Fix service setup for non-validator nodes (#378)

* Fix service setup for non-validator nodes

* Apply suggestions

polkadot/network/src/gossip.rs

@@ -169,6 +169,16 @@ pub fn register_validator<O: KnownOracle + 'static>(
 	RegisteredMessageValidator { inner: validator as _ }
 }
 
+/// Register a gossip validator for a non-authority node.
+pub fn register_non_authority_validator(service: Arc<NetworkService>) {
+	service.with_gossip(|gossip, ctx|
+		gossip.register_validator(
+			ctx,
+			POLKADOT_ENGINE_ID,
+			Arc::new(substrate_network::consensus_gossip::DiscardAll)),
+	);
+}
+
 /// A registered message validator.
 ///
 /// Create this using `register_validator`.

polkadot/service/src/lib.rs

@@ -25,7 +25,7 @@ use std::sync::Arc;
 use std::time::Duration;
 use polkadot_primitives::{parachain, Block, Hash, BlockId};
 use polkadot_runtime::{GenesisConfig, RuntimeApi};
-use polkadot_network::gossip::{self as network_gossip, Known};
+use polkadot_network::{gossip::{self as network_gossip, Known}, validation::ValidationNetwork};
 use service::{
 	FactoryFullConfiguration, FullBackend, LightBackend, FullExecutor, LightExecutor,
 	error::Error as ServiceError, TelemetryOnConnect
@@ -198,10 +198,6 @@ service::construct_service_factory! {
 					}
 				}
 
-				if service.config().roles != service::Roles::AUTHORITY {
-					return Ok(service);
-				}
-
 				if service.config().custom.collating_for.is_some() {
 					info!(
 						"The node cannot start as an authority because it is also configured to run as a collator."
@@ -241,7 +237,7 @@ service::construct_service_factory! {
 					},
 				);
 
-				use polkadot_network::validation::ValidationNetwork;
+				if service.config().roles.is_authority() {
 					let extrinsic_store = {
 						use std::path::PathBuf;
 
@@ -293,7 +289,10 @@ service::construct_service_factory! {
 
 					let babe = start_babe(babe_config)?;
 					let select = babe.select(service.on_exit()).then(|_| Ok(()));
-				service.spawn_task(Box::new(select));
+					service.spawn_essential_task(Box::new(select));
+				} else {
+					network_gossip::register_non_authority_validator(service.network());
+				}
 
 				let config = grandpa::Config {
 					// FIXME substrate#1578 make this available through chainspec
@@ -326,7 +325,7 @@ service::construct_service_factory! {
 							on_exit: service.on_exit(),
 							telemetry_on_connect: Some(telemetry_on_connect),
 						};
-						service.spawn_task(Box::new(grandpa::run_grandpa_voter(grandpa_config)?));
+						service.spawn_essential_task(Box::new(grandpa::run_grandpa_voter(grandpa_config)?));
 					},
 					(_, true) => {
 						grandpa::setup_disabled_grandpa(
@@ -336,45 +335,6 @@ service::construct_service_factory! {
 						)?;
 					},
 				}
-				// let config = grandpa::Config {
-				// 	// FIXME #1578 make this available through chainspec
-				// 	gossip_duration: Duration::from_millis(333),
-				// 	justification_period: 4096,
-				// 	name: Some(service.config().name.clone()),
-				// 	keystore: Some(service.keystore()),
-				// };
-
-				// if !service.config().disable_grandpa {
-				// 	if service.config().roles.is_authority() {
-				// 		let telemetry_on_connect = TelemetryOnConnect {
-				// 			telemetry_connection_sinks: service.telemetry_on_connect_stream(),
-				// 		};
-				// 		let grandpa_config = grandpa::GrandpaParams {
-				// 			config: config,
-				// 			link: link_half,
-				// 			network: service.network(),
-				// 			inherent_data_providers: service.config().custom.inherent_data_providers.clone(),
-				// 			on_exit: service.on_exit(),
-				// 			telemetry_on_connect: Some(telemetry_on_connect),
-				// 		};
-				// 		service.spawn_task(Box::new(grandpa::run_grandpa_voter(grandpa_config)?));
-				// 	} else {
-				// 		service.spawn_task(Box::new(grandpa::run_grandpa_observer(
-				// 			config,
-				// 			link_half,
-				// 			service.network(),
-				// 			service.on_exit(),
-				// 		)?));
-				// 	}
-				// }
-
-				// // regardless of whether grandpa is started or not, when
-				// // authoring blocks we expect inherent data regarding what our
-				// // last finalized block is, to be available.
-				// grandpa::register_finality_tracker_inherent_data_provider(
-				// 	service.client(),
-				// 	&service.config().custom.inherent_data_providers,
-				// )?;
 
 				Ok(service)
 			}