distribution/registry/storage/blobwriter_resumable.go
David Wu a927fbdb9b track digest offset in blobwriter
Signed-off-by: David Wu <david.wu@docker.com>
2018-09-12 14:53:27 -07:00

145 lines
3.4 KiB
Go

// +build !noresumabledigest
package storage
import (
"context"
"encoding"
"fmt"
"hash"
"path"
"strconv"
storagedriver "github.com/docker/distribution/registry/storage/driver"
"github.com/sirupsen/logrus"
)
// resumeDigest attempts to restore the state of the internal hash function
// by loading the most recent saved hash state equal to the current size of the blob.
func (bw *blobWriter) resumeDigest(ctx context.Context) error {
if !bw.resumableDigestEnabled {
return errResumableDigestNotAvailable
}
h, ok := bw.digester.Hash().(encoding.BinaryUnmarshaler)
if !ok {
return errResumableDigestNotAvailable
}
offset := bw.fileWriter.Size()
if offset == bw.written {
// State of digester is already at the requested offset.
return nil
}
// List hash states from storage backend.
var hashStateMatch hashStateEntry
hashStates, err := bw.getStoredHashStates(ctx)
if err != nil {
return fmt.Errorf("unable to get stored hash states with offset %d: %s", offset, err)
}
// Find the highest stored hashState with offset equal to
// the requested offset.
for _, hashState := range hashStates {
if hashState.offset == offset {
hashStateMatch = hashState
break // Found an exact offset match.
}
}
if hashStateMatch.offset == 0 {
// No need to load any state, just reset the hasher.
h.(hash.Hash).Reset()
} else {
storedState, err := bw.driver.GetContent(ctx, hashStateMatch.path)
if err != nil {
return err
}
if err = h.UnmarshalBinary(storedState); err != nil {
return err
}
bw.written = hashStateMatch.offset
}
// Mind the gap.
if gapLen := offset - bw.written; gapLen > 0 {
return errResumableDigestNotAvailable
}
return nil
}
type hashStateEntry struct {
offset int64
path string
}
// getStoredHashStates returns a slice of hashStateEntries for this upload.
func (bw *blobWriter) getStoredHashStates(ctx context.Context) ([]hashStateEntry, error) {
uploadHashStatePathPrefix, err := pathFor(uploadHashStatePathSpec{
name: bw.blobStore.repository.Named().String(),
id: bw.id,
alg: bw.digester.Digest().Algorithm(),
list: true,
})
if err != nil {
return nil, err
}
paths, err := bw.blobStore.driver.List(ctx, uploadHashStatePathPrefix)
if err != nil {
if _, ok := err.(storagedriver.PathNotFoundError); !ok {
return nil, err
}
// Treat PathNotFoundError as no entries.
paths = nil
}
hashStateEntries := make([]hashStateEntry, 0, len(paths))
for _, p := range paths {
pathSuffix := path.Base(p)
// The suffix should be the offset.
offset, err := strconv.ParseInt(pathSuffix, 0, 64)
if err != nil {
logrus.Errorf("unable to parse offset from upload state path %q: %s", p, err)
}
hashStateEntries = append(hashStateEntries, hashStateEntry{offset: offset, path: p})
}
return hashStateEntries, nil
}
func (bw *blobWriter) storeHashState(ctx context.Context) error {
if !bw.resumableDigestEnabled {
return errResumableDigestNotAvailable
}
h, ok := bw.digester.Hash().(encoding.BinaryMarshaler)
if !ok {
return errResumableDigestNotAvailable
}
state, err := h.MarshalBinary()
if err != nil {
return err
}
uploadHashStatePath, err := pathFor(uploadHashStatePathSpec{
name: bw.blobStore.repository.Named().String(),
id: bw.id,
alg: bw.digester.Digest().Algorithm(),
offset: bw.written,
})
if err != nil {
return err
}
return bw.driver.PutContent(ctx, uploadHashStatePath, state)
}