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restic/internal/index/index.go
2018-10-28 12:58:34 +01:00

407 lines
9.3 KiB
Go

// Package index contains various data structures for indexing content in a repository or backend.
package index
import (
"context"
"fmt"
"os"
"sync"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/pack"
"github.com/restic/restic/internal/restic"
"golang.org/x/sync/errgroup"
)
// Pack contains information about the contents of a pack.
type Pack struct {
ID restic.ID
Size int64
Entries []restic.Blob
}
// Index contains information about blobs and packs stored in a repo.
type Index struct {
Packs map[restic.ID]Pack
IndexIDs restic.IDSet
}
func newIndex() *Index {
return &Index{
Packs: make(map[restic.ID]Pack),
IndexIDs: restic.NewIDSet(),
}
}
const listPackWorkers = 10
// Lister lists files and their contents
type Lister interface {
// List runs fn for all files of type t in the repo.
List(ctx context.Context, t restic.FileType, fn func(restic.ID, int64) error) error
// ListPack returns the list of blobs saved in the pack id and the length
// of the file as stored in the backend.
ListPack(ctx context.Context, id restic.ID, size int64) ([]restic.Blob, int64, error)
}
// New creates a new index for repo from scratch. InvalidFiles contains all IDs
// of files that cannot be listed successfully.
func New(ctx context.Context, repo Lister, ignorePacks restic.IDSet, p *restic.Progress) (idx *Index, invalidFiles restic.IDs, err error) {
p.Start()
defer p.Done()
type Job struct {
PackID restic.ID
Size int64
}
type Result struct {
Error error
PackID restic.ID
Size int64
Entries []restic.Blob
}
inputCh := make(chan Job)
outputCh := make(chan Result)
wg, ctx := errgroup.WithContext(ctx)
// list the files in the repo, send to inputCh
wg.Go(func() error {
defer close(inputCh)
return repo.List(ctx, restic.DataFile, func(id restic.ID, size int64) error {
if ignorePacks.Has(id) {
return nil
}
job := Job{
PackID: id,
Size: size,
}
select {
case inputCh <- job:
case <-ctx.Done():
}
return nil
})
})
// run the workers listing the files, read from inputCh, send to outputCh
var workers sync.WaitGroup
for i := 0; i < listPackWorkers; i++ {
workers.Add(1)
go func() {
defer workers.Done()
for job := range inputCh {
res := Result{PackID: job.PackID}
res.Entries, res.Size, res.Error = repo.ListPack(ctx, job.PackID, job.Size)
select {
case outputCh <- res:
case <-ctx.Done():
return
}
}
}()
}
// wait until all the workers are done, then close outputCh
wg.Go(func() error {
workers.Wait()
close(outputCh)
return nil
})
idx = newIndex()
for res := range outputCh {
p.Report(restic.Stat{Blobs: 1})
if res.Error != nil {
cause := errors.Cause(res.Error)
if _, ok := cause.(pack.InvalidFileError); ok {
invalidFiles = append(invalidFiles, res.PackID)
continue
}
fmt.Fprintf(os.Stderr, "pack file cannot be listed %v: %v\n", res.PackID, res.Error)
continue
}
debug.Log("pack %v contains %d blobs", res.PackID, len(res.Entries))
err := idx.AddPack(res.PackID, res.Size, res.Entries)
if err != nil {
return nil, nil, err
}
select {
case <-ctx.Done(): // an error occurred
default:
}
}
err = wg.Wait()
if err != nil {
return nil, nil, err
}
return idx, invalidFiles, nil
}
type packJSON struct {
ID restic.ID `json:"id"`
Blobs []blobJSON `json:"blobs"`
}
type blobJSON struct {
ID restic.ID `json:"id"`
Type restic.BlobType `json:"type"`
Offset uint `json:"offset"`
Length uint `json:"length"`
}
type indexJSON struct {
Supersedes restic.IDs `json:"supersedes,omitempty"`
Packs []packJSON `json:"packs"`
}
// ListLoader allows listing files and their content, in addition to loading and unmarshaling JSON files.
type ListLoader interface {
Lister
LoadJSONUnpacked(context.Context, restic.FileType, restic.ID, interface{}) error
}
func loadIndexJSON(ctx context.Context, repo ListLoader, id restic.ID) (*indexJSON, error) {
debug.Log("process index %v\n", id)
var idx indexJSON
err := repo.LoadJSONUnpacked(ctx, restic.IndexFile, id, &idx)
if err != nil {
return nil, err
}
return &idx, nil
}
// Load creates an index by loading all index files from the repo.
func Load(ctx context.Context, repo ListLoader, p *restic.Progress) (*Index, error) {
debug.Log("loading indexes")
p.Start()
defer p.Done()
supersedes := make(map[restic.ID]restic.IDSet)
results := make(map[restic.ID]map[restic.ID]Pack)
index := newIndex()
err := repo.List(ctx, restic.IndexFile, func(id restic.ID, size int64) error {
p.Report(restic.Stat{Blobs: 1})
debug.Log("Load index %v", id)
idx, err := loadIndexJSON(ctx, repo, id)
if err != nil {
return err
}
res := make(map[restic.ID]Pack)
supersedes[id] = restic.NewIDSet()
for _, sid := range idx.Supersedes {
debug.Log(" index %v supersedes %v", id, sid)
supersedes[id].Insert(sid)
}
for _, jpack := range idx.Packs {
entries := make([]restic.Blob, 0, len(jpack.Blobs))
for _, blob := range jpack.Blobs {
entry := restic.Blob{
ID: blob.ID,
Type: blob.Type,
Offset: blob.Offset,
Length: blob.Length,
}
entries = append(entries, entry)
}
if err = index.AddPack(jpack.ID, 0, entries); err != nil {
return err
}
}
results[id] = res
index.IndexIDs.Insert(id)
return nil
})
if err != nil {
return nil, err
}
for superID, list := range supersedes {
for indexID := range list {
if _, ok := results[indexID]; !ok {
continue
}
debug.Log(" removing index %v, superseded by %v", indexID, superID)
fmt.Fprintf(os.Stderr, "index %v can be removed, superseded by index %v\n", indexID.Str(), superID.Str())
delete(results, indexID)
}
}
return index, nil
}
// AddPack adds a pack to the index. If this pack is already in the index, an
// error is returned.
func (idx *Index) AddPack(id restic.ID, size int64, entries []restic.Blob) error {
if _, ok := idx.Packs[id]; ok {
return errors.Errorf("pack %v already present in the index", id.Str())
}
idx.Packs[id] = Pack{ID: id, Size: size, Entries: entries}
return nil
}
// RemovePack deletes a pack from the index.
func (idx *Index) RemovePack(id restic.ID) error {
if _, ok := idx.Packs[id]; !ok {
return errors.Errorf("pack %v not found in the index", id.Str())
}
delete(idx.Packs, id)
return nil
}
// DuplicateBlobs returns a list of blobs that are stored more than once in the
// repo.
func (idx *Index) DuplicateBlobs() (dups restic.BlobSet) {
dups = restic.NewBlobSet()
seen := restic.NewBlobSet()
for _, p := range idx.Packs {
for _, entry := range p.Entries {
h := restic.BlobHandle{ID: entry.ID, Type: entry.Type}
if seen.Has(h) {
dups.Insert(h)
}
seen.Insert(h)
}
}
return dups
}
// PacksForBlobs returns the set of packs in which the blobs are contained.
func (idx *Index) PacksForBlobs(blobs restic.BlobSet) (packs restic.IDSet) {
packs = restic.NewIDSet()
for id, p := range idx.Packs {
for _, entry := range p.Entries {
if blobs.Has(restic.BlobHandle{ID: entry.ID, Type: entry.Type}) {
packs.Insert(id)
}
}
}
return packs
}
// Location describes the location of a blob in a pack.
type Location struct {
PackID restic.ID
restic.Blob
}
// ErrBlobNotFound is return by FindBlob when the blob could not be found in
// the index.
var ErrBlobNotFound = errors.New("blob not found in index")
// FindBlob returns a list of packs and positions the blob can be found in.
func (idx *Index) FindBlob(h restic.BlobHandle) (result []Location, err error) {
for id, p := range idx.Packs {
for _, entry := range p.Entries {
if entry.ID.Equal(h.ID) && entry.Type == h.Type {
result = append(result, Location{
PackID: id,
Blob: entry,
})
}
}
}
if len(result) == 0 {
return nil, ErrBlobNotFound
}
return result, nil
}
const maxEntries = 3000
// Saver saves structures as JSON.
type Saver interface {
SaveJSONUnpacked(ctx context.Context, t restic.FileType, item interface{}) (restic.ID, error)
}
// Save writes the complete index to the repo.
func (idx *Index) Save(ctx context.Context, repo Saver, supersedes restic.IDs) (restic.IDs, error) {
debug.Log("pack files: %d\n", len(idx.Packs))
var indexIDs []restic.ID
packs := 0
jsonIDX := &indexJSON{
Supersedes: supersedes,
Packs: make([]packJSON, 0, maxEntries),
}
for packID, pack := range idx.Packs {
debug.Log("%04d add pack %v with %d entries", packs, packID, len(pack.Entries))
b := make([]blobJSON, 0, len(pack.Entries))
for _, blob := range pack.Entries {
b = append(b, blobJSON{
ID: blob.ID,
Type: blob.Type,
Offset: blob.Offset,
Length: blob.Length,
})
}
p := packJSON{
ID: packID,
Blobs: b,
}
jsonIDX.Packs = append(jsonIDX.Packs, p)
packs++
if packs == maxEntries {
id, err := repo.SaveJSONUnpacked(ctx, restic.IndexFile, jsonIDX)
if err != nil {
return nil, err
}
debug.Log("saved new index as %v", id)
indexIDs = append(indexIDs, id)
packs = 0
jsonIDX.Packs = jsonIDX.Packs[:0]
}
}
if packs > 0 {
id, err := repo.SaveJSONUnpacked(ctx, restic.IndexFile, jsonIDX)
if err != nil {
return nil, err
}
debug.Log("saved new index as %v", id)
indexIDs = append(indexIDs, id)
}
return indexIDs, nil
}