Use SpawnNamed instead of Spawn in Overseer (#1430)

* Use SpawnNamed instead of Spawn in Overseer

* reexport SpawnNamed and fix doc tests

* Fix deps

polkadot/node/subsystem/src/lib.rs

@@ -101,7 +101,12 @@ impl From<std::convert::Infallible> for SubsystemError {
 /// An asynchronous subsystem task..
 ///
 /// In essence it's just a newtype wrapping a `BoxFuture`.
-pub struct SpawnedSubsystem(pub BoxFuture<'static, ()>);
+pub struct SpawnedSubsystem {
+	/// Name of the subsystem being spawned.
+	pub name: &'static str,
+	/// The task of the subsystem being spawned.
+	pub future: BoxFuture<'static, ()>,
+}
 
 /// A `Result` type that wraps [`SubsystemError`].
 ///
@@ -130,7 +135,7 @@ pub trait SubsystemContext: Send + 'static {
 	async fn recv(&mut self) -> SubsystemResult<FromOverseer<Self::Message>>;
 
 	/// Spawn a child task on the executor.
-	async fn spawn(&mut self, s: Pin<Box<dyn Future<Output = ()> + Send>>) -> SubsystemResult<()>;
+	async fn spawn(&mut self, name: &'static str, s: Pin<Box<dyn Future<Output = ()> + Send>>) -> SubsystemResult<()>;
 
 	/// Send a direct message to some other `Subsystem`, routed based on message type.
 	async fn send_message(&mut self, msg: AllMessages) -> SubsystemResult<()>;
@@ -159,7 +164,7 @@ pub struct DummySubsystem;
 
 impl<C: SubsystemContext> Subsystem<C> for DummySubsystem {
 	fn start(self, mut ctx: C) -> SpawnedSubsystem {
-		SpawnedSubsystem(Box::pin(async move {
+		let future = Box::pin(async move {
 			loop {
 				match ctx.recv().await {
 					Ok(FromOverseer::Signal(OverseerSignal::Conclude)) => return,
@@ -167,6 +172,11 @@ impl<C: SubsystemContext> Subsystem<C> for DummySubsystem {
 					_ => continue,
 				}
 			}
-		}))
+		});
+
+		SpawnedSubsystem {
+			name: "DummySubsystem",
+			future,
+		}
 	}
 }

polkadot/node/subsystem/src/util.rs

@@ -30,7 +30,7 @@ use futures::{
 	prelude::*,
 	select,
 	stream::Stream,
-	task::{self, Spawn, SpawnError, SpawnExt},
+	task,
 };
 use futures_timer::Delay;
 use keystore::KeyStorePtr;
@@ -40,7 +40,10 @@ use polkadot_primitives::v1::{
 	EncodeAs, Hash, HeadData, Id as ParaId, Signed, SigningContext,
 	ValidatorId, ValidatorIndex, ValidatorPair,
 };
-use sp_core::Pair;
+use sp_core::{
+	Pair,
+	traits::SpawnNamed,
+};
 use std::{
 	collections::HashMap,
 	convert::{TryFrom, TryInto},
@@ -64,9 +67,6 @@ pub enum Error {
 	/// Attempted to send on a MPSC channel which has been canceled
 	#[from]
 	Mpsc(mpsc::SendError),
-	/// Attempted to spawn a new task, and failed
-	#[from]
-	Spawn(SpawnError),
 	/// Attempted to convert from an AllMessages to a FromJob, and failed.
 	SenderConversion(String),
 	/// The local node is not a validator.
@@ -358,7 +358,7 @@ pub struct Jobs<Spawner, Job: JobTrait> {
 	job: std::marker::PhantomData<Job>,
 }
 
-impl<Spawner: Spawn, Job: JobTrait> Jobs<Spawner, Job> {
+impl<Spawner: SpawnNamed, Job: JobTrait> Jobs<Spawner, Job> {
 	/// Create a new Jobs manager which handles spawning appropriate jobs.
 	pub fn new(spawner: Spawner) -> Self {
 		Self {
@@ -391,7 +391,7 @@ impl<Spawner: Spawn, Job: JobTrait> Jobs<Spawner, Job> {
 			let _ = future.await;
 			let _ = finished_tx.send(());
 		};
-		self.spawner.spawn(future)?;
+		self.spawner.spawn(Job::NAME, future.boxed());
 
 		// this handle lets us remove the appropriate receiver from self.outgoing_msgs
 		// when it's time to stop the job.
@@ -444,7 +444,7 @@ impl<Spawner, Job: JobTrait> PinnedDrop for Jobs<Spawner, Job> {
 
 impl<Spawner, Job> Stream for Jobs<Spawner, Job>
 where
-	Spawner: Spawn,
+	Spawner: SpawnNamed,
 	Job: JobTrait,
 {
 	type Item = Job::FromJob;
@@ -476,7 +476,7 @@ pub struct JobManager<Spawner, Context, Job: JobTrait> {
 
 impl<Spawner, Context, Job> JobManager<Spawner, Context, Job>
 where
-	Spawner: Spawn + Clone + Send + Unpin,
+	Spawner: SpawnNamed + Clone + Send + Unpin,
 	Context: SubsystemContext,
 	Job: JobTrait,
 	Job::RunArgs: Clone,
@@ -595,7 +595,7 @@ where
 
 impl<Spawner, Context, Job> Subsystem<Context> for JobManager<Spawner, Context, Job>
 where
-	Spawner: Spawn + Send + Clone + Unpin + 'static,
+	Spawner: SpawnNamed + Send + Clone + Unpin + 'static,
 	Context: SubsystemContext,
 	<Context as SubsystemContext>::Message: Into<Job::ToJob>,
 	Job: JobTrait + Send,
@@ -606,8 +606,13 @@ where
 		let spawner = self.spawner.clone();
 		let run_args = self.run_args.clone();
 
-		SpawnedSubsystem(Box::pin(async move {
+		let future = Box::pin(async move {
 			Self::run(ctx, run_args, spawner).await;
-		}))
+		});
+
+		SpawnedSubsystem {
+			name: "JobManager",
+			future,
+		}
 	}
 }