Use BABE instead of AuRa in node (#3171)

* babe: add babe module trait

* babe: track current slot and epoch start slot

* babe: implement ShouldEndSession based on epochs

* babe: rename weight type to avoid ambiguities

* babe: expose epoch start slot in Epoch digest

* babe: use epoch start for validating epoch transitions

* babe: make the epoch duration a parameter type

* babe: remove unused fields from config

* node: update runtime to use babe instead of aura

* node: use babe instead of aura

* core: generate sr25519 keys from seed and add to keystore

* core: remove AuthorityKeyring

* node: remove unused primitive types related to babe crypto

* uniform babe primitives crate import name

* wrap long lines

* babe: fix find_epoch_digest

* fork-tree: fix find_node_where

* node: set babe epoch duration to "10 minutes"

* babe: cleanup import key cache if authorities don't change

* node: make integration test compile (but fail)

* node: bump spec_version

* node: fix import

* babe: don't use constants in storage fields array sizes

* babe: account for first epoch slot way in the past

* babe: signal next epoch change (not current)

* babe: calculate next epoch randomness with next epoch index

* babe: track next epoch in node

* babe: cache current epoch and authorities separately

* babe: generate valid babe vrf proofs in integration test

* babe: cleanup claim_slot

* babe: perform threshold calculation according to spec

* babe: compute relative weight in threshold

* babe: more precise threshold calculation

* babe: use floats for threshold exponent calculation

* babe: update constant c

substrate/node/runtime/src/lib.rs

@@ -26,9 +26,10 @@ use support::{
 };
 use substrate_primitives::u32_trait::{_1, _2, _3, _4};
 use node_primitives::{
-	AccountId, AccountIndex, AuraId, Balance, BlockNumber, Hash, Index,
+	AccountId, AccountIndex, Balance, BlockNumber, Hash, Index,
 	Moment, Signature,
 };
+use babe::{AuthorityId as BabeId};
 use grandpa::fg_primitives::{self, ScheduledChange};
 use client::{
 	block_builder::api::{self as block_builder_api, InherentData, CheckInherentsResult},
@@ -137,9 +138,12 @@ impl system::Trait for Runtime {
 	type MaximumBlockLength = MaximumBlockLength;
 }
 
-impl aura::Trait for Runtime {
-	type HandleReport = aura::StakingSlasher<Runtime>;
-	type AuthorityId = AuraId;
+parameter_types! {
+	pub const EpochDuration: u64 = 10 * MINUTES;
+}
+
+impl babe::Trait for Runtime {
+	type EpochDuration = EpochDuration;
 }
 
 impl indices::Trait for Runtime {
@@ -177,7 +181,7 @@ parameter_types! {
 }
 impl timestamp::Trait for Runtime {
 	type Moment = Moment;
-	type OnTimestampSet = Aura;
+	type OnTimestampSet = Babe;
 	type MinimumPeriod = MinimumPeriod;
 }
 
@@ -193,17 +197,14 @@ impl authorship::Trait for Runtime {
 	type EventHandler = ();
 }
 
-parameter_types! {
-	pub const Period: BlockNumber = 10 * MINUTES;
-	pub const Offset: BlockNumber = 0;
-}
-
-type SessionHandlers = (Grandpa, Aura, ImOnline);
+type SessionHandlers = (Grandpa, Babe, ImOnline);
 
 impl_opaque_keys! {
 	pub struct SessionKeys {
 		#[id(key_types::ED25519)]
 		pub ed25519: GrandpaId,
+		#[id(key_types::SR25519)]
+		pub sr25519: BabeId,
 	}
 }
 
@@ -216,7 +217,7 @@ impl_opaque_keys! {
 impl session::Trait for Runtime {
 	type OnSessionEnding = Staking;
 	type SessionHandler = SessionHandlers;
-	type ShouldEndSession = session::PeriodicSessions<Period, Offset>;
+	type ShouldEndSession = Babe;
 	type Event = Event;
 	type Keys = SessionKeys;
 	type ValidatorId = AccountId;
@@ -378,12 +379,12 @@ impl sudo::Trait for Runtime {
 }
 
 impl im_online::Trait for Runtime {
-	type AuthorityId = AuraId;
+	type AuthorityId = BabeId;
 	type Call = Call;
 	type Event = Event;
 	type SessionsPerEra = SessionsPerEra;
 	type UncheckedExtrinsic = UncheckedExtrinsic;
-	type IsValidAuthorityId = Aura;
+	type IsValidAuthorityId = Babe;
 }
 
 impl grandpa::Trait for Runtime {
@@ -408,7 +409,7 @@ construct_runtime!(
 		UncheckedExtrinsic = UncheckedExtrinsic
 	{
 		System: system::{Module, Call, Storage, Config, Event},
-		Aura: aura::{Module, Call, Storage, Config<T>, Inherent(Timestamp)},
+		Babe: babe::{Module, Call, Storage, Config, Inherent(Timestamp)},
 		Timestamp: timestamp::{Module, Call, Storage, Inherent},
 		Authorship: authorship::{Module, Call, Storage},
 		Indices: indices,
@@ -525,12 +526,23 @@ impl_runtime_apis! {
 		}
 	}
 
-	impl consensus_aura::AuraApi<Block, AuraId> for Runtime {
-		fn slot_duration() -> u64 {
-			Aura::slot_duration()
+	impl babe_primitives::BabeApi<Block> for Runtime {
+		fn startup_data() -> babe_primitives::BabeConfiguration {
+			babe_primitives::BabeConfiguration {
+				median_required_blocks: 1000,
+				slot_duration: Babe::slot_duration(),
+				c: (3, 10),
+			}
 		}
-		fn authorities() -> Vec<AuraId> {
-			Aura::authorities()
+
+		fn epoch() -> babe_primitives::Epoch {
+			babe_primitives::Epoch {
+				start_slot: Babe::epoch_start_slot(),
+				authorities: Babe::authorities(),
+				epoch_index: Babe::epoch_index(),
+				randomness: Babe::randomness(),
+				duration: EpochDuration::get(),
+			}
 		}
 	}
 }