = Result<PoVBlock, io::Error>> + Send>> {
+
 		let parachain = candidate.parachain_index;
 		let parent_hash = self.parent_hash;
+		let network = self.network.clone();
+		let candidate = candidate.clone();
+		let (tx, rx) = oneshot::channel();

 		let canon_roots = self.api.runtime_api().ingress(
 			&BlockId::hash(parent_hash),
@@ -676,15 +612,24 @@ impl<P: ProvideRuntimeApi + Send, E, N, T> LeafWorkDataFetcher<P, E, N, T> where
 				)
 			);

-		let candidate = candidate.clone();
-		let (tx, rx) = oneshot::channel();
-		self.network.with_spec(move |spec, ctx| {
-			if let Ok(Some(canon_roots)) = canon_roots {
-				let inner_rx = spec.fetch_pov_block(ctx, &candidate, parent_hash, canon_roots);
-				let _ = tx.send(inner_rx);
-			}
-		});
-		PoVReceiver { outer: rx, inner: None }
+		async move {
+			network.with_spec(move |spec, ctx| {
+				if let Ok(Some(canon_roots)) = canon_roots {
+					let inner_rx = spec.fetch_pov_block(ctx, &candidate, parent_hash, canon_roots);
+					let _ = tx.send(inner_rx);
+				}
+			});
+
+			let map_err = |_| io::Error::new(
+				io::ErrorKind::Other,
+				"Sending end of channel hung up",
+			);
+
+			rx.await
+				.map_err(map_err)?
+				.await
+				.map_err(map_err)
+		}.boxed()
 	}
 }

@@ -8,7 +8,7 @@ edition = "2018"
 futures = "0.3.1"
 futures-timer = "2.0"
 parking_lot = "0.9.0"
-tokio = { version = "0.2.4", features = ["rt-core", "blocking"] }
+tokio = { version = "0.2.4", features = ["rt-core"] }
 derive_more = "0.14.1"
 log = "0.4.8"
 exit-future = "0.2.0"
@@ -32,8 +32,6 @@ use parachain::{wasm_executor::{self, ExternalitiesError, ExecutionMode}, Messag
 use trie::TrieConfiguration;
 use futures::prelude::*;
 use log::debug;
-use std::task::{Poll, Context};
-use std::pin::Pin;

 /// Encapsulates connections to collators and allows collation on any parachain.
 ///
@@ -58,94 +56,41 @@ pub trait Collators: Clone {
 }

 /// A future which resolves when a collation is available.
-///
-/// This future is fused.
-pub struct CollationFetch<C: Collators, P> {
+pub async fn collation_fetch<C: Collators, P>(
 	parachain: ParaId,
 	relay_parent_hash: Hash,
-	relay_parent: BlockId,
 	collators: C,
-	live_fetch: Option<C::Collation>,
 	client: Arc<P>,
 	max_block_data_size: Option<u64>,
-}
-
-impl<C: Collators, P> CollationFetch<C, P> {
-	/// Create a new collation fetcher for the given chain.
-	pub fn new(
-		parachain: ParaId,
-		relay_parent_hash: Hash,
-		collators: C,
-		client: Arc<P>,
-		max_block_data_size: Option<u64>,
-	) -> Self {
-		CollationFetch {
-			relay_parent: BlockId::hash(relay_parent_hash),
-			relay_parent_hash,
-			collators,
-			client,
-			parachain,
-			live_fetch: None,
-			max_block_data_size,
-		}
-	}
-
-	/// Access the underlying relay parent hash.
-	pub fn relay_parent(&self) -> Hash {
-		self.relay_parent_hash
-	}
-
-	/// Access the local parachain ID.
-	pub fn parachain(&self) -> ParaId {
-		self.parachain
-	}
-}
-
-impl<C, P> Future for CollationFetch<C, P>
+) -> Result<(Collation, OutgoingMessages, Balance),C::Error>
 	where
 		P::Api: ParachainHost<Block, Error = sp_blockchain::Error>,
 		C: Collators + Unpin,
 		P: ProvideRuntimeApi,
 		<C as Collators>::Collation: Unpin,
 {
-	type Output = Result<(Collation, OutgoingMessages, Balance),C::Error>;
+	let relay_parent = BlockId::hash(relay_parent_hash);

-	fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
-		let this = Pin::into_inner(self);
+	loop {
+		let collation = collators.collate(parachain, relay_parent_hash)
+			.await?;

-		loop {
-			let collation = {
-				let parachain = this.parachain.clone();
-				let (r, c)  = (this.relay_parent_hash, &this.collators);
+		let res = validate_collation(
+			&*client,
+			&relay_parent,
+			&collation,
+			max_block_data_size,
+		);

-				let future = this.live_fetch
-					.get_or_insert_with(move || c.collate(parachain, r));
+		match res {
+			Ok((messages, fees)) => {
+				return Ok((collation, messages, fees))
+			}
+			Err(e) => {
+				debug!("Failed to validate parachain due to API error: {}", e);

-				match Pin::new(future).poll(cx) {
-					Poll::Ready(Ok(c)) => c,
-					Poll::Ready(Err(err)) => return Poll::Ready(Err(err)),
-					Poll::Pending => return Poll::Pending
-				}
-			};
-
-			let res = validate_collation(
-				&*this.client,
-				&this.relay_parent,
-				&collation,
-				this.max_block_data_size,
-			);
-
-			match res {
-				Ok((messages, fees)) => {
-					return Poll::Ready(Ok((collation, messages, fees)))
-				}
-				Err(e) => {
-					debug!("Failed to validate parachain due to API error: {}", e);
-
-					// just continue if we got a bad collation or failed to validate
-					this.live_fetch = None;
-					this.collators.note_bad_collator(collation.info.collator)
-				}
+				// just continue if we got a bad collation or failed to validate
+				collators.note_bad_collator(collation.info.collator)
 			}
 		}
 	}
@@ -34,8 +34,6 @@ use std::{
 	pin::Pin,
 	sync::Arc,
 	time::{self, Duration, Instant},
-	task::{Poll, Context},
-	mem,
 };

 use babe_primitives::BabeApi;
@@ -60,8 +58,8 @@ use txpool_api::{TransactionPool, InPoolTransaction};

 use attestation_service::ServiceHandle;
 use futures::prelude::*;
-use futures::{future::{self, Either, select, ready}, stream::unfold, task::{Spawn, SpawnExt}};
-use collation::CollationFetch;
+use futures::{future::{select, ready}, stream::unfold, task::{Spawn, SpawnExt}};
+use collation::collation_fetch;
 use dynamic_inclusion::DynamicInclusion;
 use inherents::InherentData;
 use sp_timestamp::TimestampInherentData;
@@ -396,7 +394,7 @@ impl<C, N, P> ParachainValidation<C, N, P> where

 		let with_router = move |router: N::TableRouter| {
 			// fetch a local collation from connected collators.
-			let collation_work = CollationFetch::new(
+			let collation_work = collation_fetch(
 				validation_para,
 				relay_parent,
 				collators,
@@ -611,14 +609,13 @@ impl<C, TxPool> consensus::Proposer<Block> for Proposer<C, TxPool> where
 	C::Api: ParachainHost<Block> + BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
 {
 	type Error = Error;
-	type Create = Either<CreateProposal<C, TxPool>, future::Ready<Result<Block, Error>>>;
+	type Create = Pin<Box<dyn Future<Output = Result<Block, Error>> + Send>>;

 	fn propose(&mut self,
 		inherent_data: InherentData,
 		inherent_digests: DigestFor<Block>,
 		max_duration: Duration,
 	) -> Self::Create {
-		const ATTEMPT_PROPOSE_EVERY: Duration = Duration::from_millis(100);
 		const SLOT_DURATION_DENOMINATOR: u64 = 3; // wait up to 1/3 of the slot for candidates.

 		let initial_included = self.tracker.table.includable_count();
@@ -630,56 +627,59 @@ impl<C, TxPool> consensus::Proposer<Block> for Proposer<C, TxPool> where
 			Duration::from_millis(self.slot_duration / SLOT_DURATION_DENOMINATOR),
 		);

-		let enough_candidates = dynamic_inclusion.acceptable_in(
-			now,
-			initial_included,
-		).unwrap_or_else(|| Duration::from_millis(1));
+		let parent_hash = self.parent_hash.clone();
+		let parent_number = self.parent_number.clone();
+		let parent_id = self.parent_id.clone();
+		let client = self.client.clone();
+		let transaction_pool = self.transaction_pool.clone();
+		let table = self.tracker.table.clone();

-		let believed_timestamp = match inherent_data.timestamp_inherent_data() {
-			Ok(timestamp) => timestamp,
-			Err(e) => return Either::Right(future::err(Error::InherentError(e))),
-		};
+		async move {
+			let enough_candidates = dynamic_inclusion.acceptable_in(
+				now,
+				initial_included,
+			).unwrap_or_else(|| Duration::from_millis(1));

-		// set up delay until next allowed timestamp.
-		let current_timestamp = current_timestamp();
-		let delay_future = if current_timestamp >= believed_timestamp {
-			None
-		} else {
-			Some(Delay::new(Duration::from_millis (current_timestamp - believed_timestamp)))
-		};
+			let believed_timestamp = match inherent_data.timestamp_inherent_data() {
+				Ok(timestamp) => timestamp,
+				Err(e) => return Err(Error::InherentError(e)),
+			};

-		let timing = ProposalTiming {
-			minimum: delay_future,
-			attempt_propose: Box::new(interval(ATTEMPT_PROPOSE_EVERY)),
-			enough_candidates: Delay::new(enough_candidates),
-			dynamic_inclusion,
-			last_included: initial_included,
-		};
+			let deadline_diff = max_duration - max_duration / 3;
+			let deadline = match Instant::now().checked_add(deadline_diff) {
+				None => return Err(Error::DeadlineComputeFailure(deadline_diff)),
+				Some(d) => d,
+			};

-		let deadline_diff = max_duration - max_duration / 3;
-		let deadline = match Instant::now().checked_add(deadline_diff) {
-			None => return Either::Right(
-				future::err(Error::DeadlineComputeFailure(deadline_diff)),
-			),
-			Some(d) => d,
-		};
-
-		Either::Left(CreateProposal {
-			state: CreateProposalState::Pending(CreateProposalData {
-				parent_hash: self.parent_hash.clone(),
-				parent_number: self.parent_number.clone(),
-				parent_id: self.parent_id.clone(),
-				client: self.client.clone(),
-				transaction_pool: self.transaction_pool.clone(),
-				table: self.tracker.table.clone(),
+			let data = CreateProposalData {
+				parent_hash,
+				parent_number,
+				parent_id,
+				client,
+				transaction_pool,
+				table,
 				believed_minimum_timestamp: believed_timestamp,
-				timing,
 				inherent_data: Some(inherent_data),
 				inherent_digests,
 				// leave some time for the proposal finalisation
 				deadline,
+			};
+
+			// set up delay until next allowed timestamp.
+			let current_timestamp = current_timestamp();
+			if current_timestamp < believed_timestamp {
+				Delay::new(Duration::from_millis(current_timestamp - believed_timestamp))
+					.await;
+			}
+
+			Delay::new(enough_candidates).await;
+
+			tokio_executor::blocking::run(move || {
+				let proposed_candidates = data.table.proposed_set();
+				data.propose_with(proposed_candidates)
 			})
-		})
+				.await
+		}.boxed()
 	}
 }

@@ -689,67 +689,6 @@ fn current_timestamp() -> u64 {
 		.as_millis() as u64
 }

-struct ProposalTiming {
-	minimum: Option<Delay>,
-	attempt_propose: Box<dyn Stream<Item=()> + Send + Unpin>,
-	dynamic_inclusion: DynamicInclusion,
-	enough_candidates: Delay,
-	last_included: usize,
-}
-
-impl ProposalTiming {
-	// whether it's time to attempt a proposal.
-	// shouldn't be called outside of the context of a task.
-	fn poll(&mut self, cx: &mut Context, included: usize) -> Poll<()> {
-		// first drain from the interval so when the minimum delay is up
-		// we don't have any notifications built up.
-		//
-		// this interval is just meant to produce periodic task wakeups
-		// that lead to the `dynamic_inclusion` getting updated as necessary.
-		while let Poll::Ready(x) = self.attempt_propose.poll_next_unpin(cx) {
-			x.expect("timer still alive; intervals never end; qed");
-		}
-
-		// wait until the minimum time has passed.
-		if let Some(mut minimum) = self.minimum.take() {
-			if let Poll::Pending = minimum.poll_unpin(cx) {
-				self.minimum = Some(minimum);
-				return Poll::Pending;
-			}
-		}
-
-		if included == self.last_included {
-			return self.enough_candidates.poll_unpin(cx);
-		}
-
-		// the amount of includable candidates has changed. schedule a wakeup
-		// if it's not sufficient anymore.
-		match self.dynamic_inclusion.acceptable_in(Instant::now(), included) {
-			Some(instant) => {
-				self.last_included = included;
-				self.enough_candidates.reset(Instant::now() + instant);
-				self.enough_candidates.poll_unpin(cx)
-			}
-			None => Poll::Ready(()),
-		}
-	}
-}
-
-/// Future which resolves upon the creation of a proposal.
-pub struct CreateProposal<C: Send + Sync, TxPool> {
-	state: CreateProposalState<C, TxPool>,
-}
-
-/// Current status of the proposal future.
-enum CreateProposalState<C: Send + Sync, TxPool> {
-	/// Pending inclusion, with given proposal data.
-	Pending(CreateProposalData<C, TxPool>),
-	/// Represents the state when we switch from pending to fired.
-	Switching,
-	/// Block proposing has fired.
-	Fired(tokio_executor::blocking::Blocking<Result<Block, Error>>),
-}
-
 /// Inner data of the create proposal.
 struct CreateProposalData<C: Send + Sync, TxPool> {
 	parent_hash: Hash,
@@ -758,7 +697,6 @@ struct CreateProposalData<C: Send + Sync, TxPool> {
 	client: Arc<C>,
 	transaction_pool: Arc<TxPool>,
 	table: Arc<SharedTable>,
-	timing: ProposalTiming,
 	believed_minimum_timestamp: u64,
 	inherent_data: Option<InherentData>,
 	inherent_digests: DigestFor<Block>,
@@ -859,58 +797,6 @@ impl<C, TxPool> CreateProposalData<C, TxPool> where
 	}
 }

-impl<C, TxPool> Future for CreateProposal<C, TxPool> where
-	TxPool: TransactionPool<Block=Block> + 'static,
-	C: ProvideRuntimeApi + HeaderBackend<Block> + Send + Sync + 'static,
-	C::Api: ParachainHost<Block> + BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
-{
-	type Output = Result<Block, Error>;
-
-	fn poll(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
-		let mut state = CreateProposalState::Switching;
-		mem::swap(&mut state, &mut self.state);
-
-		// 1. try to propose if we have enough includable candidates and other
-		// delays have concluded.
-		let data = match state {
-			CreateProposalState::Pending(mut data) => {
-				let included = data.table.includable_count();
-				match data.timing.poll(cx, included) {
-					Poll::Pending => {
-						self.state = CreateProposalState::Pending(data);
-						return Poll::Pending
-					},
-					Poll::Ready(()) => (),
-				}
-
-				data
-			},
-			CreateProposalState::Switching =>
-				unreachable!(
-					"State Switching are only created on call, \
-					and immediately swapped out; \
-					the data being read is from state; \
-					thus Switching will never be reachable here; qed"
-				),
-			CreateProposalState::Fired(mut future) => {
-				let ret = Pin::new(&mut future).poll(cx);
-				self.state = CreateProposalState::Fired(future);
-				return ret
-			},
-		};
-
-		// 2. propose
-		let mut future = tokio_executor::blocking::run(move || {
-			let proposed_candidates = data.table.proposed_set();
-			data.propose_with(proposed_candidates)
-		});
-		let polled = Pin::new(&mut future).poll(cx);
-		self.state = CreateProposalState::Fired(future);
-
-		polled
-	}
-}
-
 #[cfg(test)]
 mod tests {
 	use super::*;
@@ -17,16 +17,13 @@
 //! Implements a future which resolves when all of the candidates referenced are includable.

 use std::collections::HashMap;
-
-use futures::prelude::*;
 use futures::channel::oneshot;
-use std::pin::Pin;
-use std::task::{Poll, Context};
-
 use polkadot_primitives::Hash;

 /// Track includability of a set of candidates,
-pub(super) fn track<I: IntoIterator<Item=(Hash, bool)>>(candidates: I) -> (IncludabilitySender, Includable) {
+pub(super) fn track<I: IntoIterator<Item=(Hash, bool)>>(candidates: I)
+	-> (IncludabilitySender, oneshot::Receiver<()>) {
+
 	let (tx, rx) = oneshot::channel();
 	let tracking: HashMap<_, _> = candidates.into_iter().collect();
 	let includable_count = tracking.values().filter(|x| **x).count();
@@ -39,10 +36,7 @@ pub(super) fn track<I: IntoIterator<Item=(Hash, bool)>>(candidates: I) -> (Inclu

 	sender.try_complete();

-	(
-		sender,
-		Includable(rx),
-	)
+	(sender, rx)
 }

 /// The sending end of the includability sender.
@@ -93,17 +87,6 @@ impl IncludabilitySender {
 	}
 }

-/// Future that resolves when all the candidates within are includable.
-pub struct Includable(oneshot::Receiver<()>);
-
-impl Future for Includable {
-	type Output = Result<(), oneshot::Canceled>;
-
-	fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
-		Pin::new(&mut Pin::into_inner(self).0).poll(cx)
-	}
-}
-
 #[cfg(test)]
 mod tests {
 	use super::*;
@@ -30,6 +30,7 @@ use polkadot_primitives::parachain::{

 use parking_lot::Mutex;
 use futures::prelude::*;
+use futures::channel::oneshot;
 use log::{warn, debug};
 use bitvec::bitvec;

@@ -40,7 +41,6 @@ use runtime_primitives::traits::ProvideRuntimeApi;

 mod includable;

-pub use self::includable::Includable;
 pub use table::{SignedStatement, Statement};
 pub use table::generic::Statement as GenericStatement;

@@ -543,7 +543,7 @@ impl SharedTable {
 	}

 	/// Track includability  of a given set of candidate hashes.
-	pub fn track_includability<I>(&self, iterable: I) -> Includable
+	pub fn track_includability<I>(&self, iterable: I) -> oneshot::Receiver<()>
 		where I: IntoIterator<Item=Hash>
 	{
 		let mut inner = self.inner.lock();