ImageDestination: add blob locking

Extend the ImageDestination interface with methods for locking and
unlocking a blob:

1) LockBlob() for locking a given blob.

2) UnlockBlobk() for unlocking a blob.

3) SupportsBlobLocks() to indicate whether the image destination
   supports lock semantics or not.

Signed-off-by: Valentin Rothberg <[email protected]>

directory/directory_dest.go

@@ -129,6 +129,27 @@ func (d *dirImageDestination) HasThreadSafePutBlob() bool {
 	return false
 }
 
+// SupportsBlobLocks indicates whether the ImageDestination supports blob
+// locking.
+func (d *dirImageDestination) SupportsBlobLocks() bool {
+	return false
+}
+
+// LockBlob can be used to synchronize operations on it (e.g., copying).
+func (d *dirImageDestination) LockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
+// UnlockBlob unlocks the blob.  Note that it is safe to call UnlockBlob()
+// multiple times.  Only the first call is unlocking the blob.  This is
+// required to unlock a blob in the presence of errors or panics during copy
+// operations.
+func (d *dirImageDestination) UnlockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
 // PutBlob writes contents of stream and returns data representing the result (with all data filled in).
 // inputInfo.Digest can be optionally provided if known; it is not mandatory for the implementation to verify it.
 // inputInfo.Size is the expected length of stream, if known.

docker/docker_image_dest.go

@@ -117,6 +117,27 @@ func (d *dockerImageDestination) HasThreadSafePutBlob() bool {
 	return true
 }
 
+// SupportsBlobLocks indicates whether the ImageDestination supports blob
+// locking.
+func (d *dockerImageDestination) SupportsBlobLocks() bool {
+	return false
+}
+
+// LockBlob can be used to synchronize operations on it (e.g., copying).
+func (d *dockerImageDestination) LockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
+// UnlockBlob unlocks the blob.  Note that it is safe to call UnlockBlob()
+// multiple times.  Only the first call is unlocking the blob.  This is
+// required to unlock a blob in the presence of errors or panics during copy
+// operations.
+func (d *dockerImageDestination) UnlockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
 // PutBlob writes contents of stream and returns data representing the result (with all data filled in).
 // inputInfo.Digest can be optionally provided if known; it is not mandatory for the implementation to verify it.
 // inputInfo.Size is the expected length of stream, if known.

docker/tarfile/dest.go

@@ -87,6 +87,27 @@ func (d *Destination) HasThreadSafePutBlob() bool {
 	return false
 }
 
+// SupportsBlobLocks indicates whether the ImageDestination supports blob
+// locking.
+func (d *Destination) SupportsBlobLocks() bool {
+	return false
+}
+
+// LockBlob can be used to synchronize operations on it (e.g., copying).
+func (d *Destination) LockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
+// UnlockBlob unlocks the blob.  Note that it is safe to call UnlockBlob()
+// multiple times.  Only the first call is unlocking the blob.  This is
+// required to unlock a blob in the presence of errors or panics during copy
+// operations.
+func (d *Destination) UnlockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
 // PutBlob writes contents of stream and returns data representing the result (with all data filled in).
 // inputInfo.Digest can be optionally provided if known; it is not mandatory for the implementation to verify it.
 // inputInfo.Size is the expected length of stream, if known.

image/docker_schema2_test.go

@@ -401,6 +401,15 @@ func (d *memoryImageDest) IgnoresEmbeddedDockerReference() bool {
 func (d *memoryImageDest) HasThreadSafePutBlob() bool {
 	panic("Unexpected call to a mock function")
 }
+func (d *memoryImageDest) SupportsBlobLocks() bool {
+	panic("Unexpected call to a mock function")
+}
+func (d *memoryImageDest) LockBlob(b types.BlobInfo) error {
+	panic("Unexpected call to a mock function")
+}
+func (d *memoryImageDest) UnlockBlob(b types.BlobInfo) error {
+	panic("Unexpected call to a mock function")
+}
 func (d *memoryImageDest) PutBlob(ctx context.Context, stream io.Reader, inputInfo types.BlobInfo, cache types.BlobInfoCache, isConfig bool) (types.BlobInfo, error) {
 	if d.storedBlobs == nil {
 		d.storedBlobs = make(map[digest.Digest][]byte)

oci/archive/oci_dest.go

@@ -82,6 +82,27 @@ func (d *ociArchiveImageDestination) HasThreadSafePutBlob() bool {
 	return false
 }
 
+// SupportsBlobLocks indicates whether the ImageDestination supports blob
+// locking.
+func (d *ociArchiveImageDestination) SupportsBlobLocks() bool {
+	return false
+}
+
+// LockBlob can be used to synchronize operations on it (e.g., copying).
+func (d *ociArchiveImageDestination) LockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
+// UnlockBlob unlocks the blob.  Note that it is safe to call UnlockBlob()
+// multiple times.  Only the first call is unlocking the blob.  This is
+// required to unlock a blob in the presence of errors or panics during copy
+// operations.
+func (d *ociArchiveImageDestination) UnlockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
 // PutBlob writes contents of stream and returns data representing the result.
 // inputInfo.Digest can be optionally provided if known; it is not mandatory for the implementation to verify it.
 // inputInfo.Size is the expected length of stream, if known.

oci/layout/oci_dest.go

@@ -112,6 +112,27 @@ func (d *ociImageDestination) HasThreadSafePutBlob() bool {
 	return false
 }
 
+// SupportsBlobLocks indicates whether the ImageDestination supports blob
+// locking.
+func (d *ociImageDestination) SupportsBlobLocks() bool {
+	return false
+}
+
+// LockBlob can be used to synchronize operations on it (e.g., copying).
+func (d *ociImageDestination) LockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
+// UnlockBlob unlocks the blob.  Note that it is safe to call UnlockBlob()
+// multiple times.  Only the first call is unlocking the blob.  This is
+// required to unlock a blob in the presence of errors or panics during copy
+// operations.
+func (d *ociImageDestination) UnlockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
 // PutBlob writes contents of stream and returns data representing the result.
 // inputInfo.Digest can be optionally provided if known; it is not mandatory for the implementation to verify it.
 // inputInfo.Size is the expected length of stream, if known.

openshift/openshift.go

@@ -388,6 +388,27 @@ func (d *openshiftImageDestination) HasThreadSafePutBlob() bool {
 	return false
 }
 
+// SupportsBlobLocks indicates whether the ImageDestination supports blob
+// locking.
+func (d *openshiftImageDestination) SupportsBlobLocks() bool {
+	return false
+}
+
+// LockBlob can be used to synchronize operations on it (e.g., copying).
+func (d *openshiftImageDestination) LockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
+// UnlockBlob unlocks the blob.  Note that it is safe to call UnlockBlob()
+// multiple times.  Only the first call is unlocking the blob.  This is
+// required to unlock a blob in the presence of errors or panics during copy
+// operations.
+func (d *openshiftImageDestination) UnlockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
 // PutBlob writes contents of stream and returns data representing the result (with all data filled in).
 // inputInfo.Digest can be optionally provided if known; it is not mandatory for the implementation to verify it.
 // inputInfo.Size is the expected length of stream, if known.

ostree/ostree_dest.go

@@ -137,6 +137,27 @@ func (d *ostreeImageDestination) HasThreadSafePutBlob() bool {
 	return false
 }
 
+// SupportsBlobLocks indicates whether the ImageDestination supports blob
+// locking.
+func (d *ostreeImageDestination) SupportsBlobLocks() bool {
+	return false
+}
+
+// LockBlob can be used to synchronize operations on it (e.g., copying).
+func (d *ostreeImageDestination) LockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
+// UnlockBlob unlocks the blob.  Note that it is safe to call UnlockBlob()
+// multiple times.  Only the first call is unlocking the blob.  This is
+// required to unlock a blob in the presence of errors or panics during copy
+// operations.
+func (d *ostreeImageDestination) UnlockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
 // PutBlob writes contents of stream and returns data representing the result.
 // inputInfo.Digest can be optionally provided if known; it is not mandatory for the implementation to verify it.
 // inputInfo.Size is the expected length of stream, if known.

storage/storage_image.go

@@ -360,6 +360,27 @@ func (s *storageImageDestination) HasThreadSafePutBlob() bool {
 	return true
 }
 
+// SupportsBlobLocks indicates whether the ImageDestination supports blob
+// locking.
+func (d *storageImageDestination) SupportsBlobLocks() bool {
+	return false
+}
+
+// LockBlob can be used to synchronize operations on it (e.g., copying).
+func (s *storageImageDestination) LockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
+// UnlockBlob unlocks the blob.  Note that it is safe to call UnlockBlob()
+// multiple times.  Only the first call is unlocking the blob.  This is
+// required to unlock a blob in the presence of errors or panics during copy
+// operations.
+func (s *storageImageDestination) UnlockBlob(b types.BlobInfo) error {
+	// NOOP for this type.
+	return nil
+}
+
 // PutBlob writes contents of stream and returns data representing the result.
 // inputInfo.Digest can be optionally provided if known; it is not mandatory for the implementation to verify it.
 // inputInfo.Size is the expected length of stream, if known.

types/types.go

@@ -287,6 +287,15 @@ type ImageDestination interface {
 	// - Uploaded data MAY be visible to others before Commit() is called
 	// - Uploaded data MAY be removed or MAY remain around if Close() is called without Commit() (i.e. rollback is allowed but not guaranteed)
 	Commit(ctx context.Context) error
+	// SupportsBlobLocks indicates whether the ImageDestination supports blob locking.
+	SupportsBlobLocks() bool
+	// LockBlob can be used to synchronize operations on it (e.g., copying).
+	LockBlob(BlobInfo) error
+	// UnlockBlob unlocks the blob.  Note that it is safe to call
+	// UnlockBlob() multiple times.  Only the first call is unlocking the
+	// blob.  This is required to unlock a blob in the presence of errors
+	// or panics during copy operations.
+	UnlockBlob(BlobInfo) error
 }
 
 // ManifestTypeRejectedError is returned by ImageDestination.PutManifest if the destination is in principle available,