mirror of
https://github.com/restic/restic.git
synced 2024-07-27 12:37:40 +02:00
378 lines
10 KiB
Go
378 lines
10 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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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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state *fileState
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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.BlobType, restic.ID) []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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allowRecursiveDelete bool
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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.BlobType, restic.ID) []restic.PackedBlob,
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connections uint,
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sparse bool,
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allowRecursiveDelete 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, allowRecursiveDelete),
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zeroChunk: repository.ZeroChunk(),
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sparse: sparse,
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progress: progress,
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allowRecursiveDelete: allowRecursiveDelete,
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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, state *fileState) {
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r.files = append(r.files, &fileInfo{location: location, blobs: content, size: size, state: state})
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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, idx int, fileOffset int64)) error {
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if len(blobIDs) == 0 {
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return nil
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}
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fileOffset := int64(0)
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for i, blobID := range blobIDs {
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packs := r.idx(restic.DataBlob, blobID)
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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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pb := packs[0]
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fn(pb.PackID, pb.Blob, i, fileOffset)
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fileOffset += int64(pb.DataLength())
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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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file.blobs = packsMap
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}
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restoredBlobs := false
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err := r.forEachBlob(fileBlobs, func(packID restic.ID, blob restic.Blob, idx int, fileOffset int64) {
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if !file.state.HasMatchingBlob(idx) {
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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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}
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restoredBlobs = true
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} else {
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r.reportBlobProgress(file, uint64(blob.DataLength()))
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// completely ignore blob
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return
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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 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 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 file.state != nil {
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// The restorer currently cannot punch new holes into an existing files.
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// Thus sections that contained data but should be sparse after restoring
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// the snapshot would still contain the old data resulting in a corrupt restore.
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file.sparse = false
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}
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// empty file or one with already uptodate content. Make sure that the file size is correct
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if !restoredBlobs {
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err := r.truncateFileToSize(file.location, file.size)
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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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// the progress events were already sent for non-zero size files
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if file.size == 0 {
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r.reportBlobProgress(file, 0)
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}
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}
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}
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// drop no longer necessary file list
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r.files = nil
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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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defer close(downloadCh)
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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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return nil
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})
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return wg.Wait()
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}
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func (r *fileRestorer) truncateFileToSize(location string, size int64) error {
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f, err := createFile(r.targetPath(location), size, false, r.allowRecursiveDelete)
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if err != nil {
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return err
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}
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return f.Close()
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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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err := r.forEachBlob(fileBlobs, func(packID restic.ID, blob restic.Blob, idx int, fileOffset int64) {
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if packID.Equal(pack.id) && !file.state.HasMatchingBlob(idx) {
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addBlob(blob, fileOffset)
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}
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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.DataBlob, blob.id)
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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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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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switch err {
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case nil, context.Canceled, context.DeadlineExceeded:
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// Context errors are permanent.
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return err
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default:
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return r.Error(file.location, err)
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}
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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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// avoid long cancelation delays for frequently used blobs
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if ctx.Err() != nil {
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return ctx.Err()
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}
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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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r.reportBlobProgress(file, uint64(len(blobData)))
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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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func (r *fileRestorer) reportBlobProgress(file *fileInfo, blobSize uint64) {
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action := restore.ActionFileUpdated
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if file.state == nil {
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action = restore.ActionFileRestored
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}
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r.progress.AddProgress(file.location, action, uint64(blobSize), uint64(file.size))
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}
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