Initial version of the polite-grandpa networking protocol (#2110)

* Consensus status packet

* Allow for repropagation after status

* More generic gossip

* add a basic view struct and gossip module

* move gossip stuff to the gossip module

* integrate view into gossip

* some reshuffling

* alter rules for keeping one commit at a time in view

* Allow sending addressed messages

* don't cast outgoing votes if we know that we voted before

* Handle one hop messages

* initial run at polite grandpa

* build WASM

* handle neighbor messages

* refactor validator's internals into an Inner struct

* gossip only knows to keep or discard messages. optimize should_send_to

* Periodic rebroadcast

* implement `should_send_to` and message_expired

* track peers' best received commit height

* Pass peer id to topic steam

* kill rebroadcasting network

* Notify about existing peers

* clean up network APIs a bunch

* implement gossip::send_message for direct messages

* refactor network trait

* implement gossip::send_message for direct messages

* get all non set-change tests passing

* treat unknown rebroadcasts as broadcasts

* get all other main tests passing

* remove unimplemented test

* everything compiles

* treat unknown rebroadcasts as broadcasts

* Rebradcast interval

* Apply suggestions from code review

Style

Co-Authored-By: arkpar <arkady.paronyan@gmail.com>

* Style

* some module docs

* address some grumbles + docs

* allow rebroadcast every few minutes

* send_topic && generic context

* some tests for view change

* more grumbles & tests

* use send_peer

substrate/core/network/src/test/mod.rs

@@ -35,7 +35,7 @@ use consensus::import_queue::{BasicQueue, ImportQueue, IncomingBlock};
 use consensus::import_queue::{Link, SharedBlockImport, SharedJustificationImport, Verifier};
 use consensus::{Error as ConsensusError, ErrorKind as ConsensusErrorKind};
 use consensus::{BlockOrigin, ForkChoiceStrategy, ImportBlock, JustificationImport};
-use crate::consensus_gossip::ConsensusGossip;
+use crate::consensus_gossip::{ConsensusGossip, MessageRecipient as GossipMessageRecipient, TopicNotification};
 use crossbeam_channel::{self as channel, Sender, select};
 use futures::Future;
 use futures::sync::{mpsc, oneshot};
@@ -260,14 +260,12 @@ impl<D, S: NetworkSpecialization<Block> + Clone> Peer<D, S> {
 	}
 
 	// SyncOracle: are we connected to any peer?
-	#[cfg(test)]
-	fn is_offline(&self) -> bool {
+	pub fn is_offline(&self) -> bool {
 		self.is_offline.load(Ordering::Relaxed)
 	}
 
 	// SyncOracle: are we in the process of catching-up with the chain?
-	#[cfg(test)]
-	fn is_major_syncing(&self) -> bool {
+	pub fn is_major_syncing(&self) -> bool {
 		self.is_major_syncing.load(Ordering::Relaxed)
 	}
 
@@ -366,9 +364,10 @@ impl<D, S: NetworkSpecialization<Block> + Clone> Peer<D, S> {
 		data: Vec<u8>,
 		force: bool,
 	) {
+		let recipient = if force { GossipMessageRecipient::BroadcastToAll } else { GossipMessageRecipient::BroadcastNew };
 		let _ = self
 			.protocol_sender
-			.send(ProtocolMsg::GossipConsensusMessage(topic, engine_id, data, force));
+			.send(ProtocolMsg::GossipConsensusMessage(topic, engine_id, data, recipient));
 	}
 
 	pub fn consensus_gossip_collect_garbage_for_topic(&self, _topic: <Block as BlockT>::Hash) {
@@ -380,7 +379,7 @@ impl<D, S: NetworkSpecialization<Block> + Clone> Peer<D, S> {
 		&self,
 		engine_id: ConsensusEngineId,
 		topic: <Block as BlockT>::Hash,
-	) -> mpsc::UnboundedReceiver<Vec<u8>> {
+	) -> mpsc::UnboundedReceiver<TopicNotification> {
 		let (tx, rx) = oneshot::channel();
 		self.with_gossip(move |gossip, _| {
 			let inner_rx = gossip.messages_for(engine_id, topic);