kvserver: make AdminRelocateRange work with non-voting replicas

This commit teaches `RelocateRange` to work with non-voters. This lets
the merge queue rebalance a range that has non-voters so the merge can
actually proceed, as range merges require that replica sets of the LHS
and RHS ranges must be aligned.

Release note: None

pkg/kv/batch.go

@@ -685,7 +685,9 @@ func (b *Batch) adminChangeReplicas(
 
 // adminRelocateRange is only exported on DB. It is here for symmetry with the
 // other operations.
-func (b *Batch) adminRelocateRange(key interface{}, targets []roachpb.ReplicationTarget) {
+func (b *Batch) adminRelocateRange(
+	key interface{}, voterTargets, nonVoterTargets []roachpb.ReplicationTarget,
+) {
 	k, err := marshalKey(key)
 	if err != nil {
 		b.initResult(0, 0, notRaw, err)
@@ -695,7 +697,8 @@ func (b *Batch) adminRelocateRange(key interface{}, targets []roachpb.Replicatio
 		RequestHeader: roachpb.RequestHeader{
 			Key: k,
 		},
-		Targets: targets,
+		VoterTargets:    voterTargets,
+		NonVoterTargets: nonVoterTargets,
 	}
 	b.appendReqs(req)
 	b.initResult(1, 0, notRaw, nil)

pkg/kv/db.go

@@ -608,10 +608,10 @@ func (db *DB) AdminChangeReplicas(
 // AdminRelocateRange relocates the replicas for a range onto the specified
 // list of stores.
 func (db *DB) AdminRelocateRange(
-	ctx context.Context, key interface{}, targets []roachpb.ReplicationTarget,
+	ctx context.Context, key interface{}, voterTargets, nonVoterTargets []roachpb.ReplicationTarget,
 ) error {
 	b := &Batch{}
-	b.adminRelocateRange(key, targets)
+	b.adminRelocateRange(key, voterTargets, nonVoterTargets)
 	return getOneErr(db.Run(ctx, b), b)
 }
 

pkg/kv/kvserver/allocator.go

@@ -494,17 +494,17 @@ func (a *Allocator) AllocateTarget(
 
 func (a *Allocator) allocateTargetFromList(
 	ctx context.Context,
-	sl StoreList,
+	candidateStores StoreList,
 	zone *zonepb.ZoneConfig,
-	candidateReplicas []roachpb.ReplicaDescriptor,
+	existingReplicas []roachpb.ReplicaDescriptor,
 	options scorerOptions,
 ) (*roachpb.StoreDescriptor, string) {
 	analyzedConstraints := constraint.AnalyzeConstraints(
-		ctx, a.storePool.getStoreDescriptor, candidateReplicas, zone)
+		ctx, a.storePool.getStoreDescriptor, existingReplicas, zone)
 	candidates := allocateCandidates(
 		ctx,
-		sl, analyzedConstraints, candidateReplicas,
-		a.storePool.getLocalitiesByStore(candidateReplicas),
+		candidateStores, analyzedConstraints, existingReplicas,
+		a.storePool.getLocalitiesByStore(existingReplicas),
 		a.storePool.isNodeReadyForRoutineReplicaTransfer,
 		options,
 	)
@@ -559,17 +559,17 @@ func (a Allocator) RemoveTarget(
 	}
 
 	// Retrieve store descriptors for the provided candidates from the StorePool.
-	existingStoreIDs := make(roachpb.StoreIDSlice, len(candidates))
+	candidateStoreIDs := make(roachpb.StoreIDSlice, len(candidates))
 	for i, exist := range candidates {
-		existingStoreIDs[i] = exist.StoreID
+		candidateStoreIDs[i] = exist.StoreID
 	}
-	sl, _, _ := a.storePool.getStoreListFromIDs(existingStoreIDs, storeFilterNone)
+	candidateStoreList, _, _ := a.storePool.getStoreListFromIDs(candidateStoreIDs, storeFilterNone)
 
 	analyzedConstraints := constraint.AnalyzeConstraints(
 		ctx, a.storePool.getStoreDescriptor, existingReplicas, zone)
 	options := a.scorerOptions()
 	rankedCandidates := removeCandidates(
-		sl,
+		candidateStoreList,
 		analyzedConstraints,
 		a.storePool.getLocalitiesByStore(existingReplicas),
 		options,

pkg/kv/kvserver/allocator_scorer.go

@@ -408,16 +408,16 @@ func (cl candidateList) removeCandidate(c candidate) candidateList {
 // stores that meet the criteria are included in the list.
 func allocateCandidates(
 	ctx context.Context,
-	sl StoreList,
+	candidateStores StoreList,
 	constraints constraint.AnalyzedConstraints,
-	existing []roachpb.ReplicaDescriptor,
+	existingReplicas []roachpb.ReplicaDescriptor,
 	existingStoreLocalities map[roachpb.StoreID]roachpb.Locality,
 	isNodeValidForRoutineReplicaTransfer func(context.Context, roachpb.NodeID) bool,
 	options scorerOptions,
 ) candidateList {
 	var candidates candidateList
-	for _, s := range sl.stores {
-		if nodeHasReplica(s.Node.NodeID, existing) {
+	for _, s := range candidateStores.stores {
+		if nodeHasReplica(s.Node.NodeID, existingReplicas) {
 			continue
 		}
 		if !isNodeValidForRoutineReplicaTransfer(ctx, s.Node.NodeID) {
@@ -432,14 +432,14 @@ func allocateCandidates(
 			continue
 		}
 		diversityScore := diversityAllocateScore(s, existingStoreLocalities)
-		balanceScore := balanceScore(sl, s.Capacity, options)
+		balanceScore := balanceScore(candidateStores, s.Capacity, options)
 		var convergesScore int
 		if options.qpsRebalanceThreshold > 0 {
-			if s.Capacity.QueriesPerSecond < underfullThreshold(sl.candidateQueriesPerSecond.mean, options.qpsRebalanceThreshold) {
+			if s.Capacity.QueriesPerSecond < underfullThreshold(candidateStores.candidateQueriesPerSecond.mean, options.qpsRebalanceThreshold) {
 				convergesScore = 1
-			} else if s.Capacity.QueriesPerSecond < sl.candidateQueriesPerSecond.mean {
+			} else if s.Capacity.QueriesPerSecond < candidateStores.candidateQueriesPerSecond.mean {
 				convergesScore = 0
-			} else if s.Capacity.QueriesPerSecond < overfullThreshold(sl.candidateQueriesPerSecond.mean, options.qpsRebalanceThreshold) {
+			} else if s.Capacity.QueriesPerSecond < overfullThreshold(candidateStores.candidateQueriesPerSecond.mean, options.qpsRebalanceThreshold) {
 				convergesScore = -1
 			} else {
 				convergesScore = -2