Create metadata db object

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

metadata/bolt.go

@@ -19,7 +19,7 @@ func WithTransactionContext(ctx context.Context, tx *bolt.Tx) context.Context {
 
 // view gets a bolt db transaction either from the context
 // or starts a new one with the provided bolt database.
-func view(ctx context.Context, db *bolt.DB, fn func(*bolt.Tx) error) error {
+func view(ctx context.Context, db *DB, fn func(*bolt.Tx) error) error {
 	tx, ok := ctx.Value(transactionKey{}).(*bolt.Tx)
 	if !ok {
 		return db.View(fn)
@@ -29,7 +29,7 @@ func view(ctx context.Context, db *bolt.DB, fn func(*bolt.Tx) error) error {
 
 // update gets a writable bolt db transaction either from the context
 // or starts a new one with the provided bolt database.
-func update(ctx context.Context, db *bolt.DB, fn func(*bolt.Tx) error) error {
+func update(ctx context.Context, db *DB, fn func(*bolt.Tx) error) error {
 	tx, ok := ctx.Value(transactionKey{}).(*bolt.Tx)
 	if !ok {
 		return db.Update(fn)

metadata/content.go

@@ -19,12 +19,12 @@ import (
 
 type contentStore struct {
 	content.Store
-	db *bolt.DB
+	db *DB
 }
 
 // NewContentStore returns a namespaced content store using an existing
 // content store interface.
-func NewContentStore(db *bolt.DB, cs content.Store) content.Store {
+func NewContentStore(db *DB, cs content.Store) content.Store {
 	return &contentStore{
 		Store: cs,
 		db:    db,
@@ -353,7 +353,7 @@ type namespacedWriter struct {
 	content.Writer
 	ref       string
 	namespace string
-	db        *bolt.DB
+	db        *DB
 }
 
 func (nw *namespacedWriter) Commit(ctx context.Context, size int64, expected digest.Digest, opts ...content.Opt) error {

metadata/db.go

@@ -0,0 +1,21 @@
+package metadata
+
+import "github.com/boltdb/bolt"
+
+type DB struct {
+	db *bolt.DB
+}
+
+func NewDB(db *bolt.DB) *DB {
+	return &DB{
+		db: db,
+	}
+}
+
+func (m *DB) View(fn func(*bolt.Tx) error) error {
+	return m.db.View(fn)
+}
+
+func (m *DB) Update(fn func(*bolt.Tx) error) error {
+	return m.db.Update(fn)
+}

metadata/snapshot.go

@@ -19,12 +19,12 @@ import (
 type snapshotter struct {
 	snapshot.Snapshotter
 	name string
-	db   *bolt.DB
+	db   *DB
 }
 
 // NewSnapshotter returns a new Snapshotter which namespaces the given snapshot
 // using the provided name and metadata store.
-func NewSnapshotter(db *bolt.DB, name string, sn snapshot.Snapshotter) snapshot.Snapshotter {
+func NewSnapshotter(db *DB, name string, sn snapshot.Snapshotter) snapshot.Snapshotter {
 	return &snapshotter{
 		Snapshotter: sn,
 		name:        name,