Change SpawnedSubsystem type to log subsystem errors (#1878)

* Change SpawnedSubsystem type to log subsystem errors

* Remove clone

polkadot/node/collation-generation/src/lib.rs

@@ -165,7 +165,10 @@ where
 	Context: SubsystemContext<Message = CollationGenerationMessage>,
 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
-		let future = Box::pin(self.run(ctx));
+		let future = Box::pin(async move {
+			self.run(ctx).await;
+			Ok(())
+		});
 
 		SpawnedSubsystem {
 			name: "collation-generation-subsystem",

polkadot/node/core/av-store/src/lib.rs

@@ -27,7 +27,7 @@ use std::sync::Arc;
 use std::time::{Duration, SystemTime, SystemTimeError, UNIX_EPOCH};
 
 use codec::{Encode, Decode};
-use futures::{select, channel::oneshot, future::{self, Either}, Future, FutureExt};
+use futures::{select, channel::oneshot, future::{self, Either}, Future, FutureExt, TryFutureExt};
 use futures_timer::Delay;
 use kvdb_rocksdb::{Database, DatabaseConfig};
 use kvdb::{KeyValueDB, DBTransaction};
@@ -969,9 +969,7 @@ where
 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let future = run(self, ctx)
-			.map(|r| if let Err(e) = r {
-				log::error!(target: "availabilitystore", "Subsystem exited with an error {:?}", e);
-			})
+			.map_err(|e| SubsystemError::with_origin("availability-store", e))
 			.boxed();
 
 		SpawnedSubsystem {

polkadot/node/core/candidate-validation/src/lib.rs

@@ -121,7 +121,6 @@ impl<S, C> Subsystem<C> for CandidateValidationSubsystem<S> where
 	fn start(self, ctx: C) -> SpawnedSubsystem {
 		let future = run(ctx, self.spawn, self.metrics)
 			.map_err(|e| SubsystemError::with_origin("candidate-validation", e))
-			.map(|_| ())
 			.boxed();
 		SpawnedSubsystem {
 			name: "candidate-validation-subsystem",

polkadot/node/core/chain-api/src/lib.rs

@@ -67,7 +67,6 @@ impl<Client, Context> Subsystem<Context> for ChainApiSubsystem<Client> where
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let future = run(ctx, self)
 			.map_err(|e| SubsystemError::with_origin("chain-api", e))
-			.map(|_| ())
 			.boxed();
 		SpawnedSubsystem {
 			future,

polkadot/node/core/runtime-api/src/lib.rs

@@ -60,7 +60,7 @@ impl<Client, Context> Subsystem<Context> for RuntimeApiSubsystem<Client> where
 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		SpawnedSubsystem {
-			future: run(ctx, self).map(|_| ()).boxed(),
+			future: run(ctx, self).boxed(),
 			name: "runtime-api-subsystem",
 		}
 	}

polkadot/node/network/availability-distribution/src/lib.rs

@@ -823,7 +823,6 @@ where
 		let future = self
 			.run(ctx)
 			.map_err(|e| SubsystemError::with_origin("availability-distribution", e))
-			.map(|_| ())
 			.boxed();
 
 		SpawnedSubsystem {

polkadot/node/network/bitfield-distribution/src/lib.rs

@@ -585,7 +585,7 @@ where
 			.map_err(|e| {
 				SubsystemError::with_origin("bitfield-distribution", e)
 			})
-			.map(|_| ()).boxed();
+			.boxed();
 
 		SpawnedSubsystem {
 			name: "bitfield-distribution-subsystem",

polkadot/node/network/bridge/src/lib.rs

@@ -231,7 +231,6 @@ impl<Net, AD, Context> Subsystem<Context> for NetworkBridge<Net, AD>
 			.map_err(|e| {
 				SubsystemError::with_origin("network-bridge", e)
 			})
-			.map(|_| ())
 			.boxed();
 		SpawnedSubsystem {
 			name: "network-bridge-subsystem",

polkadot/node/network/collator-protocol/src/lib.rs

@@ -20,7 +20,7 @@
 #![deny(missing_docs, unused_crate_dependencies)]
 
 use std::time::Duration;
-use futures::{channel::oneshot, FutureExt};
+use futures::{channel::oneshot, FutureExt, TryFutureExt};
 use log::trace;
 use thiserror::Error;
 
@@ -122,9 +122,14 @@ where
 	Context: SubsystemContext<Message = CollatorProtocolMessage> + Sync + Send,
 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
+		let future = self
+			.run(ctx)
+			.map_err(|e| SubsystemError::with_origin("collator-protocol", e))
+			.boxed();
+
 		SpawnedSubsystem {
 			name: "collator-protocol-subsystem",
-			future: self.run(ctx).map(|_| ()).boxed(),
+			future,
 		}
 	}
 }

polkadot/node/network/pov-distribution/src/lib.rs

@@ -66,7 +66,6 @@ impl<C> Subsystem<C> for PoVDistribution
 		// within `run`.
 		let future = self.run(ctx)
 			.map_err(|e| SubsystemError::with_origin("pov-distribution", e))
-			.map(|_| ())
 			.boxed();
 		SpawnedSubsystem {
 			name: "pov-distribution-subsystem",
@@ -616,4 +615,4 @@ impl metrics::Metrics for Metrics {
 }
 
 #[cfg(test)]
-mod tests;
+mod tests;

polkadot/node/network/statement-distribution/src/lib.rs

@@ -81,7 +81,7 @@ impl<C> Subsystem<C> for StatementDistribution
 		// within `run`.
 		SpawnedSubsystem {
 			name: "statement-distribution-subsystem",
-			future: self.run(ctx).map(|_| ()).boxed(),
+			future: self.run(ctx).boxed(),
 		}
 	}
 }

polkadot/node/overseer/examples/minimal-example.rs

@@ -76,6 +76,7 @@ impl<C> Subsystem<C> for Subsystem1
 	fn start(self, ctx: C) -> SpawnedSubsystem {
 		let future = Box::pin(async move {
 			Self::run(ctx).await;
+			Ok(())
 		});
 
 		SpawnedSubsystem {
@@ -121,6 +122,7 @@ impl<C> Subsystem<C> for Subsystem2
 	fn start(self, ctx: C) -> SpawnedSubsystem {
 		let future = Box::pin(async move {
 			Self::run(ctx).await;
+			Ok(())
 		});
 
 		SpawnedSubsystem {

polkadot/node/overseer/src/lib.rs

@@ -1606,7 +1606,9 @@ fn spawn<S: SpawnNamed, M: Send + 'static>(
 	let (tx, rx) = oneshot::channel();
 
 	let fut = Box::pin(async move {
-		future.await;
+		if let Err(e) = future.await {
+			log::error!("Subsystem {} exited with error {:?}", name, e);
+		}
 		let _ = tx.send(());
 	});
 
@@ -1658,8 +1660,8 @@ mod tests {
 								i += 1;
 								continue;
 							}
-							Ok(FromOverseer::Signal(OverseerSignal::Conclude)) => return,
-							Err(_) => return,
+							Ok(FromOverseer::Signal(OverseerSignal::Conclude)) => return Ok(()),
+							Err(_) => return Ok(()),
 							_ => (),
 						}
 					}
@@ -1704,11 +1706,13 @@ mod tests {
 							Ok(Some(_)) => {
 								continue;
 							}
-							Err(_) => return,
+							Err(_) => return Ok(()),
 							_ => (),
 						}
 						pending!();
 					}
+
+					Ok(())
 				}),
 			}
 		}
@@ -1724,6 +1728,7 @@ mod tests {
 				name: "test-subsystem-4",
 				future: Box::pin(async move {
 					// Do nothing and exit.
+					Ok(())
 				}),
 			}
 		}
@@ -1902,11 +1907,13 @@ mod tests {
 								continue;
 							},
 							Ok(Some(_)) => continue,
-							Err(_) => return,
+							Err(_) => break,
 							_ => (),
 						}
 						pending!();
 					}
+
+					Ok(())
 				}),
 			}
 		}
@@ -1931,11 +1938,13 @@ mod tests {
 								continue;
 							},
 							Ok(Some(_)) => continue,
-							Err(_) => return,
+							Err(_) => break,
 							_ => (),
 						}
 						pending!();
 					}
+
+					Ok(())
 				}),
 			}
 		}
@@ -2180,6 +2189,8 @@ mod tests {
 						}
 						pending!();
 					}
+
+					Ok(())
 				}),
 			}
 		}

polkadot/node/subsystem-test-helpers/src/lib.rs

@@ -303,11 +303,11 @@ impl<C: SubsystemContext<Message = Msg>, Msg: Send + 'static> Subsystem<C> for F
 		let future = Box::pin(async move {
 			loop {
 				match ctx.recv().await {
-					Ok(FromOverseer::Signal(OverseerSignal::Conclude)) => return,
+					Ok(FromOverseer::Signal(OverseerSignal::Conclude)) => return Ok(()),
 					Ok(FromOverseer::Communication { msg }) => {
 						let _ = self.0.send(msg).await;
 					},
-					Err(_) => return,
+					Err(_) => return Ok(()),
 					_ => (),
 				}
 			}

polkadot/node/subsystem-util/src/lib.rs

@@ -942,6 +942,7 @@ where
 
 		let future = Box::pin(async move {
 			Self::run(ctx, run_args, metrics, spawner, errors).await;
+			Ok(())
 		});
 
 		SpawnedSubsystem {

polkadot/node/subsystem/src/lib.rs

@@ -164,7 +164,7 @@ pub struct SpawnedSubsystem {
 	/// Name of the subsystem being spawned.
 	pub name: &'static str,
 	/// The task of the subsystem being spawned.
-	pub future: BoxFuture<'static, ()>,
+	pub future: BoxFuture<'static, SubsystemResult<()>>,
 }
 
 /// A `Result` type that wraps [`SubsystemError`].
@@ -233,8 +233,8 @@ impl<C: SubsystemContext> Subsystem<C> for DummySubsystem {
 		let future = Box::pin(async move {
 			loop {
 				match ctx.recv().await {
-					Ok(FromOverseer::Signal(OverseerSignal::Conclude)) => return,
-					Err(_) => return,
+					Ok(FromOverseer::Signal(OverseerSignal::Conclude)) => return Ok(()),
+					Err(_) => return Ok(()),
 					_ => continue,
 				}
 			}