consensus-slots: cleanup SlotDuration config (#10878)

* consensus-slots: cleanup the SlotDuration config

* fix tests

* address review comments

substrate/Cargo.lock

@@ -9627,6 +9627,8 @@ dependencies = [
  "serde",
  "sp-arithmetic",
  "sp-runtime",
+ "sp-std",
+ "sp-timestamp",
 ]
 
 [[package]]

substrate/bin/node-template/node/src/service.rs

@@ -8,7 +8,6 @@ use sc_finality_grandpa::SharedVoterState;
 use sc_keystore::LocalKeystore;
 use sc_service::{error::Error as ServiceError, Configuration, TaskManager};
 use sc_telemetry::{Telemetry, TelemetryWorker};
-use sp_consensus::SlotData;
 use sp_consensus_aura::sr25519::AuthorityPair as AuraPair;
 use std::{sync::Arc, time::Duration};
 
@@ -111,7 +110,7 @@ pub fn new_partial(
 		telemetry.as_ref().map(|x| x.handle()),
 	)?;
 
-	let slot_duration = sc_consensus_aura::slot_duration(&*client)?.slot_duration();
+	let slot_duration = sc_consensus_aura::slot_duration(&*client)?;
 
 	let import_queue =
 		sc_consensus_aura::import_queue::<AuraPair, _, _, _, _, _, _>(ImportQueueParams {
@@ -122,7 +121,7 @@ pub fn new_partial(
 				let timestamp = sp_timestamp::InherentDataProvider::from_system_time();
 
 				let slot =
-					sp_consensus_aura::inherents::InherentDataProvider::from_timestamp_and_duration(
+					sp_consensus_aura::inherents::InherentDataProvider::from_timestamp_and_slot_duration(
 						*timestamp,
 						slot_duration,
 					);
@@ -260,7 +259,6 @@ pub fn new_full(mut config: Configuration) -> Result<TaskManager, ServiceError>
 			sp_consensus::CanAuthorWithNativeVersion::new(client.executor().clone());
 
 		let slot_duration = sc_consensus_aura::slot_duration(&*client)?;
-		let raw_slot_duration = slot_duration.slot_duration();
 
 		let aura = sc_consensus_aura::start_aura::<AuraPair, _, _, _, _, _, _, _, _, _, _, _>(
 			StartAuraParams {
@@ -273,9 +271,9 @@ pub fn new_full(mut config: Configuration) -> Result<TaskManager, ServiceError>
 					let timestamp = sp_timestamp::InherentDataProvider::from_system_time();
 
 					let slot =
-						sp_consensus_aura::inherents::InherentDataProvider::from_timestamp_and_duration(
+						sp_consensus_aura::inherents::InherentDataProvider::from_timestamp_and_slot_duration(
 							*timestamp,
-							raw_slot_duration,
+							slot_duration,
 						);
 
 					Ok((timestamp, slot))

substrate/bin/node/cli/src/service.rs

@@ -212,7 +212,7 @@ pub fn new_partial(
 			let timestamp = sp_timestamp::InherentDataProvider::from_system_time();
 
 			let slot =
-				sp_consensus_babe::inherents::InherentDataProvider::from_timestamp_and_duration(
+				sp_consensus_babe::inherents::InherentDataProvider::from_timestamp_and_slot_duration(
 					*timestamp,
 					slot_duration,
 				);
@@ -419,7 +419,7 @@ pub fn new_full_base(
 					let timestamp = sp_timestamp::InherentDataProvider::from_system_time();
 
 					let slot =
-						sp_consensus_babe::inherents::InherentDataProvider::from_timestamp_and_duration(
+						sp_consensus_babe::inherents::InherentDataProvider::from_timestamp_and_slot_duration(
 							*timestamp,
 							slot_duration,
 						);
@@ -650,7 +650,10 @@ mod tests {
 						.epoch_changes()
 						.shared_data()
 						.epoch_data(&epoch_descriptor, |slot| {
-							sc_consensus_babe::Epoch::genesis(&babe_link.config(), slot)
+							sc_consensus_babe::Epoch::genesis(
+								babe_link.config().genesis_config(),
+								slot,
+							)
 						})
 						.unwrap();
 

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

@@ -77,14 +77,11 @@ pub use sp_consensus::SyncOracle;
 pub use sp_consensus_aura::{
 	digests::CompatibleDigestItem,
 	inherents::{InherentDataProvider, InherentType as AuraInherent, INHERENT_IDENTIFIER},
-	AuraApi, ConsensusLog, AURA_ENGINE_ID,
+	AuraApi, ConsensusLog, SlotDuration, AURA_ENGINE_ID,
 };
 
 type AuthorityId<P> = <P as Pair>::Public;
 
-/// Slot duration type for Aura.
-pub type SlotDuration = sc_consensus_slots::SlotDuration<sp_consensus_aura::SlotDuration>;
-
 /// Get the slot duration for Aura.
 pub fn slot_duration<A, B, C>(client: &C) -> CResult<SlotDuration>
 where
@@ -94,9 +91,7 @@ where
 	C::Api: AuraApi<B, A>,
 {
 	let best_block_id = BlockId::Hash(client.usage_info().chain.best_hash);
-	let slot_duration = client.runtime_api().slot_duration(&best_block_id)?;
-
-	Ok(SlotDuration::new(slot_duration))
+	client.runtime_api().slot_duration(&best_block_id).map_err(|err| err.into())
 }
 
 /// Get slot author for given block along with authorities.
@@ -574,7 +569,7 @@ mod tests {
 	use sc_network_test::{Block as TestBlock, *};
 	use sp_application_crypto::key_types::AURA;
 	use sp_consensus::{
-		AlwaysCanAuthor, DisableProofRecording, NoNetwork as DummyOracle, Proposal, SlotData,
+		AlwaysCanAuthor, DisableProofRecording, NoNetwork as DummyOracle, Proposal,
 	};
 	use sp_consensus_aura::sr25519::AuthorityPair;
 	use sp_inherents::InherentData;
@@ -672,14 +667,14 @@ mod tests {
 			let client = client.as_client();
 			let slot_duration = slot_duration(&*client).expect("slot duration available");
 
-			assert_eq!(slot_duration.slot_duration().as_millis() as u64, SLOT_DURATION);
+			assert_eq!(slot_duration.as_millis() as u64, SLOT_DURATION);
 			import_queue::AuraVerifier::new(
 				client,
 				Box::new(|_, _| async {
 					let timestamp = TimestampInherentDataProvider::from_system_time();
-					let slot = InherentDataProvider::from_timestamp_and_duration(
+					let slot = InherentDataProvider::from_timestamp_and_slot_duration(
 						*timestamp,
-						Duration::from_secs(6),
+						SlotDuration::from_millis(6000),
 					);
 
 					Ok((timestamp, slot))
@@ -762,9 +757,9 @@ mod tests {
 					justification_sync_link: (),
 					create_inherent_data_providers: |_, _| async {
 						let timestamp = TimestampInherentDataProvider::from_system_time();
-						let slot = InherentDataProvider::from_timestamp_and_duration(
+						let slot = InherentDataProvider::from_timestamp_and_slot_duration(
 							*timestamp,
-							Duration::from_secs(6),
+							SlotDuration::from_millis(6000),
 						);
 
 						Ok((timestamp, slot))

substrate/client/consensus/babe/rpc/src/lib.rs

@@ -207,7 +207,7 @@ where
 			&parent.hash(),
 			parent.number().clone(),
 			slot.into(),
-			|slot| Epoch::genesis(&babe_config, slot),
+			|slot| Epoch::genesis(babe_config.genesis_config(), slot),
 		)
 		.map_err(|e| Error::Consensus(ConsensusError::ChainLookup(e.to_string())))?
 		.ok_or(Error::Consensus(ConsensusError::InvalidAuthoritiesSet))

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

@@ -66,9 +66,7 @@
 #![forbid(unsafe_code)]
 #![warn(missing_docs)]
 
-use std::{
-	borrow::Cow, collections::HashMap, convert::TryInto, pin::Pin, sync::Arc, time::Duration, u64,
-};
+use std::{borrow::Cow, collections::HashMap, convert::TryInto, pin::Pin, sync::Arc, u64};
 
 use codec::{Decode, Encode};
 use futures::{
@@ -106,10 +104,10 @@ use sp_block_builder::BlockBuilder as BlockBuilderApi;
 use sp_blockchain::{Error as ClientError, HeaderBackend, HeaderMetadata, Result as ClientResult};
 use sp_consensus::{
 	BlockOrigin, CacheKeyId, CanAuthorWith, Environment, Error as ConsensusError, Proposer,
-	SelectChain, SlotData,
+	SelectChain,
 };
 use sp_consensus_babe::inherents::BabeInherentData;
-use sp_consensus_slots::Slot;
+use sp_consensus_slots::{Slot, SlotDuration};
 use sp_core::{crypto::ByteArray, ExecutionContext};
 use sp_inherents::{CreateInherentDataProviders, InherentData, InherentDataProvider};
 use sp_keystore::{SyncCryptoStore, SyncCryptoStorePtr};
@@ -328,17 +326,15 @@ pub struct BabeIntermediate<B: BlockT> {
 /// Intermediate key for Babe engine.
 pub static INTERMEDIATE_KEY: &[u8] = b"babe1";
 
-/// A slot duration.
-///
-/// Create with [`Self::get`].
-// FIXME: Once Rust has higher-kinded types, the duplication between this
-// and `super::babe::Config` can be eliminated.
-// https://github.com/paritytech/substrate/issues/2434
+/// Configuration for BABE used for defining block verification parameters as
+/// well as authoring (e.g. the slot duration).
 #[derive(Clone)]
-pub struct Config(sc_consensus_slots::SlotDuration<BabeGenesisConfiguration>);
+pub struct Config {
+	genesis_config: BabeGenesisConfiguration,
+}
 
 impl Config {
-	/// Fetch the config from the runtime.
+	/// Create a new config by reading the genesis configuration from the runtime.
 	pub fn get<B: BlockT, C>(client: &C) -> ClientResult<Self>
 	where
 		C: AuxStore + ProvideRuntimeApi<B> + UsageProvider<B>,
@@ -355,7 +351,7 @@ impl Config {
 
 		let version = runtime_api.api_version::<dyn BabeApi<B>>(&best_block_id)?;
 
-		let slot_duration = if version == Some(1) {
+		let genesis_config = if version == Some(1) {
 			#[allow(deprecated)]
 			{
 				runtime_api.configuration_before_version_2(&best_block_id)?.into()
@@ -368,20 +364,17 @@ impl Config {
 			))
 		};
 
-		Ok(Self(sc_consensus_slots::SlotDuration::new(slot_duration)))
+		Ok(Config { genesis_config })
 	}
 
-	/// Get the inner slot duration
-	pub fn slot_duration(&self) -> Duration {
-		self.0.slot_duration()
+	/// Get the genesis configuration.
+	pub fn genesis_config(&self) -> &BabeGenesisConfiguration {
+		&self.genesis_config
 	}
-}
 
-impl std::ops::Deref for Config {
-	type Target = BabeGenesisConfiguration;
-
-	fn deref(&self) -> &BabeGenesisConfiguration {
-		&*self.0
+	/// Get the slot duration defined in the genesis configuration.
+	pub fn slot_duration(&self) -> SlotDuration {
+		SlotDuration::from_millis(self.genesis_config.slot_duration)
 	}
 }
 
@@ -488,7 +481,6 @@ where
 {
 	const HANDLE_BUFFER_SIZE: usize = 1024;
 
-	let config = babe_link.config;
 	let slot_notification_sinks = Arc::new(Mutex::new(Vec::new()));
 
 	let worker = BabeSlotWorker {
@@ -502,7 +494,7 @@ where
 		keystore,
 		epoch_changes: babe_link.epoch_changes.clone(),
 		slot_notification_sinks: slot_notification_sinks.clone(),
-		config: config.clone(),
+		config: babe_link.config.clone(),
 		block_proposal_slot_portion,
 		max_block_proposal_slot_portion,
 		telemetry,
@@ -510,7 +502,7 @@ where
 
 	info!(target: "babe", "👶 Starting BABE Authorship worker");
 	let inner = sc_consensus_slots::start_slot_worker(
-		config.0.clone(),
+		babe_link.config.slot_duration(),
 		select_chain,
 		worker,
 		sync_oracle,
@@ -521,7 +513,8 @@ where
 	let (worker_tx, worker_rx) = channel(HANDLE_BUFFER_SIZE);
 
 	let answer_requests =
-		answer_requests(worker_rx, config.0, client, babe_link.epoch_changes.clone());
+		answer_requests(worker_rx, babe_link.config, client, babe_link.epoch_changes.clone());
+
 	Ok(BabeWorker {
 		inner: Box::pin(future::join(inner, answer_requests).map(|_| ())),
 		slot_notification_sinks,
@@ -531,7 +524,7 @@ where
 
 async fn answer_requests<B: BlockT, C>(
 	mut request_rx: Receiver<BabeRequest<B>>,
-	genesis_config: sc_consensus_slots::SlotDuration<BabeGenesisConfiguration>,
+	config: Config,
 	client: Arc<C>,
 	epoch_changes: SharedEpochChanges<B, Epoch>,
 ) where
@@ -561,7 +554,7 @@ async fn answer_requests<B: BlockT, C>(
 
 					let viable_epoch = epoch_changes
 						.viable_epoch(&epoch_descriptor, |slot| {
-							Epoch::genesis(&genesis_config, slot)
+							Epoch::genesis(&config.genesis_config, slot)
 						})
 						.ok_or_else(|| Error::<B>::FetchEpoch(parent_hash))?;
 
@@ -720,7 +713,9 @@ where
 	fn authorities_len(&self, epoch_descriptor: &Self::EpochData) -> Option<usize> {
 		self.epoch_changes
 			.shared_data()
-			.viable_epoch(&epoch_descriptor, |slot| Epoch::genesis(&self.config, slot))
+			.viable_epoch(&epoch_descriptor, |slot| {
+				Epoch::genesis(&self.config.genesis_config, slot)
+			})
 			.map(|epoch| epoch.as_ref().authorities.len())
 	}
 
@@ -735,7 +730,9 @@ where
 			slot,
 			self.epoch_changes
 				.shared_data()
-				.viable_epoch(&epoch_descriptor, |slot| Epoch::genesis(&self.config, slot))?
+				.viable_epoch(&epoch_descriptor, |slot| {
+					Epoch::genesis(&self.config.genesis_config, slot)
+				})?
 				.as_ref(),
 			&self.keystore,
 		);
@@ -1165,7 +1162,9 @@ where
 				.map_err(|e| Error::<Block>::ForkTree(Box::new(e)))?
 				.ok_or_else(|| Error::<Block>::FetchEpoch(parent_hash))?;
 			let viable_epoch = epoch_changes
-				.viable_epoch(&epoch_descriptor, |slot| Epoch::genesis(&self.config, slot))
+				.viable_epoch(&epoch_descriptor, |slot| {
+					Epoch::genesis(&self.config.genesis_config, slot)
+				})
 				.ok_or_else(|| Error::<Block>::FetchEpoch(parent_hash))?;
 
 			// We add one to the current slot to allow for some small drift.
@@ -1498,7 +1497,9 @@ where
 				old_epoch_changes = Some((*epoch_changes).clone());
 
 				let viable_epoch = epoch_changes
-					.viable_epoch(&epoch_descriptor, |slot| Epoch::genesis(&self.config, slot))
+					.viable_epoch(&epoch_descriptor, |slot| {
+						Epoch::genesis(&self.config.genesis_config, slot)
+					})
 					.ok_or_else(|| {
 						ConsensusError::ClientImport(Error::<Block>::FetchEpoch(parent_hash).into())
 					})?;
@@ -1684,7 +1685,8 @@ pub fn block_import<Client, Block: BlockT, I>(
 where
 	Client: AuxStore + HeaderBackend<Block> + HeaderMetadata<Block, Error = sp_blockchain::Error>,
 {
-	let epoch_changes = aux_schema::load_epoch_changes::<Block, _>(&*client, &config)?;
+	let epoch_changes =
+		aux_schema::load_epoch_changes::<Block, _>(&*client, &config.genesis_config)?;
 	let link = BabeLink { epoch_changes: epoch_changes.clone(), config: config.clone() };
 
 	// NOTE: this isn't entirely necessary, but since we didn't use to prune the

substrate/client/consensus/babe/src/tests.rs

@@ -143,7 +143,7 @@ impl DummyProposer {
 				&self.parent_hash,
 				self.parent_number,
 				this_slot,
-				|slot| Epoch::genesis(&self.factory.config, slot),
+				|slot| Epoch::genesis(self.factory.config.genesis_config(), slot),
 			)
 			.expect("client has data to find epoch")
 			.expect("can compute epoch for baked block");
@@ -336,9 +336,9 @@ impl TestNetFactory for BabeTestNet {
 				select_chain: longest_chain,
 				create_inherent_data_providers: Box::new(|_, _| async {
 					let timestamp = TimestampInherentDataProvider::from_system_time();
-					let slot = InherentDataProvider::from_timestamp_and_duration(
+					let slot = InherentDataProvider::from_timestamp_and_slot_duration(
 						*timestamp,
-						Duration::from_secs(6),
+						SlotDuration::from_millis(6000),
 					);
 
 					Ok((timestamp, slot))
@@ -449,9 +449,9 @@ fn run_one_test(mutator: impl Fn(&mut TestHeader, Stage) + Send + Sync + 'static
 				sync_oracle: DummyOracle,
 				create_inherent_data_providers: Box::new(|_, _| async {
 					let timestamp = TimestampInherentDataProvider::from_system_time();
-					let slot = InherentDataProvider::from_timestamp_and_duration(
+					let slot = InherentDataProvider::from_timestamp_and_slot_duration(
 						*timestamp,
-						Duration::from_secs(6),
+						SlotDuration::from_millis(6000),
 					);
 
 					Ok((timestamp, slot))
@@ -699,12 +699,12 @@ fn importing_block_one_sets_genesis_epoch() {
 		&mut block_import,
 	);
 
-	let genesis_epoch = Epoch::genesis(&data.link.config, 999.into());
+	let genesis_epoch = Epoch::genesis(data.link.config.genesis_config(), 999.into());
 
 	let epoch_changes = data.link.epoch_changes.shared_data();
 	let epoch_for_second_block = epoch_changes
 		.epoch_data_for_child_of(descendent_query(&*client), &block_hash, 1, 1000.into(), |slot| {
-			Epoch::genesis(&data.link.config, slot)
+			Epoch::genesis(data.link.config.genesis_config(), slot)
 		})
 		.unwrap()
 		.unwrap();

substrate/client/consensus/manual-seal/src/consensus/aura.rs

@@ -22,13 +22,12 @@
 use crate::{ConsensusDataProvider, Error};
 use sc_client_api::{AuxStore, UsageProvider};
 use sc_consensus::BlockImportParams;
-use sc_consensus_aura::slot_duration;
 use sp_api::{ProvideRuntimeApi, TransactionFor};
 use sp_blockchain::{HeaderBackend, HeaderMetadata};
 use sp_consensus_aura::{
 	digests::CompatibleDigestItem,
 	sr25519::{AuthorityId, AuthoritySignature},
-	AuraApi,
+	AuraApi, Slot, SlotDuration,
 };
 use sp_inherents::InherentData;
 use sp_runtime::{traits::Block as BlockT, Digest, DigestItem};
@@ -37,8 +36,8 @@ use std::{marker::PhantomData, sync::Arc};
 
 /// Consensus data provider for Aura.
 pub struct AuraConsensusDataProvider<B, C> {
-	// slot duration in milliseconds
-	slot_duration: u64,
+	// slot duration
+	slot_duration: SlotDuration,
 	// phantom data for required generics
 	_phantom: PhantomData<(B, C)>,
 }
@@ -52,8 +51,8 @@ where
 	/// Creates a new instance of the [`AuraConsensusDataProvider`], requires that `client`
 	/// implements [`sp_consensus_aura::AuraApi`]
 	pub fn new(client: Arc<C>) -> Self {
-		let slot_duration =
-			(*slot_duration(&*client).expect("slot_duration is always present; qed.")).get();
+		let slot_duration = sc_consensus_aura::slot_duration(&*client)
+			.expect("slot_duration is always present; qed.");
 
 		Self { slot_duration, _phantom: PhantomData }
 	}
@@ -76,13 +75,15 @@ where
 		_parent: &B::Header,
 		inherents: &InherentData,
 	) -> Result<Digest, Error> {
-		let time_stamp =
-			*inherents.timestamp_inherent_data()?.expect("Timestamp is always present; qed");
+		let timestamp =
+			inherents.timestamp_inherent_data()?.expect("Timestamp is always present; qed");
+
 		// we always calculate the new slot number based on the current time-stamp and the slot
 		// duration.
 		let digest_item = <DigestItem as CompatibleDigestItem<AuthoritySignature>>::aura_pre_digest(
-			(time_stamp / self.slot_duration).into(),
+			Slot::from_timestamp(timestamp, self.slot_duration),
 		);
+
 		Ok(Digest { logs: vec![digest_item] })
 	}
 

substrate/client/consensus/manual-seal/src/consensus/babe.rs

@@ -169,7 +169,9 @@ where
 			.ok_or_else(|| sp_consensus::Error::InvalidAuthoritiesSet)?;
 
 		let epoch = epoch_changes
-			.viable_epoch(&epoch_descriptor, |slot| Epoch::genesis(&self.config, slot))
+			.viable_epoch(&epoch_descriptor, |slot| {
+				Epoch::genesis(self.config.genesis_config(), slot)
+			})
 			.ok_or_else(|| {
 				log::info!(target: "babe", "create_digest: no viable_epoch :(");
 				sp_consensus::Error::InvalidAuthoritiesSet
@@ -283,15 +285,17 @@ where
 			let timestamp = inherents
 				.timestamp_inherent_data()?
 				.ok_or_else(|| Error::StringError("No timestamp inherent data".into()))?;
-			let slot = *timestamp / self.config.slot_duration;
+
+			let slot = Slot::from_timestamp(timestamp, self.config.slot_duration());
+
 			// manually hard code epoch descriptor
 			epoch_descriptor = match epoch_descriptor {
 				ViableEpochDescriptor::Signaled(identifier, _header) =>
 					ViableEpochDescriptor::Signaled(
 						identifier,
 						EpochHeader {
-							start_slot: slot.into(),
-							end_slot: (slot * self.config.epoch_length).into(),
+							start_slot: slot,
+							end_slot: (*slot * self.config.genesis_config().epoch_length).into(),
 						},
 					),
 				_ => unreachable!(

substrate/client/consensus/manual-seal/src/consensus/timestamp.rs

@@ -21,8 +21,6 @@
 
 use crate::Error;
 use sc_client_api::{AuxStore, UsageProvider};
-use sc_consensus_aura::slot_duration;
-use sc_consensus_babe::Config;
 use sp_api::ProvideRuntimeApi;
 use sp_blockchain::HeaderBackend;
 use sp_consensus_aura::{
@@ -30,6 +28,7 @@ use sp_consensus_aura::{
 	AuraApi,
 };
 use sp_consensus_babe::BabeApi;
+use sp_consensus_slots::{Slot, SlotDuration};
 use sp_inherents::{InherentData, InherentDataProvider, InherentIdentifier};
 use sp_runtime::{
 	generic::BlockId,
@@ -53,7 +52,7 @@ pub struct SlotTimestampProvider {
 	// holds the unix millisecnd timestamp for the most recent block
 	unix_millis: atomic::AtomicU64,
 	// configured slot_duration in the runtime
-	slot_duration: u64,
+	slot_duration: SlotDuration,
 }
 
 impl SlotTimestampProvider {
@@ -64,7 +63,7 @@ impl SlotTimestampProvider {
 		C: AuxStore + HeaderBackend<B> + ProvideRuntimeApi<B> + UsageProvider<B>,
 		C::Api: BabeApi<B>,
 	{
-		let slot_duration = Config::get(&*client)?.slot_duration;
+		let slot_duration = sc_consensus_babe::Config::get(&*client)?.slot_duration();
 
 		let time = Self::with_header(&client, slot_duration, |header| {
 			let slot_number = *sc_consensus_babe::find_pre_digest::<B>(&header)
@@ -83,7 +82,7 @@ impl SlotTimestampProvider {
 		C: AuxStore + HeaderBackend<B> + ProvideRuntimeApi<B> + UsageProvider<B>,
 		C::Api: AuraApi<B, AuthorityId>,
 	{
-		let slot_duration = (*slot_duration(&*client)?).get();
+		let slot_duration = sc_consensus_aura::slot_duration(&*client)?;
 
 		let time = Self::with_header(&client, slot_duration, |header| {
 			let slot_number = *sc_consensus_aura::find_pre_digest::<B, AuthoritySignature>(&header)
@@ -94,7 +93,11 @@ impl SlotTimestampProvider {
 		Ok(Self { unix_millis: atomic::AtomicU64::new(time), slot_duration })
 	}
 
-	fn with_header<F, C, B>(client: &Arc<C>, slot_duration: u64, func: F) -> Result<u64, Error>
+	fn with_header<F, C, B>(
+		client: &Arc<C>,
+		slot_duration: SlotDuration,
+		func: F,
+	) -> Result<u64, Error>
 	where
 		B: BlockT,
 		C: AuxStore + HeaderBackend<B> + UsageProvider<B>,
@@ -110,7 +113,7 @@ impl SlotTimestampProvider {
 				.ok_or_else(|| "best header not found in the db!".to_string())?;
 			let slot = func(header)?;
 			// add the slot duration so there's no collision of slots
-			(slot * slot_duration) + slot_duration
+			(slot * slot_duration.as_millis() as u64) + slot_duration.as_millis() as u64
 		} else {
 			// this is the first block, use the correct time.
 			let now = SystemTime::now();
@@ -123,8 +126,11 @@ impl SlotTimestampProvider {
 	}
 
 	/// Get the current slot number
-	pub fn slot(&self) -> u64 {
-		self.unix_millis.load(atomic::Ordering::SeqCst) / self.slot_duration
+	pub fn slot(&self) -> Slot {
+		Slot::from_timestamp(
+			self.unix_millis.load(atomic::Ordering::SeqCst).into(),
+			self.slot_duration,
+		)
 	}
 
 	/// Gets the current time stamp.
@@ -140,8 +146,10 @@ impl InherentDataProvider for SlotTimestampProvider {
 		inherent_data: &mut InherentData,
 	) -> Result<(), sp_inherents::Error> {
 		// we update the time here.
-		let new_time: InherentType =
-			self.unix_millis.fetch_add(self.slot_duration, atomic::Ordering::SeqCst).into();
+		let new_time: InherentType = self
+			.unix_millis
+			.fetch_add(self.slot_duration.as_millis() as u64, atomic::Ordering::SeqCst)
+			.into();
 		inherent_data.put_data(INHERENT_IDENTIFIER, &new_time)?;
 		Ok(())
 	}

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

@@ -32,15 +32,14 @@ pub use aux_schema::{check_equivocation, MAX_SLOT_CAPACITY, PRUNING_BOUND};
 pub use slots::SlotInfo;
 use slots::Slots;
 
-use codec::{Decode, Encode};
 use futures::{future::Either, Future, TryFutureExt};
 use futures_timer::Delay;
-use log::{debug, error, info, warn};
+use log::{debug, info, warn};
 use sc_consensus::{BlockImport, JustificationSyncLink};
 use sc_telemetry::{telemetry, TelemetryHandle, CONSENSUS_DEBUG, CONSENSUS_INFO, CONSENSUS_WARN};
 use sp_arithmetic::traits::BaseArithmetic;
-use sp_consensus::{CanAuthorWith, Proposer, SelectChain, SlotData, SyncOracle};
-use sp_consensus_slots::Slot;
+use sp_consensus::{CanAuthorWith, Proposer, SelectChain, SyncOracle};
+use sp_consensus_slots::{Slot, SlotDuration};
 use sp_inherents::CreateInherentDataProviders;
 use sp_runtime::{
 	generic::BlockId,
@@ -459,8 +458,8 @@ impl_inherent_data_provider_ext_tuple!(T, S, A, B, C, D, E, F, G, H, I, J);
 ///
 /// Every time a new slot is triggered, `worker.on_slot` is called and the future it returns is
 /// polled until completion, unless we are major syncing.
-pub async fn start_slot_worker<B, C, W, T, SO, CIDP, CAW, Proof>(
-	slot_duration: SlotDuration<T>,
+pub async fn start_slot_worker<B, C, W, SO, CIDP, CAW, Proof>(
+	slot_duration: SlotDuration,
 	client: C,
 	mut worker: W,
 	mut sync_oracle: SO,
@@ -471,15 +470,11 @@ pub async fn start_slot_worker<B, C, W, T, SO, CIDP, CAW, Proof>(
 	C: SelectChain<B>,
 	W: SlotWorker<B, Proof>,
 	SO: SyncOracle + Send,
-	T: SlotData + Clone,
 	CIDP: CreateInherentDataProviders<B, ()> + Send,
 	CIDP::InherentDataProviders: InherentDataProviderExt + Send,
 	CAW: CanAuthorWith<B> + Send,
 {
-	let SlotDuration(slot_duration) = slot_duration;
-
-	let mut slots =
-		Slots::new(slot_duration.slot_duration(), create_inherent_data_providers, client);
+	let mut slots = Slots::new(slot_duration.as_duration(), create_inherent_data_providers, client);
 
 	loop {
 		let slot_info = match slots.next_slot().await {
@@ -523,45 +518,6 @@ pub enum CheckedHeader<H, S> {
 	Checked(H, S),
 }
 
-#[derive(Debug, thiserror::Error)]
-#[allow(missing_docs)]
-pub enum Error<T>
-where
-	T: Debug,
-{
-	#[error("Slot duration is invalid: {0:?}")]
-	SlotDurationInvalid(SlotDuration<T>),
-}
-
-/// A slot duration. Create with [`Self::new`].
-#[derive(Clone, Copy, Debug, Encode, Decode, Hash, PartialOrd, Ord, PartialEq, Eq)]
-pub struct SlotDuration<T>(T);
-
-impl<T> Deref for SlotDuration<T> {
-	type Target = T;
-	fn deref(&self) -> &T {
-		&self.0
-	}
-}
-
-impl<T: SlotData> SlotData for SlotDuration<T> {
-	fn slot_duration(&self) -> std::time::Duration {
-		self.0.slot_duration()
-	}
-}
-
-impl<T: Clone + Send + Sync + 'static> SlotDuration<T> {
-	/// Create a new instance of `Self`.
-	pub fn new(val: T) -> Self {
-		Self(val)
-	}
-
-	/// Returns slot data value.
-	pub fn get(&self) -> T {
-		self.0.clone()
-	}
-}
-
 /// A unit type wrapper to express the proportion of a slot.
 pub struct SlotProportion(f32);
 

substrate/primitives/consensus/aura/src/inherents.rs

@@ -58,12 +58,11 @@ impl InherentDataProvider {
 
 	/// Creates the inherent data provider by calculating the slot from the given
 	/// `timestamp` and `duration`.
-	pub fn from_timestamp_and_duration(
+	pub fn from_timestamp_and_slot_duration(
 		timestamp: sp_timestamp::Timestamp,
-		duration: std::time::Duration,
+		slot_duration: sp_consensus_slots::SlotDuration,
 	) -> Self {
-		let slot =
-			InherentType::from((timestamp.as_duration().as_millis() / duration.as_millis()) as u64);
+		let slot = InherentType::from_timestamp(timestamp, slot_duration);
 
 		Self { slot }
 	}

substrate/primitives/consensus/aura/src/lib.rs

@@ -62,7 +62,7 @@ pub mod ed25519 {
 	pub type AuthorityId = app_ed25519::Public;
 }
 
-pub use sp_consensus_slots::Slot;
+pub use sp_consensus_slots::{Slot, SlotDuration};
 
 /// The `ConsensusEngineId` of AuRa.
 pub const AURA_ENGINE_ID: ConsensusEngineId = [b'a', b'u', b'r', b'a'];
@@ -93,28 +93,3 @@ sp_api::decl_runtime_apis! {
 		fn authorities() -> Vec<AuthorityId>;
 	}
 }
-
-/// Aura slot duration.
-///
-/// Internally stored as milliseconds.
-#[derive(sp_runtime::RuntimeDebug, Encode, Decode, PartialEq, Clone, Copy)]
-pub struct SlotDuration(u64);
-
-impl SlotDuration {
-	/// Initialize from the given milliseconds.
-	pub fn from_millis(val: u64) -> Self {
-		Self(val)
-	}
-
-	/// Returns the slot duration in milli seconds.
-	pub fn get(&self) -> u64 {
-		self.0
-	}
-}
-
-#[cfg(feature = "std")]
-impl sp_consensus::SlotData for SlotDuration {
-	fn slot_duration(&self) -> std::time::Duration {
-		std::time::Duration::from_millis(self.0)
-	}
-}

substrate/primitives/consensus/babe/src/inherents.rs

@@ -18,7 +18,6 @@
 //! Inherents for BABE
 
 use sp_inherents::{Error, InherentData, InherentIdentifier};
-
 use sp_std::result::Result;
 
 /// The BABE inherent identifier.
@@ -60,12 +59,11 @@ impl InherentDataProvider {
 
 	/// Creates the inherent data provider by calculating the slot from the given
 	/// `timestamp` and `duration`.
-	pub fn from_timestamp_and_duration(
+	pub fn from_timestamp_and_slot_duration(
 		timestamp: sp_timestamp::Timestamp,
-		duration: std::time::Duration,
+		slot_duration: sp_consensus_slots::SlotDuration,
 	) -> Self {
-		let slot =
-			InherentType::from((timestamp.as_duration().as_millis() / duration.as_millis()) as u64);
+		let slot = InherentType::from_timestamp(timestamp, slot_duration);
 
 		Self { slot }
 	}

substrate/primitives/consensus/babe/src/lib.rs

@@ -79,7 +79,7 @@ pub const MEDIAN_ALGORITHM_CARDINALITY: usize = 1200; // arbitrary suggestion by
 /// The index of an authority.
 pub type AuthorityIndex = u32;
 
-pub use sp_consensus_slots::Slot;
+pub use sp_consensus_slots::{Slot, SlotDuration};
 
 /// An equivocation proof for multiple block authorships on the same slot (i.e. double vote).
 pub type EquivocationProof<H> = sp_consensus_slots::EquivocationProof<H, AuthorityId>;
@@ -237,13 +237,6 @@ impl AllowedSlots {
 	}
 }
 
-#[cfg(feature = "std")]
-impl sp_consensus::SlotData for BabeGenesisConfiguration {
-	fn slot_duration(&self) -> std::time::Duration {
-		std::time::Duration::from_millis(self.slot_duration)
-	}
-}
-
 /// Configuration data used by the BABE consensus engine.
 #[derive(Clone, PartialEq, Eq, Encode, Decode, RuntimeDebug, MaxEncodedLen, TypeInfo)]
 #[cfg_attr(feature = "std", derive(Serialize, Deserialize))]

substrate/primitives/consensus/common/src/lib.rs

@@ -327,9 +327,3 @@ impl<Block: BlockT> CanAuthorWith<Block> for NeverCanAuthor {
 		Err("Authoring is always disabled.".to_string())
 	}
 }
-
-/// A type from which a slot duration can be obtained.
-pub trait SlotData {
-	/// Gets the slot duration.
-	fn slot_duration(&self) -> sp_std::time::Duration;
-}

substrate/primitives/consensus/slots/Cargo.toml

@@ -16,8 +16,10 @@ targets = ["x86_64-unknown-linux-gnu"]
 codec = { package = "parity-scale-codec", version = "2.2.0", default-features = false, features = ["derive", "max-encoded-len"] }
 scale-info = { version = "1.0", default-features = false, features = ["derive"] }
 serde = { version = "1.0", features = ["derive"], optional = true }
-sp-runtime = { version = "5.0.0", default-features = false, path = "../../runtime" }
 sp-arithmetic = { version = "4.0.0", default-features = false, path = "../../arithmetic" }
+sp-runtime = { version = "5.0.0", default-features = false, path = "../../runtime" }
+sp-std = { version = "4.0.0", default-features = false, path = "../../std" }
+sp-timestamp = { version = "4.0.0-dev", default-features = false, path = "../../timestamp" }
 
 [features]
 default = ["std"]
@@ -25,6 +27,8 @@ std = [
 	"codec/std",
 	"scale-info/std",
 	"serde",
-	"sp-runtime/std",
 	"sp-arithmetic/std",
+	"sp-runtime/std",
+	"sp-std/std",
+	"sp-timestamp/std",
 ]

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

@@ -21,6 +21,7 @@
 
 use codec::{Decode, Encode, MaxEncodedLen};
 use scale_info::TypeInfo;
+use sp_timestamp::Timestamp;
 
 /// Unit type wrapper that represents a slot.
 #[derive(Debug, Encode, MaxEncodedLen, Decode, Eq, Clone, Copy, Default, Ord, TypeInfo)]
@@ -64,6 +65,11 @@ impl<T: Into<u64> + Copy> core::cmp::PartialOrd<T> for Slot {
 }
 
 impl Slot {
+	/// Create a new slot by calculating it from the given timestamp and slot duration.
+	pub const fn from_timestamp(timestamp: Timestamp, slot_duration: SlotDuration) -> Self {
+		Slot(timestamp.as_millis() / slot_duration.as_millis())
+	}
+
 	/// Saturating addition.
 	pub fn saturating_add<T: Into<u64>>(self, rhs: T) -> Self {
 		Self(self.0.saturating_add(rhs.into()))
@@ -94,6 +100,32 @@ impl From<Slot> for u64 {
 	}
 }
 
+/// A slot duration defined in milliseconds.
+#[derive(Clone, Copy, Debug, Encode, Decode, Hash, PartialOrd, Ord, PartialEq, Eq, TypeInfo)]
+pub struct SlotDuration(u64);
+
+impl SlotDuration {
+	/// Initialize from the given milliseconds.
+	pub const fn from_millis(millis: u64) -> Self {
+		Self(millis)
+	}
+}
+
+impl SlotDuration {
+	/// Returns `self` as a `u64` representing the duration in milliseconds.
+	pub const fn as_millis(&self) -> u64 {
+		self.0
+	}
+}
+
+#[cfg(feature = "std")]
+impl SlotDuration {
+	/// Returns `self` as [`sp_std::time::Duration`].
+	pub const fn as_duration(&self) -> sp_std::time::Duration {
+		sp_std::time::Duration::from_millis(self.0)
+	}
+}
+
 /// Represents an equivocation proof. An equivocation happens when a validator
 /// produces more than one block on the same slot. The proof of equivocation
 /// are the given distinct headers that were signed by the validator and which

substrate/primitives/timestamp/src/lib.rs

@@ -42,10 +42,16 @@ impl Timestamp {
 	}
 
 	/// Returns `self` as [`Duration`].
-	pub fn as_duration(self) -> Duration {
+	pub const fn as_duration(self) -> Duration {
 		Duration::from_millis(self.0)
 	}
 
+	/// Returns `self` as a `u64` representing the elapsed time since the UNIX_EPOCH in
+	/// milliseconds.
+	pub const fn as_millis(&self) -> u64 {
+		self.0
+	}
+
 	/// Checked subtraction that returns `None` on an underflow.
 	pub fn checked_sub(self, other: Self) -> Option<Self> {
 		self.0.checked_sub(other.0).map(Self)