grandpa: sentry favorite peers

bin/node-template/node/src/service.rs

@@ -141,6 +141,7 @@ pub fn new_full(config: Configuration)
 		justification_period: 512,
 		name: Some(name),
 		observer_enabled: false,
+		favorite_peers: Default::default(),
 		keystore,
 		is_authority,
 	};

bin/node/cli/src/service.rs

@@ -125,12 +125,14 @@ macro_rules! new_full {
 			name,
 			disable_grandpa,
 			sentry_nodes,
+			reserved_nodes,
 		) = (
 			$config.roles.is_authority(),
 			$config.force_authoring,
 			$config.name.clone(),
 			$config.disable_grandpa,
 			$config.network.sentry_nodes.clone(),
+			$config.network.reserved_nodes.clone(),
 		);
 
 		// sentry nodes announce themselves as authorities to the network
@@ -190,7 +192,7 @@ macro_rules! new_full {
 			let authority_discovery = sc_authority_discovery::AuthorityDiscovery::new(
 				service.client(),
 				network,
-				sentry_nodes,
+				sentry_nodes.clone(),
 				service.keystore(),
 				dht_event_stream,
 				service.prometheus_registry(),
@@ -207,12 +209,21 @@ macro_rules! new_full {
 			None
 		};
 
+		// add reserved and sentry nodes as favorite peers to GRANDPA
+		let favorite_peers = reserved_nodes
+			.into_iter()
+			.chain(sentry_nodes.into_iter())
+			.filter_map(|n| sc_network::config::parse_str_addr(&n).ok())
+			.map(|(peer_id, _)| peer_id)
+			.collect();
+
 		let config = grandpa::Config {
 			// FIXME #1578 make this available through chainspec
 			gossip_duration: std::time::Duration::from_millis(333),
 			justification_period: 512,
 			name: Some(name),
 			observer_enabled: false,
+			favorite_peers,
 			keystore,
 			is_authority,
 		};

client/finality-grandpa/src/communication/gossip.rs

@@ -1110,6 +1110,9 @@ impl<Block: BlockT> Inner<Block> {
 		let round_duration = self.config.gossip_duration * ROUND_DURATION;
 		let round_elapsed = self.round_start.elapsed();
 
+		if self.config.favorite_peers.contains(who) {
+			return true;
+		}
 
 		if !self.config.is_authority
 			&& round_elapsed < round_duration * PROPAGATION_ALL
@@ -1170,6 +1173,10 @@ impl<Block: BlockT> Inner<Block> {
 		let round_duration = self.config.gossip_duration * ROUND_DURATION;
 		let round_elapsed = self.round_start.elapsed();
 
+		if self.config.favorite_peers.contains(who) {
+			return true;
+		}
+
 		if peer.roles.is_authority() {
 			let authorities = self.peers.authorities();
 

client/finality-grandpa/src/lib.rs

@@ -52,6 +52,8 @@
 //! or prune any signaled changes based on whether the signaling block is
 //! included in the newly-finalized chain.
 
+use std::collections::HashSet;
+
 use futures::prelude::*;
 use futures::StreamExt;
 use log::{debug, info};
@@ -204,6 +206,10 @@ pub struct Config {
 	pub is_authority: bool,
 	/// Some local identifier of the voter.
 	pub name: Option<String>,
+	/// The set of favorite peers which we should treat preferably when gossiping messages
+	/// (i.e. we prioritize sending any data to them over other peers). The favorite peers
+	/// are usually reserved nodes and/or sentry nodes.
+	pub favorite_peers: HashSet<sc_network::PeerId>,
 	/// The keystore that manages the keys of this node.
 	pub keystore: Option<sc_keystore::KeyStorePtr>,
 }

client/network/src/service.rs

@@ -205,15 +205,30 @@ impl<B: BlockT + 'static, H: ExHashT> NetworkWorker<B, H> {
 			)?;
 
 		// Initialize the reserved peers.
-		for reserved in params.network_config.reserved_nodes.iter() {
-			if let Ok((peer_id, addr)) = parse_str_addr(reserved) {
+		let mut add_reserved = |node| {
+			if let Ok((peer_id, addr)) = parse_str_addr(node) {
 				reserved_nodes.push(peer_id.clone());
 				known_addresses.push((peer_id, addr));
-			} else {
+				return true;
+			}
+
+			false
+		};
+
+		for reserved in params.network_config.reserved_nodes.iter() {
+			if !add_reserved(reserved) {
 				warn!(target: "sub-libp2p", "Not a valid reserved node address: {}", reserved);
 			}
 		}
 
+		// treat sentry nodes as reserved for the peerset, we always want to maintain connections to
+		// our sentries.
+		for sentry in params.network_config.sentry_nodes.iter() {
+			if !add_reserved(sentry) {
+				warn!(target: "sub-libp2p", "Not a valid sentry node address: {}", sentry);
+			}
+		}
+
 		let peerset_config = sc_peerset::PeersetConfig {
 			in_peers: params.network_config.in_peers,
 			out_peers: params.network_config.out_peers,