Remove metadata store interface

Layer metadata storage has not been implemented outside of the layer
store and will be deprecated by containerd metadata storage. To prepare
for this and freeze the current metadata storage, remove the exported
interface and make it internal to the layer store.

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

layer/filestore.go

@@ -37,10 +37,10 @@ type fileMetadataTransaction struct {
 	ws    *ioutils.AtomicWriteSet
 }
 
-// NewFSMetadataStore returns an instance of a metadata store
+// newFSMetadataStore returns an instance of a metadata store
 // which is backed by files on disk using the provided root
 // as the root of metadata files.
-func NewFSMetadataStore(root string) (MetadataStore, error) {
+func newFSMetadataStore(root string) (*fileMetadataStore, error) {
 	if err := os.MkdirAll(root, 0700); err != nil {
 		return nil, err
 	}
@@ -66,7 +66,7 @@ func (fms *fileMetadataStore) getMountFilename(mount, filename string) string {
 	return filepath.Join(fms.getMountDirectory(mount), filename)
 }
 
-func (fms *fileMetadataStore) StartTransaction() (MetadataTransaction, error) {
+func (fms *fileMetadataStore) StartTransaction() (*fileMetadataTransaction, error) {
 	tmpDir := filepath.Join(fms.root, "tmp")
 	if err := os.MkdirAll(tmpDir, 0755); err != nil {
 		return nil, err

layer/filestore_test.go

@@ -24,12 +24,12 @@ func newFileMetadataStore(t *testing.T) (*fileMetadataStore, string, func()) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	fms, err := NewFSMetadataStore(td)
+	fms, err := newFSMetadataStore(td)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	return fms.(*fileMetadataStore), td, func() {
+	return fms, td, func() {
 		if err := os.RemoveAll(td); err != nil {
 			t.Logf("Failed to cleanup %q: %s", td, err)
 		}

layer/layer.go

@@ -201,54 +201,6 @@ type DescribableStore interface {
 	RegisterWithDescriptor(io.Reader, ChainID, distribution.Descriptor) (Layer, error)
 }
 
-// MetadataTransaction represents functions for setting layer metadata
-// with a single transaction.
-type MetadataTransaction interface {
-	SetSize(int64) error
-	SetParent(parent ChainID) error
-	SetDiffID(DiffID) error
-	SetCacheID(string) error
-	SetDescriptor(distribution.Descriptor) error
-	setOS(string) error
-	TarSplitWriter(compressInput bool) (io.WriteCloser, error)
-
-	Commit(ChainID) error
-	Cancel() error
-	String() string
-}
-
-// MetadataStore represents a backend for persisting
-// metadata about layers and providing the metadata
-// for restoring a Store.
-type MetadataStore interface {
-	// StartTransaction starts an update for new metadata
-	// which will be used to represent an ID on commit.
-	StartTransaction() (MetadataTransaction, error)
-
-	GetSize(ChainID) (int64, error)
-	GetParent(ChainID) (ChainID, error)
-	GetDiffID(ChainID) (DiffID, error)
-	GetCacheID(ChainID) (string, error)
-	GetDescriptor(ChainID) (distribution.Descriptor, error)
-	getOS(ChainID) (string, error)
-	TarSplitReader(ChainID) (io.ReadCloser, error)
-
-	SetMountID(string, string) error
-	SetInitID(string, string) error
-	SetMountParent(string, ChainID) error
-
-	GetMountID(string) (string, error)
-	GetInitID(string) (string, error)
-	GetMountParent(string) (ChainID, error)
-
-	// List returns the full list of referenced
-	// read-only and read-write layers
-	List() ([]ChainID, []string, error)
-
-	Remove(ChainID) error
-	RemoveMount(string) error
-}
-
 // CreateChainID returns ID for a layerDigest slice
 func CreateChainID(dgsts []DiffID) ChainID {
 	return createChainIDFromParent("", dgsts...)

layer/layer_store.go

@@ -27,7 +27,7 @@ import (
 const maxLayerDepth = 125
 
 type layerStore struct {
-	store       MetadataStore
+	store       *fileMetadataStore
 	driver      graphdriver.Driver
 	useTarSplit bool
 
@@ -65,18 +65,15 @@ func NewStoreFromOptions(options StoreOptions) (Store, error) {
 	}
 	logrus.Debugf("Initialized graph driver %s", driver)
 
-	fms, err := NewFSMetadataStore(fmt.Sprintf(options.MetadataStorePathTemplate, driver))
-	if err != nil {
-		return nil, err
-	}
+	root := fmt.Sprintf(options.MetadataStorePathTemplate, driver)
 
-	return NewStoreFromGraphDriver(fms, driver, options.OS)
+	return newStoreFromGraphDriver(root, driver, options.OS)
 }
 
-// NewStoreFromGraphDriver creates a new Store instance using the provided
+// newStoreFromGraphDriver creates a new Store instance using the provided
 // metadata store and graph driver. The metadata store will be used to restore
 // the Store.
-func NewStoreFromGraphDriver(store MetadataStore, driver graphdriver.Driver, os string) (Store, error) {
+func newStoreFromGraphDriver(root string, driver graphdriver.Driver, os string) (Store, error) {
 	if !system.IsOSSupported(os) {
 		return nil, fmt.Errorf("failed to initialize layer store as operating system '%s' is not supported", os)
 	}
@@ -85,8 +82,13 @@ func NewStoreFromGraphDriver(store MetadataStore, driver graphdriver.Driver, os
 		caps = capDriver.Capabilities()
 	}
 
+	ms, err := newFSMetadataStore(root)
+	if err != nil {
+		return nil, err
+	}
+
 	ls := &layerStore{
-		store:       store,
+		store:       ms,
 		driver:      driver,
 		layerMap:    map[ChainID]*roLayer{},
 		mounts:      map[string]*mountedLayer{},
@@ -94,7 +96,7 @@ func NewStoreFromGraphDriver(store MetadataStore, driver graphdriver.Driver, os
 		os:          os,
 	}
 
-	ids, mounts, err := store.List()
+	ids, mounts, err := ms.List()
 	if err != nil {
 		return nil, err
 	}
@@ -225,7 +227,7 @@ func (ls *layerStore) loadMount(mount string) error {
 	return nil
 }
 
-func (ls *layerStore) applyTar(tx MetadataTransaction, ts io.Reader, parent string, layer *roLayer) error {
+func (ls *layerStore) applyTar(tx *fileMetadataTransaction, ts io.Reader, parent string, layer *roLayer) error {
 	digester := digest.Canonical.Digester()
 	tr := io.TeeReader(ts, digester.Hash())
 

layer/layer_test.go

@@ -69,11 +69,8 @@ func newTestStore(t *testing.T) (Store, string, func()) {
 	}
 
 	graph, graphcleanup := newTestGraphDriver(t)
-	fms, err := NewFSMetadataStore(td)
-	if err != nil {
-		t.Fatal(err)
-	}
-	ls, err := NewStoreFromGraphDriver(fms, graph, runtime.GOOS)
+
+	ls, err := newStoreFromGraphDriver(td, graph, runtime.GOOS)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -403,7 +400,7 @@ func TestStoreRestore(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	ls2, err := NewStoreFromGraphDriver(ls.(*layerStore).store, ls.(*layerStore).driver, runtime.GOOS)
+	ls2, err := newStoreFromGraphDriver(ls.(*layerStore).store.root, ls.(*layerStore).driver, runtime.GOOS)
 	if err != nil {
 		t.Fatal(err)
 	}

layer/migration_test.go

@@ -90,11 +90,8 @@ func TestLayerMigration(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	fms, err := NewFSMetadataStore(filepath.Join(td, "layers"))
-	if err != nil {
-		t.Fatal(err)
-	}
-	ls, err := NewStoreFromGraphDriver(fms, graph, runtime.GOOS)
+	root := filepath.Join(td, "layers")
+	ls, err := newStoreFromGraphDriver(root, graph, runtime.GOOS)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -218,11 +215,8 @@ func TestLayerMigrationNoTarsplit(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	fms, err := NewFSMetadataStore(filepath.Join(td, "layers"))
-	if err != nil {
-		t.Fatal(err)
-	}
-	ls, err := NewStoreFromGraphDriver(fms, graph, runtime.GOOS)
+	root := filepath.Join(td, "layers")
+	ls, err := newStoreFromGraphDriver(root, graph, runtime.GOOS)
 	if err != nil {
 		t.Fatal(err)
 	}

layer/ro_layer.go

@@ -121,7 +121,7 @@ func (rl *roLayer) depth() int {
 	return rl.parent.depth() + 1
 }
 
-func storeLayer(tx MetadataTransaction, layer *roLayer) error {
+func storeLayer(tx *fileMetadataTransaction, layer *roLayer) error {
 	if err := tx.SetDiffID(layer.diffID); err != nil {
 		return err
 	}