Ensure all known BFT messages are imported when starting consensus (#147)

* a little more BFT tracing

* import cached BFT messages into the produced stream

polkadot/consensus/src/service.rs

@@ -22,7 +22,6 @@
 use std::thread;
 use std::time::{Duration, Instant};
 use std::sync::Arc;
-use std::collections::{HashMap, VecDeque};
 use futures::{future, Future, Stream, Sink, Async, Canceled, Poll};
 use parking_lot::Mutex;
 use substrate_network as net;
@@ -41,7 +40,6 @@ use error;
 
 const TIMER_DELAY_MS: u64 = 5000;
 const TIMER_INTERVAL_MS: u64 = 500;
-const MESSAGE_LIFETIME_SEC: u64 = 10;
 
 struct BftSink<E> {
 	network: Arc<net::ConsensusService>,
@@ -49,49 +47,9 @@ struct BftSink<E> {
 	_e: ::std::marker::PhantomData<E>,
 }
 
-#[derive(Clone)]
-struct SharedMessageCollection {
-	/// Messages for consensus over a block with known hash. Also holds timestamp of the first message.
-	messages: Arc<Mutex<HashMap<HeaderHash, (Instant, VecDeque<net::LocalizedBftMessage>)>>>,
-}
-
-impl SharedMessageCollection {
-	fn new() -> SharedMessageCollection {
-		SharedMessageCollection {
-			messages: Arc::new(Mutex::new(HashMap::new())),
-		}
-	}
-
-	fn select(&self, parent_hash: HeaderHash, stream: net::BftMessageStream, authorities: Vec<AuthorityId>) -> Messages {
-		Messages {
-			messages: self.messages.lock().remove(&parent_hash).map(|(_, m)| m).unwrap_or_else(VecDeque::new),
-			parent_hash,
-			network_stream: stream,
-			authorities: authorities,
-			collection: self.clone(),
-		}
-	}
-
-	fn push(&self, message: net::LocalizedBftMessage) {
-		self.messages.lock()
-			.entry(message.parent_hash)
-			.or_insert_with(|| (Instant::now(), VecDeque::new()))
-			.1.push_back(message);
-	}
-
-	fn collect_garbage(&self) {
-		let expiration = Duration::from_secs(MESSAGE_LIFETIME_SEC);
-		let now = Instant::now();
-		self.messages.lock().retain(|_, &mut (timestamp, _)| timestamp < now + expiration);
-	}
-}
-
 struct Messages {
-	parent_hash: HeaderHash,
-	messages: VecDeque<net::LocalizedBftMessage>,
 	network_stream: net::BftMessageStream,
 	authorities: Vec<AuthorityId>,
-	collection: SharedMessageCollection,
 }
 
 impl Stream for Messages {
@@ -99,14 +57,6 @@ impl Stream for Messages {
 	type Error = bft::Error;
 
 	fn poll(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
-		// push buffered messages first
-		while let Some(message) = self.messages.pop_front() {
-			match process_message(message, &self.authorities) {
-				Ok(message) => return Ok(Async::Ready(Some(message))),
-				Err(e) => debug!("Message validation failed: {:?}", e),
-			}
-		}
-
 		// check the network
 		loop {
 			match self.network_stream.poll() {
@@ -114,15 +64,11 @@ impl Stream for Messages {
 				Ok(Async::NotReady) => return Ok(Async::NotReady),
 				Ok(Async::Ready(None)) => return Ok(Async::NotReady), // the input stream for agreements is never meant to logically end.
 				Ok(Async::Ready(Some(message))) => {
-					if message.parent_hash == self.parent_hash {
-						match process_message(message, &self.authorities) {
-							Ok(message) => return Ok(Async::Ready(Some(message))),
-							Err(e) => {
-								debug!("Message validation failed: {:?}", e);
-							}
+					match process_message(message, &self.authorities) {
+						Ok(message) => return Ok(Async::Ready(Some(message))),
+						Err(e) => {
+							debug!("Message validation failed: {:?}", e);
 						}
-					} else {
-						self.collection.push(message);
 					}
 				}
 			}
@@ -226,18 +172,17 @@ fn start_bft<F, C>(
 	client: &bft::Authorities,
 	network: Arc<net::ConsensusService>,
 	bft_service: &BftService<F, C>,
-	messages: SharedMessageCollection
 ) where
 	F: bft::ProposerFactory + 'static,
 	C: bft::BlockImport + bft::Authorities + 'static,
 	<F as bft::ProposerFactory>::Error: ::std::fmt::Debug,
 	<F::Proposer as bft::Proposer>::Error: ::std::fmt::Display + Into<error::Error>,
 {
-	let hash = header.blake2_256().into();
-	if bft_service.live_agreement().map_or(false, |h| h == hash) {
+	let parent_hash = header.blake2_256().into();
+	if bft_service.live_agreement().map_or(false, |h| h == parent_hash) {
 		return;
 	}
-	let authorities = match client.authorities(&BlockId::Hash(hash)) {
+	let authorities = match client.authorities(&BlockId::Hash(parent_hash)) {
 		Ok(authorities) => authorities,
 		Err(e) => {
 			debug!("Error reading authorities: {:?}", e);
@@ -245,12 +190,16 @@ fn start_bft<F, C>(
 		}
 	};
 
-	let input = messages.select(hash, network.bft_messages(), authorities).map_err(|e| e.into());
-	let output = BftSink { network: network, parent_hash: hash.clone(), _e: Default::default() };
-	match bft_service.build_upon(&header, input, output) {
+	let input = Messages {
+		network_stream: network.bft_messages(parent_hash),
+		authorities,
+	};
+
+	let output = BftSink { network: network, parent_hash: parent_hash, _e: Default::default() };
+	match bft_service.build_upon(&header, input.map_err(Into::into), output) {
 		Ok(Some(bft)) => handle.spawn(bft),
 		Ok(None) => {},
-		Err(e) => debug!(target: "bft","BFT agreement error: {:?}", e),
+		Err(e) => debug!(target: "bft", "BFT agreement error: {:?}", e),
 	}
 }
 
@@ -281,7 +230,6 @@ impl Service {
 				network: Network(network.clone()),
 				handle: core.handle(),
 			};
-			let messages = SharedMessageCollection::new();
 			let bft_service = Arc::new(BftService::new(client.clone(), key, factory));
 
 			let notifications = {
@@ -289,11 +237,10 @@ impl Service {
 				let network = network.clone();
 				let client = client.clone();
 				let bft_service = bft_service.clone();
-				let messages = messages.clone();
 
 				client.import_notification_stream().for_each(move |notification| {
 					if notification.is_new_best {
-						start_bft(&notification.header, handle.clone(), &*client, network.clone(), &*bft_service, messages.clone());
+						start_bft(&notification.header, handle.clone(), &*client, network.clone(), &*bft_service);
 					}
 					Ok(())
 				})
@@ -316,16 +263,14 @@ impl Service {
 				let c = client.clone();
 				let s = bft_service.clone();
 				let n = network.clone();
-				let m = messages.clone();
 				let handle = core.handle();
 
 				interval.map_err(|e| debug!("Timer error: {:?}", e)).for_each(move |_| {
 					if let Ok(best_block) = c.best_block_header() {
 						let hash = best_block.blake2_256();
-						m.collect_garbage();
 						if hash == prev_best {
 							debug!("Starting consensus round after a timeout");
-							start_bft(&best_block, handle.clone(), &*c, n.clone(), &*s, m.clone());
+							start_bft(&best_block, handle.clone(), &*c, n.clone(), &*s);
 						}
 						prev_best = hash;
 					}