Update metadata image store to be initialized once

The boltdb image store now manages its own transactions when
one is not provided, but allows the caller to pass in a
transaction through the context. This makes the image store
more similar to the content and snapshot stores. Additionally,
use the reference to the metadata database to mark the content
store as dirty after an image has been deleted. The deletion
of an image means a reference to a piece of content is gone
and therefore garbage collection should be run to check if
any resources can be cleaned up as a result.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

metadata/images.go

@@ -20,12 +20,12 @@ import (
 )
 
 type imageStore struct {
-	tx *bolt.Tx
+	db *DB
 }
 
 // NewImageStore returns a store backed by a bolt DB
-func NewImageStore(tx *bolt.Tx) images.Store {
-	return &imageStore{tx: tx}
+func NewImageStore(db *DB) images.Store {
+	return &imageStore{db: db}
 }
 
 func (s *imageStore) Get(ctx context.Context, name string) (images.Image, error) {
@@ -36,19 +36,25 @@ func (s *imageStore) Get(ctx context.Context, name string) (images.Image, error)
 		return images.Image{}, err
 	}
 
-	bkt := getImagesBucket(s.tx, namespace)
-	if bkt == nil {
-		return images.Image{}, errors.Wrapf(errdefs.ErrNotFound, "image %q", name)
-	}
+	if err := view(ctx, s.db, func(tx *bolt.Tx) error {
+		bkt := getImagesBucket(tx, namespace)
+		if bkt == nil {
+			return errors.Wrapf(errdefs.ErrNotFound, "image %q", name)
+		}
 
-	ibkt := bkt.Bucket([]byte(name))
-	if ibkt == nil {
-		return images.Image{}, errors.Wrapf(errdefs.ErrNotFound, "image %q", name)
-	}
+		ibkt := bkt.Bucket([]byte(name))
+		if ibkt == nil {
+			return errors.Wrapf(errdefs.ErrNotFound, "image %q", name)
+		}
 
-	image.Name = name
-	if err := readImage(&image, ibkt); err != nil {
-		return images.Image{}, errors.Wrapf(err, "image %q", name)
+		image.Name = name
+		if err := readImage(&image, ibkt); err != nil {
+			return errors.Wrapf(err, "image %q", name)
+		}
+
+		return nil
+	}); err != nil {
+		return images.Image{}, err
 	}
 
 	return image, nil
@@ -65,28 +71,30 @@ func (s *imageStore) List(ctx context.Context, fs ...string) ([]images.Image, er
 		return nil, errors.Wrapf(errdefs.ErrInvalidArgument, err.Error())
 	}
 
-	bkt := getImagesBucket(s.tx, namespace)
-	if bkt == nil {
-		return nil, nil // empty store
-	}
-
 	var m []images.Image
-	if err := bkt.ForEach(func(k, v []byte) error {
-		var (
-			image = images.Image{
-				Name: string(k),
+	if err := view(ctx, s.db, func(tx *bolt.Tx) error {
+		bkt := getImagesBucket(tx, namespace)
+		if bkt == nil {
+			return nil // empty store
+		}
+
+		return bkt.ForEach(func(k, v []byte) error {
+			var (
+				image = images.Image{
+					Name: string(k),
+				}
+				kbkt = bkt.Bucket(k)
+			)
+
+			if err := readImage(&image, kbkt); err != nil {
+				return err
 			}
-			kbkt = bkt.Bucket(k)
-		)
 
-		if err := readImage(&image, kbkt); err != nil {
-			return err
-		}
-
-		if filter.Match(adaptImage(image)) {
-			m = append(m, image)
-		}
-		return nil
+			if filter.Match(adaptImage(image)) {
+				m = append(m, image)
+			}
+			return nil
+		})
 	}); err != nil {
 		return nil, err
 	}
@@ -100,11 +108,16 @@ func (s *imageStore) Create(ctx context.Context, image images.Image) (images.Ima
 		return images.Image{}, err
 	}
 
-	if err := validateImage(&image); err != nil {
-		return images.Image{}, err
-	}
+	if err := update(ctx, s.db, func(tx *bolt.Tx) error {
+		if err := validateImage(&image); err != nil {
+			return err
+		}
+
+		bkt, err := createImagesBucket(tx, namespace)
+		if err != nil {
+			return err
+		}
 
-	return image, withImagesBucket(s.tx, namespace, func(bkt *bolt.Bucket) error {
 		ibkt, err := bkt.CreateBucket([]byte(image.Name))
 		if err != nil {
 			if err != bolt.ErrBucketExists {
@@ -117,7 +130,11 @@ func (s *imageStore) Create(ctx context.Context, image images.Image) (images.Ima
 		image.CreatedAt = time.Now().UTC()
 		image.UpdatedAt = image.CreatedAt
 		return writeImage(ibkt, &image)
-	})
+	}); err != nil {
+		return images.Image{}, err
+	}
+
+	return image, nil
 }
 
 func (s *imageStore) Update(ctx context.Context, image images.Image, fieldpaths ...string) (images.Image, error) {
@@ -131,7 +148,13 @@ func (s *imageStore) Update(ctx context.Context, image images.Image, fieldpaths
 	}
 
 	var updated images.Image
-	return updated, withImagesBucket(s.tx, namespace, func(bkt *bolt.Bucket) error {
+
+	if err := update(ctx, s.db, func(tx *bolt.Tx) error {
+		bkt, err := createImagesBucket(tx, namespace)
+		if err != nil {
+			return err
+		}
+
 		ibkt := bkt.Bucket([]byte(image.Name))
 		if ibkt == nil {
 			return errors.Wrapf(errdefs.ErrNotFound, "image %q", image.Name)
@@ -180,7 +203,12 @@ func (s *imageStore) Update(ctx context.Context, image images.Image, fieldpaths
 		updated.CreatedAt = createdat
 		updated.UpdatedAt = time.Now().UTC()
 		return writeImage(ibkt, &updated)
-	})
+	}); err != nil {
+		return images.Image{}, err
+	}
+
+	return updated, nil
+
 }
 
 func (s *imageStore) Delete(ctx context.Context, name string, opts ...images.DeleteOpt) error {
@@ -189,11 +217,24 @@ func (s *imageStore) Delete(ctx context.Context, name string, opts ...images.Del
 		return err
 	}
 
-	return withImagesBucket(s.tx, namespace, func(bkt *bolt.Bucket) error {
-		err := bkt.DeleteBucket([]byte(name))
+	return update(ctx, s.db, func(tx *bolt.Tx) error {
+		bkt := getImagesBucket(tx, namespace)
+		if bkt == nil {
+			return errors.Wrapf(errdefs.ErrNotFound, "image %q", name)
+		}
+
+		err = bkt.DeleteBucket([]byte(name))
 		if err == bolt.ErrBucketNotFound {
 			return errors.Wrapf(errdefs.ErrNotFound, "image %q", name)
 		}
+
+		// A reference to a piece of content has been removed,
+		// mark content store as dirty for triggering garbage
+		// collection
+		s.db.dirtyL.Lock()
+		s.db.dirtyCS = true
+		s.db.dirtyL.Unlock()
+
 		return err
 	})
 }