[backport] Lower bft timeout (#484)

* v0.2.3

* Lower bft timeout

* force BFT delay in consensus service, not in proposer logic (#477)

* move forced delay to consensus service

* fiddle with logging

consensus/src/lib.rs

@@ -258,8 +258,6 @@ impl<C, N, P> bft::Environment<Block> for ProposerFactory<C, N, P>
 	) -> Result<(Self::Proposer, Self::Input, Self::Output), Error> {
 		use runtime_primitives::traits::{Hash as HashT, BlakeTwo256};
 
-		const DELAY_UNTIL: Duration = Duration::from_millis(5000);
-
 		let parent_hash = parent_header.hash().into();
 
 		let id = BlockId::hash(parent_hash);
@@ -290,9 +288,6 @@ impl<C, N, P> bft::Environment<Block> for ProposerFactory<C, N, P>
 			self.parachain_empty_duration.clone(),
 		);
 
-		debug!(target: "bft", "Initialising consensus proposer. Refusing to evaluate for {:?} from now.",
-			DELAY_UNTIL);
-
 		let validation_para = match local_duty.validation {
 			Chain::Relay => None,
 			Chain::Parachain(id) => Some(id),
@@ -315,7 +310,6 @@ impl<C, N, P> bft::Environment<Block> for ProposerFactory<C, N, P>
 			client: self.client.clone(),
 			dynamic_inclusion,
 			local_key: sign_with,
-			minimum_delay: now + DELAY_UNTIL,
 			parent_hash,
 			parent_id: id,
 			parent_number: parent_header.number,
@@ -370,7 +364,6 @@ pub struct Proposer<C: PolkadotApi> {
 	client: Arc<C>,
 	dynamic_inclusion: DynamicInclusion,
 	local_key: Arc<ed25519::Pair>,
-	minimum_delay: Instant,
 	parent_hash: Hash,
 	parent_id: BlockId,
 	parent_number: BlockNumber,
@@ -401,17 +394,10 @@ impl<C> bft::Proposer<Block> for Proposer<C>
 			initial_included,
 		).unwrap_or_else(|| now + Duration::from_millis(1));
 
-		let minimum_delay = if self.minimum_delay > now + ATTEMPT_PROPOSE_EVERY {
-			Some(Delay::new(self.minimum_delay))
-		} else {
-			None
-		};
-
 		let timing = ProposalTiming {
 			attempt_propose: Interval::new(now + ATTEMPT_PROPOSE_EVERY, ATTEMPT_PROPOSE_EVERY),
 			enough_candidates: Delay::new(enough_candidates),
 			dynamic_inclusion: self.dynamic_inclusion.clone(),
-			minimum_delay,
 			last_included: initial_included,
 		};
 
@@ -484,11 +470,7 @@ impl<C> bft::Proposer<Block> for Proposer<C>
 			// delay casting vote until able according to minimum block time,
 			// timestamp delay, and count delay.
 			// construct a future from the maximum of the two durations.
-			let max_delay = [timestamp_delay, count_delay, Some(self.minimum_delay)]
-				.iter()
-				.cloned()
-				.max()
-				.expect("iterator not empty; thus max returns `Some`; qed");
+			let max_delay = ::std::cmp::max(timestamp_delay, count_delay);
 
 			let temporary_delay = match max_delay {
 				Some(duration) => future::Either::A(
@@ -610,7 +592,6 @@ struct ProposalTiming {
 	attempt_propose: Interval,
 	dynamic_inclusion: DynamicInclusion,
 	enough_candidates: Delay,
-	minimum_delay: Option<Delay>,
 	last_included: usize,
 }
 
@@ -627,12 +608,6 @@ impl ProposalTiming {
 			x.expect("timer still alive; intervals never end; qed");
 		}
 
-		if let Some(ref mut min) = self.minimum_delay {
-			try_ready!(min.poll().map_err(ErrorKind::Timer));
-		}
-
-		self.minimum_delay = None; // after this point, the future must have completed.
-
 		if included == self.last_included {
 			return self.enough_candidates.poll().map_err(ErrorKind::Timer);
 		}

consensus/src/service.rs

@@ -38,7 +38,7 @@ use transaction_pool::TransactionPool;
 use tokio::executor::current_thread::TaskExecutor as LocalThreadHandle;
 use tokio::runtime::TaskExecutor as ThreadPoolHandle;
 use tokio::runtime::current_thread::Runtime as LocalRuntime;
-use tokio::timer::Interval;
+use tokio::timer::{Delay, Interval};
 
 use super::{Network, Collators, ProposerFactory};
 use error;
@@ -49,8 +49,8 @@ const TIMER_INTERVAL_MS: u64 = 500;
 // spin up an instance of BFT agreement on the current thread's executor.
 // panics if there is no current thread executor.
 fn start_bft<F, C>(
-	header: &Header,
-	bft_service: &BftService<Block, F, C>,
+	header: Header,
+	bft_service: Arc<BftService<Block, F, C>>,
 ) where
 	F: bft::Environment<Block> + 'static,
 	C: bft::BlockImport<Block> + bft::Authorities<Block> + 'static,
@@ -58,14 +58,35 @@ fn start_bft<F, C>(
 	<F::Proposer as bft::Proposer<Block>>::Error: ::std::fmt::Display + Into<error::Error>,
 	<F as bft::Environment<Block>>::Error: ::std::fmt::Display
 {
+	const DELAY_UNTIL: Duration = Duration::from_millis(5000);
+
 	let mut handle = LocalThreadHandle::current();
-	match bft_service.build_upon(&header) {
-		Ok(Some(bft)) => if let Err(e) = handle.spawn_local(Box::new(bft)) {
-			debug!(target: "bft", "Couldn't initialize BFT agreement: {:?}", e);
-		},
-		Ok(None) => {},
-		Err(e) => warn!(target: "bft", "BFT agreement error: {}", e),
-	}
+	let work = Delay::new(Instant::now() + DELAY_UNTIL)
+		.then(move |res| {
+			if let Err(e) = res {
+				warn!(target: "bft", "Failed to force delay of consensus: {:?}", e);
+			}
+
+			match bft_service.build_upon(&header) {
+				Ok(maybe_bft_work) => {
+					if maybe_bft_work.is_some() {
+						debug!(target: "bft", "Starting agreement. After forced delay for {:?}",
+							DELAY_UNTIL);
+					}
+
+					maybe_bft_work
+				}
+				Err(e) => {
+					warn!(target: "bft", "BFT agreement error: {}", e);
+					None
+				}
+			}
+		})
+		.map(|_| ());
+
+	if let Err(e) = handle.spawn_local(Box::new(work)) {
+    	debug!(target: "bft", "Couldn't initialize BFT agreement: {:?}", e);
+    }
 }
 
 /// Consensus service. Starts working when created.
@@ -113,7 +134,7 @@ impl Service {
 
 				client.import_notification_stream().for_each(move |notification| {
 					if notification.is_new_best {
-						start_bft(&notification.header, &*bft_service);
+						start_bft(notification.header, bft_service.clone());
 					}
 					Ok(())
 				})
@@ -139,9 +160,9 @@ impl Service {
 				interval.map_err(|e| debug!("Timer error: {:?}", e)).for_each(move |_| {
 					if let Ok(best_block) = c.best_block_header() {
 						let hash = best_block.hash();
-						if hash == prev_best {
+						if hash == prev_best && s.live_agreement() != Some(hash) {
 							debug!("Starting consensus round after a timeout");
-							start_bft(&best_block, &*s);
+							start_bft(best_block, s.clone());
 						}
 						prev_best = hash;
 					}