babe: support online configuration upgrades (#5514)

* babe: support online configuration upgrades * Switch to use NextConfigDescriptor instead of changing runtime interface * Fix tests * epoch-changes: map function that allows converting with different epoch types * Add migration script for the epoch config change * Fix migration tests * Fix migration: Epoch should be EpochV0 * Update client/consensus/babe/src/lib.rs Co-Authored-By: André Silva <123550+andresilva@users.noreply.github.com> * Fix new epochChanges version * Fix unused imports Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>
2026-06-13 07:01:05 +00:00 · 2020-04-24 15:59:14 +02:00
parent a01e608dff
commit 770cc24c47
12 changed files with 300 additions and 86 deletions
@@ -59,11 +59,13 @@
 #![forbid(unsafe_code)]
 #![warn(missing_docs)]
 pub use sp_consensus_babe::{
-	BabeApi, ConsensusLog, BABE_ENGINE_ID, SlotNumber, BabeConfiguration,
+	BabeApi, ConsensusLog, BABE_ENGINE_ID, SlotNumber,
+	BabeEpochConfiguration, BabeGenesisConfiguration,
 	AuthorityId, AuthorityPair, AuthoritySignature,
 	BabeAuthorityWeight, VRF_OUTPUT_LENGTH,
 	digests::{
-		CompatibleDigestItem, NextEpochDescriptor, PreDigest, PrimaryPreDigest, SecondaryPreDigest,
+		CompatibleDigestItem, NextEpochDescriptor, NextConfigDescriptor,
+		PreDigest, PrimaryPreDigest, SecondaryPreDigest,
 	},
 };
 pub use sp_consensus::SyncOracle;
@@ -118,36 +120,43 @@ use sp_api::ApiExt;

 mod aux_schema;
 mod verification;
+mod migration;
 pub mod authorship;
 #[cfg(test)]
 mod tests;

 /// BABE epoch information
-#[derive(Decode, Encode, Default, PartialEq, Eq, Clone, Debug)]
+#[derive(Decode, Encode, PartialEq, Eq, Clone, Debug)]
 pub struct Epoch {
-	/// The epoch index
+	/// The epoch index.
 	pub epoch_index: u64,
-	/// The starting slot of the epoch,
+	/// The starting slot of the epoch.
 	pub start_slot: SlotNumber,
-	/// The duration of this epoch
+	/// The duration of this epoch.
 	pub duration: SlotNumber,
-	/// The authorities and their weights
+	/// The authorities and their weights.
 	pub authorities: Vec<(AuthorityId, BabeAuthorityWeight)>,
-	/// Randomness for this epoch
+	/// Randomness for this epoch.
 	pub randomness: [u8; VRF_OUTPUT_LENGTH],
+	/// Configuration of the epoch.
+	pub config: BabeEpochConfiguration,
 }

 impl EpochT for Epoch {
-	type NextEpochDescriptor = NextEpochDescriptor;
+	type NextEpochDescriptor = (NextEpochDescriptor, BabeEpochConfiguration);
 	type SlotNumber = SlotNumber;

-	fn increment(&self, descriptor: NextEpochDescriptor) -> Epoch {
+	fn increment(
+		&self,
+		(descriptor, config): (NextEpochDescriptor, BabeEpochConfiguration)
+	) -> Epoch {
 		Epoch {
 			epoch_index: self.epoch_index + 1,
 			start_slot: self.start_slot + self.duration,
 			duration: self.duration,
 			authorities: descriptor.authorities,
 			randomness: descriptor.randomness,
+			config,
 		}
 	}

@@ -160,6 +169,27 @@ impl EpochT for Epoch {
 	}
 }

+impl Epoch {
+	/// Create the genesis epoch (epoch #0). This is defined to start at the slot of
+	/// the first block, so that has to be provided.
+	pub fn genesis(
+		genesis_config: &BabeGenesisConfiguration,
+		slot_number: SlotNumber
+	) -> Epoch {
+		Epoch {
+			epoch_index: 0,
+			start_slot: slot_number,
+			duration: genesis_config.epoch_length,
+			authorities: genesis_config.genesis_authorities.clone(),
+			randomness: genesis_config.randomness.clone(),
+			config: BabeEpochConfiguration {
+				c: genesis_config.c,
+				secondary_slots: genesis_config.secondary_slots,
+			},
+		}
+	}
+}
+
 #[derive(derive_more::Display, Debug)]
 enum Error<B: BlockT> {
 	#[display(fmt = "Multiple BABE pre-runtime digests, rejecting!")]
@@ -168,6 +198,8 @@ enum Error<B: BlockT> {
 	NoPreRuntimeDigest,
 	#[display(fmt = "Multiple BABE epoch change digests, rejecting!")]
 	MultipleEpochChangeDigests,
+	#[display(fmt = "Multiple BABE config change digests, rejecting!")]
+	MultipleConfigChangeDigests,
 	#[display(fmt = "Could not extract timestamp and slot: {:?}", _0)]
 	Extraction(sp_consensus::Error),
 	#[display(fmt = "Could not fetch epoch at {:?}", _0)]
@@ -200,6 +232,8 @@ enum Error<B: BlockT> {
 	FetchParentHeader(sp_blockchain::Error),
 	#[display(fmt = "Expected epoch change to happen at {:?}, s{}", _0, _1)]
 	ExpectedEpochChange(B::Hash, u64),
+	#[display(fmt = "Unexpected config change")]
+	UnexpectedConfigChange,
 	#[display(fmt = "Unexpected epoch change")]
 	UnexpectedEpochChange,
 	#[display(fmt = "Parent block of {} has no associated weight", _0)]
@@ -236,7 +270,7 @@ pub static INTERMEDIATE_KEY: &[u8] = b"babe1";
 // and `super::babe::Config` can be eliminated.
 // https://github.com/paritytech/substrate/issues/2434
 #[derive(Clone)]
-pub struct Config(sc_consensus_slots::SlotDuration<BabeConfiguration>);
+pub struct Config(sc_consensus_slots::SlotDuration<BabeGenesisConfiguration>);

 impl Config {
 	/// Either fetch the slot duration from disk or compute it from the genesis
@@ -253,24 +287,12 @@ impl Config {
 			}
 		}
 	}
-
-	/// Create the genesis epoch (epoch #0). This is defined to start at the slot of
-	/// the first block, so that has to be provided.
-	pub fn genesis_epoch(&self, slot_number: SlotNumber) -> Epoch {
-		Epoch {
-			epoch_index: 0,
-			start_slot: slot_number,
-			duration: self.epoch_length,
-			authorities: self.genesis_authorities.clone(),
-			randomness: self.randomness.clone(),
-		}
-	}
 }

 impl std::ops::Deref for Config {
-	type Target = BabeConfiguration;
+	type Target = BabeGenesisConfiguration;

-	fn deref(&self) -> &BabeConfiguration {
+	fn deref(&self) -> &BabeGenesisConfiguration {
 		&*self.0
 	}
 }
@@ -428,7 +450,7 @@ impl<B, C, E, I, Error, SO> sc_consensus_slots::SimpleSlotWorker<B> for BabeWork

 	fn authorities_len(&self, epoch_descriptor: &Self::EpochData) -> Option<usize> {
 		self.epoch_changes.lock()
-			.viable_epoch(&epoch_descriptor, |slot| self.config.genesis_epoch(slot))
+			.viable_epoch(&epoch_descriptor, |slot| Epoch::genesis(&self.config, slot))
 			.map(|epoch| epoch.as_ref().authorities.len())
 	}

@@ -443,9 +465,8 @@ impl<B, C, E, I, Error, SO> sc_consensus_slots::SimpleSlotWorker<B> for BabeWork
 			slot_number,
 			self.epoch_changes.lock().viable_epoch(
 				&epoch_descriptor,
-				|slot| self.config.genesis_epoch(slot)
+				|slot| Epoch::genesis(&self.config, slot)
 			)?.as_ref(),
-			&*self.config,
 			&self.keystore,
 		);

@@ -599,6 +620,24 @@ fn find_next_epoch_digest<B: BlockT>(header: &B::Header)
 	Ok(epoch_digest)
 }

+/// Extract the BABE config change digest from the given header, if it exists.
+fn find_next_config_digest<B: BlockT>(header: &B::Header)
+	-> Result<Option<NextConfigDescriptor>, Error<B>>
+	where DigestItemFor<B>: CompatibleDigestItem,
+{
+	let mut config_digest: Option<_> = None;
+	for log in header.digest().logs() {
+		trace!(target: "babe", "Checking log {:?}, looking for epoch change digest.", log);
+		let log = log.try_to::<ConsensusLog>(OpaqueDigestItemId::Consensus(&BABE_ENGINE_ID));
+		match (log, config_digest.is_some()) {
+			(Some(ConsensusLog::NextConfigData(_)), true) => return Err(babe_err(Error::MultipleConfigChangeDigests)),
+			(Some(ConsensusLog::NextConfigData(config)), false) => config_digest = Some(config),
+			_ => trace!(target: "babe", "Ignoring digest not meant for us"),
+		}
+	}
+
+	Ok(config_digest)
+}

 #[derive(Default, Clone)]
 struct TimeSource(Arc<Mutex<(Option<Duration>, Vec<(Instant, u64)>)>>);
@@ -726,7 +765,7 @@ impl<Block, Client> Verifier<Block> for BabeVerifier<Block, Client> where
 			.ok_or_else(|| Error::<Block>::FetchEpoch(parent_hash))?;
 		let viable_epoch = epoch_changes.viable_epoch(
 			&epoch_descriptor,
-			|slot| self.config.genesis_epoch(slot)
+			|slot| Epoch::genesis(&self.config, slot)
 		).ok_or_else(|| Error::<Block>::FetchEpoch(parent_hash))?;

 		// We add one to the current slot to allow for some small drift.
@@ -736,7 +775,6 @@ impl<Block, Client> Verifier<Block> for BabeVerifier<Block, Client> where
 			pre_digest: Some(pre_digest.clone()),
 			slot_now: slot_now + 1,
 			epoch: viable_epoch.as_ref(),
-			config: &self.config,
 		};

 		match verification::check_header::<Block>(v_params)? {
@@ -958,19 +996,32 @@ impl<Block, Client, Inner> BlockImport<Block> for BabeBlockImport<Block, Client,
 		// search for this all the time so we can reject unexpected announcements.
 		let next_epoch_digest = find_next_epoch_digest::<Block>(&block.header)
 			.map_err(|e| ConsensusError::ClientImport(e.to_string()))?;
+		let next_config_digest = find_next_config_digest::<Block>(&block.header)
+			.map_err(|e| ConsensusError::ClientImport(e.to_string()))?;

-		match (first_in_epoch, next_epoch_digest.is_some()) {
-			(true, true) => {},
-			(false, false) => {},
-			(true, false) => {
+		match (first_in_epoch, next_epoch_digest.is_some(), next_config_digest.is_some()) {
+			(true, true, _) => {},
+			(false, false, false) => {},
+			(false, false, true) => {
+				return Err(
+					ConsensusError::ClientImport(
+						babe_err(Error::<Block>::UnexpectedConfigChange).into(),
+					)
+				)
+			},
+			(true, false, _) => {
 				return Err(
 					ConsensusError::ClientImport(
 						babe_err(Error::<Block>::ExpectedEpochChange(hash, slot_number)).into(),
 					)
-				);
+				)
 			},
-			(false, true) => {
-				return Err(ConsensusError::ClientImport(Error::<Block>::UnexpectedEpochChange.into()));
+			(false, true, _) => {
+				return Err(
+					ConsensusError::ClientImport(
+						babe_err(Error::<Block>::UnexpectedEpochChange).into(),
+					)
+				)
 			},
 		}

@@ -985,11 +1036,15 @@ impl<Block, Client, Inner> BlockImport<Block> for BabeBlockImport<Block, Client,

 			let viable_epoch = epoch_changes.viable_epoch(
 				&epoch_descriptor,
-				|slot| self.config.genesis_epoch(slot),
+				|slot| Epoch::genesis(&self.config, slot)
 			).ok_or_else(|| {
 				ConsensusError::ClientImport(Error::<Block>::FetchEpoch(parent_hash).into())
 			})?;

+			let epoch_config = next_config_digest.unwrap_or_else(
+				|| viable_epoch.as_ref().config.clone()
+			);
+      
 			// restrict info logging during initial sync to avoid spam
 			let log_level = if block.origin == BlockOrigin::NetworkInitialSync {
 				log::Level::Debug
@@ -1006,7 +1061,7 @@ impl<Block, Client, Inner> BlockImport<Block> for BabeBlockImport<Block, Client,
 				viable_epoch.as_ref().start_slot,
 			);

-			let next_epoch = viable_epoch.increment(next_epoch_descriptor);
+			let next_epoch = viable_epoch.increment((next_epoch_descriptor, epoch_config));

 			log!(target: "babe",
 				log_level,
@@ -1152,7 +1207,7 @@ pub fn block_import<Client, Block: BlockT, I>(
 ) -> ClientResult<(BabeBlockImport<Block, Client, I>, BabeLink<Block>)> where
 	Client: AuxStore + HeaderBackend<Block> + HeaderMetadata<Block, Error = sp_blockchain::Error>,
 {
-	let epoch_changes = aux_schema::load_epoch_changes::<Block, _>(&*client)?;
+	let epoch_changes = aux_schema::load_epoch_changes::<Block, _>(&*client, &config)?;
 	let link = BabeLink {
 		epoch_changes: epoch_changes.clone(),
 		time_source: Default::default(),
@@ -1245,13 +1300,12 @@ pub mod test_helpers {
 			&parent.hash(),
 			parent.number().clone(),
 			slot_number,
-			|slot| link.config.genesis_epoch(slot),
+			|slot| Epoch::genesis(&link.config, slot),
 		).unwrap().unwrap();

 		authorship::claim_slot(
 			slot_number,
 			&epoch,
-			&link.config,
 			keystore,
 		).map(|(digest, _)| digest)
 	}