generic implementation

Signed-off-by: Xiaoxuan Wang <[email protected]>
oras-project · Dec 20, 2023 · 73a18b1 · 73a18b1
1 parent 18435a4
commit 73a18b1
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Showing 3 changed files with 84 additions and 80 deletions.
diff --git a/content/oci/oci.go b/content/oci/oci.go
@@ -36,7 +36,6 @@ 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/internal/spec"
 )
 
 // Store implements `oras.Target`, and represents a content store
@@ -376,83 +375,6 @@ func (s *Store) writeIndexFile() error {
 	return os.WriteFile(s.indexPath, indexJSON, 0666)
 }
 
-// Referrers lists the descriptors of image or artifact manifests directly
-// referencing the given manifest descriptor.
-//
-// fn is called on the referrer results. If artifactType is not empty, only
-// referrers of the same artifact type are fed to fn.
-//
-// Reference: https://github.com/opencontainers/distribution-spec/blob/v1.1.0-rc3/spec.md#listing-referrers
-func (s *Store) Referrers(ctx context.Context, desc ocispec.Descriptor, artifactType string, fn func(referrers []ocispec.Descriptor) error) error {
-	s.sync.RLock()
-	defer s.sync.RUnlock()
-
-	if !descriptor.IsManifest(desc) {
-		return fmt.Errorf("the descriptor %v is not a manifest", desc)
-	}
-	var results []ocispec.Descriptor
-	predecessors, err := s.Predecessors(ctx, desc)
-	if err != nil {
-		return err
-	}
-	for _, node := range predecessors {
-		switch node.MediaType {
-		case ocispec.MediaTypeImageManifest:
-			fetched, err := content.FetchAll(ctx, s, node)
-			if err != nil {
-				return err
-			}
-			var manifest ocispec.Manifest
-			if err := json.Unmarshal(fetched, &manifest); err != nil {
-				return err
-			}
-			if manifest.Subject == nil || !content.Equal(*manifest.Subject, desc) {
-				continue
-			}
-			if manifest.ArtifactType != "" {
-				node.ArtifactType = manifest.ArtifactType
-			} else {
-				node.ArtifactType = manifest.Config.MediaType
-			}
-			node.Annotations = manifest.Annotations
-		case ocispec.MediaTypeImageIndex:
-			fetched, err := content.FetchAll(ctx, s, node)
-			if err != nil {
-				return err
-			}
-			var index ocispec.Index
-			if err := json.Unmarshal(fetched, &index); err != nil {
-				return err
-			}
-			if index.Subject == nil || !content.Equal(*index.Subject, desc) {
-				continue
-			}
-			node.ArtifactType = index.ArtifactType
-			node.Annotations = index.Annotations
-		case spec.MediaTypeArtifactManifest:
-			fetched, err := content.FetchAll(ctx, s, node)
-			if err != nil {
-				return err
-			}
-			var artifact spec.Artifact
-			if err := json.Unmarshal(fetched, &artifact); err != nil {
-				return err
-			}
-			if artifact.Subject == nil || !content.Equal(*artifact.Subject, desc) {
-				continue
-			}
-			node.ArtifactType = artifact.ArtifactType
-			node.Annotations = artifact.Annotations
-		default:
-			continue
-		}
-		if artifactType == "" || artifactType == node.ArtifactType {
-			results = append(results, node)
-		}
-	}
-	return fn(results)
-}
-
 // validateReference validates ref.
 func validateReference(ref string) error {
 	if ref == "" {

diff --git a/content/oci/oci_test.go b/content/oci/oci_test.go
@@ -2364,7 +2364,7 @@ func TestStore_Referrers(t *testing.T) {
 	for i := 4; i < len(wantedReferrers); i++ {
 		want := wantedReferrers[i]
 		var results []ocispec.Descriptor
-		err := s.Referrers(ctx, descs[i], "", func(referrers []ocispec.Descriptor) error {
+		err := registry.Referrers(ctx, s, descs[i], "", func(referrers []ocispec.Descriptor) error {
 			results = append(results, referrers...)
 			return nil
 		})
@@ -2391,7 +2391,7 @@ func TestStore_Referrers(t *testing.T) {
 	for i := 4; i < len(wantedReferrers); i++ {
 		want := wantedReferrers[i]
 		var results []ocispec.Descriptor
-		err := s.Referrers(ctx, descs[i], "image manifest", func(referrers []ocispec.Descriptor) error {
+		err := registry.Referrers(ctx, s, descs[i], "image manifest", func(referrers []ocispec.Descriptor) error {
 			results = append(results, referrers...)
 			return nil
 		})

diff --git a/registry/repository.go b/registry/repository.go
@@ -17,10 +17,14 @@ package registry
 
 import (
 	"context"
+	"encoding/json"
+	"fmt"
 	"io"
 
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"oras.land/oras-go/v2/content"
+	"oras.land/oras-go/v2/internal/descriptor"
+	"oras.land/oras-go/v2/internal/spec"
 )
 
 // Repository is an ORAS target and an union of the blob and the manifest CASs.
@@ -134,3 +138,81 @@ func Tags(ctx context.Context, repo TagLister) ([]string, error) {
 	}
 	return res, nil
 }
+
+// Referrers lists the descriptors of image or artifact manifests directly
+// referencing the given manifest descriptor.
+//
+// fn is called on the referrer results. If artifactType is not empty, only
+// referrers of the same artifact type are fed to fn.
+//
+// Reference: https://github.com/opencontainers/distribution-spec/blob/v1.1.0-rc3/spec.md#listing-referrers
+func Referrers(ctx context.Context, store content.ReadOnlyGraphStorage, desc ocispec.Descriptor, artifactType string, fn func(referrers []ocispec.Descriptor) error) error {
+	if !descriptor.IsManifest(desc) {
+		return fmt.Errorf("the descriptor %v is not a manifest", desc)
+	}
+	// use the Referrer API if it is available
+	if rf, ok := store.(ReferrerLister); ok {
+		return rf.Referrers(ctx, desc, artifactType, fn)
+	}
+	var results []ocispec.Descriptor
+	predecessors, err := store.Predecessors(ctx, desc)
+	if err != nil {
+		return err
+	}
+	for _, node := range predecessors {
+		switch node.MediaType {
+		case ocispec.MediaTypeImageManifest:
+			fetched, err := content.FetchAll(ctx, store, node)
+			if err != nil {
+				return err
+			}
+			var manifest ocispec.Manifest
+			if err := json.Unmarshal(fetched, &manifest); err != nil {
+				return err
+			}
+			if manifest.Subject == nil || !content.Equal(*manifest.Subject, desc) {
+				continue
+			}
+			if manifest.ArtifactType != "" {
+				node.ArtifactType = manifest.ArtifactType
+			} else {
+				node.ArtifactType = manifest.Config.MediaType
+			}
+			node.Annotations = manifest.Annotations
+		case ocispec.MediaTypeImageIndex:
+			fetched, err := content.FetchAll(ctx, store, node)
+			if err != nil {
+				return err
+			}
+			var index ocispec.Index
+			if err := json.Unmarshal(fetched, &index); err != nil {
+				return err
+			}
+			if index.Subject == nil || !content.Equal(*index.Subject, desc) {
+				continue
+			}
+			node.ArtifactType = index.ArtifactType
+			node.Annotations = index.Annotations
+		case spec.MediaTypeArtifactManifest:
+			fetched, err := content.FetchAll(ctx, store, node)
+			if err != nil {
+				return err
+			}
+			var artifact spec.Artifact
+			if err := json.Unmarshal(fetched, &artifact); err != nil {
+				return err
+			}
+			if artifact.Subject == nil || !content.Equal(*artifact.Subject, desc) {
+				continue
+			}
+			node.ArtifactType = artifact.ArtifactType
+			node.Annotations = artifact.Annotations
+		default:
+			continue
+		}
+		if artifactType == "" || artifactType == node.ArtifactType {
+			results = append(results, node)
+		}
+	}
+	return fn(results)
+}