Integrate all (dummy) subsystems with the Overseer (#1374)

* overseer: introduce a utility typemap

* it's ugly but it compiles

* move DummySubsystem to subsystem crate

* fix tests fallout

* use a struct for all subsystems

* more tests fallout

* add missing pov_distribution subsystem

* remove unused imports and bounds

* fix minimal-example

node/overseer/examples/minimal-example.rs

@@ -28,11 +28,14 @@ use futures_timer::Delay;
 use kv_log_macro as log;
 
 use polkadot_primitives::parachain::{BlockData, PoVBlock};
-use polkadot_overseer::Overseer;
+use polkadot_overseer::{Overseer, AllSubsystems};
 
-use polkadot_subsystem::{Subsystem, SubsystemContext, SpawnedSubsystem, FromOverseer};
+use polkadot_subsystem::{
+	Subsystem, SubsystemContext, DummySubsystem, 
+	SpawnedSubsystem, FromOverseer,
+};
 use polkadot_subsystem::messages::{
-	AllMessages, CandidateBackingMessage, CandidateValidationMessage
+	CandidateValidationMessage, CandidateBackingMessage, AllMessages,
 };
 
 struct Subsystem1;
@@ -128,10 +131,22 @@ fn main() {
 			Delay::new(Duration::from_secs(1)).await;
 		});
 
+		let all_subsystems = AllSubsystems {
+			candidate_validation: Subsystem2,
+			candidate_backing: Subsystem1,
+			candidate_selection: DummySubsystem,
+			statement_distribution: DummySubsystem,
+			availability_distribution: DummySubsystem,
+			bitfield_distribution: DummySubsystem,
+			provisioner: DummySubsystem,
+			pov_distribution: DummySubsystem,
+			runtime_api: DummySubsystem,
+			availability_store: DummySubsystem,
+			network_bridge: DummySubsystem,
+		};
 		let (overseer, _handler) = Overseer::new(
 			vec![],
-			Subsystem2,
-			Subsystem1,
+			all_subsystems,
 			spawner,
 		).unwrap();
 		let overseer_fut = overseer.run().fuse();

node/service/src/lib.rs

@@ -29,11 +29,8 @@ use grandpa::{self, FinalityProofProvider as GrandpaFinalityProofProvider};
 use sc_executor::native_executor_instance;
 use log::info;
 use sp_blockchain::HeaderBackend;
-use polkadot_overseer::{self as overseer, BlockInfo, Overseer, OverseerHandler};
-use polkadot_subsystem::{
-	Subsystem, SubsystemContext, SpawnedSubsystem,
-	messages::{CandidateValidationMessage, CandidateBackingMessage},
-};
+use polkadot_overseer::{self as overseer, AllSubsystems, BlockInfo, Overseer, OverseerHandler};
+use polkadot_subsystem::DummySubsystem;
 use polkadot_node_core_proposer::ProposerFactory;
 use sp_trie::PrefixedMemoryDB;
 pub use service::{
@@ -275,38 +272,28 @@ macro_rules! new_full_start {
 	}}
 }
 
-struct CandidateValidationSubsystem;
-
-impl<C> Subsystem<C> for CandidateValidationSubsystem
-	where C: SubsystemContext<Message = CandidateValidationMessage>
-{
-	fn start(self, mut ctx: C) -> SpawnedSubsystem {
-		SpawnedSubsystem(Box::pin(async move {
-			while let Ok(_) = ctx.recv().await {}
-		}))
-	}
-}
-
-struct CandidateBackingSubsystem;
-
-impl<C> Subsystem<C> for CandidateBackingSubsystem
-	where C: SubsystemContext<Message = CandidateBackingMessage>
-{
-	fn start(self, mut ctx: C) -> SpawnedSubsystem {
-		SpawnedSubsystem(Box::pin(async move {
-			while let Ok(_) = ctx.recv().await {}
-		}))
-	}
-}
-
 fn real_overseer<S: futures::task::Spawn>(
 	leaves: impl IntoIterator<Item = BlockInfo>,
 	s: S,
 ) -> Result<(Overseer<S>, OverseerHandler), ServiceError> {
-	let validation = CandidateValidationSubsystem;
-	let candidate_backing = CandidateBackingSubsystem;
-	Overseer::new(leaves, validation, candidate_backing, s)
-		.map_err(|e| ServiceError::Other(format!("Failed to create an Overseer: {:?}", e)))
+	let all_subsystems = AllSubsystems {
+		candidate_validation: DummySubsystem,
+		candidate_backing: DummySubsystem,
+		candidate_selection: DummySubsystem,
+		statement_distribution: DummySubsystem,
+		availability_distribution: DummySubsystem,
+		bitfield_distribution: DummySubsystem,
+		provisioner: DummySubsystem,
+		pov_distribution: DummySubsystem,
+		runtime_api: DummySubsystem,
+		availability_store: DummySubsystem,
+		network_bridge: DummySubsystem,
+	};
+	Overseer::new(
+		leaves, 
+		all_subsystems,
+		s,
+	).map_err(|e| ServiceError::Other(format!("Failed to create an Overseer: {:?}", e)))
 }
 
 /// Builds a new service for a full client.

node/subsystem/src/lib.rs

@@ -148,3 +148,21 @@ pub trait Subsystem<C: SubsystemContext> {
 	/// Start this `Subsystem` and return `SpawnedSubsystem`.
 	fn start(self, ctx: C) -> SpawnedSubsystem;
 }
+
+/// A dummy subsystem that implements [`Subsystem`] for all
+/// types of messages. Used for tests or as a placeholder.
+pub struct DummySubsystem;
+
+impl<C: SubsystemContext> Subsystem<C> for DummySubsystem {
+	fn start(self, mut ctx: C) -> SpawnedSubsystem {
+		SpawnedSubsystem(Box::pin(async move {
+			loop {
+				match ctx.recv().await {
+					Ok(FromOverseer::Signal(OverseerSignal::Conclude)) => return,
+					Err(_) => return,
+					_ => continue,
+				}
+			}
+		}))
+	}
+}