raft: restart using last written entry also

main.go

@@ -107,7 +107,7 @@ func startRaft(id int64, peerIDs []int64, waldir string) (raft.Node, *wal.WAL) {
 
 	// restart a node from previous wal
 	// TODO(xiangli): check snapshot; not open from one
-	w, err := wal.OpenAtIndex(waldir, 1)
+	w, err := wal.OpenAtIndex(waldir, 0)
 	if err != nil {
 		log.Fatal(err)
 	}

raft/log.go

@@ -38,6 +38,11 @@ func (l *raftLog) isEmpty() bool {
 	return l.offset == 0 && len(l.ents) == 1
 }
 
+func (l *raftLog) load(ents []pb.Entry) {
+	l.ents = ents
+	l.unstable = l.offset + int64(len(ents))
+}
+
 func (l *raftLog) String() string {
 	return fmt.Sprintf("offset=%d committed=%d applied=%d len(ents)=%d", l.offset, l.committed, l.applied, len(l.ents))
 }

raft/node_test.go

@@ -171,6 +171,7 @@ func TestNode(t *testing.T) {
 
 func TestNodeRestart(t *testing.T) {
 	entries := []raftpb.Entry{
+		{},
 		{Term: 1, Index: 1},
 		{Term: 1, Index: 2, Data: []byte("foo")},
 	}
@@ -179,7 +180,7 @@ func TestNodeRestart(t *testing.T) {
 	want := Ready{
 		State: emptyState,
 		// commit upto index commit index in st
-		CommittedEntries: entries[:st.Commit],
+		CommittedEntries: entries[1 : st.Commit+1],
 	}
 
 	n := Restart(1, []int64{1}, 0, 0, st, entries)

raft/raft.go

@@ -503,8 +503,7 @@ func (r *raft) loadEnts(ents []pb.Entry) {
 	if !r.raftLog.isEmpty() {
 		panic("cannot load entries when log is not empty")
 	}
-	r.raftLog.append(0, ents...)
-	r.raftLog.unstable = r.raftLog.lastIndex() + 1
+	r.raftLog.load(ents)
 }
 
 func (r *raft) loadState(state pb.State) {

wal/wal.go

@@ -65,7 +65,6 @@ type WAL struct {
 }
 
 // Create creates a WAL ready for appending records.
-// The index of first record saved MUST be 0.
 func Create(dirpath string) (*WAL, error) {
 	log.Printf("path=%s wal.create", dirpath)
 	if Exist(dirpath) {