done implementation

Signed-off-by: Xiaoxuan Wang <wangxiaoxuan119@gmail.com>

content/oci/oci.go

@@ -36,6 +36,7 @@ import (
 	"oras.land/oras-go/v2/internal/descriptor"
 	"oras.land/oras-go/v2/internal/graph"
 	"oras.land/oras-go/v2/internal/resolver"
+	"oras.land/oras-go/v2/registry"
 )
 
 // Store implements `oras.Target`, and represents a content store
@@ -61,6 +62,11 @@ type Store struct {
 	//   - Default value: true.
 	AutoGC bool
 
+	// AutoRemoveReferrers controls if the OCI store will automatically delete its
+	// referrers when a manifest is deleted.
+	//   - Default value: true.
+	AutoRemoveReferrers bool
+
 	root        string
 	indexPath   string
 	index       *ocispec.Index
@@ -93,13 +99,14 @@ func NewWithContext(ctx context.Context, root string) (*Store, error) {
 	}
 
 	store := &Store{
-		AutoSaveIndex: true,
-		AutoGC:        true,
-		root:          rootAbs,
-		indexPath:     filepath.Join(rootAbs, ocispec.ImageIndexFile),
-		storage:       storage,
-		tagResolver:   resolver.NewMemory(),
-		graph:         graph.NewMemory(),
+		AutoSaveIndex:       true,
+		AutoGC:              true,
+		AutoRemoveReferrers: true,
+		root:                rootAbs,
+		indexPath:           filepath.Join(rootAbs, ocispec.ImageIndexFile),
+		storage:             storage,
+		tagResolver:         resolver.NewMemory(),
+		graph:               graph.NewMemory(),
 	}
 
 	if err := ensureDir(filepath.Join(rootAbs, ocispec.ImageBlobsDir)); err != nil {
@@ -155,6 +162,16 @@ func (s *Store) Exists(ctx context.Context, target ocispec.Descriptor) (bool, er
 // fail on certain systems (i.e. NTFS), if there is a process (i.e. an unclosed
 // Reader) using target.
 func (s *Store) Delete(ctx context.Context, target ocispec.Descriptor) error {
+	// get referrers first to avoid deadlock
+	var referrers []ocispec.Descriptor
+	if descriptor.IsManifest(target) && s.AutoRemoveReferrers {
+		res, err := registry.Referrers(ctx, s, target, "")
+		referrers = append(referrers, res...)
+		if err != nil {
+			return err
+		}
+	}
+
 	s.sync.Lock()
 	defer s.sync.Unlock()
 
@@ -166,8 +183,24 @@ func (s *Store) Delete(ctx context.Context, target ocispec.Descriptor) error {
 
 	// delete the dangling nodes caused by the delete
 	if s.AutoGC {
-		return s.cleanGraphs(ctx, danglings)
+		if err := s.cleanGraphs(ctx, danglings); err != nil {
+			return err
+		}
 	}
+
+	// delete the referrers
+	for _, desc := range referrers {
+		danglings, err := s.delete(ctx, desc)
+		if err != nil {
+			return err
+		}
+		if s.AutoGC {
+			if err := s.cleanGraphs(ctx, danglings); err != nil {
+				return err
+			}
+		}
+	}
+
 	return nil
 }
 
@@ -195,8 +228,7 @@ func (s *Store) delete(ctx context.Context, target ocispec.Descriptor) ([]ocispe
 }
 
 func (s *Store) cleanGraphs(ctx context.Context, danglings []ocispec.Descriptor) error {
-	// for each item in dangling, if it exists and it is dangling, remove it and
-	// add new dangling nodes into dangling
+	// for each item in danglings, remove it and add new dangling nodes into danglings
 	for len(danglings) > 0 {
 		node := danglings[0]
 		danglings = danglings[1:]

content/oci/oci_test.go

@@ -2375,13 +2375,13 @@ func TestStore_DeleteWithGarbageCollection(t *testing.T) {
 	}
 
 	// blob 1, 3, 4, 6 and 8 are now deleted, and other blobs are still present
-	notPresent = []ocispec.Descriptor{descs[1], descs[3], descs[4], descs[6], descs[8]}
+	notPresent = []ocispec.Descriptor{descs[1], descs[3], descs[4], descs[6], descs[8], descs[9]}
 	for _, node := range notPresent {
 		if exists, _ := s.Exists(egCtx, node); exists {
 			t.Errorf("%v should not exist in store", node)
 		}
 	}
-	stillPresent = []ocispec.Descriptor{descs[0], descs[2], descs[5], descs[7], descs[9]}
+	stillPresent = []ocispec.Descriptor{descs[0], descs[2], descs[5], descs[7]}
 	for _, node := range stillPresent {
 		if exists, _ := s.Exists(egCtx, node); !exists {
 			t.Errorf("%v should exist in store", node)
@@ -2390,16 +2390,16 @@ func TestStore_DeleteWithGarbageCollection(t *testing.T) {
 
 	// verify predecessors information
 	wants := [][]ocispec.Descriptor{
-		{descs[5], descs[9]}, // Blob 0
-		nil,                  // Blob 1
-		{descs[5], descs[9]}, // Blob 2
-		nil,                  // Blob 3
-		{descs[7]},           // Blob 4's predecessor is descs[7], even though blob 4 no longer exist
-		{descs[7]},           // Blob 5
-		{descs[9]},           // Blob 6's predecessor is descs[9], even though blob 6 no longer exist
-		nil,                  // Blob 7
-		nil,                  // Blob 8
-		nil,                  // Blob 9
+		{descs[5]}, // Blob 0
+		nil,        // Blob 1
+		{descs[5]}, // Blob 2
+		nil,        // Blob 3
+		{descs[7]}, // Blob 4's predecessor is descs[7], even though blob 4 no longer exist
+		{descs[7]}, // Blob 5
+		nil,        // Blob 6
+		nil,        // Blob 7
+		nil,        // Blob 8
+		nil,        // Blob 9
 	}
 	for i, want := range wants {
 		predecessors, err := s.Predecessors(ctx, descs[i])