/
object_manager.go
300 lines (232 loc) · 7.6 KB
/
object_manager.go
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// Package object implements repository support for content-addressable objects of arbitrary size.
package object
import (
"bytes"
"context"
"encoding/json"
"io"
"github.com/pkg/errors"
"github.com/kopia/kopia/internal/buf"
"github.com/kopia/kopia/repo/compression"
"github.com/kopia/kopia/repo/content"
"github.com/kopia/kopia/repo/splitter"
)
// maxCompressionOverheadPerSegment is maximum overhead that compression can incur.
const maxCompressionOverheadPerSegment = 16384
// ErrObjectNotFound is returned when an object cannot be found.
var ErrObjectNotFound = errors.New("object not found")
// Reader allows reading, seeking, getting the length of and closing of a repository object.
type Reader interface {
io.Reader
io.Seeker
io.Closer
Length() int64
}
type contentManager interface {
ContentInfo(ctx context.Context, contentID content.ID) (content.Info, error)
GetContent(ctx context.Context, contentID content.ID) ([]byte, error)
WriteContent(ctx context.Context, data []byte, prefix content.ID) (content.ID, error)
}
// Format describes the format of objects in a repository.
type Format struct {
Splitter string `json:"splitter,omitempty"` // splitter used to break objects into pieces of content
}
// Manager implements a content-addressable storage on top of blob storage.
type Manager struct {
Format Format
contentMgr contentManager
trace func(message string, args ...interface{})
newSplitter splitter.Factory
bufferPool *buf.Pool
}
// NewWriter creates an ObjectWriter for writing to the repository.
func (om *Manager) NewWriter(ctx context.Context, opt WriterOptions) Writer {
w := &objectWriter{
ctx: ctx,
om: om,
splitter: om.newSplitter(),
description: opt.Description,
prefix: opt.Prefix,
compressor: compression.ByName[opt.Compressor],
}
// point the slice at the embedded array, so that we avoid allocations most of the time
w.indirectIndex = w.indirectIndexBuf[:0]
if opt.AsyncWrites > 0 {
w.asyncWritesSemaphore = make(chan struct{}, opt.AsyncWrites)
}
w.initBuffer()
return w
}
// Open creates new ObjectReader for reading given object from a repository.
func (om *Manager) Open(ctx context.Context, objectID ID) (Reader, error) {
return om.openAndAssertLength(ctx, objectID, -1)
}
func (om *Manager) openAndAssertLength(ctx context.Context, objectID ID, assertLength int64) (Reader, error) {
if indexObjectID, ok := objectID.IndexObjectID(); ok {
rd, err := om.Open(ctx, indexObjectID)
if err != nil {
return nil, err
}
defer rd.Close() //nolint:errcheck
seekTable, err := om.flattenListChunk(rd)
if err != nil {
return nil, err
}
totalLength := seekTable[len(seekTable)-1].endOffset()
return &objectReader{
ctx: ctx,
repo: om,
seekTable: seekTable,
totalLength: totalLength,
}, nil
}
return om.newRawReader(ctx, objectID, assertLength)
}
// VerifyObject ensures that all objects backing ObjectID are present in the repository
// and returns the content IDs of which it is composed.
func (om *Manager) VerifyObject(ctx context.Context, oid ID) ([]content.ID, error) {
tracker := &contentIDTracker{}
if err := om.verifyObjectInternal(ctx, oid, tracker); err != nil {
return nil, err
}
return tracker.contentIDs(), nil
}
func (om *Manager) verifyIndirectObjectInternal(ctx context.Context, indexObjectID ID, tracker *contentIDTracker) error {
if err := om.verifyObjectInternal(ctx, indexObjectID, tracker); err != nil {
return errors.Wrap(err, "unable to read index")
}
rd, err := om.Open(ctx, indexObjectID)
if err != nil {
return err
}
defer rd.Close() //nolint:errcheck
seekTable, err := om.flattenListChunk(rd)
if err != nil {
return err
}
for _, m := range seekTable {
err := om.verifyObjectInternal(ctx, m.Object, tracker)
if err != nil {
return err
}
}
return nil
}
func (om *Manager) verifyObjectInternal(ctx context.Context, oid ID, tracker *contentIDTracker) error {
if indexObjectID, ok := oid.IndexObjectID(); ok {
return om.verifyIndirectObjectInternal(ctx, indexObjectID, tracker)
}
if contentID, _, ok := oid.ContentID(); ok {
if _, err := om.contentMgr.ContentInfo(ctx, contentID); err != nil {
return err
}
tracker.addContentID(contentID)
return nil
}
return errors.Errorf("unrecognized object type: %v", oid)
}
func nullTrace(message string, args ...interface{}) {
}
// ManagerOptions specifies object manager options.
type ManagerOptions struct {
Trace func(message string, args ...interface{})
}
// NewObjectManager creates an ObjectManager with the specified content manager and format.
func NewObjectManager(ctx context.Context, bm contentManager, f Format, opts ManagerOptions) (*Manager, error) {
om := &Manager{
contentMgr: bm,
Format: f,
trace: nullTrace,
}
splitterID := f.Splitter
if splitterID == "" {
splitterID = "FIXED"
}
os := splitter.GetFactory(splitterID)
if os == nil {
return nil, errors.Errorf("unsupported splitter %q", f.Splitter)
}
om.newSplitter = splitter.Pooled(os)
om.bufferPool = buf.NewPool(ctx, om.newSplitter().MaxSegmentSize()+maxCompressionOverheadPerSegment, "object-manager")
if opts.Trace != nil {
om.trace = opts.Trace
} else {
om.trace = nullTrace
}
return om, nil
}
// Close closes the object manager.
func (om *Manager) Close() error {
om.bufferPool.Close()
return nil
}
/*
{"stream":"kopia:indirect","entries":[
{"l":1698099,"o":"D13ea27f9ad891ad4a2edfa983906863d"},
{"s":1698099,"l":1302081,"o":"De8ca8327cd3af5f4edbd5ed1009c525e"},
{"s":3000180,"l":4352499,"o":"D6b6eb48ca5361d06d72fe193813e42e1"},
{"s":7352679,"l":1170821,"o":"Dd14653f76b63802ed48be64a0e67fea9"},
{"s":91094118,"l":1645153,"o":"Daa55df764d881a1daadb5ea9de17abbb"}
]}
*/
type indirectObject struct {
StreamID string `json:"stream"`
Entries []indirectObjectEntry `json:"entries"`
}
func (om *Manager) flattenListChunk(rawReader io.Reader) ([]indirectObjectEntry, error) {
var ind indirectObject
if err := json.NewDecoder(rawReader).Decode(&ind); err != nil {
return nil, errors.Wrap(err, "invalid indirect object")
}
return ind.Entries, nil
}
func (om *Manager) newRawReader(ctx context.Context, objectID ID, assertLength int64) (Reader, error) {
if contentID, compressed, ok := objectID.ContentID(); ok {
payload, err := om.contentMgr.GetContent(ctx, contentID)
if err == content.ErrContentNotFound {
return nil, ErrObjectNotFound
}
if err != nil {
return nil, errors.Wrap(err, "unexpected content error")
}
if compressed {
var b bytes.Buffer
if err = om.decompress(&b, payload); err != nil {
return nil, errors.Wrap(err, "decompression error")
}
payload = b.Bytes()
}
if assertLength != -1 && int64(len(payload)) != assertLength {
return nil, errors.Wrapf(err, "unexpected chunk length %v, expected %v", len(payload), assertLength)
}
return newObjectReaderWithData(payload), nil
}
return nil, errors.Errorf("unsupported object ID: %v", objectID)
}
func (om *Manager) decompress(output *bytes.Buffer, b []byte) error {
compressorID, err := compression.IDFromHeader(b)
if err != nil {
return errors.Wrap(err, "invalid compression header")
}
compressor := compression.ByHeaderID[compressorID]
if compressor == nil {
return errors.Errorf("unsupported compressor %x", compressorID)
}
return compressor.Decompress(output, b)
}
type readerWithData struct {
io.ReadSeeker
length int64
}
func (rwd *readerWithData) Close() error {
return nil
}
func (rwd *readerWithData) Length() int64 {
return rwd.length
}
func newObjectReaderWithData(data []byte) Reader {
return &readerWithData{
ReadSeeker: bytes.NewReader(data),
length: int64(len(data)),
}
}