Fix currently-checking-cache

node/core/approval-voting/src/lib.rs

@@ -68,7 +68,9 @@ use futures::{
 };
 
 use std::{
-	collections::{btree_map::Entry, BTreeMap, HashMap, HashSet},
+	collections::{
+		btree_map::Entry as BTMEntry, hash_map::Entry as HMEntry, BTreeMap, HashMap, HashSet,
+	},
 	sync::Arc,
 	time::Duration,
 };
@@ -400,7 +402,7 @@ impl Wakeups {
 			}
 
 			// we are replacing previous wakeup with an earlier one.
-			if let Entry::Occupied(mut entry) = self.wakeups.entry(*prev) {
+			if let BTMEntry::Occupied(mut entry) = self.wakeups.entry(*prev) {
 				if let Some(pos) =
 					entry.get().iter().position(|x| x == &(block_hash, candidate_hash))
 				{
@@ -436,7 +438,7 @@ impl Wakeups {
 		});
 
 		for (tick, pruned) in pruned_wakeups {
-			if let Entry::Occupied(mut entry) = self.wakeups.entry(tick) {
+			if let BTMEntry::Occupied(mut entry) = self.wakeups.entry(tick) {
 				entry.get_mut().retain(|wakeup| !pruned.contains(wakeup));
 				if entry.get().is_empty() {
 					let _ = entry.remove();
@@ -457,10 +459,10 @@ impl Wakeups {
 			Some(tick) => {
 				clock.wait(tick).await;
 				match self.wakeups.entry(tick) {
-					Entry::Vacant(_) => {
+					BTMEntry::Vacant(_) => {
 						panic!("entry is known to exist since `first` was `Some`; qed")
 					},
-					Entry::Occupied(mut entry) => {
+					BTMEntry::Occupied(mut entry) => {
 						let (hash, candidate_hash) = entry.get_mut().pop()
 							.expect("empty entries are removed here and in `schedule`; no other mutation of this map; qed");
 
@@ -509,7 +511,7 @@ impl ApprovalState {
 struct CurrentlyCheckingSet {
 	/// Invariant: The contained `Vec` needs to stay sorted as we are using `binary_search_by_key`
 	/// on it.
-	candidate_hash_map: HashMap<CandidateHash, Vec<Hash>>,
+	candidate_hash_map: HashMap<CandidateHash, HashSet<Hash>>,
 	currently_checking: FuturesUnordered<BoxFuture<'static, ApprovalState>>,
 }
 
@@ -529,21 +531,26 @@ impl CurrentlyCheckingSet {
 		relay_block: Hash,
 		launch_work: impl Future<Output = SubsystemResult<RemoteHandle<ApprovalState>>>,
 	) -> SubsystemResult<()> {
-		let val = self.candidate_hash_map.entry(candidate_hash).or_insert(Default::default());
-
-		if let Err(k) = val.binary_search_by_key(&relay_block, |v| *v) {
-			let _ = val.insert(k, relay_block);
-			let work = launch_work.await?;
-			self.currently_checking.push(Box::pin(async move {
-				match work.timeout(APPROVAL_CHECKING_TIMEOUT).await {
-					None => ApprovalState {
-						candidate_hash,
-						validator_index,
-						approval_outcome: ApprovalOutcome::TimedOut,
-					},
-					Some(approval_state) => approval_state,
-				}
-			}));
+		match self.candidate_hash_map.entry(candidate_hash) {
+			HMEntry::Occupied(mut entry) => {
+				// validation already undergoing. just add the relay hash if unknown.
+				entry.get_mut().insert(relay_block);
+			},
+			HMEntry::Vacant(entry) => {
+				// validation not ongoing. launch work and time out the remote handle.
+				entry.insert(HashSet::new()).insert(relay_block);
+				let work = launch_work.await?;
+				self.currently_checking.push(Box::pin(async move {
+					match work.timeout(APPROVAL_CHECKING_TIMEOUT).await {
+						None => ApprovalState {
+							candidate_hash,
+							validator_index,
+							approval_outcome: ApprovalOutcome::TimedOut,
+						},
+						Some(approval_state) => approval_state,
+					}
+				}));
+			},
 		}
 
 		Ok(())
@@ -552,7 +559,7 @@ impl CurrentlyCheckingSet {
 	pub async fn next(
 		&mut self,
 		approvals_cache: &mut lru::LruCache<CandidateHash, ApprovalOutcome>,
-	) -> (Vec<Hash>, ApprovalState) {
+	) -> (HashSet<Hash>, ApprovalState) {
 		if !self.currently_checking.is_empty() {
 			if let Some(approval_state) = self.currently_checking.next().await {
 				let out = self