util/multiprovider: Implement Info

Require base provides to implement both content.InfoReaderProvider.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

cache/remote.go

@@ -18,6 +18,7 @@ import (
 	"github.com/moby/buildkit/util/leaseutil"
 	"github.com/moby/buildkit/util/progress/logs"
 	"github.com/moby/buildkit/util/pull/pullprogress"
+	digest "github.com/opencontainers/go-digest"
 	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/pkg/errors"
 	"golang.org/x/sync/errgroup"
@@ -85,7 +86,7 @@ func (sr *immutableRef) GetRemotes(ctx context.Context, createIfNeeded bool, ref
 	return res, nil
 }
 
-func appendRemote(parents []*solver.Remote, desc ocispecs.Descriptor, p content.Provider) (res []*solver.Remote) {
+func appendRemote(parents []*solver.Remote, desc ocispecs.Descriptor, p content.InfoReaderProvider) (res []*solver.Remote) {
 	for _, pRemote := range parents {
 		provider := contentutil.NewMultiProvider(pRemote.Provider)
 		provider.Add(desc.Digest, p)
@@ -276,6 +277,10 @@ func (mp *lazyMultiProvider) ReaderAt(ctx context.Context, desc ocispecs.Descrip
 	return mp.mprovider.ReaderAt(ctx, desc)
 }
 
+func (mp *lazyMultiProvider) Info(ctx context.Context, dgst digest.Digest) (content.Info, error) {
+	return mp.mprovider.Info(ctx, dgst)
+}
+
 func (mp *lazyMultiProvider) Unlazy(ctx context.Context) error {
 	eg, egctx := errgroup.WithContext(ctx)
 	for _, p := range mp.plist {
@@ -304,6 +309,16 @@ func (p lazyRefProvider) ReaderAt(ctx context.Context, desc ocispecs.Descriptor)
 	return p.ref.cm.ContentStore.ReaderAt(ctx, desc)
 }
 
+func (p lazyRefProvider) Info(ctx context.Context, dgst digest.Digest) (content.Info, error) {
+	if dgst != p.desc.Digest {
+		return content.Info{}, errdefs.ErrNotFound
+	}
+	if err := p.Unlazy(ctx); err != nil {
+		return content.Info{}, errdefs.ErrNotFound
+	}
+	return p.ref.cm.ContentStore.Info(ctx, dgst)
+}
+
 func (p lazyRefProvider) Unlazy(ctx context.Context) error {
 	_, err := p.ref.cm.unlazyG.Do(ctx, string(p.desc.Digest), func(ctx context.Context) (_ struct{}, rerr error) {
 		if isLazy, err := p.ref.isLazy(ctx); err != nil {

cache/remotecache/v1/chains.go

@@ -10,6 +10,7 @@ import (
 	"github.com/moby/buildkit/solver"
 	digest "github.com/opencontainers/go-digest"
 	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/pkg/errors"
 )
 
 func NewCacheChains() *CacheChains {
@@ -120,6 +121,20 @@ type DescriptorProviderPair struct {
 	Provider   content.Provider
 }
 
+func (p DescriptorProviderPair) ReaderAt(ctx context.Context, desc ocispecs.Descriptor) (content.ReaderAt, error) {
+	return p.Provider.ReaderAt(ctx, desc)
+}
+
+func (p DescriptorProviderPair) Info(ctx context.Context, dgst digest.Digest) (content.Info, error) {
+	if dgst != p.Descriptor.Digest {
+		return content.Info{}, errors.Errorf("content not found %s", dgst)
+	}
+	return content.Info{
+		Digest: p.Descriptor.Digest,
+		Size:   p.Descriptor.Size,
+	}, nil
+}
+
 // item is an implementation of a record in the cache chain. After validation,
 // normalization and marshalling into the cache config, the item results form
 // into the "layers", while the digests and the links form into the "records".

cache/remotecache/v1/parse.go

@@ -82,7 +82,7 @@ func parseRecord(cc CacheConfig, idx int, provider DescriptorProvider, t solver.
 			}
 
 			remote.Descriptors = append(remote.Descriptors, descPair.Descriptor)
-			mp.Add(descPair.Descriptor.Digest, descPair.Provider)
+			mp.Add(descPair.Descriptor.Digest, descPair)
 		}
 		if remote != nil {
 			remote.Provider = mp
@@ -123,12 +123,12 @@ func getRemoteChain(layers []CacheLayer, idx int, provider DescriptorProvider, v
 		}
 		r.Descriptors = append(r.Descriptors, descPair.Descriptor)
 		mp := contentutil.NewMultiProvider(r.Provider)
-		mp.Add(descPair.Descriptor.Digest, descPair.Provider)
+		mp.Add(descPair.Descriptor.Digest, descPair)
 		r.Provider = mp
 		return r, nil
 	}
 	return &solver.Remote{
 		Descriptors: []ocispecs.Descriptor{descPair.Descriptor},
-		Provider:    descPair.Provider,
+		Provider:    descPair,
 	}, nil
 }

solver/types.go

@@ -142,7 +142,7 @@ type CacheExporterRecord interface {
 // TODO: add closer to keep referenced data from getting deleted
 type Remote struct {
 	Descriptors []ocispecs.Descriptor
-	Provider    content.Provider
+	Provider    content.InfoReaderProvider
 }
 
 // CacheLink is a link between two cache records

util/contentutil/multiprovider.go

@@ -13,18 +13,18 @@ import (
 )
 
 // NewMultiProvider creates a new mutable provider with a base provider
-func NewMultiProvider(base content.Provider) *MultiProvider {
+func NewMultiProvider(base content.InfoReaderProvider) *MultiProvider {
 	return &MultiProvider{
 		base: base,
-		sub:  map[digest.Digest]content.Provider{},
+		sub:  map[digest.Digest]content.InfoReaderProvider{},
 	}
 }
 
 // MultiProvider is a provider backed by a mutable map of providers
 type MultiProvider struct {
 	mu   sync.RWMutex
-	base content.Provider
-	sub  map[digest.Digest]content.Provider
+	base content.InfoReaderProvider
+	sub  map[digest.Digest]content.InfoReaderProvider
 }
 
 func (mp *MultiProvider) SnapshotLabels(descs []ocispecs.Descriptor, index int) map[string]string {
@@ -85,8 +85,22 @@ func (mp *MultiProvider) ReaderAt(ctx context.Context, desc ocispecs.Descriptor)
 	return mp.base.ReaderAt(ctx, desc)
 }
 
+// Info returns a content.Info
+func (mp *MultiProvider) Info(ctx context.Context, dgst digest.Digest) (content.Info, error) {
+	mp.mu.RLock()
+	if p, ok := mp.sub[dgst]; ok {
+		mp.mu.RUnlock()
+		return p.Info(ctx, dgst)
+	}
+	mp.mu.RUnlock()
+	if mp.base == nil {
+		return content.Info{}, errors.Wrapf(errdefs.ErrNotFound, "content %v", dgst)
+	}
+	return mp.base.Info(ctx, dgst)
+}
+
 // Add adds a new child provider for a specific digest
-func (mp *MultiProvider) Add(dgst digest.Digest, p content.Provider) {
+func (mp *MultiProvider) Add(dgst digest.Digest, p content.InfoReaderProvider) {
 	mp.mu.Lock()
 	defer mp.mu.Unlock()
 	mp.sub[dgst] = p