frostfs-sdk-go/object/transformer/transformer.go
Evgenii Stratonikov b696d3c70e [#19] transformer: Make writeChunk non-recursive
Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>
2023-03-15 05:39:09 +00:00

295 lines
7.1 KiB
Go

package transformer
import (
"crypto/sha256"
"fmt"
"hash"
"io"
"github.com/TrueCloudLab/frostfs-sdk-go/checksum"
"github.com/TrueCloudLab/frostfs-sdk-go/object"
oid "github.com/TrueCloudLab/frostfs-sdk-go/object/id"
"github.com/TrueCloudLab/tzhash/tz"
)
type payloadSizeLimiter struct {
maxSize, written uint64
withoutHomomorphicHash bool
targetInit func() ObjectTarget
target ObjectTarget
current, parent *object.Object
currentHashers, parentHashers []*payloadChecksumHasher
previous []oid.ID
chunkWriter io.Writer
splitID *object.SplitID
parAttrs []object.Attribute
}
type payloadChecksumHasher struct {
hasher hash.Hash
checksumWriter func([]byte)
}
// NewPayloadSizeLimiter returns ObjectTarget instance that restricts payload length
// of the writing object and writes generated objects to targets from initializer.
//
// Calculates and adds homomorphic hash to resulting objects only if withoutHomomorphicHash
// is false.
//
// Objects w/ payload size less or equal than max size remain untouched.
func NewPayloadSizeLimiter(maxSize uint64, withoutHomomorphicHash bool, targetInit TargetInitializer) ObjectTarget {
return &payloadSizeLimiter{
maxSize: maxSize,
withoutHomomorphicHash: withoutHomomorphicHash,
targetInit: targetInit,
splitID: object.NewSplitID(),
}
}
func (s *payloadSizeLimiter) WriteHeader(hdr *object.Object) 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.detachParent()
}
// set previous object to the last previous identifier
s.current.SetPreviousID(s.previous[ln-1])
}
s.initializeCurrent()
}
func fromObject(obj *object.Object) *object.Object {
cnr, _ := obj.ContainerID()
res := object.New()
res.SetContainerID(cnr)
res.SetOwnerID(obj.OwnerID())
res.SetAttributes(obj.Attributes()...)
res.SetType(obj.Type())
// obj.SetSplitID creates splitHeader but we don't need to do it in case
// of small objects, so we should make nil check.
if obj.SplitID() != nil {
res.SetSplitID(obj.SplitID())
}
return res
}
func (s *payloadSizeLimiter) initializeCurrent() {
// initialize current object target
s.target = s.targetInit()
// create payload hashers
s.currentHashers = payloadHashersForObject(s.current, s.withoutHomomorphicHash)
// 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.Object, withoutHomomorphicHash bool) []*payloadChecksumHasher {
hashers := make([]*payloadChecksumHasher, 0, 2)
hashers = append(hashers, &payloadChecksumHasher{
hasher: sha256.New(),
checksumWriter: func(binChecksum []byte) {
if ln := len(binChecksum); ln != sha256.Size {
panic(fmt.Sprintf("wrong checksum length: expected %d, has %d", sha256.Size, ln))
}
csSHA := [sha256.Size]byte{}
copy(csSHA[:], binChecksum)
var cs checksum.Checksum
cs.SetSHA256(csSHA)
obj.SetPayloadChecksum(cs)
},
})
if !withoutHomomorphicHash {
hashers = append(hashers, &payloadChecksumHasher{
hasher: tz.New(),
checksumWriter: func(binChecksum []byte) {
if ln := len(binChecksum); ln != tz.Size {
panic(fmt.Sprintf("wrong checksum length: expected %d, has %d", tz.Size, ln))
}
csTZ := [tz.Size]byte{}
copy(csTZ[:], binChecksum)
var cs checksum.Checksum
cs.SetTillichZemor(csTZ)
obj.SetPayloadHomomorphicHash(cs)
},
})
}
return hashers
}
func (s *payloadSizeLimiter) release(finalize bool) (*AccessIdentifiers, error) {
// Arg finalize is true only when called from Close method.
// We finalize parent and generate linking objects only if it is more
// than 1 object in split-chain.
withParent := finalize && len(s.previous) > 0
if withParent {
writeHashes(s.parentHashers)
s.parent.SetPayloadSize(s.written)
s.current.SetParent(s.parent)
}
// release current object
writeHashes(s.currentHashers)
// release current, get its id
if err := s.target.WriteHeader(s.current); err != nil {
return nil, fmt.Errorf("could not write header: %w", err)
}
ids, err := s.target.Close()
if err != nil {
return nil, fmt.Errorf("could not close target: %w", err)
}
// save identifier of the released object
s.previous = append(s.previous, ids.SelfID)
if withParent {
// generate and release linking object
s.initializeLinking(ids.ParentHeader)
s.initializeCurrent()
if _, err := s.release(false); err != nil {
return nil, fmt.Errorf("could not release linking object: %w", err)
}
}
return ids, nil
}
func writeHashes(hashers []*payloadChecksumHasher) {
for i := range hashers {
hashers[i].checksumWriter(hashers[i].hasher.Sum(nil))
}
}
func (s *payloadSizeLimiter) initializeLinking(parHdr *object.Object) {
s.current = fromObject(s.current)
s.current.SetParent(parHdr)
s.current.SetChildren(s.previous...)
s.current.SetSplitID(s.splitID)
}
func (s *payloadSizeLimiter) writeChunk(chunk []byte) error {
for {
// 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 {
s.prepareFirstChild()
}
// we need to release current object
if _, err := s.release(false); err != nil {
return fmt.Errorf("could not release object: %w", err)
}
// 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 fmt.Errorf("could not write chunk to target: %w", err)
}
// increase written bytes counter
s.written += cut
if cut == ln {
return nil
}
// if there are more bytes in buffer we call method again to start filling another object
chunk = chunk[cut:]
}
}
func (s *payloadSizeLimiter) prepareFirstChild() {
// initialize split header with split ID on first object in chain
s.current.InitRelations()
s.current.SetSplitID(s.splitID)
// cut source attributes
s.parAttrs = s.current.Attributes()
s.current.SetAttributes()
// attributes will be added to parent in detachParent
}
func (s *payloadSizeLimiter) detachParent() {
s.parent = s.current
s.current = fromObject(s.parent)
s.parent.ResetRelations()
s.parent.SetSignature(nil)
s.parentHashers = s.currentHashers
// return source attributes
s.parent.SetAttributes(s.parAttrs...)
}