kvserver/closedts: optimize sidetransport closer

The sidetransport sender periodically loops through all the tracked
ranges and checks if it can advance their closedts. This patch makes the
hot loop a little more efficient by collapsing two operations that used
to take the replica lock separately: getting its descriptor and checking
the bump.

Also another small change - learners are considered among the followers
or a range that need closed ts communicated to them. There was no good
reason to exclude them, and including them is a bit more efficient.

Release note: None
Release justification: Improvement to very new functionality.

pkg/kv/kvserver/closedts/sidetransport/sender.go

@@ -121,7 +121,6 @@ type Replica interface {
 	// Accessors.
 	StoreID() roachpb.StoreID
 	GetRangeID() roachpb.RangeID
-	Desc() *roachpb.RangeDescriptor
 
 	// BumpSideTransportClosed advances the range's closed timestamp if it can.
 	// If the closed timestamp is advanced, the function synchronizes with
@@ -135,11 +134,16 @@ type Replica interface {
 	//
 	// If the closed timestamp was advanced, the function returns a LAI to be
 	// attached to the newly closed timestamp.
+	//
+	// The desired closed timestamp is passed as a map from range policy to
+	// timestamp; this function looks up the entry for this range.
+	//
+	// The RangeDescriptor is returned in both the true and false cases.
 	BumpSideTransportClosed(
 		ctx context.Context,
 		now hlc.ClockTimestamp,
 		targetByPolicy [roachpb.MAX_CLOSED_TIMESTAMP_POLICY]hlc.Timestamp,
-	) (bool, ctpb.LAI, roachpb.RangeClosedTimestampPolicy)
+	) (bool, ctpb.LAI, roachpb.RangeClosedTimestampPolicy, *roachpb.RangeDescriptor)
 }
 
 // NewSender creates a Sender. Run must be called on it afterwards to get it to
@@ -332,17 +336,19 @@ func (s *Sender) publish(ctx context.Context) hlc.ClockTimestamp {
 		lhRangeID := lh.GetRangeID()
 		lastMsg, tracked := s.trackedMu.tracked[lhRangeID]
 
-		// Make sure that we're communicating with all of the range's followers.
-		// Note that we're including this range's followers before deciding below if
-		// this message will include this range. This is because we don't want
-		// dynamic conditions about the activity of this range to dictate the
-		// opening and closing of connections to the other nodes.
-		for _, repl := range lh.Desc().Replicas().VoterFullAndNonVoterDescriptors() {
-			nodesWithFollowers.Add(int(repl.NodeID))
+		// Check whether the desired timestamp can be closed on this range.
+		canClose, lai, policy, desc := lh.BumpSideTransportClosed(ctx, now, s.trackedMu.lastClosed)
+
+		// Ensure that we're communicating with all of the range's followers. Note
+		// that we're including this range's followers before deciding below if the
+		// current message will include this range; we don't want dynamic conditions
+		// about the activity of this range to dictate the opening and closing of
+		// connections to the other nodes.
+		repls := desc.Replicas().Descriptors()
+		for i := range repls {
+			nodesWithFollowers.Add(int(repls[i].NodeID))
 		}
 
-		// Check whether the desired timestamp can be closed on this range.
-		canClose, lai, policy := lh.BumpSideTransportClosed(ctx, now, s.trackedMu.lastClosed)
 		if !canClose {
 			// We can't close the desired timestamp. If this range was tracked, we
 			// need to un-track it.

pkg/kv/kvserver/closedts/sidetransport/sender_test.go

@@ -51,15 +51,12 @@ var _ Replica = &mockReplica{}
 
 func (m *mockReplica) StoreID() roachpb.StoreID    { return m.storeID }
 func (m *mockReplica) GetRangeID() roachpb.RangeID { return m.rangeID }
-func (m *mockReplica) Desc() *roachpb.RangeDescriptor {
-	m.mu.Lock()
-	defer m.mu.Unlock()
-	return &m.mu.desc
-}
 func (m *mockReplica) BumpSideTransportClosed(
 	_ context.Context, _ hlc.ClockTimestamp, _ [roachpb.MAX_CLOSED_TIMESTAMP_POLICY]hlc.Timestamp,
-) (bool, ctpb.LAI, roachpb.RangeClosedTimestampPolicy) {
-	return m.canBump, m.lai, m.policy
+) (bool, ctpb.LAI, roachpb.RangeClosedTimestampPolicy, *roachpb.RangeDescriptor) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return m.canBump, m.lai, m.policy, &m.mu.desc
 }
 
 func (m *mockReplica) removeReplica(nid roachpb.NodeID) {

pkg/kv/kvserver/replica_closedts.go

@@ -79,21 +79,24 @@ func (r *Replica) EmitMLAI() {
 // This is called by the closed timestamp side-transport. The desired closed timestamp
 // is passed as a map from range policy to timestamp; this function looks up the entry
 // for this range.
+//
+// The RangeDescriptor is returned in both the true and false cases.
 func (r *Replica) BumpSideTransportClosed(
 	ctx context.Context,
 	now hlc.ClockTimestamp,
 	targetByPolicy [roachpb.MAX_CLOSED_TIMESTAMP_POLICY]hlc.Timestamp,
-) (ok bool, _ ctpb.LAI, _ roachpb.RangeClosedTimestampPolicy) {
+) (ok bool, _ ctpb.LAI, _ roachpb.RangeClosedTimestampPolicy, _ *roachpb.RangeDescriptor) {
 	r.mu.Lock()
 	defer r.mu.Unlock()
+	desc := r.descRLocked()
 
 	// This method can be called even after a Replica is destroyed and removed
 	// from the Store's replicas map, because unlinkReplicaByRangeIDLocked does
 	// not synchronize with sidetransport.Sender.publish, which maintains a
 	// local copy of its leaseholder map. To avoid issues resulting from this,
 	// we first check if the replica is destroyed.
 	if _, err := r.isDestroyedRLocked(); err != nil {
-		return false, 0, 0
+		return false, 0, 0, desc
 	}
 
 	lai := ctpb.LAI(r.mu.state.LeaseAppliedIndex)
@@ -104,17 +107,17 @@ func (r *Replica) BumpSideTransportClosed(
 	// matter.
 	valid := st.IsValid() || st.State == kvserverpb.LeaseState_UNUSABLE
 	if !valid || !st.OwnedBy(r.StoreID()) {
-		return false, 0, 0
+		return false, 0, 0, desc
 	}
 	if st.ClosedTimestampUpperBound().Less(target) {
-		return false, 0, 0
+		return false, 0, 0, desc
 	}
 
 	// If the range is merging into its left-hand neighbor, we can't close
 	// timestamps any more because the joint-range would not be aware of reads
 	// performed based on this advanced closed timestamp.
 	if r.mergeInProgressRLocked() {
-		return false, 0, 0
+		return false, 0, 0, desc
 	}
 
 	// If there are pending Raft proposals in-flight or committed entries that
@@ -130,20 +133,20 @@ func (r *Replica) BumpSideTransportClosed(
 	// proposals and their timestamps are still tracked in proposal buffer's
 	// tracker, and they'll be considered below.
 	if len(r.mu.proposals) > 0 || r.mu.applyingEntries {
-		return false, 0, 0
+		return false, 0, 0, desc
 	}
 
 	// MaybeForwardClosedLocked checks that there are no evaluating requests
 	// writing under target.
 	if !r.mu.proposalBuf.MaybeForwardClosedLocked(ctx, target) {
-		return false, 0, 0
+		return false, 0, 0, desc
 	}
 
 	// Update the replica directly since there's no side-transport connection to
 	// the local node.
 	r.mu.sideTransportClosedTimestamp = target
 	r.mu.sideTransportCloseTimestampLAI = lai
-	return true, lai, policy
+	return true, lai, policy, desc
 }
 
 // closedTimestampTargetRLocked computes the timestamp we'd like to close for

pkg/kv/kvserver/replica_closedts_test.go

@@ -259,7 +259,7 @@ func TestBumpSideTransportClosed(t *testing.T) {
 				var targets [roachpb.MAX_CLOSED_TIMESTAMP_POLICY]hlc.Timestamp
 				targets[roachpb.LAG_BY_CLUSTER_SETTING] = a.target.Add(-1, 0)
 				return nil, nil, testutils.SucceedsSoonError(func() error {
-					ok, _, _ := a.repl.BumpSideTransportClosed(ctx, a.now, targets)
+					ok, _, _, _ := a.repl.BumpSideTransportClosed(ctx, a.now, targets)
 					if !ok {
 						return errors.New("bumping side-transport unexpectedly failed")
 					}
@@ -276,7 +276,7 @@ func TestBumpSideTransportClosed(t *testing.T) {
 				var targets [roachpb.MAX_CLOSED_TIMESTAMP_POLICY]hlc.Timestamp
 				targets[roachpb.LAG_BY_CLUSTER_SETTING] = a.target
 				return nil, nil, testutils.SucceedsSoonError(func() error {
-					ok, _, _ := a.repl.BumpSideTransportClosed(ctx, a.now, targets)
+					ok, _, _, _ := a.repl.BumpSideTransportClosed(ctx, a.now, targets)
 					if !ok {
 						return errors.New("bumping side-transport unexpectedly failed")
 					}
@@ -293,7 +293,7 @@ func TestBumpSideTransportClosed(t *testing.T) {
 				var targets [roachpb.MAX_CLOSED_TIMESTAMP_POLICY]hlc.Timestamp
 				targets[roachpb.LAG_BY_CLUSTER_SETTING] = a.target.Add(1, 0)
 				return nil, nil, testutils.SucceedsSoonError(func() error {
-					ok, _, _ := a.repl.BumpSideTransportClosed(ctx, a.now, targets)
+					ok, _, _, _ := a.repl.BumpSideTransportClosed(ctx, a.now, targets)
 					if !ok {
 						return errors.New("bumping side-transport unexpectedly failed")
 					}
@@ -393,14 +393,14 @@ func TestBumpSideTransportClosed(t *testing.T) {
 			// would be a serious bug.
 			if exp {
 				testutils.SucceedsSoon(t, func() error {
-					ok, _, _ := repl.BumpSideTransportClosed(ctx, now, targets)
+					ok, _, _, _ := repl.BumpSideTransportClosed(ctx, now, targets)
 					if !ok {
 						return errors.New("bumping side-transport unexpectedly failed")
 					}
 					return nil
 				})
 			} else {
-				ok, _, _ := repl.BumpSideTransportClosed(ctx, now, targets)
+				ok, _, _, _ := repl.BumpSideTransportClosed(ctx, now, targets)
 				require.False(t, ok)
 			}
 
@@ -462,7 +462,7 @@ func BenchmarkBumpSideTransportClosed(b *testing.B) {
 		targets[roachpb.LAG_BY_CLUSTER_SETTING] = now.ToTimestamp()
 
 		// Perform the call.
-		ok, _, _ := r.BumpSideTransportClosed(ctx, now, targets)
+		ok, _, _, _ := r.BumpSideTransportClosed(ctx, now, targets)
 		if !ok {
 			b.Fatal("BumpSideTransportClosed unexpectedly failed")
 		}