frostfs-node/pkg/services/object_manager/transformer/transformer.go

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package transformer
import (
"crypto/sha256"
"fmt"
"hash"
"io"
"github.com/nspcc-dev/neofs-api-go/pkg"
objectSDK "github.com/nspcc-dev/neofs-api-go/pkg/object"
"github.com/nspcc-dev/neofs-node/pkg/core/object"
"github.com/nspcc-dev/tzhash/tz"
"github.com/pkg/errors"
)
type payloadSizeLimiter struct {
maxSize, written uint64
targetInit func() ObjectTarget
target ObjectTarget
current, parent *object.RawObject
currentHashers, parentHashers []*payloadChecksumHasher
previous []*objectSDK.ID
chunkWriter io.Writer
}
type payloadChecksumHasher struct {
hasher hash.Hash
checksumWriter func([]byte)
}
const tzChecksumSize = 64
// NewPayloadSizeLimiter returns ObjectTarget instance that restricts payload length
// of the writing object and writes generated objects to targets from initializer.
//
// Objects w/ payload size less or equal than max size remain untouched.
//
// TODO: describe behavior in details.
func NewPayloadSizeLimiter(maxSize uint64, targetInit TargetInitializer) ObjectTarget {
return &payloadSizeLimiter{
maxSize: maxSize,
targetInit: targetInit,
}
}
func (s *payloadSizeLimiter) WriteHeader(hdr *object.RawObject) error {
s.current = fromObject(hdr)
s.initialize()
return nil
}
func (s *payloadSizeLimiter) Write(p []byte) (int, error) {
if err := s.writeChunk(p); err != nil {
return 0, err
}
return len(p), nil
}
func (s *payloadSizeLimiter) Close() (*AccessIdentifiers, error) {
return s.release(true)
}
func (s *payloadSizeLimiter) initialize() {
// if it is an object after the 1st
if ln := len(s.previous); ln > 0 {
// initialize parent object once (after 1st object)
if ln == 1 {
s.parent = s.current
s.parent.ResetRelations()
s.parentHashers = s.currentHashers
s.current = fromObject(s.parent)
}
// set previous object to the last previous identifier
s.current.SetPreviousID(s.previous[ln-1])
}
s.initializeCurrent()
}
func fromObject(obj *object.RawObject) *object.RawObject {
res := object.NewRaw()
res.SetContainerID(obj.ContainerID())
res.SetOwnerID(obj.OwnerID())
res.SetAttributes(obj.Attributes()...)
res.SetType(obj.Type())
return res
}
func (s *payloadSizeLimiter) initializeCurrent() {
// initialize current object target
s.target = s.targetInit()
// create payload hashers
s.currentHashers = payloadHashersForObject(s.current)
// compose multi-writer from target and all payload hashers
ws := make([]io.Writer, 0, 1+len(s.currentHashers)+len(s.parentHashers))
ws = append(ws, s.target)
for i := range s.currentHashers {
ws = append(ws, s.currentHashers[i].hasher)
}
for i := range s.parentHashers {
ws = append(ws, s.parentHashers[i].hasher)
}
s.chunkWriter = io.MultiWriter(ws...)
}
func payloadHashersForObject(obj *object.RawObject) []*payloadChecksumHasher {
return []*payloadChecksumHasher{
{
hasher: sha256.New(),
checksumWriter: func(cs []byte) {
if ln := len(cs); ln != sha256.Size {
panic(fmt.Sprintf("wrong checksum length: expected %d, has %d", ln, sha256.Size))
}
csSHA := [sha256.Size]byte{}
copy(csSHA[:], cs)
checksum := pkg.NewChecksum()
checksum.SetSHA256(csSHA)
obj.SetPayloadChecksum(checksum)
},
},
{
hasher: tz.New(),
checksumWriter: func(cs []byte) {
if ln := len(cs); ln != tzChecksumSize {
panic(fmt.Sprintf("wrong checksum length: expected %d, has %d", ln, tzChecksumSize))
}
csTZ := [tzChecksumSize]byte{}
copy(csTZ[:], cs)
checksum := pkg.NewChecksum()
checksum.SetTillichZemor(csTZ)
obj.SetPayloadHomomorphicHash(checksum)
},
},
}
}
func (s *payloadSizeLimiter) release(close bool) (*AccessIdentifiers, error) {
// Arg close is true only from Close method.
// We finalize parent and generate linking objects only if it is more
// than 1 object in split-chain.
withParent := close && len(s.previous) > 0
if withParent {
writeHashes(s.parentHashers)
s.parent.SetPayloadSize(s.written)
s.current.SetParent(s.parent.SDK().Object())
}
// release current object
writeHashes(s.currentHashers)
// release current, get its id
if err := s.target.WriteHeader(s.current); err != nil {
return nil, errors.Wrap(err, "could not write header")
}
ids, err := s.target.Close()
if err != nil {
return nil, errors.Wrap(err, "could not close target")
}
// save identifier of the released object
s.previous = append(s.previous, ids.SelfID())
if withParent {
// generate and release linking object
s.initializeLinking()
s.initializeCurrent()
if _, err := s.release(false); err != nil {
return nil, errors.Wrap(err, "could not release linking object")
}
}
return ids, nil
}
func writeHashes(hashers []*payloadChecksumHasher) {
for i := range hashers {
hashers[i].checksumWriter(hashers[i].hasher.Sum(nil))
}
}
func (s *payloadSizeLimiter) initializeLinking() {
id := s.current.ParentID()
s.current = fromObject(s.current)
s.current.SetParentID(id)
s.current.SetChildren(s.previous...)
}
func (s *payloadSizeLimiter) writeChunk(chunk []byte) error {
// statement is true if the previous write of bytes reached exactly the boundary.
if s.written > 0 && s.written%s.maxSize == 0 {
if s.written == s.maxSize {
// initialize blank split header on first object in chain
s.current.InitRelations()
}
// we need to release current object
if _, err := s.release(false); err != nil {
return errors.Wrap(err, "could not release object")
}
// initialize another object
s.initialize()
}
var (
ln = uint64(len(chunk))
cut = ln
leftToEdge = s.maxSize - s.written%s.maxSize
)
// write bytes no further than the boundary of the current object
if ln > leftToEdge {
cut = leftToEdge
}
if _, err := s.chunkWriter.Write(chunk[:cut]); err != nil {
return errors.Wrap(err, "could not write chunk to target")
}
// increase written bytes counter
s.written += cut
// if there are more bytes in buffer we call method again to start filling another object
if ln > leftToEdge {
return s.writeChunk(chunk[cut:])
}
return nil
}