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2c310a526e
LoadBlobsFromPack is now part of the repository struct. This ensures that users of that method don't have to deal will internals of the repository implementation. The filerestorer tests now also contain far fewer pack file implementation details.
358 lines
9.9 KiB
Go
358 lines
9.9 KiB
Go
package restorer
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import (
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"context"
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"path/filepath"
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"sync"
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"golang.org/x/sync/errgroup"
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"github.com/restic/restic/internal/debug"
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"github.com/restic/restic/internal/errors"
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"github.com/restic/restic/internal/repository"
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"github.com/restic/restic/internal/restic"
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"github.com/restic/restic/internal/ui/restore"
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)
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// TODO if a blob is corrupt, there may be good blob copies in other packs
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// TODO evaluate if it makes sense to split download and processing workers
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// pro: can (slowly) read network and decrypt/write files concurrently
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// con: each worker needs to keep one pack in memory
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const (
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largeFileBlobCount = 25
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)
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// information about regular file being restored
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type fileInfo struct {
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lock sync.Mutex
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inProgress bool
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sparse bool
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size int64
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location string // file on local filesystem relative to restorer basedir
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blobs interface{} // blobs of the file
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}
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type fileBlobInfo struct {
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id restic.ID // the blob id
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offset int64 // blob offset in the file
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}
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// information about a data pack required to restore one or more files
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type packInfo struct {
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id restic.ID // the pack id
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files map[*fileInfo]struct{} // set of files that use blobs from this pack
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}
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type blobsLoaderFn func(ctx context.Context, packID restic.ID, blobs []restic.Blob, handleBlobFn func(blob restic.BlobHandle, buf []byte, err error) error) error
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// fileRestorer restores set of files
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type fileRestorer struct {
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idx func(restic.BlobHandle) []restic.PackedBlob
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blobsLoader blobsLoaderFn
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workerCount int
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filesWriter *filesWriter
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zeroChunk restic.ID
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sparse bool
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progress *restore.Progress
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dst string
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files []*fileInfo
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Error func(string, error) error
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}
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func newFileRestorer(dst string,
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blobsLoader blobsLoaderFn,
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idx func(restic.BlobHandle) []restic.PackedBlob,
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connections uint,
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sparse bool,
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progress *restore.Progress) *fileRestorer {
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// as packs are streamed the concurrency is limited by IO
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workerCount := int(connections)
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return &fileRestorer{
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idx: idx,
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blobsLoader: blobsLoader,
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filesWriter: newFilesWriter(workerCount),
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zeroChunk: repository.ZeroChunk(),
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sparse: sparse,
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progress: progress,
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workerCount: workerCount,
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dst: dst,
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Error: restorerAbortOnAllErrors,
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}
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}
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func (r *fileRestorer) addFile(location string, content restic.IDs, size int64) {
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r.files = append(r.files, &fileInfo{location: location, blobs: content, size: size})
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}
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func (r *fileRestorer) targetPath(location string) string {
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return filepath.Join(r.dst, location)
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}
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func (r *fileRestorer) forEachBlob(blobIDs []restic.ID, fn func(packID restic.ID, packBlob restic.Blob)) error {
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if len(blobIDs) == 0 {
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return nil
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}
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for _, blobID := range blobIDs {
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packs := r.idx(restic.BlobHandle{ID: blobID, Type: restic.DataBlob})
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if len(packs) == 0 {
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return errors.Errorf("Unknown blob %s", blobID.String())
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}
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fn(packs[0].PackID, packs[0].Blob)
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}
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return nil
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}
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func (r *fileRestorer) restoreFiles(ctx context.Context) error {
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packs := make(map[restic.ID]*packInfo) // all packs
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// Process packs in order of first access. While this cannot guarantee
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// that file chunks are restored sequentially, it offers a good enough
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// approximation to shorten restore times by up to 19% in some test.
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var packOrder restic.IDs
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// create packInfo from fileInfo
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for _, file := range r.files {
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fileBlobs := file.blobs.(restic.IDs)
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largeFile := len(fileBlobs) > largeFileBlobCount
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var packsMap map[restic.ID][]fileBlobInfo
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if largeFile {
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packsMap = make(map[restic.ID][]fileBlobInfo)
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}
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fileOffset := int64(0)
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err := r.forEachBlob(fileBlobs, func(packID restic.ID, blob restic.Blob) {
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if largeFile {
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packsMap[packID] = append(packsMap[packID], fileBlobInfo{id: blob.ID, offset: fileOffset})
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fileOffset += int64(blob.DataLength())
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}
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pack, ok := packs[packID]
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if !ok {
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pack = &packInfo{
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id: packID,
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files: make(map[*fileInfo]struct{}),
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}
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packs[packID] = pack
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packOrder = append(packOrder, packID)
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}
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pack.files[file] = struct{}{}
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if blob.ID.Equal(r.zeroChunk) {
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file.sparse = r.sparse
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}
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})
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if len(fileBlobs) == 1 {
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// no need to preallocate files with a single block, thus we can always consider them to be sparse
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// in addition, a short chunk will never match r.zeroChunk which would prevent sparseness for short files
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file.sparse = r.sparse
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}
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if err != nil {
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// repository index is messed up, can't do anything
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return err
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}
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if largeFile {
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file.blobs = packsMap
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}
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}
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wg, ctx := errgroup.WithContext(ctx)
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downloadCh := make(chan *packInfo)
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worker := func() error {
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for pack := range downloadCh {
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if err := r.downloadPack(ctx, pack); err != nil {
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return err
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}
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}
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return nil
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}
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for i := 0; i < r.workerCount; i++ {
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wg.Go(worker)
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}
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// the main restore loop
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wg.Go(func() error {
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for _, id := range packOrder {
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pack := packs[id]
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// allow garbage collection of packInfo
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delete(packs, id)
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select {
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case <-ctx.Done():
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return ctx.Err()
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case downloadCh <- pack:
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debug.Log("Scheduled download pack %s", pack.id.Str())
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}
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}
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close(downloadCh)
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return nil
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})
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return wg.Wait()
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}
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type blobToFileOffsetsMapping map[restic.ID]struct {
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files map[*fileInfo][]int64 // file -> offsets (plural!) of the blob in the file
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blob restic.Blob
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}
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func (r *fileRestorer) downloadPack(ctx context.Context, pack *packInfo) error {
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// calculate blob->[]files->[]offsets mappings
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blobs := make(blobToFileOffsetsMapping)
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for file := range pack.files {
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addBlob := func(blob restic.Blob, fileOffset int64) {
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blobInfo, ok := blobs[blob.ID]
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if !ok {
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blobInfo.files = make(map[*fileInfo][]int64)
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blobInfo.blob = blob
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blobs[blob.ID] = blobInfo
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}
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blobInfo.files[file] = append(blobInfo.files[file], fileOffset)
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}
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if fileBlobs, ok := file.blobs.(restic.IDs); ok {
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fileOffset := int64(0)
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err := r.forEachBlob(fileBlobs, func(packID restic.ID, blob restic.Blob) {
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if packID.Equal(pack.id) {
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addBlob(blob, fileOffset)
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}
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fileOffset += int64(blob.DataLength())
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})
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if err != nil {
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// restoreFiles should have caught this error before
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panic(err)
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}
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} else if packsMap, ok := file.blobs.(map[restic.ID][]fileBlobInfo); ok {
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for _, blob := range packsMap[pack.id] {
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idxPacks := r.idx(restic.BlobHandle{ID: blob.id, Type: restic.DataBlob})
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for _, idxPack := range idxPacks {
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if idxPack.PackID.Equal(pack.id) {
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addBlob(idxPack.Blob, blob.offset)
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break
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}
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}
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}
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}
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}
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// track already processed blobs for precise error reporting
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processedBlobs := restic.NewBlobSet()
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for _, entry := range blobs {
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occurrences := 0
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for _, offsets := range entry.files {
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occurrences += len(offsets)
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}
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// With a maximum blob size of 8MB, the normal blob streaming has to write
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// at most 800MB for a single blob. This should be short enough to avoid
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// network connection timeouts. Based on a quick test, a limit of 100 only
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// selects a very small number of blobs (the number of references per blob
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// - aka. `count` - seem to follow a expontential distribution)
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if occurrences > 100 {
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// process frequently referenced blobs first as these can take a long time to write
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// which can cause backend connections to time out
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delete(blobs, entry.blob.ID)
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partialBlobs := blobToFileOffsetsMapping{entry.blob.ID: entry}
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err := r.downloadBlobs(ctx, pack.id, partialBlobs, processedBlobs)
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if err := r.reportError(blobs, processedBlobs, err); err != nil {
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return err
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}
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}
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}
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if len(blobs) == 0 {
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return nil
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}
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err := r.downloadBlobs(ctx, pack.id, blobs, processedBlobs)
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return r.reportError(blobs, processedBlobs, err)
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}
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func (r *fileRestorer) sanitizeError(file *fileInfo, err error) error {
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if err != nil {
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err = r.Error(file.location, err)
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}
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return err
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}
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func (r *fileRestorer) reportError(blobs blobToFileOffsetsMapping, processedBlobs restic.BlobSet, err error) error {
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if err == nil {
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return nil
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}
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// only report error for not yet processed blobs
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affectedFiles := make(map[*fileInfo]struct{})
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for _, entry := range blobs {
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if processedBlobs.Has(entry.blob.BlobHandle) {
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continue
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}
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for file := range entry.files {
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affectedFiles[file] = struct{}{}
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}
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}
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for file := range affectedFiles {
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if errFile := r.sanitizeError(file, err); errFile != nil {
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return errFile
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}
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}
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return nil
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}
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func (r *fileRestorer) downloadBlobs(ctx context.Context, packID restic.ID,
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blobs blobToFileOffsetsMapping, processedBlobs restic.BlobSet) error {
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blobList := make([]restic.Blob, 0, len(blobs))
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for _, entry := range blobs {
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blobList = append(blobList, entry.blob)
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}
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return r.blobsLoader(ctx, packID, blobList,
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func(h restic.BlobHandle, blobData []byte, err error) error {
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processedBlobs.Insert(h)
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blob := blobs[h.ID]
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if err != nil {
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for file := range blob.files {
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if errFile := r.sanitizeError(file, err); errFile != nil {
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return errFile
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}
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}
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return nil
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}
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for file, offsets := range blob.files {
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for _, offset := range offsets {
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writeToFile := func() error {
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// this looks overly complicated and needs explanation
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// two competing requirements:
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// - must create the file once and only once
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// - should allow concurrent writes to the file
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// so write the first blob while holding file lock
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// write other blobs after releasing the lock
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createSize := int64(-1)
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file.lock.Lock()
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if file.inProgress {
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file.lock.Unlock()
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} else {
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defer file.lock.Unlock()
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file.inProgress = true
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createSize = file.size
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}
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writeErr := r.filesWriter.writeToFile(r.targetPath(file.location), blobData, offset, createSize, file.sparse)
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if r.progress != nil {
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r.progress.AddProgress(file.location, uint64(len(blobData)), uint64(file.size))
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}
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return writeErr
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}
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err := r.sanitizeError(file, writeToFile())
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if err != nil {
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return err
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}
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}
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}
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return nil
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})
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}
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