create parallel tasks extension (#5249)

substrate/client/service/src/builder.rs

@@ -263,6 +263,7 @@ fn new_full_parts<TBl, TRtApi, TExecDisp>(
 			fork_blocks,
 			bad_blocks,
 			extensions,
+			Box::new(tasks_builder.spawn_handle()),
 			config.prometheus_config.as_ref().map(|config| config.registry.clone()),
 		)?
 	};
@@ -366,6 +367,7 @@ impl ServiceBuilder<(), (), (), (), (), (), (), (), (), (), ()> {
 			sc_client::light::new_fetch_checker::<_, TBl, _>(
 				light_blockchain.clone(),
 				executor.clone(),
+				Box::new(tasks_builder.spawn_handle()),
 			),
 		);
 		let fetcher = Arc::new(sc_network::config::OnDemand::new(fetch_checker));
@@ -375,6 +377,7 @@ impl ServiceBuilder<(), (), (), (), (), (), (), (), (), (), ()> {
 			backend.clone(),
 			config.expect_chain_spec().as_storage_builder(),
 			executor,
+			Box::new(tasks_builder.spawn_handle()),
 			config.prometheus_config.as_ref().map(|config| config.registry.clone()),
 		)?);
 

substrate/client/service/src/task_manager.rs

@@ -26,6 +26,7 @@ use futures::{
 	compat::*,
 	task::{Spawn, FutureObj, SpawnError},
 };
+use sc_client_api::CloneableSpawn;
 
 /// Type alias for service task executor (usually runtime).
 pub type ServiceTaskExecutor = Arc<dyn Fn(Pin<Box<dyn Future<Output = ()> + Send>>) + Send + Sync>;
@@ -118,6 +119,12 @@ impl Spawn for SpawnTaskHandle {
 	}
 }
 
+impl sc_client_api::CloneableSpawn for SpawnTaskHandle {
+	fn clone(&self) -> Box<dyn CloneableSpawn> {
+		Box::new(Clone::clone(self))
+	}
+}
+
 type Boxed01Future01 = Box<dyn futures01::Future<Item = (), Error = ()> + Send + 'static>;
 
 impl futures01::future::Executor<Boxed01Future01> for SpawnTaskHandle {