skip passed slots and wake up service correctly (#4212)

substrate/client/consensus/slots/src/lib.rs

@@ -122,6 +122,19 @@ pub trait SimpleSlotWorker<B: BlockT> {
 		let (timestamp, slot_number, slot_duration) =
 			(slot_info.timestamp, slot_info.number, slot_info.duration);
 
+		{
+			let slot_now = SignedDuration::default().slot_now(slot_duration);
+			if slot_now > slot_number {
+				// if this is behind, return.
+					debug!(target: self.logging_target(),
+					"Skipping proposal slot {} since our current view is {}",
+					slot_number, slot_now,
+				);
+
+				return Box::pin(future::ready(Ok(())));
+			}
+		}
+
 		let epoch_data = match self.epoch_data(&chain_head, slot_number) {
 			Ok(epoch_data) => epoch_data,
 			Err(err) => {

substrate/client/service/src/builder.rs

@@ -49,7 +49,7 @@ use sr_primitives::traits::{
 use substrate_executor::{NativeExecutor, NativeExecutionDispatch};
 use std::{
 	io::{Read, Write, Seek},
-	marker::PhantomData, sync::Arc, sync::atomic::AtomicBool, time::SystemTime
+	marker::PhantomData, sync::Arc, time::SystemTime
 };
 use sysinfo::{get_current_pid, ProcessExt, System, SystemExt};
 use tel::{telemetry, SUBSTRATE_INFO};
@@ -823,6 +823,9 @@ ServiceBuilder<
 		let (to_spawn_tx, to_spawn_rx) =
 			mpsc::unbounded::<Box<dyn Future<Item = (), Error = ()> + Send>>();
 
+		// A side-channel for essential tasks to communicate shutdown.
+		let (essential_failed_tx, essential_failed_rx) = mpsc::unbounded();
+
 		let import_queue = Box::new(import_queue);
 		let chain_info = client.info().chain;
 
@@ -1183,7 +1186,8 @@ ServiceBuilder<
 			transaction_pool,
 			exit,
 			signal: Some(signal),
-			essential_failed: Arc::new(AtomicBool::new(false)),
+			essential_failed_tx,
+			essential_failed_rx,
 			to_spawn_tx,
 			to_spawn_rx,
 			to_poll: Vec::new(),

substrate/client/service/src/lib.rs

@@ -31,7 +31,6 @@ use std::io;
 use std::marker::PhantomData;
 use std::net::SocketAddr;
 use std::collections::HashMap;
-use std::sync::atomic::{AtomicBool, Ordering};
 use std::time::{Duration, Instant};
 use futures::sync::mpsc;
 use parking_lot::Mutex;
@@ -85,9 +84,11 @@ pub struct Service<TBl, TCl, TSc, TNetStatus, TNet, TTxPool, TOc> {
 	exit: exit_future::Exit,
 	/// A signal that makes the exit future above resolve, fired on service drop.
 	signal: Option<Signal>,
-	/// Set to `true` when a spawned essential task has failed. The next time
+	/// Send a signal when a spawned essential task has concluded. The next time
 	/// the service future is polled it should complete with an error.
-	essential_failed: Arc<AtomicBool>,
+	essential_failed_tx: mpsc::UnboundedSender<()>,
+	/// A receiver for spawned essential-tasks concluding.
+	essential_failed_rx: mpsc::UnboundedReceiver<()>,
 	/// Sender for futures that must be spawned as background tasks.
 	to_spawn_tx: mpsc::UnboundedSender<Box<dyn Future<Item = (), Error = ()> + Send>>,
 	/// Receiver for futures that must be spawned as background tasks.
@@ -239,12 +240,12 @@ where
 	}
 
 	fn spawn_essential_task(&self, task: impl Future<Item = (), Error = ()> + Send + 'static) {
-		let essential_failed = self.essential_failed.clone();
+		let essential_failed = self.essential_failed_tx.clone();
 		let essential_task = std::panic::AssertUnwindSafe(task)
 			.catch_unwind()
 			.then(move |_| {
 				error!("Essential task failed. Shutting down service.");
-				essential_failed.store(true, Ordering::Relaxed);
+				let _ = essential_failed.send(());
 				Ok(())
 			});
 		let task = essential_task.select(self.on_exit()).then(|_| Ok(()));
@@ -297,9 +298,14 @@ impl<TBl, TCl, TSc, TNetStatus, TNet, TTxPool, TOc> Future for
 	type Error = Error;
 
 	fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
-		if self.essential_failed.load(Ordering::Relaxed) {
+		match self.essential_failed_rx.poll() {
+			Ok(Async::NotReady) => {},
+			Ok(Async::Ready(_)) | Err(_) => {
+				// Ready(None) should not be possible since we hold a live
+				// sender.
 				return Err(Error::Other("Essential task failed.".into()));
 			}
+		}
 
 		while let Ok(Async::Ready(Some(task_to_spawn))) = self.to_spawn_rx.poll() {
 			let executor = tokio_executor::DefaultExecutor::current();