distribution/docs/storage/layerstore.go

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package storage
import (
"time"
"code.google.com/p/go-uuid/uuid"
ctxu "github.com/docker/distribution/context"
"github.com/docker/distribution/digest"
"github.com/docker/distribution/manifest"
storagedriver "github.com/docker/distribution/registry/storage/driver"
)
type layerStore struct {
repository *repository
}
func (ls *layerStore) Exists(digest digest.Digest) (bool, error) {
ctxu.GetLogger(ls.repository.ctx).Debug("(*layerStore).Exists")
// Because this implementation just follows blob links, an existence check
// is pretty cheap by starting and closing a fetch.
_, err := ls.Fetch(digest)
if err != nil {
switch err.(type) {
case ErrUnknownLayer:
return false, nil
}
return false, err
}
return true, nil
}
func (ls *layerStore) Fetch(dgst digest.Digest) (Layer, error) {
ctxu.GetLogger(ls.repository.ctx).Debug("(*layerStore).Fetch")
bp, err := ls.path(dgst)
if err != nil {
return nil, err
}
fr, err := newFileReader(ls.repository.driver, bp)
if err != nil {
return nil, err
}
return &layerReader{
fileReader: *fr,
name: ls.repository.Name(),
digest: dgst,
}, nil
}
// Upload begins a layer upload, returning a handle. If the layer upload
// is already in progress or the layer has already been uploaded, this
// will return an error.
func (ls *layerStore) Upload() (LayerUpload, error) {
ctxu.GetLogger(ls.repository.ctx).Debug("(*layerStore).Upload")
// NOTE(stevvooe): Consider the issues with allowing concurrent upload of
// the same two layers. Should it be disallowed? For now, we allow both
// parties to proceed and the the first one uploads the layer.
uuid := uuid.New()
startedAt := time.Now().UTC()
path, err := ls.repository.registry.pm.path(uploadDataPathSpec{
name: ls.repository.Name(),
uuid: uuid,
})
if err != nil {
return nil, err
}
startedAtPath, err := ls.repository.registry.pm.path(uploadStartedAtPathSpec{
name: ls.repository.Name(),
uuid: uuid,
})
if err != nil {
return nil, err
}
// Write a startedat file for this upload
if err := ls.repository.driver.PutContent(startedAtPath, []byte(startedAt.Format(time.RFC3339))); err != nil {
return nil, err
}
return ls.newLayerUpload(uuid, path, startedAt)
}
// Resume continues an in progress layer upload, returning the current
// state of the upload.
func (ls *layerStore) Resume(uuid string) (LayerUpload, error) {
ctxu.GetLogger(ls.repository.ctx).Debug("(*layerStore).Resume")
startedAtPath, err := ls.repository.registry.pm.path(uploadStartedAtPathSpec{
name: ls.repository.Name(),
uuid: uuid,
})
if err != nil {
return nil, err
}
startedAtBytes, err := ls.repository.driver.GetContent(startedAtPath)
if err != nil {
switch err := err.(type) {
case storagedriver.PathNotFoundError:
return nil, ErrLayerUploadUnknown
default:
return nil, err
}
}
startedAt, err := time.Parse(time.RFC3339, string(startedAtBytes))
if err != nil {
return nil, err
}
path, err := ls.repository.pm.path(uploadDataPathSpec{
name: ls.repository.Name(),
uuid: uuid,
})
if err != nil {
return nil, err
}
return ls.newLayerUpload(uuid, path, startedAt)
}
// newLayerUpload allocates a new upload controller with the given state.
func (ls *layerStore) newLayerUpload(uuid, path string, startedAt time.Time) (LayerUpload, error) {
fw, err := newFileWriter(ls.repository.driver, path)
if err != nil {
return nil, err
}
return &layerUploadController{
layerStore: ls,
uuid: uuid,
startedAt: startedAt,
fileWriter: *fw,
}, nil
}
func (ls *layerStore) path(dgst digest.Digest) (string, error) {
// We must traverse this path through the link to enforce ownership.
layerLinkPath, err := ls.repository.registry.pm.path(layerLinkPathSpec{name: ls.repository.Name(), digest: dgst})
if err != nil {
return "", err
}
blobPath, err := ls.repository.blobStore.resolve(layerLinkPath)
if err != nil {
switch err := err.(type) {
case storagedriver.PathNotFoundError:
return "", ErrUnknownLayer{manifest.FSLayer{BlobSum: dgst}}
default:
return "", err
}
}
return blobPath, nil
}