add a current_epoch to BabeApi (#7789)

* add a `current_epoch` to BabeApi

* add current_epoch_start back again

* fix node-runtime

* bump spec version

substrate/bin/node/runtime/src/lib.rs

@@ -111,7 +111,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	// and set impl_version to 0. If only runtime
 	// implementation changes and behavior does not, then leave spec_version as
 	// is and increment impl_version.
-	spec_version: 260,
+	spec_version: 261,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 2,
@@ -1141,6 +1141,10 @@ impl_runtime_apis! {
 			Babe::current_epoch_start()
 		}
 
+		fn current_epoch() -> sp_consensus_babe::Epoch {
+			Babe::current_epoch()
+		}
+
 		fn generate_key_ownership_proof(
 			_slot_number: sp_consensus_babe::SlotNumber,
 			authority_id: sp_consensus_babe::AuthorityId,

substrate/frame/babe/src/lib.rs

@@ -43,7 +43,7 @@ use sp_timestamp::OnTimestampSet;
 use sp_consensus_babe::{
 	digests::{NextConfigDescriptor, NextEpochDescriptor, PreDigest},
 	inherents::{BabeInherentData, INHERENT_IDENTIFIER},
-	BabeAuthorityWeight, ConsensusLog, EquivocationProof, SlotNumber, BABE_ENGINE_ID,
+	BabeAuthorityWeight, ConsensusLog, Epoch, EquivocationProof, SlotNumber, BABE_ENGINE_ID,
 };
 use sp_consensus_vrf::schnorrkel;
 use sp_inherents::{InherentData, InherentIdentifier, MakeFatalError, ProvideInherent};
@@ -486,6 +486,17 @@ impl<T: Config> Module<T> {
 		(EpochIndex::get() * T::EpochDuration::get()) + GenesisSlot::get()
 	}
 
+	/// Produces information about the current epoch.
+	pub fn current_epoch() -> Epoch {
+		Epoch {
+			epoch_index: EpochIndex::get(),
+			start_slot: Self::current_epoch_start(),
+			duration: T::EpochDuration::get(),
+			authorities: Self::authorities(),
+			randomness: Self::randomness(),
+		}
+	}
+
 	fn deposit_consensus<U: Encode>(new: U) {
 		let log: DigestItem<T::Hash> = DigestItem::Consensus(BABE_ENGINE_ID, new.encode());
 		<frame_system::Module<T>>::deposit_log(log.into())

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

@@ -350,6 +350,21 @@ impl OpaqueKeyOwnershipProof {
 	}
 }
 
+/// BABE epoch information
+#[derive(Decode, Encode, PartialEq, Eq, Clone, Debug)]
+pub struct Epoch {
+	/// The epoch index.
+	pub epoch_index: u64,
+	/// The starting slot of the epoch.
+	pub start_slot: SlotNumber,
+	/// The duration of this epoch.
+	pub duration: SlotNumber,
+	/// The authorities and their weights.
+	pub authorities: Vec<(AuthorityId, BabeAuthorityWeight)>,
+	/// Randomness for this epoch.
+	pub randomness: [u8; VRF_OUTPUT_LENGTH],
+}
+
 sp_api::decl_runtime_apis! {
 	/// API necessary for block authorship with BABE.
 	#[api_version(2)]
@@ -364,6 +379,9 @@ sp_api::decl_runtime_apis! {
 		/// Returns the slot number that started the current epoch.
 		fn current_epoch_start() -> SlotNumber;
 
+		/// Returns information regarding the current epoch.
+		fn current_epoch() -> Epoch;
+
 		/// Generates a proof of key ownership for the given authority in the
 		/// current epoch. An example usage of this module is coupled with the
 		/// session historical module to prove that a given authority key is

substrate/test-utils/runtime/src/lib.rs

@@ -732,10 +732,14 @@ cfg_if! {
 					}
 				}
 
-				fn current_epoch_start() -> SlotNumber {
+				fn current_epoch_start() -> sp_consensus_babe::SlotNumber {
 					<pallet_babe::Module<Runtime>>::current_epoch_start()
 				}
 
+				fn current_epoch() -> sp_consensus_babe::Epoch {
+					<pallet_babe::Module<Runtime>>::current_epoch()
+				}
+
 				fn submit_report_equivocation_unsigned_extrinsic(
 					_equivocation_proof: sp_consensus_babe::EquivocationProof<
 						<Block as BlockT>::Header,
@@ -983,10 +987,14 @@ cfg_if! {
 					}
 				}
 
-				fn current_epoch_start() -> SlotNumber {
+				fn current_epoch_start() -> sp_consensus_babe::SlotNumber {
 					<pallet_babe::Module<Runtime>>::current_epoch_start()
 				}
 
+				fn current_epoch() -> sp_consensus_babe::Epoch {
+					<pallet_babe::Module<Runtime>>::current_epoch()
+				}
+
 				fn submit_report_equivocation_unsigned_extrinsic(
 					_equivocation_proof: sp_consensus_babe::EquivocationProof<
 						<Block as BlockT>::Header,