[#291] object: Use PayloadSizeLimiter from SDK

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>
This commit is contained in:
Evgenii Stratonikov 2023-04-27 18:46:42 +03:00
parent 35ea207df6
commit b2ffd7df53
11 changed files with 23 additions and 597 deletions

2
go.mod
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@ -5,7 +5,7 @@ go 1.18
require ( require (
git.frostfs.info/TrueCloudLab/frostfs-api-go/v2 v2.15.1-0.20230418080822-bd44a3f47b85 git.frostfs.info/TrueCloudLab/frostfs-api-go/v2 v2.15.1-0.20230418080822-bd44a3f47b85
git.frostfs.info/TrueCloudLab/frostfs-contract v0.0.0-20230307110621-19a8ef2d02fb git.frostfs.info/TrueCloudLab/frostfs-contract v0.0.0-20230307110621-19a8ef2d02fb
git.frostfs.info/TrueCloudLab/frostfs-sdk-go v0.0.0-20230418145405-db5b89496d68 git.frostfs.info/TrueCloudLab/frostfs-sdk-go v0.0.0-20230503082209-d4fe9a193d1a
git.frostfs.info/TrueCloudLab/hrw v1.2.0 git.frostfs.info/TrueCloudLab/hrw v1.2.0
git.frostfs.info/TrueCloudLab/tzhash v1.8.0 git.frostfs.info/TrueCloudLab/tzhash v1.8.0
github.com/cheggaaa/pb v1.0.29 github.com/cheggaaa/pb v1.0.29

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go.sum

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@ -10,10 +10,10 @@ import (
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object" "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
svcutil "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/util" svcutil "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/util"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/placement" "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/placement"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/transformer"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util" "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger" "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger"
objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object" objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/transformer"
"go.uber.org/zap" "go.uber.org/zap"
) )
@ -206,8 +206,9 @@ func (t *distributedTarget) iteratePlacement(ctx context.Context) (*transformer.
id, _ = t.obj.ID() id, _ = t.obj.ID()
return new(transformer.AccessIdentifiers). return &transformer.AccessIdentifiers{
WithSelfID(id), nil SelfID: id,
}, nil
} }
func (t *distributedTarget) iterateAddresses(ctx context.Context, traverser *placement.Traverser, addrs []placement.Node, resErr *atomic.Value) bool { func (t *distributedTarget) iterateAddresses(ctx context.Context, traverser *placement.Traverser, addrs []placement.Node, resErr *atomic.Value) bool {

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@ -5,9 +5,9 @@ import (
"fmt" "fmt"
objectCore "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object" objectCore "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/transformer"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object" "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id" oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/transformer"
) )
// ObjectStorage is an object storage interface. // ObjectStorage is an object storage interface.
@ -61,6 +61,7 @@ func (t *localTarget) Close(ctx context.Context) (*transformer.AccessIdentifiers
id, _ := t.obj.ID() id, _ := t.obj.ID()
return new(transformer.AccessIdentifiers). return &transformer.AccessIdentifiers{
WithSelfID(id), nil SelfID: id,
}, nil
} }

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@ -10,9 +10,9 @@ import (
objectcore "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object" objectcore "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
internalclient "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/internal/client" internalclient "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/internal/client"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/util" "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/util"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/transformer"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/netmap" "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/netmap"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object" "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/transformer"
) )
type remoteTarget struct { type remoteTarget struct {
@ -68,8 +68,7 @@ func (t *remoteTarget) Close(ctx context.Context) (*transformer.AccessIdentifier
return nil, fmt.Errorf("(%T) could not put object to %s: %w", t, t.nodeInfo.AddressGroup(), err) return nil, fmt.Errorf("(%T) could not put object to %s: %w", t, t.nodeInfo.AddressGroup(), err)
} }
return new(transformer.AccessIdentifiers). return &transformer.AccessIdentifiers{SelfID: res.ID()}, nil
WithSelfID(res.ID()), nil
} }
// NewRemoteSender creates, initializes and returns new RemoteSender instance. // NewRemoteSender creates, initializes and returns new RemoteSender instance.

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@ -10,9 +10,9 @@ import (
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/netmap" "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/netmap"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/util" "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/util"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/placement" "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/placement"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/transformer"
containerSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container" containerSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object" "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/transformer"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/user" "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/user"
) )
@ -126,18 +126,14 @@ func (p *Streamer) initTrustedTarget(prm *PutInitPrm) error {
p.sessionKey = sessionKey p.sessionKey = sessionKey
p.target = &validatingTarget{ p.target = &validatingTarget{
fmt: p.fmtValidator, fmt: p.fmtValidator,
nextTarget: transformer.NewPayloadSizeLimiter( nextTarget: transformer.NewPayloadSizeLimiter(transformer.Params{
p.maxPayloadSz,
containerSDK.IsHomomorphicHashingDisabled(prm.cnr),
func() transformer.ObjectTarget {
return transformer.NewFormatTarget(&transformer.FormatterParams{
Key: sessionKey, Key: sessionKey,
NextTarget: p.newCommonTarget(prm), NextTargetInit: func() transformer.ObjectTarget { return p.newCommonTarget(prm) },
SessionToken: sToken,
NetworkState: p.networkState, NetworkState: p.networkState,
}) MaxSize: p.maxPayloadSz,
}, WithoutHomomorphicHash: containerSDK.IsHomomorphicHashingDisabled(prm.cnr),
), SessionToken: sToken,
}),
} }
return nil return nil
@ -273,7 +269,7 @@ func (p *Streamer) Close(ctx context.Context) (*PutResponse, error) {
return nil, fmt.Errorf("(%T) could not close object target: %w", p, err) return nil, fmt.Errorf("(%T) could not close object target: %w", p, err)
} }
id := ids.ParentID() id := ids.ParentID
if id != nil { if id != nil {
return &PutResponse{ return &PutResponse{
id: *id, id: *id,
@ -281,6 +277,6 @@ func (p *Streamer) Close(ctx context.Context) (*PutResponse, error) {
} }
return &PutResponse{ return &PutResponse{
id: ids.SelfID(), id: ids.SelfID,
}, nil }, nil
} }

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@ -9,9 +9,9 @@ import (
"hash" "hash"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object" "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/transformer"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/checksum" "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/checksum"
objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object" objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/transformer"
"git.frostfs.info/TrueCloudLab/tzhash/tz" "git.frostfs.info/TrueCloudLab/tzhash/tz"
) )

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@ -1,114 +0,0 @@
package transformer
import (
"context"
"crypto/ecdsa"
"fmt"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/netmap"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/session"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/version"
)
type formatter struct {
prm *FormatterParams
obj *object.Object
sz uint64
}
// FormatterParams groups NewFormatTarget parameters.
type FormatterParams struct {
Key *ecdsa.PrivateKey
NextTarget ObjectTarget
SessionToken *session.Object
NetworkState netmap.State
}
// NewFormatTarget returns ObjectTarget instance that finalizes object structure
// and writes it to the next target.
//
// Chunks must be written before the WriteHeader call.
//
// Object changes:
// - sets version to current SDK version;
// - sets payload size to the total length of all written chunks;
// - sets session token;
// - sets number of creation epoch;
// - calculates and sets verification fields (ID, Signature).
func NewFormatTarget(p *FormatterParams) ObjectTarget {
return &formatter{
prm: p,
}
}
func (f *formatter) WriteHeader(_ context.Context, obj *object.Object) error {
f.obj = obj
return nil
}
func (f *formatter) Write(ctx context.Context, p []byte) (n int, err error) {
n, err = f.prm.NextTarget.Write(ctx, p)
f.sz += uint64(n)
return
}
func (f *formatter) Close(ctx context.Context) (*AccessIdentifiers, error) {
curEpoch := f.prm.NetworkState.CurrentEpoch()
ver := version.Current()
f.obj.SetVersion(&ver)
f.obj.SetPayloadSize(f.sz)
f.obj.SetSessionToken(f.prm.SessionToken)
f.obj.SetCreationEpoch(curEpoch)
var (
parID *oid.ID
parHdr *object.Object
)
if par := f.obj.Parent(); par != nil && par.Signature() == nil {
rawPar := object.NewFromV2(par.ToV2())
rawPar.SetSessionToken(f.prm.SessionToken)
rawPar.SetCreationEpoch(curEpoch)
if err := object.SetIDWithSignature(*f.prm.Key, rawPar); err != nil {
return nil, fmt.Errorf("could not finalize parent object: %w", err)
}
id, _ := rawPar.ID()
parID = &id
parHdr = rawPar
f.obj.SetParent(parHdr)
}
if err := object.SetIDWithSignature(*f.prm.Key, f.obj); err != nil {
return nil, fmt.Errorf("could not finalize object: %w", err)
}
if err := f.prm.NextTarget.WriteHeader(ctx, f.obj); err != nil {
return nil, fmt.Errorf("could not write header to next target: %w", err)
}
if _, err := f.prm.NextTarget.Close(ctx); err != nil {
return nil, fmt.Errorf("could not close next target: %w", err)
}
id, _ := f.obj.ID()
return new(AccessIdentifiers).
WithSelfID(id).
WithParentID(parID).
WithParent(parHdr), nil
}

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@ -1,294 +0,0 @@
package transformer
import (
"context"
"crypto/sha256"
"fmt"
"hash"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/checksum"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
"git.frostfs.info/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 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(_ context.Context, hdr *object.Object) error {
s.current = fromObject(hdr)
s.initialize()
return nil
}
func (s *payloadSizeLimiter) Write(ctx context.Context, p []byte) (int, error) {
if err := s.writeChunk(ctx, p); err != nil {
return 0, err
}
return len(p), nil
}
func (s *payloadSizeLimiter) Close(ctx context.Context) (*AccessIdentifiers, error) {
return s.release(ctx, 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([]writer, 0, 1+len(s.currentHashers)+len(s.parentHashers))
ws = append(ws, s.target)
for i := range s.currentHashers {
ws = append(ws, newWriter(s.currentHashers[i].hasher))
}
for i := range s.parentHashers {
ws = append(ws, newWriter(s.parentHashers[i].hasher))
}
s.chunkWriter = newMultiWriter(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(ctx context.Context, 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(ctx, s.current); err != nil {
return nil, fmt.Errorf("could not write header: %w", err)
}
ids, err := s.target.Close(ctx)
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.Parent())
s.initializeCurrent()
if _, err := s.release(ctx, 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(ctx context.Context, 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 {
s.prepareFirstChild()
}
// we need to release current object
if _, err := s.release(ctx, 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(ctx, chunk[:cut]); err != nil {
return fmt.Errorf("could not write chunk to target: %w", err)
}
// 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(ctx, chunk[cut:])
}
return nil
}
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...)
}

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@ -1,111 +0,0 @@
package transformer
import (
"context"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
)
// AccessIdentifiers represents group of the object identifiers
// that are returned after writing the object.
// Consists of the ID of the stored object and the ID of the parent object.
type AccessIdentifiers struct {
par *oid.ID
self oid.ID
parHdr *object.Object
}
// ObjectTarget is an interface of the object writer.
type ObjectTarget interface {
// WriteHeader writes object header w/ payload part.
// The payload of the object may be incomplete.
//
// Must be called exactly once. Control remains with the caller.
// Missing a call or re-calling can lead to undefined behavior
// that depends on the implementation.
//
// Must not be called after Close call.
WriteHeader(context.Context, *object.Object) error
// Write writes object payload chunk.
//
// Can be called multiple times.
//
// Must not be called after Close call.
Write(ctx context.Context, p []byte) (n int, err error)
// Close is used to finish object writing.
//
// Close must return access identifiers of the object
// that has been written.
//
// Must be called no more than once. Control remains with the caller.
// Re-calling can lead to undefined behavior
// that depends on the implementation.
Close(ctx context.Context) (*AccessIdentifiers, error)
}
// TargetInitializer represents ObjectTarget constructor.
type TargetInitializer func() ObjectTarget
// SelfID returns identifier of the written object.
func (a AccessIdentifiers) SelfID() oid.ID {
return a.self
}
// WithSelfID returns AccessIdentifiers with passed self identifier.
func (a *AccessIdentifiers) WithSelfID(v oid.ID) *AccessIdentifiers {
res := a
if res == nil {
res = new(AccessIdentifiers)
}
res.self = v
return res
}
// ParentID return identifier of the parent of the written object.
func (a *AccessIdentifiers) ParentID() *oid.ID {
if a != nil {
return a.par
}
return nil
}
// WithParentID returns AccessIdentifiers with passed parent identifier.
func (a *AccessIdentifiers) WithParentID(v *oid.ID) *AccessIdentifiers {
res := a
if res == nil {
res = new(AccessIdentifiers)
}
res.par = v
return res
}
// Parent return identifier of the parent of the written object.
func (a *AccessIdentifiers) Parent() *object.Object {
if a != nil {
return a.parHdr
}
return nil
}
// WithParent returns AccessIdentifiers with passed parent identifier.
func (a *AccessIdentifiers) WithParent(v *object.Object) *AccessIdentifiers {
res := a
if res == nil {
res = new(AccessIdentifiers)
}
res.parHdr = v
return res
}

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@ -1,52 +0,0 @@
package transformer
import (
"context"
"io"
)
type writer interface {
Write(ctx context.Context, p []byte) (n int, err error)
}
type multiWriter struct {
writers []writer
}
func (t *multiWriter) Write(ctx context.Context, p []byte) (n int, err error) {
for _, w := range t.writers {
n, err = w.Write(ctx, p)
if err != nil {
return
}
if n != len(p) {
err = io.ErrShortWrite
return
}
}
return len(p), nil
}
func newMultiWriter(writers ...writer) writer {
allWriters := make([]writer, 0, len(writers))
for _, w := range writers {
if mw, ok := w.(*multiWriter); ok {
allWriters = append(allWriters, mw.writers...)
} else {
allWriters = append(allWriters, w)
}
}
return &multiWriter{allWriters}
}
type writerWrapper struct {
Writer io.Writer
}
func (w *writerWrapper) Write(_ context.Context, p []byte) (n int, err error) {
return w.Writer.Write(p)
}
func newWriter(w io.Writer) writer {
return &writerWrapper{Writer: w}
}