raft: return non-nil Inflights in raft status

raft/rawnode.go

@@ -218,18 +218,17 @@ func (rn *RawNode) Advance(rd Ready) {
 	rn.commitReady(rd)
 }
 
-// Status returns the current status of the given group.
-func (rn *RawNode) Status() *Status {
+// Status returns the current status of the given group. This allocates, see
+// BasicStatus and WithProgress for allocation-friendlier choices.
+func (rn *RawNode) Status() Status {
 	status := getStatus(rn.raft)
-	return &status
+	return status
 }
 
-// StatusWithoutProgress returns a Status without populating the Progress field
-// (and returns the Status as a value to avoid forcing it onto the heap). This
-// is more performant if the Progress is not required. See WithProgress for an
-// allocation-free way to introspect the Progress.
-func (rn *RawNode) StatusWithoutProgress() Status {
-	return getStatusWithoutProgress(rn.raft)
+// BasicStatus returns a BasicStatus. Notably this does not contain the
+// Progress map; see WithProgress for an allocation-free way to inspect it.
+func (rn *RawNode) BasicStatus() BasicStatus {
+	return getBasicStatus(rn.raft)
 }
 
 // ProgressType indicates the type of replica a Progress corresponds to.

raft/rawnode_test.go

@@ -21,6 +21,7 @@ import (
 	"reflect"
 	"testing"
 
+	"go.etcd.io/etcd/raft/quorum"
 	"go.etcd.io/etcd/raft/raftpb"
 	"go.etcd.io/etcd/raft/tracker"
 )
@@ -43,7 +44,7 @@ func (a *rawNodeAdapter) TransferLeadership(ctx context.Context, lead, transfere
 func (a *rawNodeAdapter) Stop() {}
 
 // RawNode returns a *Status.
-func (a *rawNodeAdapter) Status() Status { return *a.RawNode.Status() }
+func (a *rawNodeAdapter) Status() Status { return a.RawNode.Status() }
 
 // RawNode takes a Ready. It doesn't really have to do that I think? It can hold on
 // to it internally. But maybe that approach is frail.
@@ -439,14 +440,33 @@ func TestRawNodeRestartFromSnapshot(t *testing.T) {
 // no dependency check between Ready() and Advance()
 
 func TestRawNodeStatus(t *testing.T) {
-	storage := NewMemoryStorage()
-	rawNode, err := NewRawNode(newTestConfig(1, nil, 10, 1, storage), []Peer{{ID: 1}})
+	s := NewMemoryStorage()
+	rn, err := NewRawNode(newTestConfig(1, []uint64{1}, 10, 1, s), nil)
 	if err != nil {
 		t.Fatal(err)
 	}
-	status := rawNode.Status()
-	if status == nil {
-		t.Errorf("expected status struct, got nil")
+	if status := rn.Status(); status.Progress != nil {
+		t.Fatalf("expected no Progress because not leader: %+v", status.Progress)
+	}
+	if err := rn.Campaign(); err != nil {
+		t.Fatal(err)
+	}
+	status := rn.Status()
+	if status.Lead != 1 {
+		t.Fatal("not lead")
+	}
+	if status.RaftState != StateLeader {
+		t.Fatal("not leader")
+	}
+	if exp, act := *rn.raft.prs.Progress[1], status.Progress[1]; !reflect.DeepEqual(exp, act) {
+		t.Fatalf("want: %+v\ngot:  %+v", exp, act)
+	}
+	expCfg := tracker.Config{Voters: quorum.JointConfig{
+		quorum.MajorityConfig{1: {}},
+		nil,
+	}}
+	if !reflect.DeepEqual(expCfg, status.Config) {
+		t.Fatalf("want: %+v\ngot:  %+v", expCfg, status.Config)
 	}
 }
 
@@ -590,7 +610,7 @@ func TestRawNodeBoundedLogGrowthWithPartition(t *testing.T) {
 	checkUncommitted(0)
 }
 
-func BenchmarkStatusProgress(b *testing.B) {
+func BenchmarkStatus(b *testing.B) {
 	setup := func(members int) *RawNode {
 		peers := make([]uint64, members)
 		for i := range peers {
@@ -607,8 +627,6 @@ func BenchmarkStatusProgress(b *testing.B) {
 
 	for _, members := range []int{1, 3, 5, 100} {
 		b.Run(fmt.Sprintf("members=%d", members), func(b *testing.B) {
-			// NB: call getStatus through rn.Status because that incurs an additional
-			// allocation.
 			rn := setup(members)
 
 			b.Run("Status", func(b *testing.B) {
@@ -630,10 +648,10 @@ func BenchmarkStatusProgress(b *testing.B) {
 				}
 			})
 
-			b.Run("StatusWithoutProgress", func(b *testing.B) {
+			b.Run("BasicStatus", func(b *testing.B) {
 				b.ReportAllocs()
 				for i := 0; i < b.N; i++ {
-					_ = rn.StatusWithoutProgress()
+					_ = rn.BasicStatus()
 				}
 			})
 

raft/status.go

@@ -21,14 +21,22 @@ import (
 	"go.etcd.io/etcd/raft/tracker"
 )
 
+// Status contains information about this Raft peer and its view of the system.
+// The Progress is only populated on the leader.
 type Status struct {
+	BasicStatus
+	Config   tracker.Config
+	Progress map[uint64]tracker.Progress
+}
+
+// BasicStatus contains basic information about the Raft peer. It does not allocate.
+type BasicStatus struct {
 	ID uint64
 
 	pb.HardState
 	SoftState
 
-	Applied  uint64
-	Progress map[uint64]tracker.Progress
+	Applied uint64
 
 	LeadTransferee uint64
 }
@@ -37,19 +45,17 @@ func getProgressCopy(r *raft) map[uint64]tracker.Progress {
 	m := make(map[uint64]tracker.Progress)
 	r.prs.Visit(func(id uint64, pr *tracker.Progress) {
 		var p tracker.Progress
-		p, pr = *pr, nil /* avoid accidental reuse below */
-
-		// The inflight buffer is tricky to copy and besides, it isn't exposed
-		// to the client, so pretend it's nil.
-		p.Inflights = nil
+		p = *pr
+		p.Inflights = pr.Inflights.Clone()
+		pr = nil
 
 		m[id] = p
 	})
 	return m
 }
 
-func getStatusWithoutProgress(r *raft) Status {
-	s := Status{
+func getBasicStatus(r *raft) BasicStatus {
+	s := BasicStatus{
 		ID:             r.id,
 		LeadTransferee: r.leadTransferee,
 	}
@@ -61,10 +67,12 @@ func getStatusWithoutProgress(r *raft) Status {
 
 // getStatus gets a copy of the current raft status.
 func getStatus(r *raft) Status {
-	s := getStatusWithoutProgress(r)
+	var s Status
+	s.BasicStatus = getBasicStatus(r)
 	if s.RaftState == StateLeader {
 		s.Progress = getProgressCopy(r)
 	}
+	s.Config = r.prs.Config.Clone()
 	return s
 }
 

raft/tracker/inflights.go

@@ -40,6 +40,14 @@ func NewInflights(size int) *Inflights {
 	}
 }
 
+// Clone returns an *Inflights that is identical to but shares no memory with
+// the receiver.
+func (in *Inflights) Clone() *Inflights {
+	ins := *in
+	ins.buffer = append([]uint64(nil), in.buffer...)
+	return &ins
+}
+
 // Add notifies the Inflights that a new message with the given index is being
 // dispatched. Full() must be called prior to Add() to verify that there is room
 // for one more message, and consecutive calls to add Add() must provide a