snap: separate Load to Load and snapNames

snap/snapshotter.go

@@ -47,20 +47,10 @@ func (s *Snapshotter) Save(snapshot *raft.Snapshot) error {
 }
 
 func (s *Snapshotter) Load() (*raft.Snapshot, error) {
-	dir, err := os.Open(s.dir)
+	names, err := s.snapNames()
 	if err != nil {
 		return nil, err
 	}
-	defer dir.Close()
-	names, err := dir.Readdirnames(-1)
-	if err != nil {
-		return nil, err
-	}
-	if len(names) == 0 {
-		return nil, ErrNoSnapshot
-	}
-	sort.Sort(sort.Reverse(sort.StringSlice(names)))
-
 	var snap raft.Snapshot
 	var serializedSnap Snapshot
 	var b []byte
@@ -91,3 +81,22 @@ func (s *Snapshotter) Load() (*raft.Snapshot, error) {
 	}
 	return &snap, nil
 }
+
+// snapNames returns the filename of the snapshots in logical time order (from newest to oldest).
+// If there is no avaliable snapshots, an ErrNoSnapshot will be returned.
+func (s *Snapshotter) snapNames() ([]string, error) {
+	dir, err := os.Open(s.dir)
+	if err != nil {
+		return nil, err
+	}
+	defer dir.Close()
+	names, err := dir.Readdirnames(-1)
+	if err != nil {
+		return nil, err
+	}
+	if len(names) == 0 {
+		return nil, ErrNoSnapshot
+	}
+	sort.Sort(sort.Reverse(sort.StringSlice(names)))
+	return names, nil
+}

snap/snapshotter_test.go

@@ -85,6 +85,31 @@ func TestFailback(t *testing.T) {
 	}
 }
 
+func TestSnapNames(t *testing.T) {
+	dir := path.Join(os.TempDir(), "snapshot")
+	os.Mkdir(dir, 0700)
+	defer os.RemoveAll(dir)
+	for i := 1; i <= 5; i++ {
+		if f, err := os.Create(path.Join(dir, fmt.Sprintf("%d", i))); err != nil {
+			t.Fatal(err)
+		} else {
+			f.Close()
+		}
+	}
+	ss := New(dir)
+	names, err := ss.snapNames()
+	if err != nil {
+		t.Errorf("err = %v, want nil", err)
+	}
+	if len(names) != 5 {
+		t.Errorf("len = %d, want 10", len(names))
+	}
+	w := []string{"5", "4", "3", "2", "1"}
+	if !reflect.DeepEqual(names, w) {
+		t.Errorf("names = %v, want %v", names, w)
+	}
+}
+
 func TestLoadNewestSnap(t *testing.T) {
 	dir := path.Join(os.TempDir(), "snapshot")
 	os.Mkdir(dir, 0700)