raft: not set applied when restored from snapshot

applied is only updated by application level through Advance.

raft/log.go

@@ -115,10 +115,12 @@ func (l *raftLog) unstableEnts() []pb.Entry {
 }
 
 // nextEnts returns all the available entries for execution.
-// all the returned entries will be marked as applied.
+// If applied is smaller than the index of snapshot, it returns all committed
+// entries after the index of snapshot.
 func (l *raftLog) nextEnts() (ents []pb.Entry) {
-	if l.committed > l.applied {
+	off := max(l.applied, l.snapshot.Index)
-		return l.slice(l.applied+1, l.committed+1)
+	if l.committed > off {
+		return l.slice(off+1, l.committed+1)
 	}
 	return nil
 }
@@ -211,7 +213,6 @@ func (l *raftLog) restore(s pb.Snapshot) {
 	l.ents = []pb.Entry{{Term: s.Term}}
 	l.unstable = s.Index + 1
 	l.committed = s.Index
-	l.applied = s.Index
 	l.offset = s.Index
 	l.snapshot = s
 }

raft/log_test.go

@@ -326,6 +326,37 @@ func TestCompactionSideEffects(t *testing.T) {
 	}
 }
 
+func TestNextEnts(t *testing.T) {
+	snap := pb.Snapshot{Term: 1, Index: 3}
+	ents := []pb.Entry{
+		{Term: 1, Index: 3},
+		{Term: 1, Index: 4},
+		{Term: 1, Index: 5},
+		{Term: 1, Index: 6},
+	}
+	tests := []struct {
+		applied uint64
+		wents   []pb.Entry
+	}{
+		{0, ents[1:3]},
+		{3, ents[1:3]},
+		{4, ents[2:3]},
+		{5, nil},
+	}
+	for i, tt := range tests {
+		raftLog := newLog()
+		raftLog.restore(snap)
+		raftLog.load(ents)
+		raftLog.maybeCommit(5, 1)
+		raftLog.appliedTo(tt.applied)
+
+		ents := raftLog.nextEnts()
+		if !reflect.DeepEqual(ents, tt.wents) {
+			t.Errorf("#%d: ents = %+v, want %+v", i, ents, tt.wents)
+		}
+	}
+}
+
 func TestUnstableEnts(t *testing.T) {
 	previousEnts := []pb.Entry{{Term: 1, Index: 1}, {Term: 2, Index: 2}}
 	tests := []struct {
@@ -435,9 +466,6 @@ func TestLogRestore(t *testing.T) {
 	if raftLog.offset != index {
 		t.Errorf("offset = %d, want %d", raftLog.offset, index)
 	}
-	if raftLog.applied != index {
-		t.Errorf("applied = %d, want %d", raftLog.applied, index)
-	}
 	if raftLog.committed != index {
 		t.Errorf("comitted = %d, want %d", raftLog.committed, index)
 	}

raft/node.go

@@ -171,6 +171,7 @@ func RestartNode(id uint64, election, heartbeat int, snapshot *pb.Snapshot, st p
 	r := newRaft(id, nil, election, heartbeat)
 	if snapshot != nil {
 		r.restore(*snapshot)
+		r.raftLog.appliedTo(snapshot.Index)
 	}
 	if !isHardStateEqual(st, emptyState) {
 		r.loadState(st)

raft/node_test.go

@@ -368,6 +368,39 @@ func TestNodeRestart(t *testing.T) {
 	}
 }
 
+func TestNodeRestartFromSnapshot(t *testing.T) {
+	snap := &raftpb.Snapshot{
+		Data:  []byte("some data"),
+		Nodes: []uint64{1, 2},
+		Index: 2,
+		Term:  1,
+	}
+	entries := []raftpb.Entry{
+		{Term: 1, Index: 2},
+		{Term: 1, Index: 3, Data: []byte("foo")},
+	}
+	st := raftpb.HardState{Term: 1, Commit: 3}
+
+	want := Ready{
+		HardState: emptyState,
+		// commit upto index commit index in st
+		CommittedEntries: entries[1:],
+	}
+
+	n := RestartNode(1, 10, 1, snap, st, entries)
+	if g := <-n.Ready(); !reflect.DeepEqual(g, want) {
+		t.Errorf("g = %+v,\n             w   %+v", g, want)
+	} else {
+		n.Advance()
+	}
+
+	select {
+	case rd := <-n.Ready():
+		t.Errorf("unexpected Ready: %+v", rd)
+	case <-time.After(time.Millisecond):
+	}
+}
+
 // TestCompacts ensures Node.Compact creates a correct raft snapshot and compacts
 // the raft log (call raft.compact)
 func TestNodeCompact(t *testing.T) {