Don't repeatedly lookup keys in `babe_epochAuthorship` rpc function (#5962)

* babe: don't repeatedly lookup keys in authorship rpc function

Expose a new function `claim_slot_using_keypars` in Babe so that the `babe_epochAuthorship` can
lookup authorship for all slots in the epoch without repeatedly looking up keys in the keystore.

Time to run the `babe_epochAuthorship` RPC call goes from 7s to 25ms on a local dev chain on my
machine.

* babe: pass reference to slice instead of ref to Vec

* babe: fix bunch of clippy warnings

substrate/client/consensus/babe/rpc/src/lib.rs

@@ -116,9 +116,20 @@ impl<B, C, SC> BabeApi for BabeRPCHandler<B, C, SC>
 
 			let mut claims: HashMap<AuthorityId, EpochAuthorship> = HashMap::new();
 
+			let key_pairs = {
+				let keystore = keystore.read();
+				epoch.authorities.iter().enumerate()
+				.flat_map(|(i, a)| {
+					keystore.key_pair::<sp_consensus_babe::AuthorityPair>(&a.0).ok().map(|kp| (kp, i))
+				})
+				.collect::<Vec<_>>()
+			};
+
 			for slot_number in epoch_start..epoch_end {
 				let epoch = epoch_data(&shared_epoch, &client, &babe_config, slot_number, &select_chain)?;
-				if let Some((claim, key)) = authorship::claim_slot(slot_number, &epoch, &keystore) {
+				if let Some((claim, key)) =
+					authorship::claim_slot_using_key_pairs(slot_number, &epoch, &key_pairs)
+				{
 					match claim {
 						PreDigest::Primary { .. } => {
 							claims.entry(key.public()).or_default().primary.push(slot_number);
@@ -163,7 +174,7 @@ pub enum Error {
 impl From<Error> for jsonrpc_core::Error {
 	fn from(error: Error) -> Self {
 		jsonrpc_core::Error {
-			message: format!("{}", error).into(),
+			message: format!("{}", error),
 			code: jsonrpc_core::ErrorCode::ServerError(1234),
 			data: None,
 		}

substrate/client/consensus/babe/src/authorship.rs

@@ -124,7 +124,7 @@ pub(super) fn secondary_slot_author(
 fn claim_secondary_slot(
 	slot_number: SlotNumber,
 	epoch: &Epoch,
-	keystore: &KeyStorePtr,
+	key_pairs: &[(AuthorityPair, usize)],
 	author_secondary_vrf: bool,
 ) -> Option<(PreDigest, AuthorityPair)> {
 	let Epoch { authorities, randomness, epoch_index, .. } = epoch;
@@ -139,14 +139,7 @@ fn claim_secondary_slot(
 		*randomness,
 	)?;
 
-	let keystore = keystore.read();
-
-	for (pair, authority_index) in authorities.iter()
-		.enumerate()
-		.flat_map(|(i, a)| {
-			keystore.key_pair::<AuthorityPair>(&a.0).ok().map(|kp| (kp, i))
-		})
-	{
+	for (pair, authority_index) in key_pairs {
 		if pair.public() == *expected_author {
 			let pre_digest = if author_secondary_vrf {
 				let transcript = super::authorship::make_transcript(
@@ -161,16 +154,16 @@ fn claim_secondary_slot(
 					slot_number,
 					vrf_output: VRFOutput(s.0.to_output()),
 					vrf_proof: VRFProof(s.1),
-					authority_index: authority_index as u32,
+					authority_index: *authority_index as u32,
 				})
 			} else {
 				PreDigest::SecondaryPlain(SecondaryPlainPreDigest {
 					slot_number,
-					authority_index: authority_index as u32,
+					authority_index: *authority_index as u32,
 				})
 			};
 
-			return Some((pre_digest, pair));
+			return Some((pre_digest, pair.clone()));
 		}
 	}
 
@@ -186,7 +179,26 @@ pub fn claim_slot(
 	epoch: &Epoch,
 	keystore: &KeyStorePtr,
 ) -> Option<(PreDigest, AuthorityPair)> {
-	claim_primary_slot(slot_number, epoch, epoch.config.c, keystore)
+	let key_pairs = {
+		let keystore = keystore.read();
+		epoch.authorities.iter()
+			.enumerate()
+			.flat_map(|(i, a)| {
+				keystore.key_pair::<AuthorityPair>(&a.0).ok().map(|kp| (kp, i))
+			})
+			.collect::<Vec<_>>()
+	};
+	claim_slot_using_key_pairs(slot_number, epoch, &key_pairs)
+}
+
+/// Like `claim_slot`, but allows passing an explicit set of key pairs. Useful if we intend
+/// to make repeated calls for different slots using the same key pairs.
+pub fn claim_slot_using_key_pairs(
+	slot_number: SlotNumber,
+	epoch: &Epoch,
+	key_pairs: &[(AuthorityPair, usize)],
+) -> Option<(PreDigest, AuthorityPair)> {
+	claim_primary_slot(slot_number, epoch, epoch.config.c, &key_pairs)
 		.or_else(|| {
 			if epoch.config.allowed_slots.is_secondary_plain_slots_allowed() ||
 				epoch.config.allowed_slots.is_secondary_vrf_slots_allowed()
@@ -194,7 +206,7 @@ pub fn claim_slot(
 				claim_secondary_slot(
 					slot_number,
 					&epoch,
-					keystore,
+					&key_pairs,
 					epoch.config.allowed_slots.is_secondary_vrf_slots_allowed(),
 				)
 			} else {
@@ -216,39 +228,33 @@ fn claim_primary_slot(
 	slot_number: SlotNumber,
 	epoch: &Epoch,
 	c: (u64, u64),
-	keystore: &KeyStorePtr,
+	key_pairs: &[(AuthorityPair, usize)],
 ) -> Option<(PreDigest, AuthorityPair)> {
 	let Epoch { authorities, randomness, epoch_index, .. } = epoch;
-	let keystore = keystore.read();
 
-	for (pair, authority_index) in authorities.iter()
-		.enumerate()
-		.flat_map(|(i, a)| {
-			keystore.key_pair::<AuthorityPair>(&a.0).ok().map(|kp| (kp, i))
-		})
-	{
+	for (pair, authority_index) in key_pairs {
 		let transcript = super::authorship::make_transcript(randomness, slot_number, *epoch_index);
 
 		// Compute the threshold we will use.
 		//
 		// We already checked that authorities contains `key.public()`, so it can't
 		// be empty.  Therefore, this division in `calculate_threshold` is safe.
-		let threshold = super::authorship::calculate_primary_threshold(c, authorities, authority_index);
+		let threshold = super::authorship::calculate_primary_threshold(c, authorities, *authority_index);
 
-		let pre_digest = get_keypair(&pair)
+		let pre_digest = get_keypair(pair)
 			.vrf_sign_after_check(transcript, |inout| super::authorship::check_primary_threshold(inout, threshold))
 			.map(|s| {
 				PreDigest::Primary(PrimaryPreDigest {
 					slot_number,
 					vrf_output: VRFOutput(s.0.to_output()),
 					vrf_proof: VRFProof(s.1),
-					authority_index: authority_index as u32,
+					authority_index: *authority_index as u32,
 				})
 			});
 
 		// early exit on first successful claim
 		if let Some(pre_digest) = pre_digest {
-			return Some((pre_digest, pair));
+			return Some((pre_digest, pair.clone()));
 		}
 	}
 

substrate/client/consensus/babe/src/aux_schema.rs

@@ -112,7 +112,7 @@ pub(crate) fn write_epoch_changes<Block: BlockT, F, R>(
 /// Write the cumulative chain-weight of a block ot aux storage.
 pub(crate) fn write_block_weight<H: Encode, F, R>(
 	block_hash: H,
-	block_weight: &BabeBlockWeight,
+	block_weight: BabeBlockWeight,
 	write_aux: F,
 ) -> R where
 	F: FnOnce(&[(Vec<u8>, &[u8])]) -> R,

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

@@ -78,7 +78,6 @@ use std::{
 	collections::HashMap, sync::Arc, u64, pin::Pin, time::{Instant, Duration},
 	any::Any, borrow::Cow
 };
-use sp_consensus_babe;
 use sp_consensus::{ImportResult, CanAuthorWith};
 use sp_consensus::import_queue::{
 	BoxJustificationImport, BoxFinalityProofImport,
@@ -186,7 +185,7 @@ impl Epoch {
 			start_slot: slot_number,
 			duration: genesis_config.epoch_length,
 			authorities: genesis_config.genesis_authorities.clone(),
-			randomness: genesis_config.randomness.clone(),
+			randomness: genesis_config.randomness,
 			config: BabeEpochConfiguration {
 				c: genesis_config.c,
 				allowed_slots: genesis_config.allowed_slots,
@@ -399,7 +398,7 @@ pub fn start_babe<B, C, SC, E, I, SO, CAW, Error>(BabeParams {
 
 	register_babe_inherent_data_provider(&inherent_data_providers, config.slot_duration())?;
 	sc_consensus_uncles::register_uncles_inherent_data_provider(
-		client.clone(),
+		client,
 		select_chain.clone(),
 		&inherent_data_providers,
 	)?;
@@ -494,7 +493,7 @@ impl<B, C, E, I, Error, SO> sc_consensus_slots::SimpleSlotWorker<B> for BabeWork
 			&self.keystore,
 		);
 
-		if let Some(_) = s {
+		if s.is_some() {
 			debug!(target: "babe", "Claimed slot {}", slot_number);
 		}
 
@@ -796,7 +795,7 @@ impl<Block, Client> Verifier<Block> for BabeVerifier<Block, Client> where
 		// FIXME #1019 in the future, alter this queue to allow deferring of headers
 		let v_params = verification::VerificationParams {
 			header: header.clone(),
-			pre_digest: Some(pre_digest.clone()),
+			pre_digest: Some(pre_digest),
 			slot_now: slot_now + 1,
 			epoch: viable_epoch.as_ref(),
 		};
@@ -952,7 +951,7 @@ impl<Block, Client, Inner> BlockImport<Block> for BabeBlockImport<Block, Client,
 		new_cache: HashMap<CacheKeyId, Vec<u8>>,
 	) -> Result<ImportResult, Self::Error> {
 		let hash = block.post_hash();
-		let number = block.header.number().clone();
+		let number = *block.header.number();
 
 		// early exit if block already in chain, otherwise the check for
 		// epoch changes will error when trying to re-import an epoch change
@@ -1133,7 +1132,7 @@ impl<Block, Client, Inner> BlockImport<Block> for BabeBlockImport<Block, Client,
 
 		aux_schema::write_block_weight(
 			hash,
-			&total_weight,
+			total_weight,
 			|values| block.auxiliary.extend(
 				values.iter().map(|(k, v)| (k.to_vec(), Some(v.to_vec())))
 			),
@@ -1153,7 +1152,7 @@ impl<Block, Client, Inner> BlockImport<Block> for BabeBlockImport<Block, Client,
 				aux_schema::load_block_weight(&*self.client, last_best)
 					.map_err(|e| ConsensusError::ChainLookup(format!("{:?}", e)))?
 					.ok_or_else(
-						|| ConsensusError::ChainLookup(format!("No block weight for parent header."))
+						|| ConsensusError::ChainLookup("No block weight for parent header.".to_string())
 					)?
 			};
 
@@ -1170,7 +1169,7 @@ impl<Block, Client, Inner> BlockImport<Block> for BabeBlockImport<Block, Client,
 
 		// revert to the original epoch changes in case there's an error
 		// importing the block
-		if let Err(_) = import_result {
+		if import_result.is_err() {
 			if let Some(old_epoch_changes) = old_epoch_changes {
 				*epoch_changes = old_epoch_changes;
 			}
@@ -1283,7 +1282,7 @@ pub fn import_queue<Block: BlockT, Client, Inner>(
 	register_babe_inherent_data_provider(&inherent_data_providers, babe_link.config.slot_duration)?;
 
 	let verifier = BabeVerifier {
-		client: client.clone(),
+		client,
 		inherent_data_providers,
 		config: babe_link.config,
 		epoch_changes: babe_link.epoch_changes,