babe: only process vrf on module finalization (#11113)

* babe: only process vrf on block execution finalization

* babe: rename CurrentBlockRandomness to PreviousBlockRandomness

* babe: add test for initialization ordering

* babe: rename PreviousBlockRandomness to ParentBlockRandomness

* babe: re-add CurrentBlockRandomness with deprecation notice

* babe: export CurrentBlockRandomness

* babe: silence deprecation warning when exporting CurrentBlockRandomness

* babe: suggestion from code review

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* babe: flatten nested option

* babe: rustfmt

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

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

@@ -22,13 +22,14 @@ use super::{
 	BabeEpochConfiguration, Slot, BABE_ENGINE_ID,
 };
 use codec::{Decode, Encode, MaxEncodedLen};
+use scale_info::TypeInfo;
 use sp_runtime::{DigestItem, RuntimeDebug};
 use sp_std::vec::Vec;
 
 use sp_consensus_vrf::schnorrkel::{Randomness, VRFOutput, VRFProof};
 
 /// Raw BABE primary slot assignment pre-digest.
-#[derive(Clone, RuntimeDebug, Encode, Decode)]
+#[derive(Clone, RuntimeDebug, Encode, Decode, MaxEncodedLen, TypeInfo)]
 pub struct PrimaryPreDigest {
 	/// Authority index
 	pub authority_index: super::AuthorityIndex,
@@ -41,7 +42,7 @@ pub struct PrimaryPreDigest {
 }
 
 /// BABE secondary slot assignment pre-digest.
-#[derive(Clone, RuntimeDebug, Encode, Decode)]
+#[derive(Clone, RuntimeDebug, Encode, Decode, MaxEncodedLen, TypeInfo)]
 pub struct SecondaryPlainPreDigest {
 	/// Authority index
 	///
@@ -55,7 +56,7 @@ pub struct SecondaryPlainPreDigest {
 }
 
 /// BABE secondary deterministic slot assignment with VRF outputs.
-#[derive(Clone, RuntimeDebug, Encode, Decode)]
+#[derive(Clone, RuntimeDebug, Encode, Decode, MaxEncodedLen, TypeInfo)]
 pub struct SecondaryVRFPreDigest {
 	/// Authority index
 	pub authority_index: super::AuthorityIndex,
@@ -70,7 +71,7 @@ pub struct SecondaryVRFPreDigest {
 /// A BABE pre-runtime digest. This contains all data required to validate a
 /// block and for the BABE runtime module. Slots can be assigned to a primary
 /// (VRF based) and to a secondary (slot number based).
-#[derive(Clone, RuntimeDebug, Encode, Decode)]
+#[derive(Clone, RuntimeDebug, Encode, Decode, MaxEncodedLen, TypeInfo)]
 pub enum PreDigest {
 	/// A primary VRF-based slot assignment.
 	#[codec(index = 1)]
@@ -102,6 +103,11 @@ impl PreDigest {
 		}
 	}
 
+	/// Returns true if this pre-digest is for a primary slot assignment.
+	pub fn is_primary(&self) -> bool {
+		matches!(self, PreDigest::Primary(..))
+	}
+
 	/// Returns the weight _added_ by this digest, not the cumulative weight
 	/// of the chain.
 	pub fn added_weight(&self) -> crate::BabeBlockWeight {
@@ -111,11 +117,12 @@ impl PreDigest {
 		}
 	}
 
-	/// Returns the VRF output, if it exists.
-	pub fn vrf_output(&self) -> Option<&VRFOutput> {
+	/// Returns the VRF output and proof, if they exist.
+	pub fn vrf(&self) -> Option<(&VRFOutput, &VRFProof)> {
 		match self {
-			PreDigest::Primary(primary) => Some(&primary.vrf_output),
-			PreDigest::SecondaryVRF(secondary) => Some(&secondary.vrf_output),
+			PreDigest::Primary(primary) => Some((&primary.vrf_output, &primary.vrf_proof)),
+			PreDigest::SecondaryVRF(secondary) =>
+				Some((&secondary.vrf_output, &secondary.vrf_proof)),
 			PreDigest::SecondaryPlain(_) => None,
 		}
 	}

substrate/primitives/consensus/vrf/Cargo.toml

@@ -14,6 +14,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 
 [dependencies]
 codec = { package = "parity-scale-codec", version = "3.0.0", default-features = false }
+scale-info = { version = "2.0.1", default-features = false }
 schnorrkel = { version = "0.9.1", default-features = false, features = ["preaudit_deprecated", "u64_backend"] }
 sp-core = { version = "6.0.0", default-features = false, path = "../../core" }
 sp-runtime = { version = "6.0.0", default-features = false, path = "../../runtime" }
@@ -23,6 +24,7 @@ sp-std = { version = "4.0.0", default-features = false, path = "../../std" }
 default = ["std"]
 std = [
 	"codec/std",
+	"scale-info/std",
 	"schnorrkel/std",
 	"sp-core/std",
 	"sp-runtime/std",

substrate/primitives/consensus/vrf/src/schnorrkel.rs

@@ -17,7 +17,8 @@
 
 //! Schnorrkel-based VRF.
 
-use codec::{Decode, Encode, EncodeLike};
+use codec::{Decode, Encode, EncodeLike, MaxEncodedLen};
+use scale_info::TypeInfo;
 use schnorrkel::errors::MultiSignatureStage;
 use sp_core::U512;
 use sp_std::{
@@ -65,6 +66,20 @@ impl Decode for VRFOutput {
 	}
 }
 
+impl MaxEncodedLen for VRFOutput {
+	fn max_encoded_len() -> usize {
+		<[u8; VRF_OUTPUT_LENGTH]>::max_encoded_len()
+	}
+}
+
+impl TypeInfo for VRFOutput {
+	type Identity = [u8; VRF_OUTPUT_LENGTH];
+
+	fn type_info() -> scale_info::Type {
+		Self::Identity::type_info()
+	}
+}
+
 impl TryFrom<[u8; VRF_OUTPUT_LENGTH]> for VRFOutput {
 	type Error = SignatureError;
 
@@ -117,6 +132,20 @@ impl Decode for VRFProof {
 	}
 }
 
+impl MaxEncodedLen for VRFProof {
+	fn max_encoded_len() -> usize {
+		<[u8; VRF_PROOF_LENGTH]>::max_encoded_len()
+	}
+}
+
+impl TypeInfo for VRFProof {
+	type Identity = [u8; VRF_PROOF_LENGTH];
+
+	fn type_info() -> scale_info::Type {
+		Self::Identity::type_info()
+	}
+}
+
 impl TryFrom<[u8; VRF_PROOF_LENGTH]> for VRFProof {
 	type Error = SignatureError;