CLI API refactoring and improvement (#4692)

It changes the way we extended the CLI functionalities of substrate to allow more flexibility. (If this was not clear, here is another version: it changes the `sc_cli` API to allow more flexibility).

This touches a few important things:
 - the startup of the async task with tokei:
    This was in node and node-template and I moved it to substrate. The idea is to have 1 time the code that handles unix signals (SIGTERM and SIGINT) properly. It is however possible to make this more generic to wait for a future instead and provide only a helper for the basic handling of SIGTERM and SIGINT.
 - increased the version of structopt and tokei
 - no more use of structopt internal's API
 - less use of generics

Related to #4643 and https://github.com/paritytech/cumulus/pull/42: the implementation of "into_configuration" and "get_config" are similar but with better flexibility so it is now possible in cumulus to have the command-line arguments only of the run command for polkadot if we want

Related to https://github.com/paritytech/cumulus/issues/24 and https://github.com/paritytech/cumulus/issues/34 : it will now be possible to make a configuration struct for polkadot with some overrides of the default parameters much more easily.

substrate/client/service/src/builder.rs

@@ -72,10 +72,10 @@ use grafana_data_source::{self, record_metrics};
 /// The order in which the `with_*` methods are called doesn't matter, as the correct binding of
 /// generics is done when you call `build`.
 ///
-pub struct ServiceBuilder<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp,
+pub struct ServiceBuilder<TBl, TRtApi, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp,
 	TNetP, TExPool, TRpc, Backend>
 {
-	config: Configuration<TCfg, TGen, TCSExt>,
+	config: Configuration<TGen, TCSExt>,
 	pub (crate) client: Arc<TCl>,
 	backend: Arc<Backend>,
 	keystore: Arc<RwLock<Keystore>>,
@@ -144,8 +144,8 @@ type TFullParts<TBl, TRtApi, TExecDisp> = (
 );
 
 /// Creates a new full client for the given config.
-pub fn new_full_client<TBl, TRtApi, TExecDisp, TCfg, TGen, TCSExt>(
-	config: &Configuration<TCfg, TGen, TCSExt>,
+pub fn new_full_client<TBl, TRtApi, TExecDisp, TGen, TCSExt>(
+	config: &Configuration<TGen, TCSExt>,
 ) -> Result<TFullClient<TBl, TRtApi, TExecDisp>, Error> where
 	TBl: BlockT,
 	TExecDisp: NativeExecutionDispatch + 'static,
@@ -155,8 +155,8 @@ pub fn new_full_client<TBl, TRtApi, TExecDisp, TCfg, TGen, TCSExt>(
 	new_full_parts(config).map(|parts| parts.0)
 }
 
-fn new_full_parts<TBl, TRtApi, TExecDisp, TCfg, TGen, TCSExt>(
-	config: &Configuration<TCfg, TGen, TCSExt>,
+fn new_full_parts<TBl, TRtApi, TExecDisp, TGen, TCSExt>(
+	config: &Configuration<TGen, TCSExt>,
 ) -> Result<TFullParts<TBl, TRtApi, TExecDisp>,	Error> where
 	TBl: BlockT,
 	TExecDisp: NativeExecutionDispatch + 'static,
@@ -177,13 +177,14 @@ fn new_full_parts<TBl, TRtApi, TExecDisp, TCfg, TGen, TCSExt>(
 		config.default_heap_pages,
 	);
 
-	let fork_blocks = config.chain_spec
+	let chain_spec = config.expect_chain_spec();
+	let fork_blocks = chain_spec
 		.extensions()
 		.get::<sc_client::ForkBlocks<TBl>>()
 		.cloned()
 		.unwrap_or_default();
 
-	let bad_blocks = config.chain_spec
+	let bad_blocks = chain_spec
 		.extensions()
 		.get::<sc_client::BadBlocks<TBl>>()
 		.cloned()
@@ -214,7 +215,7 @@ fn new_full_parts<TBl, TRtApi, TExecDisp, TCfg, TGen, TCSExt>(
 		sc_client_db::new_client(
 			db_config,
 			executor,
-			&config.chain_spec,
+			config.expect_chain_spec(),
 			fork_blocks,
 			bad_blocks,
 			extensions,
@@ -224,15 +225,14 @@ fn new_full_parts<TBl, TRtApi, TExecDisp, TCfg, TGen, TCSExt>(
 	Ok((client, backend, keystore))
 }
 
-impl<TCfg, TGen, TCSExt> ServiceBuilder<(), (), TCfg, TGen, TCSExt, (), (), (), (), (), (), (), (), (), ()>
+impl<TGen, TCSExt> ServiceBuilder<(), (), TGen, TCSExt, (), (), (), (), (), (), (), (), (), ()>
 where TGen: RuntimeGenesis, TCSExt: Extension {
 	/// Start the service builder with a configuration.
 	pub fn new_full<TBl: BlockT, TRtApi, TExecDisp: NativeExecutionDispatch + 'static>(
-		config: Configuration<TCfg, TGen, TCSExt>
+		config: Configuration<TGen, TCSExt>
 	) -> Result<ServiceBuilder<
 		TBl,
 		TRtApi,
-		TCfg,
 		TGen,
 		TCSExt,
 		TFullClient<TBl, TRtApi, TExecDisp>,
@@ -270,11 +270,10 @@ where TGen: RuntimeGenesis, TCSExt: Extension {
 
 	/// Start the service builder with a configuration.
 	pub fn new_light<TBl: BlockT, TRtApi, TExecDisp: NativeExecutionDispatch + 'static>(
-		config: Configuration<TCfg, TGen, TCSExt>
+		config: Configuration<TGen, TCSExt>
 	) -> Result<ServiceBuilder<
 		TBl,
 		TRtApi,
-		TCfg,
 		TGen,
 		TCSExt,
 		TLightClient<TBl, TRtApi, TExecDisp>,
@@ -332,7 +331,7 @@ where TGen: RuntimeGenesis, TCSExt: Extension {
 		let remote_blockchain = backend.remote_blockchain();
 		let client = Arc::new(sc_client::light::new_light(
 			backend.clone(),
-			&config.chain_spec,
+			config.expect_chain_spec(),
 			executor,
 		)?);
 
@@ -355,8 +354,8 @@ where TGen: RuntimeGenesis, TCSExt: Extension {
 	}
 }
 
-impl<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TNetP, TExPool, TRpc, Backend>
-	ServiceBuilder<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp,
+impl<TBl, TRtApi, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TNetP, TExPool, TRpc, Backend>
+	ServiceBuilder<TBl, TRtApi, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp,
 		TNetP, TExPool, TRpc, Backend> {
 
 	/// Returns a reference to the client that was stored in this builder.
@@ -378,9 +377,9 @@ impl<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TNet
 	pub fn with_opt_select_chain<USc>(
 		self,
 		select_chain_builder: impl FnOnce(
-			&Configuration<TCfg, TGen, TCSExt>, &Arc<Backend>
+			&Configuration<TGen, TCSExt>, &Arc<Backend>
 		) -> Result<Option<USc>, Error>
-	) -> Result<ServiceBuilder<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, USc, TImpQu, TFprb, TFpp,
+	) -> Result<ServiceBuilder<TBl, TRtApi, TGen, TCSExt, TCl, TFchr, USc, TImpQu, TFprb, TFpp,
 		TNetP, TExPool, TRpc, Backend>, Error> {
 		let select_chain = select_chain_builder(&self.config, &self.backend)?;
 
@@ -405,8 +404,8 @@ impl<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TNet
 	/// Defines which head-of-chain strategy to use.
 	pub fn with_select_chain<USc>(
 		self,
-		builder: impl FnOnce(&Configuration<TCfg, TGen, TCSExt>, &Arc<Backend>) -> Result<USc, Error>
-	) -> Result<ServiceBuilder<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, USc, TImpQu, TFprb, TFpp,
+		builder: impl FnOnce(&Configuration<TGen, TCSExt>, &Arc<Backend>) -> Result<USc, Error>
+	) -> Result<ServiceBuilder<TBl, TRtApi, TGen, TCSExt, TCl, TFchr, USc, TImpQu, TFprb, TFpp,
 		TNetP, TExPool, TRpc, Backend>, Error> {
 		self.with_opt_select_chain(|cfg, b| builder(cfg, b).map(Option::Some))
 	}
@@ -414,9 +413,9 @@ impl<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TNet
 	/// Defines which import queue to use.
 	pub fn with_import_queue<UImpQu>(
 		self,
-		builder: impl FnOnce(&Configuration<TCfg, TGen, TCSExt>, Arc<TCl>, Option<TSc>, Arc<TExPool>)
+		builder: impl FnOnce(&Configuration<TGen, TCSExt>, Arc<TCl>, Option<TSc>, Arc<TExPool>)
 			-> Result<UImpQu, Error>
-	) -> Result<ServiceBuilder<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, UImpQu, TFprb, TFpp,
+	) -> Result<ServiceBuilder<TBl, TRtApi, TGen, TCSExt, TCl, TFchr, TSc, UImpQu, TFprb, TFpp,
 			TNetP, TExPool, TRpc, Backend>, Error>
 	where TSc: Clone {
 		let import_queue = builder(
@@ -447,8 +446,8 @@ impl<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TNet
 	/// Defines which network specialization protocol to use.
 	pub fn with_network_protocol<UNetP>(
 		self,
-		network_protocol_builder: impl FnOnce(&Configuration<TCfg, TGen, TCSExt>) -> Result<UNetP, Error>
-	) -> Result<ServiceBuilder<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp,
+		network_protocol_builder: impl FnOnce(&Configuration<TGen, TCSExt>) -> Result<UNetP, Error>
+	) -> Result<ServiceBuilder<TBl, TRtApi, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp,
 		UNetP, TExPool, TRpc, Backend>, Error> {
 		let network_protocol = network_protocol_builder(&self.config)?;
 
@@ -477,7 +476,6 @@ impl<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TNet
 	) -> Result<ServiceBuilder<
 		TBl,
 		TRtApi,
-		TCfg,
 		TGen,
 		TCSExt,
 		TCl,
@@ -518,7 +516,6 @@ impl<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TNet
 	) -> Result<ServiceBuilder<
 		TBl,
 		TRtApi,
-		TCfg,
 		TGen,
 		TCSExt,
 		TCl,
@@ -539,14 +536,14 @@ impl<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TNet
 	pub fn with_import_queue_and_opt_fprb<UImpQu, UFprb>(
 		self,
 		builder: impl FnOnce(
-			&Configuration<TCfg, TGen, TCSExt>,
+			&Configuration<TGen, TCSExt>,
 			Arc<TCl>,
 			Arc<Backend>,
 			Option<TFchr>,
 			Option<TSc>,
 			Arc<TExPool>,
 		) -> Result<(UImpQu, Option<UFprb>), Error>
-	) -> Result<ServiceBuilder<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, UImpQu, UFprb, TFpp,
+	) -> Result<ServiceBuilder<TBl, TRtApi, TGen, TCSExt, TCl, TFchr, TSc, UImpQu, UFprb, TFpp,
 		TNetP, TExPool, TRpc, Backend>, Error>
 	where TSc: Clone, TFchr: Clone {
 		let (import_queue, fprb) = builder(
@@ -580,14 +577,14 @@ impl<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TNet
 	pub fn with_import_queue_and_fprb<UImpQu, UFprb>(
 		self,
 		builder: impl FnOnce(
-			&Configuration<TCfg, TGen, TCSExt>,
+			&Configuration<TGen, TCSExt>,
 			Arc<TCl>,
 			Arc<Backend>,
 			Option<TFchr>,
 			Option<TSc>,
 			Arc<TExPool>,
 		) -> Result<(UImpQu, UFprb), Error>
-	) -> Result<ServiceBuilder<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, UImpQu, UFprb, TFpp,
+	) -> Result<ServiceBuilder<TBl, TRtApi, TGen, TCSExt, TCl, TFchr, TSc, UImpQu, UFprb, TFpp,
 			TNetP, TExPool, TRpc, Backend>, Error>
 	where TSc: Clone, TFchr: Clone {
 		self.with_import_queue_and_opt_fprb(|cfg, cl, b, f, sc, tx|
@@ -604,7 +601,7 @@ impl<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TNet
 			Arc<TCl>,
 			Option<TFchr>,
 		) -> Result<UExPool, Error>
-	) -> Result<ServiceBuilder<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp,
+	) -> Result<ServiceBuilder<TBl, TRtApi, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp,
 		TNetP, UExPool, TRpc, Backend>, Error>
 	where TSc: Clone, TFchr: Clone {
 		let transaction_pool = transaction_pool_builder(
@@ -641,7 +638,7 @@ impl<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TNet
 			Option<TFchr>,
 			Option<Arc<dyn RemoteBlockchain<TBl>>>,
 		) -> Result<URpc, Error>,
-	) -> Result<ServiceBuilder<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp,
+	) -> Result<ServiceBuilder<TBl, TRtApi, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp,
 		TNetP, TExPool, URpc, Backend>, Error>
 	where TSc: Clone, TFchr: Clone {
 		let rpc_extensions = rpc_ext_builder(
@@ -705,11 +702,10 @@ pub trait ServiceBuilderCommand {
 	) -> Pin<Box<dyn Future<Output = Result<(), Error>> + Send>>;
 }
 
-impl<TBl, TRtApi, TCfg, TGen, TCSExt, TBackend, TExec, TSc, TImpQu, TNetP, TExPool, TRpc>
+impl<TBl, TRtApi, TGen, TCSExt, TBackend, TExec, TSc, TImpQu, TNetP, TExPool, TRpc>
 ServiceBuilder<
 	TBl,
 	TRtApi,
-	TCfg,
 	TGen,
 	TCSExt,
 	Client<TBackend, TExec, TBl, TRtApi>,
@@ -733,7 +729,6 @@ ServiceBuilder<
 		sp_api::ApiExt<TBl, StateBackend = TBackend::State>,
 	TBl: BlockT,
 	TRtApi: 'static + Send + Sync,
-	TCfg: Default,
 	TGen: RuntimeGenesis,
 	TCSExt: Extension,
 	TBackend: 'static + sc_client_api::backend::Backend<TBl> + Send,
@@ -799,6 +794,7 @@ ServiceBuilder<
 
 		let import_queue = Box::new(import_queue);
 		let chain_info = client.chain_info();
+		let chain_spec = config.expect_chain_spec();
 
 		let version = config.full_version();
 		info!("Highest known block at #{}", chain_info.best_number);
@@ -821,7 +817,7 @@ ServiceBuilder<
 		});
 
 		let protocol_id = {
-			let protocol_id_full = match config.chain_spec.protocol_id() {
+			let protocol_id_full = match chain_spec.protocol_id() {
 				Some(pid) => pid,
 				None => {
 					warn!("Using default protocol ID {:?} because none is configured in the \
@@ -1030,10 +1026,10 @@ ServiceBuilder<
 			use sc_rpc::{chain, state, author, system, offchain};
 
 			let system_info = sc_rpc::system::SystemInfo {
-				chain_name: config.chain_spec.name().into(),
+				chain_name: chain_spec.name().into(),
 				impl_name: config.impl_name.into(),
 				impl_version: config.impl_version.into(),
-				properties: config.chain_spec.properties().clone(),
+				properties: chain_spec.properties().clone(),
 			};
 
 			let subscriptions = sc_rpc::Subscriptions::new(Arc::new(SpawnTaskHandle {
@@ -1119,7 +1115,7 @@ ServiceBuilder<
 			let name = config.name.clone();
 			let impl_name = config.impl_name.to_owned();
 			let version = version.clone();
-			let chain_name = config.chain_spec.name().to_owned();
+			let chain_name = config.expect_chain_spec().name().to_owned();
 			let telemetry_connection_sinks_ = telemetry_connection_sinks.clone();
 			let telemetry = sc_telemetry::init_telemetry(sc_telemetry::TelemetryConfig {
 				endpoints,
@@ -1188,7 +1184,7 @@ ServiceBuilder<
 			essential_failed_rx,
 			to_spawn_tx,
 			to_spawn_rx,
-			tasks_executor: if let Some(exec) = config.tasks_executor {
+			task_executor: if let Some(exec) = config.task_executor {
 				exec
 			} else {
 				return Err(Error::TasksExecutorRequired);

substrate/client/service/src/chain_ops.rs

@@ -44,11 +44,11 @@ pub fn build_spec<G, E>(spec: ChainSpec<G, E>, raw: bool) -> error::Result<Strin
 }
 
 impl<
-	TBl, TRtApi, TCfg, TGen, TCSExt, TBackend,
+	TBl, TRtApi, TGen, TCSExt, TBackend,
 	TExec, TFchr, TSc, TImpQu, TFprb, TFpp, TNetP,
 	TExPool, TRpc, Backend
 > ServiceBuilderCommand for ServiceBuilder<
-	TBl, TRtApi, TCfg, TGen, TCSExt, Client<TBackend, TExec, TBl, TRtApi>,
+	TBl, TRtApi, TGen, TCSExt, Client<TBackend, TExec, TBl, TRtApi>,
 	TFchr, TSc, TImpQu, TFprb, TFpp, TNetP, TExPool, TRpc, Backend
 > where
 	TBl: BlockT,

substrate/client/service/src/config.rs

@@ -23,13 +23,13 @@ pub use sc_executor::WasmExecutionMethod;
 
 use std::{future::Future, path::{PathBuf, Path}, pin::Pin, net::SocketAddr, sync::Arc};
 pub use sc_transaction_pool::txpool::Options as TransactionPoolOptions;
-use sc_chain_spec::{ChainSpec, RuntimeGenesis, Extension, NoExtension};
+use sc_chain_spec::{ChainSpec, NoExtension};
 use sp_core::crypto::Protected;
 use target_info::Target;
 use sc_telemetry::TelemetryEndpoints;
 
 /// Service configuration.
-pub struct Configuration<C, G, E = NoExtension> {
+pub struct Configuration<G, E = NoExtension> {
 	/// Implementation name
 	pub impl_name: &'static str,
 	/// Implementation version
@@ -39,7 +39,7 @@ pub struct Configuration<C, G, E = NoExtension> {
 	/// Node roles.
 	pub roles: Roles,
 	/// How to spawn background tasks. Mandatory, otherwise creating a `Service` will error.
-	pub tasks_executor: Option<Box<dyn Fn(Pin<Box<dyn Future<Output = ()> + Send>>) + Send>>,
+	pub task_executor: Option<Box<dyn Fn(Pin<Box<dyn Future<Output = ()> + Send>>) + Send>>,
 	/// Extrinsic pool configuration.
 	pub transaction_pool: TransactionPoolOptions,
 	/// Network configuration.
@@ -57,9 +57,7 @@ pub struct Configuration<C, G, E = NoExtension> {
 	/// Pruning settings.
 	pub pruning: PruningMode,
 	/// Chain configuration.
-	pub chain_spec: ChainSpec<G, E>,
-	/// Custom configuration.
-	pub custom: C,
+	pub chain_spec: Option<ChainSpec<G, E>>,
 	/// Node name.
 	pub name: String,
 	/// Wasm execution method.
@@ -146,22 +144,18 @@ pub enum DatabaseConfig {
 	Custom(Arc<dyn KeyValueDB>),
 }
 
-impl<C, G, E> Configuration<C, G, E> where
-	C: Default,
-	G: RuntimeGenesis,
-	E: Extension,
-{
-	/// Create a default config for given chain spec and path to configuration dir
-	pub fn default_with_spec_and_base_path(chain_spec: ChainSpec<G, E>, config_dir: Option<PathBuf>) -> Self {
-		let mut configuration = Configuration {
+impl<G, E> Default for Configuration<G, E> {
+	/// Create a default config
+	fn default() -> Self {
+		let configuration = Configuration {
 			impl_name: "parity-substrate",
 			impl_version: "0.0.0",
 			impl_commit: "",
-			chain_spec,
-			config_dir: config_dir.clone(),
+			chain_spec: None,
+			config_dir: None,
 			name: Default::default(),
 			roles: Roles::FULL,
-			tasks_executor: None,
+			task_executor: None,
 			transaction_pool: Default::default(),
 			network: Default::default(),
 			keystore: KeystoreConfig::None,
@@ -171,7 +165,6 @@ impl<C, G, E> Configuration<C, G, E> where
 			},
 			state_cache_size: Default::default(),
 			state_cache_child_ratio: Default::default(),
-			custom: Default::default(),
 			pruning: PruningMode::default(),
 			wasm_method: WasmExecutionMethod::Interpreted,
 			execution_strategies: Default::default(),
@@ -191,16 +184,13 @@ impl<C, G, E> Configuration<C, G, E> where
 			tracing_targets: Default::default(),
 			tracing_receiver: Default::default(),
 		};
-		configuration.network.boot_nodes = configuration.chain_spec.boot_nodes().to_vec();
-
-		configuration.telemetry_endpoints = configuration.chain_spec.telemetry_endpoints().clone();
 
 		configuration
 	}
 
 }
 
-impl<C, G, E> Configuration<C, G, E> {
+impl<G, E> Configuration<G, E> {
 	/// Returns full version string of this configuration.
 	pub fn full_version(&self) -> String {
 		full_version_from_strs(self.impl_version, self.impl_commit)
@@ -216,11 +206,20 @@ impl<C, G, E> Configuration<C, G, E> {
 	pub fn in_chain_config_dir(&self, sub: &str) -> Option<PathBuf> {
 		self.config_dir.clone().map(|mut path| {
 			path.push("chains");
-			path.push(self.chain_spec.id());
+			path.push(self.expect_chain_spec().id());
 			path.push(sub);
 			path
 		})
 	}
+
+	/// Return a reference to the `ChainSpec` of this `Configuration`.
+	///
+	/// ### Panics
+	///
+	/// This method panic if the `chain_spec` is `None`
+	pub fn expect_chain_spec(&self) -> &ChainSpec<G, E> {
+		self.chain_spec.as_ref().expect("chain_spec must be specified")
+	}
 }
 
 /// Returns platform info

substrate/client/service/src/lib.rs

@@ -96,7 +96,7 @@ pub struct Service<TBl, TCl, TSc, TNetStatus, TNet, TTxPool, TOc> {
 	/// Receiver for futures that must be spawned as background tasks.
 	to_spawn_rx: mpsc::UnboundedReceiver<(Pin<Box<dyn Future<Output = ()> + Send>>, Cow<'static, str>)>,
 	/// How to spawn background tasks.
-	tasks_executor: Box<dyn Fn(Pin<Box<dyn Future<Output = ()> + Send>>) + Send>,
+	task_executor: Box<dyn Fn(Pin<Box<dyn Future<Output = ()> + Send>>) + Send>,
 	rpc_handlers: sc_rpc_server::RpcHandler<sc_rpc::Metadata>,
 	_rpc: Box<dyn std::any::Any + Send + Sync>,
 	_telemetry: Option<sc_telemetry::Telemetry>,
@@ -340,7 +340,7 @@ impl<TBl: Unpin, TCl, TSc: Unpin, TNetStatus, TNet, TTxPool, TOc> Future for
 		}
 
 		while let Poll::Ready(Some((task_to_spawn, name))) = Pin::new(&mut this.to_spawn_rx).poll_next(cx) {
-			(this.tasks_executor)(Box::pin(futures_diagnose::diagnose(name, task_to_spawn)));
+			(this.task_executor)(Box::pin(futures_diagnose::diagnose(name, task_to_spawn)));
 		}
 
 		// The service future never ends.
@@ -523,8 +523,8 @@ impl<TBl, TCl, TSc, TNetStatus, TNet, TTxPool, TOc> Drop for
 
 /// Starts RPC servers that run in their own thread, and returns an opaque object that keeps them alive.
 #[cfg(not(target_os = "unknown"))]
-fn start_rpc_servers<C, G, E, H: FnMut() -> sc_rpc_server::RpcHandler<sc_rpc::Metadata>>(
-	config: &Configuration<C, G, E>,
+fn start_rpc_servers<G, E, H: FnMut() -> sc_rpc_server::RpcHandler<sc_rpc::Metadata>>(
+	config: &Configuration<G, E>,
 	mut gen_handler: H
 ) -> Result<Box<dyn std::any::Any + Send + Sync>, error::Error> {
 	fn maybe_start_server<T, F>(address: Option<SocketAddr>, mut start: F) -> Result<Option<T>, io::Error>
@@ -564,8 +564,8 @@ fn start_rpc_servers<C, G, E, H: FnMut() -> sc_rpc_server::RpcHandler<sc_rpc::Me
 
 /// Starts RPC servers that run in their own thread, and returns an opaque object that keeps them alive.
 #[cfg(target_os = "unknown")]
-fn start_rpc_servers<C, G, E, H: FnMut() -> sc_rpc_server::RpcHandler<sc_rpc::Metadata>>(
-	_: &Configuration<C, G, E>,
+fn start_rpc_servers<G, E, H: FnMut() -> sc_rpc_server::RpcHandler<sc_rpc::Metadata>>(
+	_: &Configuration<G, E>,
 	_: H
 ) -> Result<Box<dyn std::any::Any + Send + Sync>, error::Error> {
 	Ok(Box::new(()))