Make block proposing remaining duration configurable (#4215)

* Make proposing remaining duration configurable

* Pass chain_head to proposing_remaining_duration and change default

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

@@ -38,7 +38,7 @@ use inherents::{InherentData, InherentDataProviders};
 use log::{debug, error, info, warn};
 use sr_primitives::generic::BlockId;
 use sr_primitives::traits::{ApiRef, Block as BlockT, Header, ProvideRuntimeApi};
-use std::{fmt::Debug, ops::Deref, pin::Pin, sync::Arc};
+use std::{fmt::Debug, ops::Deref, pin::Pin, sync::Arc, time::{Instant, Duration}};
 use substrate_telemetry::{telemetry, CONSENSUS_DEBUG, CONSENSUS_WARN, CONSENSUS_INFO};
 use parking_lot::Mutex;
 use client_api;
@@ -113,6 +113,25 @@ pub trait SimpleSlotWorker<B: BlockT> {
 	/// Returns a `Proposer` to author on top of the given block.
 	fn proposer(&mut self, block: &B::Header) -> Result<Self::Proposer, consensus_common::Error>;
 
+	/// Remaining duration of the slot.
+	fn slot_remaining_duration(&self, slot_info: &SlotInfo) -> Duration {
+		let now = Instant::now();
+		if now < slot_info.ends_at {
+			slot_info.ends_at.duration_since(now)
+		} else {
+			Duration::from_millis(0)
+		}
+	}
+
+	/// Remaining duration for proposing. None means unlimited.
+	fn proposing_remaining_duration(
+		&self,
+		_head: &B::Header,
+		slot_info: &SlotInfo
+	) -> Option<Duration> {
+		Some(self.slot_remaining_duration(slot_info))
+	}
+
 	/// Implements the `on_slot` functionality from `SlotWorker`.
 	fn on_slot(&mut self, chain_head: B::Header, slot_info: SlotInfo)
 		-> Pin<Box<dyn Future<Output = Result<(), consensus_common::Error>> + Send>> where
@@ -192,45 +211,43 @@ pub trait SimpleSlotWorker<B: BlockT> {
 			},
 		};
 
-		let remaining_duration = slot_info.remaining_duration();
+		let slot_remaining_duration = self.slot_remaining_duration(&slot_info);
+		let proposing_remaining_duration = self.proposing_remaining_duration(&chain_head, &slot_info);
 		let logs = self.pre_digest_data(slot_number, &claim);
 
 		// deadline our production to approx. the end of the slot
-		let proposal_work = futures::future::select(
-			proposer.propose(
-				slot_info.inherent_data,
-				sr_primitives::generic::Digest {
-					logs,
+		let proposing = proposer.propose(
+			slot_info.inherent_data,
+			sr_primitives::generic::Digest {
+				logs,
+			},
+			slot_remaining_duration,
+		).map_err(|e| consensus_common::Error::ClientImport(format!("{:?}", e)));
+		let delay: Box<dyn Future<Output=()> + Unpin + Send> = match proposing_remaining_duration {
+			Some(r) => Box::new(Delay::new(r)),
+			None => Box::new(future::pending()),
+		};
+
+		let proposal_work =
+			Box::new(futures::future::select(proposing, delay).map(move |v| match v {
+				futures::future::Either::Left((b, _)) => b.map(|b| (b, claim)),
+				futures::future::Either::Right(_) => {
+					info!("Discarding proposal for slot {}; block production took too long", slot_number);
+					// If the node was compiled with debug, tell the user to use release optimizations.
+					#[cfg(build_type="debug")]
+					info!("Recompile your node in `--release` mode to mitigate this problem.");
+					telemetry!(CONSENSUS_INFO; "slots.discarding_proposal_took_too_long";
+						"slot" => slot_number,
+					);
+					Err(consensus_common::Error::ClientImport("Timeout in the Slots proposer".into()))
 				},
-				remaining_duration,
-			).map_err(|e| consensus_common::Error::ClientImport(format!("{:?}", e))),
-			Delay::new(remaining_duration)
-		).map(|v| match v {
-			futures::future::Either::Left((b, _)) => b.map(|b| (b, claim)),
-			futures::future::Either::Right(_) =>
-				Err(consensus_common::Error::ClientImport("Timeout in the Slots proposer".into())),
-		});
+			}));
 
 		let block_import_params_maker = self.block_import_params();
 		let block_import = self.block_import();
 		let logging_target = self.logging_target();
 
 		Box::pin(proposal_work.map_ok(move |(block, claim)| {
-			// minor hack since we don't have access to the timestamp
-			// that is actually set by the proposer.
-			let slot_after_building = SignedDuration::default().slot_now(slot_duration);
-			if slot_after_building != slot_number {
-				info!("Discarding proposal for slot {}; block production took too long", slot_number);
-				// If the node was compiled with debug, tell the user to use release optimizations.
-				#[cfg(build_type="debug")]
-				info!("Recompile your node in `--release` mode to mitigate this problem.");
-				telemetry!(CONSENSUS_INFO; "slots.discarding_proposal_took_too_long";
-					"slot" => slot_number,
-				);
-
-				return;
-			}
-
 			let (header, body) = block.deconstruct();
 			let header_num = *header.number();
 			let header_hash = header.hash();

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

@@ -71,6 +71,8 @@ pub fn time_until_next(now: Duration, slot_duration: u64) -> Duration {
 pub struct SlotInfo {
 	/// The slot number.
 	pub number: u64,
+	/// The last slot number produced.
+	pub last_number: u64,
 	/// Current timestamp.
 	pub timestamp: u64,
 	/// The instant at which the slot ends.
@@ -81,18 +83,6 @@ pub struct SlotInfo {
 	pub duration: u64,
 }
 
-impl SlotInfo {
-	/// Yields the remaining duration in the slot.
-	pub fn remaining_duration(&self) -> Duration {
-		let now = Instant::now();
-		if now < self.ends_at {
-			self.ends_at.duration_since(now)
-		} else {
-			Duration::from_millis(0)
-		}
-	}
-}
-
 /// A stream that returns every time there is a new slot.
 pub(crate) struct Slots<SC> {
 	last_slot: u64,
@@ -160,11 +150,13 @@ impl<SC: SlotCompatible + Unpin> Stream for Slots<SC> {
 
 			// never yield the same slot twice.
 			if slot_num > self.last_slot {
+				let last_slot = self.last_slot;
 				self.last_slot = slot_num;
 
 				break Poll::Ready(Some(Ok(SlotInfo {
 					number: slot_num,
 					duration: self.slot_duration,
+					last_number: last_slot,
 					timestamp,
 					ends_at,
 					inherent_data,