Move AuRa digest from client to primitives (#8245)

* Move AuRa digest from client to primitives

This makes the digest stuff usable from inside the runtime ;)

* Update primitives/runtime/src/generic/digest.rs

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

* Review feedback

* Make BABE use the new functionality

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

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

@@ -77,16 +77,13 @@ use sp_consensus_slots::Slot;
 use sp_api::ApiExt;
 
 pub use sp_consensus_aura::{
-	ConsensusLog, AuraApi, AURA_ENGINE_ID,
+	ConsensusLog, AuraApi, AURA_ENGINE_ID, digests::CompatibleDigestItem,
 	inherents::{
 		InherentType as AuraInherent,
 		AuraInherentData, INHERENT_IDENTIFIER, InherentDataProvider,
 	},
 };
 pub use sp_consensus::SyncOracle;
-pub use digests::CompatibleDigestItem;
-
-mod digests;
 
 type AuthorityId<P> = <P as Pair>::Public;
 
@@ -271,7 +268,7 @@ where
 		_claim: &Self::Claim,
 	) -> Vec<sp_runtime::DigestItem<B::Hash>> {
 		vec![
-			<DigestItemFor<B> as CompatibleDigestItem<P>>::aura_pre_digest(slot),
+			<DigestItemFor<B> as CompatibleDigestItem<P::Signature>>::aura_pre_digest(slot),
 		]
 	}
 
@@ -308,7 +305,9 @@ where
 					signature, public
 				))?;
 
-			let signature_digest_item = <DigestItemFor<B> as CompatibleDigestItem<P>>::aura_seal(signature);
+			let signature_digest_item = <
+				DigestItemFor<B> as CompatibleDigestItem<P::Signature>
+			>::aura_seal(signature);
 
 			let mut import_block = BlockImportParams::new(BlockOrigin::Own, header);
 			import_block.post_digests.push(signature_digest_item);
@@ -326,7 +325,7 @@ where
 
 	fn should_backoff(&self, slot: Slot, chain_head: &B::Header) -> bool {
 		if let Some(ref strategy) = self.backoff_authoring_blocks {
-			if let Ok(chain_head_slot) = find_pre_digest::<B, P>(chain_head) {
+			if let Ok(chain_head_slot) = find_pre_digest::<B, P::Signature>(chain_head) {
 				return strategy.should_backoff(
 					*chain_head.number(),
 					chain_head_slot,
@@ -356,7 +355,7 @@ where
 	) -> Option<std::time::Duration> {
 		let slot_remaining = self.slot_remaining_duration(slot_info);
 
-		let parent_slot = match find_pre_digest::<B, P>(head) {
+		let parent_slot = match find_pre_digest::<B, P::Signature>(head) {
 			Err(_) => return Some(slot_remaining),
 			Ok(d) => d,
 		};
@@ -414,11 +413,7 @@ impl<B: BlockT> std::convert::From<Error<B>> for String {
 	}
 }
 
-fn find_pre_digest<B: BlockT, P: Pair>(header: &B::Header) -> Result<Slot, Error<B>>
-	where DigestItemFor<B>: CompatibleDigestItem<P>,
-		P::Signature: Decode,
-		P::Public: Encode + Decode + PartialEq + Clone,
-{
+fn find_pre_digest<B: BlockT, Signature: Codec>(header: &B::Header) -> Result<Slot, Error<B>> {
 	if header.number().is_zero() {
 		return Ok(0.into());
 	}
@@ -426,7 +421,7 @@ fn find_pre_digest<B: BlockT, P: Pair>(header: &B::Header) -> Result<Slot, Error
 	let mut pre_digest: Option<Slot> = None;
 	for log in header.digest().logs() {
 		trace!(target: "aura", "Checking log {:?}", log);
-		match (log.as_aura_pre_digest(), pre_digest.is_some()) {
+		match (CompatibleDigestItem::<Signature>::as_aura_pre_digest(log), pre_digest.is_some()) {
 			(Some(_), true) => Err(aura_err(Error::MultipleHeaders))?,
 			(None, _) => trace!(target: "aura", "Ignoring digest not meant for us"),
 			(s, false) => pre_digest = s,
@@ -435,8 +430,9 @@ fn find_pre_digest<B: BlockT, P: Pair>(header: &B::Header) -> Result<Slot, Error
 	pre_digest.ok_or_else(|| aura_err(Error::NoDigestFound))
 }
 
-/// check a header has been signed by the right key. If the slot is too far in the future, an error will be returned.
-/// if it's successful, returns the pre-header and the digest item containing the seal.
+/// check a header has been signed by the right key. If the slot is too far in the future, an error
+/// will be returned. If it's successful, returns the pre-header and the digest item
+/// containing the seal.
 ///
 /// This digest item will always return `Some` when used with `as_aura_seal`.
 //
@@ -447,8 +443,8 @@ fn check_header<C, B: BlockT, P: Pair>(
 	hash: B::Hash,
 	authorities: &[AuthorityId<P>],
 ) -> Result<CheckedHeader<B::Header, (Slot, DigestItemFor<B>)>, Error<B>> where
-	DigestItemFor<B>: CompatibleDigestItem<P>,
-	P::Signature: Decode,
+	DigestItemFor<B>: CompatibleDigestItem<P::Signature>,
+	P::Signature: Codec,
 	C: sc_client_api::backend::AuxStore,
 	P::Public: Encode + Decode + PartialEq + Clone,
 {
@@ -461,7 +457,7 @@ fn check_header<C, B: BlockT, P: Pair>(
 		aura_err(Error::HeaderBadSeal(hash))
 	})?;
 
-	let slot = find_pre_digest::<B, _>(&header)?;
+	let slot = find_pre_digest::<B, P::Signature>(&header)?;
 
 	if slot > slot_now {
 		header.digest_mut().push(seal);
@@ -582,7 +578,7 @@ impl<B: BlockT, C, P, CAW> Verifier<B> for AuraVerifier<C, P, CAW> where
 		ProvideCache<B> +
 		BlockOf,
 	C::Api: BlockBuilderApi<B> + AuraApi<B, AuthorityId<P>> + ApiExt<B>,
-	DigestItemFor<B>: CompatibleDigestItem<P>,
+	DigestItemFor<B>: CompatibleDigestItem<P::Signature>,
 	P: Pair + Send + Sync + 'static,
 	P::Public: Send + Sync + Hash + Eq + Clone + Decode + Encode + Debug + 'static,
 	P::Signature: Encode + Decode,
@@ -805,7 +801,7 @@ impl<Block: BlockT, C, I, P> BlockImport<Block> for AuraBlockImport<Block, C, I,
 		new_cache: HashMap<CacheKeyId, Vec<u8>>,
 	) -> Result<ImportResult, Self::Error> {
 		let hash = block.post_hash();
-		let slot = find_pre_digest::<Block, P>(&block.header)
+		let slot = find_pre_digest::<Block, P::Signature>(&block.header)
 			.expect("valid Aura headers must contain a predigest; \
 					 header has been already verified; qed");
 
@@ -816,7 +812,7 @@ impl<Block: BlockT, C, I, P> BlockImport<Block> for AuraBlockImport<Block, C, I,
 				Error::<Block>::ParentUnavailable(parent_hash, hash)
 			).into()))?;
 
-		let parent_slot = find_pre_digest::<Block, P>(&parent_header)
+		let parent_slot = find_pre_digest::<Block, P::Signature>(&parent_header)
 			.expect("valid Aura headers contain a pre-digest; \
 					parent header has already been verified; qed");
 
@@ -848,7 +844,7 @@ pub fn import_queue<B, I, C, P, S, CAW>(
 	C::Api: BlockBuilderApi<B> + AuraApi<B, AuthorityId<P>> + ApiExt<B>,
 	C: 'static + ProvideRuntimeApi<B> + BlockOf + ProvideCache<B> + Send + Sync + AuxStore + HeaderBackend<B>,
 	I: BlockImport<B, Error=ConsensusError, Transaction = sp_api::TransactionFor<C, B>> + Send + Sync + 'static,
-	DigestItemFor<B>: CompatibleDigestItem<P>,
+	DigestItemFor<B>: CompatibleDigestItem<P::Signature>,
 	P: Pair + Send + Sync + 'static,
 	P::Public: Clone + Eq + Send + Sync + Hash + Debug + Encode + Decode,
 	P::Signature: Encode + Decode,
@@ -858,7 +854,7 @@ pub fn import_queue<B, I, C, P, S, CAW>(
 	register_aura_inherent_data_provider(&inherent_data_providers, slot_duration.get())?;
 	initialize_authorities_cache(&*client)?;
 
-	let verifier = AuraVerifier {
+	let verifier = AuraVerifier::<_, P, _> {
 		client,
 		inherent_data_providers,
 		phantom: PhantomData,

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

@@ -21,22 +21,19 @@
 //! This implements the digests for AuRa, to allow the private
 //! `CompatibleDigestItem` trait to appear in public interfaces.
 
-use sp_core::Pair;
-use sp_consensus_aura::AURA_ENGINE_ID;
-use sp_runtime::generic::{DigestItem, OpaqueDigestItemId};
+use crate::AURA_ENGINE_ID;
+use sp_runtime::generic::DigestItem;
 use sp_consensus_slots::Slot;
 use codec::{Encode, Codec};
-use std::fmt::Debug;
-
-type Signature<P> = <P as Pair>::Signature;
+use sp_std::fmt::Debug;
 
 /// A digest item which is usable with aura consensus.
-pub trait CompatibleDigestItem<P: Pair>: Sized {
+pub trait CompatibleDigestItem<Signature>: Sized {
 	/// Construct a digest item which contains a signature on the hash.
-	fn aura_seal(signature: Signature<P>) -> Self;
+	fn aura_seal(signature: Signature) -> Self;
 
 	/// If this item is an Aura seal, return the signature.
-	fn as_aura_seal(&self) -> Option<Signature<P>>;
+	fn as_aura_seal(&self) -> Option<Signature>;
 
 	/// Construct a digest item which contains the slot number
 	fn aura_pre_digest(slot: Slot) -> Self;
@@ -45,17 +42,16 @@ pub trait CompatibleDigestItem<P: Pair>: Sized {
 	fn as_aura_pre_digest(&self) -> Option<Slot>;
 }
 
-impl<P, Hash> CompatibleDigestItem<P> for DigestItem<Hash> where
-	P: Pair,
-	Signature<P>: Codec,
+impl<Signature, Hash> CompatibleDigestItem<Signature> for DigestItem<Hash> where
+	Signature: Codec,
 	Hash: Debug + Send + Sync + Eq + Clone + Codec + 'static
 {
-	fn aura_seal(signature: Signature<P>) -> Self {
+	fn aura_seal(signature: Signature) -> Self {
 		DigestItem::Seal(AURA_ENGINE_ID, signature.encode())
 	}
 
-	fn as_aura_seal(&self) -> Option<Signature<P>> {
-		self.try_to(OpaqueDigestItemId::Seal(&AURA_ENGINE_ID))
+	fn as_aura_seal(&self) -> Option<Signature> {
+		self.seal_try_to(&AURA_ENGINE_ID)
 	}
 
 	fn aura_pre_digest(slot: Slot) -> Self {
@@ -63,6 +59,6 @@ impl<P, Hash> CompatibleDigestItem<P> for DigestItem<Hash> where
 	}
 
 	fn as_aura_pre_digest(&self) -> Option<Slot> {
-		self.try_to(OpaqueDigestItemId::PreRuntime(&AURA_ENGINE_ID))
+		self.pre_runtime_try_to(&AURA_ENGINE_ID)
 	}
 }

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

@@ -23,6 +23,7 @@ use codec::{Encode, Decode, Codec};
 use sp_std::vec::Vec;
 use sp_runtime::ConsensusEngineId;
 
+pub mod digests;
 pub mod inherents;
 
 pub mod sr25519 {

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

@@ -23,7 +23,7 @@ use super::{
 };
 use codec::{Codec, Decode, Encode};
 use sp_std::vec::Vec;
-use sp_runtime::{generic::OpaqueDigestItemId, DigestItem, RuntimeDebug};
+use sp_runtime::{DigestItem, RuntimeDebug};
 
 use sp_consensus_vrf::schnorrkel::{Randomness, VRFOutput, VRFProof};
 
@@ -184,7 +184,7 @@ impl<Hash> CompatibleDigestItem for DigestItem<Hash> where
 	}
 
 	fn as_babe_pre_digest(&self) -> Option<PreDigest> {
-		self.try_to(OpaqueDigestItemId::PreRuntime(&BABE_ENGINE_ID))
+		self.pre_runtime_try_to(&BABE_ENGINE_ID)
 	}
 
 	fn babe_seal(signature: AuthoritySignature) -> Self {
@@ -192,11 +192,11 @@ impl<Hash> CompatibleDigestItem for DigestItem<Hash> where
 	}
 
 	fn as_babe_seal(&self) -> Option<AuthoritySignature> {
-		self.try_to(OpaqueDigestItemId::Seal(&BABE_ENGINE_ID))
+		self.seal_try_to(&BABE_ENGINE_ID)
 	}
 
 	fn as_next_epoch_descriptor(&self) -> Option<NextEpochDescriptor> {
-		self.try_to(OpaqueDigestItemId::Consensus(&BABE_ENGINE_ID))
+		self.consensus_try_to(&BABE_ENGINE_ID)
 			.and_then(|x: super::ConsensusLog| match x {
 				super::ConsensusLog::NextEpochData(n) => Some(n),
 				_ => None,
@@ -204,7 +204,7 @@ impl<Hash> CompatibleDigestItem for DigestItem<Hash> where
 	}
 
 	fn as_next_config_descriptor(&self) -> Option<NextConfigDescriptor> {
-		self.try_to(OpaqueDigestItemId::Consensus(&BABE_ENGINE_ID))
+		self.consensus_try_to(&BABE_ENGINE_ID)
 			.and_then(|x: super::ConsensusLog| match x {
 				super::ConsensusLog::NextConfigData(n) => Some(n),
 				_ => None,

substrate/primitives/runtime/src/generic/digest.rs

@@ -62,16 +62,12 @@ impl<Hash> Digest<Hash> {
 
 	/// Get reference to the first digest item that matches the passed predicate.
 	pub fn log<T: ?Sized, F: Fn(&DigestItem<Hash>) -> Option<&T>>(&self, predicate: F) -> Option<&T> {
-		self.logs().iter()
-			.filter_map(predicate)
-			.next()
+		self.logs().iter().find_map(predicate)
 	}
 
 	/// Get a conversion of the first digest item that successfully converts using the function.
 	pub fn convert_first<T, F: Fn(&DigestItem<Hash>) -> Option<T>>(&self, predicate: F) -> Option<T> {
-		self.logs().iter()
-			.filter_map(predicate)
-			.next()
+		self.logs().iter().find_map(predicate)
 	}
 }
 
@@ -251,10 +247,7 @@ impl<Hash> DigestItem<Hash> {
 
 	/// Returns Some if `self` is a `DigestItem::Other`.
 	pub fn as_other(&self) -> Option<&[u8]> {
-		match *self {
-			DigestItem::Other(ref v) => Some(&v[..]),
-			_ => None,
-		}
+		self.dref().as_other()
 	}
 
 	/// Returns the opaque data contained in the item if `Some` if this entry has the id given.
@@ -267,6 +260,29 @@ impl<Hash> DigestItem<Hash> {
 	pub fn try_to<T: Decode>(&self, id: OpaqueDigestItemId) -> Option<T> {
 		self.dref().try_to::<T>(id)
 	}
+
+	/// Try to match this to a `Self::Seal`, check `id` matches and decode it.
+	///
+	/// Returns `None` if this isn't a seal item, the `id` doesn't match or when the decoding fails.
+	pub fn seal_try_to<T: Decode>(&self, id: &ConsensusEngineId) -> Option<T> {
+		self.dref().seal_try_to(id)
+	}
+
+	/// Try to match this to a `Self::Consensus`, check `id` matches and decode it.
+	///
+	/// Returns `None` if this isn't a consensus item, the `id` doesn't match or
+	/// when the decoding fails.
+	pub fn consensus_try_to<T: Decode>(&self, id: &ConsensusEngineId) -> Option<T> {
+		self.dref().consensus_try_to(id)
+	}
+
+	/// Try to match this to a `Self::PreRuntime`, check `id` matches and decode it.
+	///
+	/// Returns `None` if this isn't a pre-runtime item, the `id` doesn't match or
+	/// when the decoding fails.
+	pub fn pre_runtime_try_to<T: Decode>(&self, id: &ConsensusEngineId) -> Option<T> {
+		self.dref().pre_runtime_try_to(id)
+	}
 }
 
 impl<Hash: Encode> Encode for DigestItem<Hash> {
@@ -374,6 +390,41 @@ impl<'a, Hash> DigestItemRef<'a, Hash> {
 	pub fn try_to<T: Decode>(&self, id: OpaqueDigestItemId) -> Option<T> {
 		self.try_as_raw(id).and_then(|mut x| Decode::decode(&mut x).ok())
 	}
+
+	/// Try to match this to a `Self::Seal`, check `id` matches and decode it.
+	///
+	/// Returns `None` if this isn't a seal item, the `id` doesn't match or when the decoding fails.
+	pub fn seal_try_to<T: Decode>(&self, id: &ConsensusEngineId) -> Option<T> {
+		match self {
+			Self::Seal(v, s) if *v == id =>
+				Decode::decode(&mut &s[..]).ok(),
+			_ => None,
+		}
+	}
+
+	/// Try to match this to a `Self::Consensus`, check `id` matches and decode it.
+	///
+	/// Returns `None` if this isn't a consensus item, the `id` doesn't match or
+	/// when the decoding fails.
+	pub fn consensus_try_to<T: Decode>(&self, id: &ConsensusEngineId) -> Option<T> {
+		match self {
+			Self::Consensus(v, s) if *v == id =>
+				Decode::decode(&mut &s[..]).ok(),
+			_ => None,
+		}
+	}
+
+	/// Try to match this to a `Self::PreRuntime`, check `id` matches and decode it.
+	///
+	/// Returns `None` if this isn't a pre-runtime item, the `id` doesn't match or
+	/// when the decoding fails.
+	pub fn pre_runtime_try_to<T: Decode>(&self, id: &ConsensusEngineId) -> Option<T> {
+		match self {
+			Self::PreRuntime(v, s) if *v == id =>
+				Decode::decode(&mut &s[..]).ok(),
+			_ => None,
+		}
+	}
 }
 
 impl<'a, Hash: Encode> Encode for DigestItemRef<'a, Hash> {