wal: record and check snapshot

etcdctl/command/backup_command.go

@@ -28,6 +28,7 @@ import (
 	"github.com/coreos/etcd/pkg/pbutil"
 	"github.com/coreos/etcd/snap"
 	"github.com/coreos/etcd/wal"
+	"github.com/coreos/etcd/wal/walpb"
 )
 
 func NewBackupCommand() cli.Command {
@@ -57,16 +58,16 @@ func handleBackup(c *cli.Context) {
 	if err != nil && err != snap.ErrNoSnapshot {
 		log.Fatal(err)
 	}
-	var index uint64
+	var walsnap walpb.Snapshot
 	if snapshot != nil {
-		index = snapshot.Metadata.Index
+		walsnap.Index, walsnap.Term = snapshot.Metadata.Index, snapshot.Metadata.Term
 		newss := snap.New(destSnap)
 		if err := newss.SaveSnap(*snapshot); err != nil {
 			log.Fatal(err)
 		}
 	}
 
-	w, err := wal.OpenNotInUse(srcWAL, index)
+	w, err := wal.OpenNotInUse(srcWAL, walsnap)
 	if err != nil {
 		log.Fatal(err)
 	}

etcdserver/force_cluster.go

@@ -26,10 +26,15 @@ import (
 	"github.com/coreos/etcd/raft"
 	"github.com/coreos/etcd/raft/raftpb"
 	"github.com/coreos/etcd/wal"
+	"github.com/coreos/etcd/wal/walpb"
 )
 
-func restartAsStandaloneNode(cfg *ServerConfig, index uint64, snapshot *raftpb.Snapshot) (types.ID, raft.Node, *raft.MemoryStorage, *wal.WAL) {
-	w, id, cid, st, ents := readWAL(cfg.WALDir(), index)
+func restartAsStandaloneNode(cfg *ServerConfig, snapshot *raftpb.Snapshot) (types.ID, raft.Node, *raft.MemoryStorage, *wal.WAL) {
+	var walsnap walpb.Snapshot
+	if snapshot != nil {
+		walsnap.Index, walsnap.Term = snapshot.Metadata.Index, snapshot.Metadata.Term
+	}
+	w, id, cid, st, ents := readWAL(cfg.WALDir(), walsnap)
 	cfg.Cluster.SetID(cid)
 
 	// discard the previously uncommitted entries

etcdserver/server.go

@@ -46,6 +46,7 @@ import (
 	"github.com/coreos/etcd/snap"
 	"github.com/coreos/etcd/store"
 	"github.com/coreos/etcd/wal"
+	"github.com/coreos/etcd/wal/walpb"
 
 	"github.com/coreos/etcd/Godeps/_workspace/src/golang.org/x/net/context"
 )
@@ -219,7 +220,6 @@ func NewServer(cfg *ServerConfig) (*EtcdServer, error) {
 		if cfg.ShouldDiscover() {
 			log.Printf("etcdserver: discovery token ignored since a cluster has already been initialized. Valid log found at %q", cfg.WALDir())
 		}
-		var index uint64
 		snapshot, err := ss.Load()
 		if err != nil && err != snap.ErrNoSnapshot {
 			return nil, err
@@ -229,7 +229,6 @@ func NewServer(cfg *ServerConfig) (*EtcdServer, error) {
 				log.Panicf("etcdserver: recovered store from snapshot error: %v", err)
 			}
 			log.Printf("etcdserver: recovered store from snapshot at index %d", snapshot.Metadata.Index)
-			index = snapshot.Metadata.Index
 		}
 		cfg.Cluster = NewClusterFromStore(cfg.Cluster.token, st)
 		cfg.Print()
@@ -237,9 +236,9 @@ func NewServer(cfg *ServerConfig) (*EtcdServer, error) {
 			log.Printf("etcdserver: loaded cluster information from store: %s", cfg.Cluster)
 		}
 		if !cfg.ForceNewCluster {
-			id, n, s, w = restartNode(cfg, index+1, snapshot)
+			id, n, s, w = restartNode(cfg, snapshot)
 		} else {
-			id, n, s, w = restartAsStandaloneNode(cfg, index+1, snapshot)
+			id, n, s, w = restartAsStandaloneNode(cfg, snapshot)
 		}
 	default:
 		return nil, fmt.Errorf("unsupported bootstrap config")
@@ -860,6 +859,9 @@ func startNode(cfg *ServerConfig, ids []types.ID) (id types.ID, n raft.Node, s *
 	if w, err = wal.Create(cfg.WALDir(), metadata); err != nil {
 		log.Fatalf("etcdserver: create wal error: %v", err)
 	}
+	if err = w.SaveSnapshot(walpb.Snapshot{}); err != nil {
+		log.Fatalf("etcdserver: save empty snapshot error: %v", err)
+	}
 	peers := make([]raft.Peer, len(ids))
 	for i, id := range ids {
 		ctx, err := json.Marshal((*cfg.Cluster).Member(id))
@@ -875,8 +877,12 @@ func startNode(cfg *ServerConfig, ids []types.ID) (id types.ID, n raft.Node, s *
 	return
 }
 
-func restartNode(cfg *ServerConfig, index uint64, snapshot *raftpb.Snapshot) (types.ID, raft.Node, *raft.MemoryStorage, *wal.WAL) {
-	w, id, cid, st, ents := readWAL(cfg.WALDir(), index)
+func restartNode(cfg *ServerConfig, snapshot *raftpb.Snapshot) (types.ID, raft.Node, *raft.MemoryStorage, *wal.WAL) {
+	var walsnap walpb.Snapshot
+	if snapshot != nil {
+		walsnap.Index, walsnap.Term = snapshot.Metadata.Index, snapshot.Metadata.Term
+	}
+	w, id, cid, st, ents := readWAL(cfg.WALDir(), walsnap)
 	cfg.Cluster.SetID(cid)
 
 	log.Printf("etcdserver: restart member %s in cluster %s at commit index %d", id, cfg.Cluster.ID(), st.Commit)

etcdserver/storage.go

@@ -10,6 +10,7 @@ import (
 	"github.com/coreos/etcd/raft/raftpb"
 	"github.com/coreos/etcd/snap"
 	"github.com/coreos/etcd/wal"
+	"github.com/coreos/etcd/wal/walpb"
 )
 
 type Storage interface {
@@ -43,6 +44,14 @@ func (st *storage) SaveSnap(snap raftpb.Snapshot) error {
 	if err != nil {
 		return err
 	}
+	walsnap := walpb.Snapshot{
+		Index: snap.Metadata.Index,
+		Term:  snap.Metadata.Term,
+	}
+	err = st.WAL.SaveSnapshot(walsnap)
+	if err != nil {
+		return err
+	}
 	err = st.WAL.ReleaseLockTo(snap.Metadata.Index)
 	if err != nil {
 		return err
@@ -50,9 +59,9 @@ func (st *storage) SaveSnap(snap raftpb.Snapshot) error {
 	return nil
 }
 
-func readWAL(waldir string, index uint64) (w *wal.WAL, id, cid types.ID, st raftpb.HardState, ents []raftpb.Entry) {
+func readWAL(waldir string, snap walpb.Snapshot) (w *wal.WAL, id, cid types.ID, st raftpb.HardState, ents []raftpb.Entry) {
 	var err error
-	if w, err = wal.Open(waldir, index); err != nil {
+	if w, err = wal.Open(waldir, snap); err != nil {
 		log.Fatalf("etcdserver: open wal error: %v", err)
 	}
 	var wmetadata []byte

migrate/etcd4.go

@@ -12,6 +12,7 @@ import (
 	raftpb "github.com/coreos/etcd/raft/raftpb"
 	"github.com/coreos/etcd/snap"
 	"github.com/coreos/etcd/wal"
+	"github.com/coreos/etcd/wal/walpb"
 )
 
 func snapDir4(dataDir string) string {
@@ -106,13 +107,18 @@ func Migrate4To2(dataDir string, name string) error {
 	log.Printf("Log migration successful")
 
 	// migrate snapshot (if necessary) and logs
+	var walsnap walpb.Snapshot
 	if snap2 != nil {
+		walsnap.Index, walsnap.Term = snap2.Metadata.Index, snap2.Metadata.Term
 		ss := snap.New(sd2)
 		if err := ss.SaveSnap(*snap2); err != nil {
 			return err
 		}
 		log.Printf("Snapshot migration successful")
 	}
+	if err = w.SaveSnapshot(walsnap); err != nil {
+		return err
+	}
 
 	return nil
 }

tools/etcd-dump-logs/main.go

@@ -13,6 +13,7 @@ import (
 	"github.com/coreos/etcd/raft/raftpb"
 	"github.com/coreos/etcd/snap"
 	"github.com/coreos/etcd/wal"
+	"github.com/coreos/etcd/wal/walpb"
 )
 
 func main() {
@@ -24,20 +25,20 @@ func main() {
 
 	ss := snap.New(snapDir(*from))
 	snapshot, err := ss.Load()
-	var index uint64
+	var walsnap walpb.Snapshot
 	switch err {
 	case nil:
-		index = snapshot.Metadata.Index
+		walsnap.Index, walsnap.Term = snapshot.Metadata.Index, snapshot.Metadata.Term
 		nodes := genIDSlice(snapshot.Metadata.ConfState.Nodes)
 		fmt.Printf("Snapshot:\nterm=%d index=%d nodes=%s\n",
-			snapshot.Metadata.Term, index, nodes)
+			walsnap.Term, walsnap.Index, nodes)
 	case snap.ErrNoSnapshot:
 		fmt.Printf("Snapshot:\nempty\n")
 	default:
 		log.Fatalf("Failed loading snapshot: %v", err)
 	}
 
-	w, err := wal.Open(walDir(*from), index+1)
+	w, err := wal.Open(walDir(*from), walsnap)
 	if err != nil {
 		log.Fatalf("Failed opening WAL: %v", err)
 	}

wal/wal.go

@@ -38,6 +38,7 @@ const (
 	entryType
 	stateType
 	crcType
+	snapshotType
 
 	// the owner can make/remove files inside the directory
 	privateDirMode = 0700
@@ -47,6 +48,8 @@ var (
 	ErrMetadataConflict = errors.New("wal: conflicting metadata found")
 	ErrFileNotFound     = errors.New("wal: file not found")
 	ErrCRCMismatch      = errors.New("wal: crc mismatch")
+	ErrSnapshotMismatch = errors.New("wal: snapshot mismatch")
+	ErrSnapshotNotFound = errors.New("wal: snapshot not found")
 	crcTable            = crc32.MakeTable(crc32.Castagnoli)
 )
 
@@ -60,8 +63,8 @@ type WAL struct {
 	metadata []byte           // metadata recorded at the head of each WAL
 	state    raftpb.HardState // hardstate recorded at the head of WAL
 
-	ri      uint64   // index of entry to start reading
-	decoder *decoder // decoder to decode records
+	start   walpb.Snapshot // snapshot to start reading
+	decoder *decoder       // decoder to decode records
 
 	f       *os.File // underlay file opened for appending, sync
 	seq     uint64   // sequence of the wal file currently used for writes
@@ -116,23 +119,23 @@ func Create(dirpath string, metadata []byte) (*WAL, error) {
 	return w, nil
 }
 
-// Open opens the WAL at the given index.
-// The index SHOULD have been previously committed to the WAL, or the following
+// Open opens the WAL at the given snap.
+// The snap SHOULD have been previously saved to the WAL, or the following
 // ReadAll will fail.
-// The returned WAL is ready to read and the first record will be the given
-// index. The WAL cannot be appended to before reading out all of its
+// The returned WAL is ready to read and the first record will be the one after
+// the given snap. The WAL cannot be appended to before reading out all of its
 // previous records.
-func Open(dirpath string, index uint64) (*WAL, error) {
-	return openAtIndex(dirpath, index, true)
+func Open(dirpath string, snap walpb.Snapshot) (*WAL, error) {
+	return openAtIndex(dirpath, snap, true)
 }
 
 // OpenNotInUse only opens the wal files that are not in use.
 // Other than that, it is similar to Open.
-func OpenNotInUse(dirpath string, index uint64) (*WAL, error) {
-	return openAtIndex(dirpath, index, false)
+func OpenNotInUse(dirpath string, snap walpb.Snapshot) (*WAL, error) {
+	return openAtIndex(dirpath, snap, false)
 }
 
-func openAtIndex(dirpath string, index uint64, all bool) (*WAL, error) {
+func openAtIndex(dirpath string, snap walpb.Snapshot, all bool) (*WAL, error) {
 	names, err := fileutil.ReadDir(dirpath)
 	if err != nil {
 		return nil, err
@@ -142,7 +145,7 @@ func openAtIndex(dirpath string, index uint64, all bool) (*WAL, error) {
 		return nil, ErrFileNotFound
 	}
 
-	nameIndex, ok := searchIndex(names, index)
+	nameIndex, ok := searchIndex(names, snap.Index)
 	if !ok || !isValidSeq(names[nameIndex:]) {
 		return nil, ErrFileNotFound
 	}
@@ -189,7 +192,7 @@ func openAtIndex(dirpath string, index uint64, all bool) (*WAL, error) {
 	// create a WAL ready for reading
 	w := &WAL{
 		dir:     dirpath,
-		ri:      index,
+		start:   snap,
 		decoder: newDecoder(rc),
 
 		f:     f,
@@ -200,18 +203,23 @@ func openAtIndex(dirpath string, index uint64, all bool) (*WAL, error) {
 }
 
 // ReadAll reads out all records of the current WAL.
-// If it cannot read out the expected entry, it will return ErrIndexNotFound.
+// If it cannot read out the expected snap, it will return ErrSnapshotNotFound.
+// If loaded snap doesn't match with the expected one, it will return
+// ErrSnapshotMismatch.
+// TODO: detect not-last-snap error.
+// TODO: maybe loose the checking of match.
 // After ReadAll, the WAL will be ready for appending new records.
 func (w *WAL) ReadAll() (metadata []byte, state raftpb.HardState, ents []raftpb.Entry, err error) {
 	rec := &walpb.Record{}
 	decoder := w.decoder
 
+	var match bool
 	for err = decoder.decode(rec); err == nil; err = decoder.decode(rec) {
 		switch rec.Type {
 		case entryType:
 			e := mustUnmarshalEntry(rec.Data)
-			if e.Index >= w.ri {
-				ents = append(ents[:e.Index-w.ri], e)
+			if e.Index > w.start.Index {
+				ents = append(ents[:e.Index-w.start.Index-1], e)
 			}
 			w.enti = e.Index
 		case stateType:
@@ -231,6 +239,16 @@ func (w *WAL) ReadAll() (metadata []byte, state raftpb.HardState, ents []raftpb.
 				return nil, state, nil, ErrCRCMismatch
 			}
 			decoder.updateCRC(rec.Crc)
+		case snapshotType:
+			var snap walpb.Snapshot
+			pbutil.MustUnmarshal(&snap, rec.Data)
+			if snap.Index == w.start.Index {
+				if snap.Term != w.start.Term {
+					state.Reset()
+					return nil, state, nil, ErrSnapshotMismatch
+				}
+				match = true
+			}
 		default:
 			state.Reset()
 			return nil, state, nil, fmt.Errorf("unexpected block type %d", rec.Type)
@@ -240,10 +258,14 @@ func (w *WAL) ReadAll() (metadata []byte, state raftpb.HardState, ents []raftpb.
 		state.Reset()
 		return nil, state, nil, err
 	}
+	if !match {
+		state.Reset()
+		return nil, state, nil, ErrSnapshotNotFound
+	}
 
 	// close decoder, disable reading
 	w.decoder.close()
-	w.ri = 0
+	w.start = walpb.Snapshot{}
 
 	w.metadata = metadata
 	// create encoder (chain crc with the decoder), enable appending
@@ -374,6 +396,19 @@ func (w *WAL) Save(st raftpb.HardState, ents []raftpb.Entry) error {
 	return w.sync()
 }
 
+func (w *WAL) SaveSnapshot(e walpb.Snapshot) error {
+	b := pbutil.MustMarshal(&e)
+	rec := &walpb.Record{Type: snapshotType, Data: b}
+	if err := w.encoder.encode(rec); err != nil {
+		return err
+	}
+	// update enti only when snapshot is ahead of last index
+	if w.enti < e.Index {
+		w.enti = e.Index
+	}
+	return w.sync()
+}
+
 func (w *WAL) saveCrc(prevCrc uint32) error {
 	return w.encoder.encode(&walpb.Record{Type: crcType, Crc: prevCrc})
 }

wal/wal_test.go

@@ -90,7 +90,7 @@ func TestOpenAtIndex(t *testing.T) {
 	}
 	f.Close()
 
-	w, err := Open(dir, 0)
+	w, err := Open(dir, walpb.Snapshot{})
 	if err != nil {
 		t.Fatalf("err = %v, want nil", err)
 	}
@@ -109,7 +109,7 @@ func TestOpenAtIndex(t *testing.T) {
 	}
 	f.Close()
 
-	w, err = Open(dir, 5)
+	w, err = Open(dir, walpb.Snapshot{Index: 5})
 	if err != nil {
 		t.Fatalf("err = %v, want nil", err)
 	}
@@ -126,7 +126,7 @@ func TestOpenAtIndex(t *testing.T) {
 		t.Fatal(err)
 	}
 	defer os.RemoveAll(emptydir)
-	if _, err = Open(emptydir, 0); err != ErrFileNotFound {
+	if _, err = Open(emptydir, walpb.Snapshot{}); err != ErrFileNotFound {
 		t.Errorf("err = %v, want %v", err, ErrFileNotFound)
 	}
 }
@@ -168,6 +168,10 @@ func TestCut(t *testing.T) {
 	if err := w.Cut(); err != nil {
 		t.Fatal(err)
 	}
+	snap := walpb.Snapshot{Index: 2, Term: 1}
+	if err := w.SaveSnapshot(snap); err != nil {
+		t.Fatal(err)
+	}
 	wname = walName(2, 2)
 	if g := path.Base(w.f.Name()); g != wname {
 		t.Errorf("name = %s, want %s", g, wname)
@@ -183,7 +187,7 @@ func TestCut(t *testing.T) {
 	defer f.Close()
 	nw := &WAL{
 		decoder: newDecoder(f),
-		ri:      2,
+		start:   snap,
 	}
 	_, gst, _, err := nw.ReadAll()
 	if err != nil {
@@ -205,7 +209,10 @@ func TestRecover(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	ents := []raftpb.Entry{{Index: 0, Term: 0}, {Index: 1, Term: 1, Data: []byte{1}}, {Index: 2, Term: 2, Data: []byte{2}}}
+	if err := w.SaveSnapshot(walpb.Snapshot{}); err != nil {
+		t.Fatal(err)
+	}
+	ents := []raftpb.Entry{{Index: 1, Term: 1, Data: []byte{1}}, {Index: 2, Term: 2, Data: []byte{2}}}
 	for _, e := range ents {
 		if err = w.SaveEntry(&e); err != nil {
 			t.Fatal(err)
@@ -219,7 +226,7 @@ func TestRecover(t *testing.T) {
 	}
 	w.Close()
 
-	if w, err = Open(p, 0); err != nil {
+	if w, err = Open(p, walpb.Snapshot{}); err != nil {
 		t.Fatal(err)
 	}
 	metadata, state, entries, err := w.ReadAll()
@@ -319,14 +326,10 @@ func TestRecoverAfterCut(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	// TODO(unihorn): remove this when cut can operate on an empty file
-	if err = w.SaveEntry(&raftpb.Entry{}); err != nil {
-		t.Fatal(err)
-	}
-	if err = w.Cut(); err != nil {
-		t.Fatal(err)
-	}
-	for i := 1; i < 10; i++ {
+	for i := 0; i < 10; i++ {
+		if err = w.SaveSnapshot(walpb.Snapshot{Index: uint64(i)}); err != nil {
+			t.Fatal(err)
+		}
 		e := raftpb.Entry{Index: uint64(i)}
 		if err = w.SaveEntry(&e); err != nil {
 			t.Fatal(err)
@@ -342,7 +345,7 @@ func TestRecoverAfterCut(t *testing.T) {
 	}
 
 	for i := 0; i < 10; i++ {
-		w, err := Open(p, uint64(i))
+		w, err := Open(p, walpb.Snapshot{Index: uint64(i)})
 		if err != nil {
 			if i <= 4 {
 				if err != ErrFileNotFound {
@@ -362,8 +365,8 @@ func TestRecoverAfterCut(t *testing.T) {
 			t.Errorf("#%d: metadata = %s, want %s", i, metadata, "metadata")
 		}
 		for j, e := range entries {
-			if e.Index != uint64(j+i) {
-				t.Errorf("#%d: ents[%d].Index = %+v, want %+v", i, j, e.Index, j+i)
+			if e.Index != uint64(j+i+1) {
+				t.Errorf("#%d: ents[%d].Index = %+v, want %+v", i, j, e.Index, j+i+1)
 			}
 		}
 		w.Close()
@@ -381,12 +384,15 @@ func TestOpenAtUncommittedIndex(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	if err := w.SaveSnapshot(walpb.Snapshot{}); err != nil {
+		t.Fatal(err)
+	}
 	if err := w.SaveEntry(&raftpb.Entry{Index: 0}); err != nil {
 		t.Fatal(err)
 	}
 	w.Close()
 
-	w, err = Open(p, 1)
+	w, err = Open(p, walpb.Snapshot{})
 	if err != nil {
 		t.Fatal(err)
 	}

wal/walpb/record.pb.go

@@ -10,6 +10,7 @@
 
 	It has these top-level messages:
 		Record
+		Snapshot
 */
 package walpb
 
@@ -38,6 +39,16 @@ func (m *Record) Reset()         { *m = Record{} }
 func (m *Record) String() string { return proto.CompactTextString(m) }
 func (*Record) ProtoMessage()    {}
 
+type Snapshot struct {
+	Index            uint64 `protobuf:"varint,1,req,name=index" json:"index"`
+	Term             uint64 `protobuf:"varint,2,req,name=term" json:"term"`
+	XXX_unrecognized []byte `json:"-"`
+}
+
+func (m *Snapshot) Reset()         { *m = Snapshot{} }
+func (m *Snapshot) String() string { return proto.CompactTextString(m) }
+func (*Snapshot) ProtoMessage()    {}
+
 func init() {
 }
 func (m *Record) Unmarshal(data []byte) error {
@@ -134,6 +145,78 @@ func (m *Record) Unmarshal(data []byte) error {
 	}
 	return nil
 }
+func (m *Snapshot) Unmarshal(data []byte) error {
+	l := len(data)
+	index := 0
+	for index < l {
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if index >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := data[index]
+			index++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		switch fieldNum {
+		case 1:
+			if wireType != 0 {
+				return code_google_com_p_gogoprotobuf_proto.ErrWrongType
+			}
+			for shift := uint(0); ; shift += 7 {
+				if index >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := data[index]
+				index++
+				m.Index |= (uint64(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		case 2:
+			if wireType != 0 {
+				return code_google_com_p_gogoprotobuf_proto.ErrWrongType
+			}
+			for shift := uint(0); ; shift += 7 {
+				if index >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := data[index]
+				index++
+				m.Term |= (uint64(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		default:
+			var sizeOfWire int
+			for {
+				sizeOfWire++
+				wire >>= 7
+				if wire == 0 {
+					break
+				}
+			}
+			index -= sizeOfWire
+			skippy, err := code_google_com_p_gogoprotobuf_proto.Skip(data[index:])
+			if err != nil {
+				return err
+			}
+			if (index + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.XXX_unrecognized = append(m.XXX_unrecognized, data[index:index+skippy]...)
+			index += skippy
+		}
+	}
+	return nil
+}
 func (m *Record) Size() (n int) {
 	var l int
 	_ = l
@@ -148,6 +231,16 @@ func (m *Record) Size() (n int) {
 	}
 	return n
 }
+func (m *Snapshot) Size() (n int) {
+	var l int
+	_ = l
+	n += 1 + sovRecord(uint64(m.Index))
+	n += 1 + sovRecord(uint64(m.Term))
+	if m.XXX_unrecognized != nil {
+		n += len(m.XXX_unrecognized)
+	}
+	return n
+}
 
 func sovRecord(x uint64) (n int) {
 	for {
@@ -194,6 +287,32 @@ func (m *Record) MarshalTo(data []byte) (n int, err error) {
 	}
 	return i, nil
 }
+func (m *Snapshot) Marshal() (data []byte, err error) {
+	size := m.Size()
+	data = make([]byte, size)
+	n, err := m.MarshalTo(data)
+	if err != nil {
+		return nil, err
+	}
+	return data[:n], nil
+}
+
+func (m *Snapshot) MarshalTo(data []byte) (n int, err error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	data[i] = 0x8
+	i++
+	i = encodeVarintRecord(data, i, uint64(m.Index))
+	data[i] = 0x10
+	i++
+	i = encodeVarintRecord(data, i, uint64(m.Term))
+	if m.XXX_unrecognized != nil {
+		i += copy(data[i:], m.XXX_unrecognized)
+	}
+	return i, nil
+}
 func encodeFixed64Record(data []byte, offset int, v uint64) int {
 	data[offset] = uint8(v)
 	data[offset+1] = uint8(v >> 8)

wal/walpb/record.proto

@@ -12,3 +12,8 @@ message Record {
 	required uint32 crc  = 2 [(gogoproto.nullable) = false];
 	optional bytes data  = 3;
 }
+
+message Snapshot {
+	required uint64 index = 1 [(gogoproto.nullable) = false];
+	required uint64 term  = 2 [(gogoproto.nullable) = false];
+}