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Remove digest package's dependency on external sha implementation

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The change relies on a refactor of the upstream resumable sha256/sha512 package
that opts to register implementations with the standard library. This allows
the resumable support to be detected where it matters, avoiding unnecessary and
complex code. It also ensures that consumers of the digest package don't need
to depend on the forked sha implementations.

We also get an optimization with this change. If the size of data written to a
digester is the same as the file size, we check to see if the digest has been
verified. This works if the blob is written and committed in a single request.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
This commit is contained in:
Stephen J Day 2015-05-20 23:44:08 -07:00
parent fd982a8bd5
commit a0d242d9df
6 changed files with 269 additions and 226 deletions
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2
docs/client/repository.go
View file

@ -322,7 +322,7 @@ func (bs *blobs) Put(ctx context.Context, mediaType string, p []byte) (distribut
return distribution.Descriptor{}, err
}
dgstr := digest.NewCanonicalDigester()
n, err := io.Copy(writer, io.TeeReader(bytes.NewReader(p), dgstr))
n, err := io.Copy(writer, io.TeeReader(bytes.NewReader(p), dgstr.Hash()))
if err != nil {
return distribution.Descriptor{}, err
}

6
docs/handlers/api_test.go
View file

@ -214,7 +214,7 @@ func TestBlobAPI(t *testing.T) {
layerFile.Seek(0, 0)
canonicalDigester := digest.NewCanonicalDigester()
if _, err := io.Copy(canonicalDigester, layerFile); err != nil {
if _, err := io.Copy(canonicalDigester.Hash(), layerFile); err != nil {
t.Fatalf("error copying to digest: %v", err)
}
canonicalDigest := canonicalDigester.Digest()
@ -639,7 +639,7 @@ func doPushLayer(t *testing.T, ub *v2.URLBuilder, name string, dgst digest.Diges
func pushLayer(t *testing.T, ub *v2.URLBuilder, name string, dgst digest.Digest, uploadURLBase string, body io.Reader) string {
digester := digest.NewCanonicalDigester()
resp, err := doPushLayer(t, ub, name, dgst, uploadURLBase, io.TeeReader(body, &digester))
resp, err := doPushLayer(t, ub, name, dgst, uploadURLBase, io.TeeReader(body, digester.Hash()))
if err != nil {
t.Fatalf("unexpected error doing push layer request: %v", err)
}
@ -704,7 +704,7 @@ func doPushChunk(t *testing.T, uploadURLBase string, body io.Reader) (*http.Resp
digester := digest.NewCanonicalDigester()
req, err := http.NewRequest("PATCH", uploadURL, io.TeeReader(body, digester))
req, err := http.NewRequest("PATCH", uploadURL, io.TeeReader(body, digester.Hash()))
if err != nil {
t.Fatalf("unexpected error creating new request: %v", err)
}

275
docs/storage/blobwriter.go
View file

@ -3,9 +3,6 @@ package storage
import (
"fmt"
"io"
"os"
"path"
"strconv"
"time"
"github.com/Sirupsen/logrus"
@ -15,14 +12,19 @@ import (
storagedriver "github.com/docker/distribution/registry/storage/driver"
)
var (
errResumableDigestNotAvailable = fmt.Errorf("resumable digest not available")
)
// layerWriter is used to control the various aspects of resumable
// layer upload. It implements the LayerUpload interface.
type blobWriter struct {
blobStore *linkedBlobStore
id string
startedAt time.Time
resumableDigester digest.ResumableDigester
id string
startedAt time.Time
digester digest.Digester
written int64 // track the contiguous write
// implementes io.WriteSeeker, io.ReaderFrom and io.Closer to satisfy
// LayerUpload Interface
@ -82,33 +84,31 @@ func (bw *blobWriter) Cancel(ctx context.Context) error {
}
func (bw *blobWriter) Write(p []byte) (int, error) {
if bw.resumableDigester == nil {
return bw.bufferedFileWriter.Write(p)
}
// Ensure that the current write offset matches how many bytes have been
// written to the digester. If not, we need to update the digest state to
// match the current write position.
if err := bw.resumeHashAt(bw.blobStore.ctx, bw.offset); err != nil {
if err := bw.resumeDigestAt(bw.blobStore.ctx, bw.offset); err != nil && err != errResumableDigestNotAvailable {
return 0, err
}
return io.MultiWriter(&bw.bufferedFileWriter, bw.resumableDigester).Write(p)
n, err := io.MultiWriter(&bw.bufferedFileWriter, bw.digester.Hash()).Write(p)
bw.written += int64(n)
return n, err
}
func (bw *blobWriter) ReadFrom(r io.Reader) (n int64, err error) {
if bw.resumableDigester == nil {
return bw.bufferedFileWriter.ReadFrom(r)
}
// Ensure that the current write offset matches how many bytes have been
// written to the digester. If not, we need to update the digest state to
// match the current write position.
if err := bw.resumeHashAt(bw.blobStore.ctx, bw.offset); err != nil {
if err := bw.resumeDigestAt(bw.blobStore.ctx, bw.offset); err != nil && err != errResumableDigestNotAvailable {
return 0, err
}
return bw.bufferedFileWriter.ReadFrom(io.TeeReader(r, bw.resumableDigester))
nn, err := bw.bufferedFileWriter.ReadFrom(io.TeeReader(r, bw.digester.Hash()))
bw.written += nn
return nn, err
}
func (bw *blobWriter) Close() error {
@ -116,10 +116,8 @@ func (bw *blobWriter) Close() error {
return bw.err
}
if bw.resumableDigester != nil {
if err := bw.storeHashState(bw.blobStore.ctx); err != nil {
return err
}
if err := bw.storeHashState(bw.blobStore.ctx); err != nil {
return err
}
return bw.bufferedFileWriter.Close()
@ -171,13 +169,11 @@ func (bw *blobWriter) validateBlob(ctx context.Context, desc distribution.Descri
desc.Length = bw.size
}
if bw.resumableDigester != nil {
// Restore the hasher state to the end of the upload.
if err := bw.resumeHashAt(ctx, bw.size); err != nil {
return distribution.Descriptor{}, err
}
// TODO(stevvooe): This section is very meandering. Need to be broken down
// to be a lot more clear.
canonical = bw.resumableDigester.Digest()
if err := bw.resumeDigestAt(ctx, bw.size); err == nil {
canonical = bw.digester.Digest()
if canonical.Algorithm() == desc.Digest.Algorithm() {
// Common case: client and server prefer the same canonical digest
@ -189,33 +185,49 @@ func (bw *blobWriter) validateBlob(ctx context.Context, desc distribution.Descri
// uploaded content using that digest algorithm.
fullHash = true
}
} else {
} else if err == errResumableDigestNotAvailable {
// Not using resumable digests, so we need to hash the entire layer.
fullHash = true
} else {
return distribution.Descriptor{}, err
}
if fullHash {
digester := digest.NewCanonicalDigester()
digestVerifier, err := digest.NewDigestVerifier(desc.Digest)
if err != nil {
return distribution.Descriptor{}, err
// a fantastic optimization: if the the written data and the size are
// the same, we don't need to read the data from the backend. This is
// because we've written the entire file in the lifecycle of the
// current instance.
if bw.written == bw.size && digest.CanonicalAlgorithm == desc.Digest.Algorithm() {
canonical = bw.digester.Digest()
verified = desc.Digest == canonical
}
// Read the file from the backend driver and validate it.
fr, err := newFileReader(ctx, bw.bufferedFileWriter.driver, bw.path, desc.Length)
if err != nil {
return distribution.Descriptor{}, err
// If the check based on size fails, we fall back to the slowest of
// paths. We may be able to make the size-based check a stronger
// guarantee, so this may be defensive.
if !verified {
digester := digest.NewCanonicalDigester()
digestVerifier, err := digest.NewDigestVerifier(desc.Digest)
if err != nil {
return distribution.Descriptor{}, err
}
// Read the file from the backend driver and validate it.
fr, err := newFileReader(ctx, bw.bufferedFileWriter.driver, bw.path, desc.Length)
if err != nil {
return distribution.Descriptor{}, err
}
tr := io.TeeReader(fr, digester.Hash())
if _, err := io.Copy(digestVerifier, tr); err != nil {
return distribution.Descriptor{}, err
}
canonical = digester.Digest()
verified = digestVerifier.Verified()
}
tr := io.TeeReader(fr, digester)
if _, err := io.Copy(digestVerifier, tr); err != nil {
return distribution.Descriptor{}, err
}
canonical = digester.Digest()
verified = digestVerifier.Verified()
}
if !verified {
@ -298,172 +310,3 @@ func (bw *blobWriter) moveBlob(ctx context.Context, desc distribution.Descriptor
return bw.blobStore.driver.Move(ctx, bw.path, blobPath)
}
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 := bw.blobStore.pm.path(uploadHashStatePathSpec{
name: bw.blobStore.repository.Name(),
id: bw.id,
alg: bw.resumableDigester.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
}
// resumeHashAt attempts to restore the state of the internal hash function
// by loading the most recent saved hash state less than or equal to the given
// offset. Any unhashed bytes remaining less than the given offset are hashed
// from the content uploaded so far.
func (bw *blobWriter) resumeHashAt(ctx context.Context, offset int64) error {
if offset < 0 {
return fmt.Errorf("cannot resume hash at negative offset: %d", offset)
}
if offset == int64(bw.resumableDigester.Len()) {
// 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 less than or equal to
// the requested offset.
for _, hashState := range hashStates {
if hashState.offset == offset {
hashStateMatch = hashState
break // Found an exact offset match.
} else if hashState.offset < offset && hashState.offset > hashStateMatch.offset {
// This offset is closer to the requested offset.
hashStateMatch = hashState
} else if hashState.offset > offset {
// Remove any stored hash state with offsets higher than this one
// as writes to this resumed hasher will make those invalid. This
// is probably okay to skip for now since we don't expect anyone to
// use the API in this way. For that reason, we don't treat an
// an error here as a fatal error, but only log it.
if err := bw.driver.Delete(ctx, hashState.path); err != nil {
logrus.Errorf("unable to delete stale hash state %q: %s", hashState.path, err)
}
}
}
if hashStateMatch.offset == 0 {
// No need to load any state, just reset the hasher.
bw.resumableDigester.Reset()
} else {
storedState, err := bw.driver.GetContent(ctx, hashStateMatch.path)
if err != nil {
return err
}
if err = bw.resumableDigester.Restore(storedState); err != nil {
return err
}
}
// Mind the gap.
if gapLen := offset - int64(bw.resumableDigester.Len()); gapLen > 0 {
// Need to read content from the upload to catch up to the desired offset.
fr, err := newFileReader(ctx, bw.driver, bw.path, bw.size)
if err != nil {
return err
}
if _, err = fr.Seek(int64(bw.resumableDigester.Len()), os.SEEK_SET); err != nil {
return fmt.Errorf("unable to seek to layer reader offset %d: %s", bw.resumableDigester.Len(), err)
}
if _, err := io.CopyN(bw.resumableDigester, fr, gapLen); err != nil {
return err
}
}
return nil
}
func (bw *blobWriter) storeHashState(ctx context.Context) error {
uploadHashStatePath, err := bw.blobStore.pm.path(uploadHashStatePathSpec{
name: bw.blobStore.repository.Name(),
id: bw.id,
alg: bw.resumableDigester.Digest().Algorithm(),
offset: int64(bw.resumableDigester.Len()),
})
if err != nil {
return err
}
hashState, err := bw.resumableDigester.State()
if err != nil {
return err
}
return bw.driver.PutContent(ctx, uploadHashStatePath, hashState)
}
// removeResources should clean up all resources associated with the upload
// instance. An error will be returned if the clean up cannot proceed. If the
// resources are already not present, no error will be returned.
func (bw *blobWriter) removeResources(ctx context.Context) error {
dataPath, err := bw.blobStore.pm.path(uploadDataPathSpec{
name: bw.blobStore.repository.Name(),
id: bw.id,
})
if err != nil {
return err
}
// Resolve and delete the containing directory, which should include any
// upload related files.
dirPath := path.Dir(dataPath)
if err := bw.blobStore.driver.Delete(ctx, dirPath); err != nil {
switch err := err.(type) {
case storagedriver.PathNotFoundError:
break // already gone!
default:
// This should be uncommon enough such that returning an error
// should be okay. At this point, the upload should be mostly
// complete, but perhaps the backend became unaccessible.
context.GetLogger(ctx).Errorf("unable to delete layer upload resources %q: %v", dirPath, err)
return err
}
}
return nil
}

13
docs/storage/blobwriter_nonresumable.go
View file

@ -2,5 +2,16 @@
package storage
func (bw *blobWriter) setupResumableDigester() {
import (
"github.com/docker/distribution/context"
)
// resumeHashAt is a noop when resumable digest support is disabled.
func (bw *blobWriter) resumeDigestAt(ctx context.Context, offset int64) error {
return errResumableDigestNotAvailable
}
// storeHashState is a noop when resumable digest support is disabled.
func (bw *blobWriter) storeHashState(ctx context.Context) error {
return errResumableDigestNotAvailable
}

196
docs/storage/blobwriter_resumable.go
View file

@ -2,8 +2,198 @@
package storage
import "github.com/docker/distribution/digest"
import (
"fmt"
"io"
"os"
"path"
"strconv"
func (bw *blobWriter) setupResumableDigester() {
bw.resumableDigester = digest.NewCanonicalResumableDigester()
"github.com/Sirupsen/logrus"
"github.com/docker/distribution/context"
storagedriver "github.com/docker/distribution/registry/storage/driver"
"github.com/stevvooe/resumable"
// register resumable hashes with import
_ "github.com/stevvooe/resumable/sha256"
_ "github.com/stevvooe/resumable/sha512"
)
// resumeDigestAt attempts to restore the state of the internal hash function
// by loading the most recent saved hash state less than or equal to the given
// offset. Any unhashed bytes remaining less than the given offset are hashed
// from the content uploaded so far.
func (bw *blobWriter) resumeDigestAt(ctx context.Context, offset int64) error {
if offset < 0 {
return fmt.Errorf("cannot resume hash at negative offset: %d", offset)
}
h, ok := bw.digester.Hash().(resumable.Hash)
if !ok {
return errResumableDigestNotAvailable
}
if offset == int64(h.Len()) {
// 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 less than or equal to
// the requested offset.
for _, hashState := range hashStates {
if hashState.offset == offset {
hashStateMatch = hashState
break // Found an exact offset match.
} else if hashState.offset < offset && hashState.offset > hashStateMatch.offset {
// This offset is closer to the requested offset.
hashStateMatch = hashState
} else if hashState.offset > offset {
// Remove any stored hash state with offsets higher than this one
// as writes to this resumed hasher will make those invalid. This
// is probably okay to skip for now since we don't expect anyone to
// use the API in this way. For that reason, we don't treat an
// an error here as a fatal error, but only log it.
if err := bw.driver.Delete(ctx, hashState.path); err != nil {
logrus.Errorf("unable to delete stale hash state %q: %s", hashState.path, err)
}
}
}
if hashStateMatch.offset == 0 {
// No need to load any state, just reset the hasher.
h.Reset()
} else {
storedState, err := bw.driver.GetContent(ctx, hashStateMatch.path)
if err != nil {
return err
}
if err = h.Restore(storedState); err != nil {
return err
}
}
// Mind the gap.
if gapLen := offset - int64(h.Len()); gapLen > 0 {
// Need to read content from the upload to catch up to the desired offset.
fr, err := newFileReader(ctx, bw.driver, bw.path, bw.size)
if err != nil {
return err
}
if _, err = fr.Seek(int64(h.Len()), os.SEEK_SET); err != nil {
return fmt.Errorf("unable to seek to layer reader offset %d: %s", h.Len(), err)
}
if _, err := io.CopyN(h, fr, gapLen); err != nil {
return err
}
}
return nil
}
// removeResources should clean up all resources associated with the upload
// instance. An error will be returned if the clean up cannot proceed. If the
// resources are already not present, no error will be returned.
func (bw *blobWriter) removeResources(ctx context.Context) error {
dataPath, err := bw.blobStore.pm.path(uploadDataPathSpec{
name: bw.blobStore.repository.Name(),
id: bw.id,
})
if err != nil {
return err
}
// Resolve and delete the containing directory, which should include any
// upload related files.
dirPath := path.Dir(dataPath)
if err := bw.blobStore.driver.Delete(ctx, dirPath); err != nil {
switch err := err.(type) {
case storagedriver.PathNotFoundError:
break // already gone!
default:
// This should be uncommon enough such that returning an error
// should be okay. At this point, the upload should be mostly
// complete, but perhaps the backend became unaccessible.
context.GetLogger(ctx).Errorf("unable to delete layer upload resources %q: %v", dirPath, err)
return err
}
}
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 := bw.blobStore.pm.path(uploadHashStatePathSpec{
name: bw.blobStore.repository.Name(),
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 {
h, ok := bw.digester.Hash().(resumable.Hash)
if !ok {
return errResumableDigestNotAvailable
}
uploadHashStatePath, err := bw.blobStore.pm.path(uploadHashStatePathSpec{
name: bw.blobStore.repository.Name(),
id: bw.id,
alg: bw.digester.Digest().Algorithm(),
offset: int64(h.Len()),
})
if err != nil {
return err
}
hashState, err := h.State()
if err != nil {
return err
}
return bw.driver.PutContent(ctx, uploadHashStatePath, hashState)
}

3
docs/storage/linkedblobstore.go
View file

@ -164,11 +164,10 @@ func (lbs *linkedBlobStore) newBlobUpload(ctx context.Context, uuid, path string
blobStore: lbs,
id: uuid,
startedAt: startedAt,
digester: digest.NewCanonicalDigester(),
bufferedFileWriter: *fw,
}
bw.setupResumableDigester()
return bw, nil
}