package repository import ( "context" "os" "sync" "github.com/restic/restic/internal/debug" "github.com/restic/restic/internal/errors" "github.com/restic/restic/internal/fs" "github.com/restic/restic/internal/pack" "github.com/restic/restic/internal/restic" "golang.org/x/sync/errgroup" ) const numRepackWorkers = 8 // Repack takes a list of packs together with a list of blobs contained in // these packs. Each pack is loaded and the blobs listed in keepBlobs is saved // into a new pack. Returned is the list of obsolete packs which can then // be removed. // // The map keepBlobs is modified by Repack, it is used to keep track of which // blobs have been processed. func Repack(ctx context.Context, repo restic.Repository, packs restic.IDSet, keepBlobs restic.BlobSet, p *restic.Progress) (obsoletePacks restic.IDSet, err error) { if p != nil { p.Start() defer p.Done() } debug.Log("repacking %d packs while keeping %d blobs", len(packs), len(keepBlobs)) wg, ctx := errgroup.WithContext(ctx) downloadQueue := make(chan restic.ID) wg.Go(func() error { defer close(downloadQueue) for packID := range packs { select { case downloadQueue <- packID: case <-ctx.Done(): return ctx.Err() } } return nil }) type repackJob struct { tempfile *os.File hash restic.ID packLength int64 } processQueue := make(chan repackJob) // used to close processQueue once all downloaders have finished var downloadWG sync.WaitGroup downloader := func() error { defer downloadWG.Done() for packID := range downloadQueue { // load the complete pack into a temp file h := restic.Handle{Type: restic.PackFile, Name: packID.String()} tempfile, hash, packLength, err := DownloadAndHash(ctx, repo.Backend(), h) if err != nil { return errors.Wrap(err, "Repack") } debug.Log("pack %v loaded (%d bytes), hash %v", packID, packLength, hash) if !packID.Equal(hash) { return errors.Errorf("hash does not match id: want %v, got %v", packID, hash) } select { case processQueue <- repackJob{tempfile, hash, packLength}: case <-ctx.Done(): return ctx.Err() } } return nil } downloadWG.Add(numRepackWorkers) for i := 0; i < numRepackWorkers; i++ { wg.Go(downloader) } wg.Go(func() error { downloadWG.Wait() close(processQueue) return nil }) var keepMutex sync.Mutex worker := func() error { for job := range processQueue { tempfile, packID, packLength := job.tempfile, job.hash, job.packLength blobs, err := pack.List(repo.Key(), tempfile, packLength) if err != nil { return err } debug.Log("processing pack %v, blobs: %v", packID, len(blobs)) var buf []byte for _, entry := range blobs { h := restic.BlobHandle{ID: entry.ID, Type: entry.Type} keepMutex.Lock() shouldKeep := keepBlobs.Has(h) keepMutex.Unlock() if !shouldKeep { continue } debug.Log(" process blob %v", h) if uint(cap(buf)) < entry.Length { buf = make([]byte, entry.Length) } buf = buf[:entry.Length] n, err := tempfile.ReadAt(buf, int64(entry.Offset)) if err != nil { return errors.Wrap(err, "ReadAt") } if n != len(buf) { return errors.Errorf("read blob %v from %v: not enough bytes read, want %v, got %v", h, tempfile.Name(), len(buf), n) } nonce, ciphertext := buf[:repo.Key().NonceSize()], buf[repo.Key().NonceSize():] plaintext, err := repo.Key().Open(ciphertext[:0], nonce, ciphertext, nil) if err != nil { return err } id := restic.Hash(plaintext) if !id.Equal(entry.ID) { debug.Log("read blob %v/%v from %v: wrong data returned, hash is %v", h.Type, h.ID, tempfile.Name(), id) return errors.Errorf("read blob %v from %v: wrong data returned, hash is %v", h, tempfile.Name(), id) } keepMutex.Lock() // recheck whether some other worker was faster shouldKeep = keepBlobs.Has(h) if shouldKeep { keepBlobs.Delete(h) } keepMutex.Unlock() if !shouldKeep { continue } // We do want to save already saved blobs! _, _, err = repo.SaveBlob(ctx, entry.Type, plaintext, entry.ID, true) if err != nil { return err } debug.Log(" saved blob %v", entry.ID) } if err = tempfile.Close(); err != nil { return errors.Wrap(err, "Close") } if err = fs.RemoveIfExists(tempfile.Name()); err != nil { return errors.Wrap(err, "Remove") } if p != nil { p.Report(restic.Stat{Blobs: 1}) } } return nil } for i := 0; i < numRepackWorkers; i++ { wg.Go(worker) } if err := wg.Wait(); err != nil { return nil, err } if err := repo.Flush(ctx); err != nil { return nil, err } return packs, nil }