Add ImageFsInfo support

Signed-off-by: Lantao Liu <lantaol@google.com>

pkg/store/image/image.go

@@ -92,8 +92,8 @@ func (s *Store) List() []Image {
 	s.lock.RLock()
 	defer s.lock.RUnlock()
 	var images []Image
-	for _, sb := range s.images {
-		images = append(images, sb)
+	for _, i := range s.images {
+		images = append(images, i)
 	}
 	return images
 }

pkg/store/image/image_test.go

@@ -99,7 +99,7 @@ func TestImageStore(t *testing.T) {
 	imgs = s.List()
 	assert.Len(imgs, 2)
 
-	t.Logf("get should return nil after deletion")
+	t.Logf("get should return empty struct and ErrNotExist after deletion")
 	img, err := s.Get(testID)
 	assert.Equal(Image{}, img)
 	assert.Equal(store.ErrNotExist, err)

pkg/store/snapshot/snapshot.go

@@ -0,0 +1,87 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package snapshot
+
+import (
+	"sync"
+
+	"github.com/containerd/containerd/snapshot"
+
+	"github.com/kubernetes-incubator/cri-containerd/pkg/store"
+)
+
+// Snapshot contains the information about the snapshot.
+type Snapshot struct {
+	// Key is the key of the snapshot
+	Key string
+	// Kind is the kind of the snapshot (active, commited, view)
+	Kind snapshot.Kind
+	// Size is the size of the snapshot in bytes.
+	Size uint64
+	// Inodes is the number of inodes used by the snapshot
+	Inodes uint64
+	// Timestamp is latest update time (in nanoseconds) of the snapshot
+	// information.
+	Timestamp int64
+}
+
+// Store stores all snapshots.
+type Store struct {
+	lock      sync.RWMutex
+	snapshots map[string]Snapshot
+}
+
+// NewStore creates a snapshot store.
+func NewStore() *Store {
+	return &Store{snapshots: make(map[string]Snapshot)}
+}
+
+// Add a snapshot into the store.
+func (s *Store) Add(snapshot Snapshot) {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+	s.snapshots[snapshot.Key] = snapshot
+}
+
+// Get returns the snapshot with specified key. Returns store.ErrNotExist if the
+// snapshot doesn't exist.
+func (s *Store) Get(key string) (Snapshot, error) {
+	s.lock.RLock()
+	defer s.lock.RUnlock()
+	if sn, ok := s.snapshots[key]; ok {
+		return sn, nil
+	}
+	return Snapshot{}, store.ErrNotExist
+}
+
+// List lists all snapshots.
+func (s *Store) List() []Snapshot {
+	s.lock.RLock()
+	defer s.lock.RUnlock()
+	var snapshots []Snapshot
+	for _, sn := range s.snapshots {
+		snapshots = append(snapshots, sn)
+	}
+	return snapshots
+}
+
+// Delete deletes the snapshot with specified key.
+func (s *Store) Delete(key string) {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+	delete(s.snapshots, key)
+}

pkg/store/snapshot/snapshot_test.go

@@ -0,0 +1,84 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package snapshot
+
+import (
+	"testing"
+	"time"
+
+	"github.com/containerd/containerd/snapshot"
+	assertlib "github.com/stretchr/testify/assert"
+
+	"github.com/kubernetes-incubator/cri-containerd/pkg/store"
+)
+
+func TestSnapshotStore(t *testing.T) {
+	snapshots := map[string]Snapshot{
+		"key1": {
+			Key:       "key1",
+			Kind:      snapshot.KindActive,
+			Size:      10,
+			Inodes:    100,
+			Timestamp: time.Now().UnixNano(),
+		},
+		"key2": {
+			Key:       "key2",
+			Kind:      snapshot.KindCommitted,
+			Size:      20,
+			Inodes:    200,
+			Timestamp: time.Now().UnixNano(),
+		},
+		"key3": {
+			Key:       "key3",
+			Kind:      snapshot.KindView,
+			Size:      0,
+			Inodes:    0,
+			Timestamp: time.Now().UnixNano(),
+		},
+	}
+	assert := assertlib.New(t)
+
+	s := NewStore()
+
+	t.Logf("should be able to add snapshot")
+	for _, sn := range snapshots {
+		s.Add(sn)
+	}
+
+	t.Logf("should be able to get snapshot")
+	for id, sn := range snapshots {
+		got, err := s.Get(id)
+		assert.NoError(err)
+		assert.Equal(sn, got)
+	}
+
+	t.Logf("should be able to list snapshot")
+	sns := s.List()
+	assert.Len(sns, 3)
+
+	testKey := "key2"
+
+	t.Logf("should be able to delete snapshot")
+	s.Delete(testKey)
+	sns = s.List()
+	assert.Len(sns, 2)
+
+	t.Logf("get should return empty struct and ErrNotExist after deletion")
+	sn, err := s.Get(testKey)
+	assert.Equal(Snapshot{}, sn)
+	assert.Equal(store.ErrNotExist, err)
+}