distribution/storage/layer.go
2014-12-23 17:13:02 -08:00

100 lines
2.9 KiB
Go

package storage
import (
"fmt"
"io"
"time"
"github.com/docker/distribution/digest"
)
// Layer provides a readable and seekable layer object. Typically,
// implementations are *not* goroutine safe.
type Layer interface {
// http.ServeContent requires an efficient implementation of
// ReadSeeker.Seek(0, os.SEEK_END).
io.ReadSeeker
io.Closer
// Name returns the repository under which this layer is linked.
Name() string // TODO(stevvooe): struggling with nomenclature: should this be "repo" or "name"?
// Digest returns the unique digest of the blob, which is the tarsum for
// layers.
Digest() digest.Digest
// CreatedAt returns the time this layer was created. Until we implement
// Stat call on storagedriver, this just returns the zero time.
CreatedAt() time.Time
}
// LayerUpload provides a handle for working with in-progress uploads.
// Instances can be obtained from the LayerService.Upload and
// LayerService.Resume.
type LayerUpload interface {
io.WriteCloser
// UUID returns the identifier for this upload.
UUID() string
// Name of the repository under which the layer will be linked.
Name() string
// Offset returns the position of the last byte written to this layer.
Offset() int64
// TODO(stevvooe): Consider completely removing the size check from this
// interface. The digest check may be adequate and we are making it
// optional in the HTTP API.
// Finish marks the upload as completed, returning a valid handle to the
// uploaded layer. The final size and digest are validated against the
// contents of the uploaded layer. If the size is negative, only the
// digest will be checked.
Finish(size int64, digest digest.Digest) (Layer, error)
// Cancel the layer upload process.
Cancel() error
}
var (
// ErrLayerExists returned when layer already exists
ErrLayerExists = fmt.Errorf("layer exists")
// ErrLayerTarSumVersionUnsupported when tarsum is unsupported version.
ErrLayerTarSumVersionUnsupported = fmt.Errorf("unsupported tarsum version")
// ErrLayerUploadUnknown returned when upload is not found.
ErrLayerUploadUnknown = fmt.Errorf("layer upload unknown")
// ErrLayerClosed returned when an operation is attempted on a closed
// Layer or LayerUpload.
ErrLayerClosed = fmt.Errorf("layer closed")
)
// ErrUnknownLayer returned when layer cannot be found.
type ErrUnknownLayer struct {
FSLayer FSLayer
}
func (err ErrUnknownLayer) Error() string {
return fmt.Sprintf("unknown layer %v", err.FSLayer.BlobSum)
}
// ErrLayerInvalidDigest returned when tarsum check fails.
type ErrLayerInvalidDigest struct {
FSLayer FSLayer
}
func (err ErrLayerInvalidDigest) Error() string {
return fmt.Sprintf("invalid digest for referenced layer: %v", err.FSLayer.BlobSum)
}
// ErrLayerInvalidSize returned when length check fails.
type ErrLayerInvalidSize struct {
Size int64
}
func (err ErrLayerInvalidSize) Error() string {
return fmt.Sprintf("invalid layer size: %d", err.Size)
}