Add repacker

checker/repacker.go

@@ -0,0 +1,108 @@
+package checker
+
+import (
+	"errors"
+
+	"github.com/restic/restic/backend"
+	"github.com/restic/restic/debug"
+	"github.com/restic/restic/repository"
+)
+
+// Repacker extracts still used blobs from packs with unused blobs and creates
+// new packs.
+type Repacker struct {
+	unusedBlobs []backend.ID
+	src, dst    *repository.Repository
+}
+
+// NewRepacker returns a new repacker that (when Repack() in run) cleans up the
+// repository and creates new packs and indexs so that all blobs in unusedBlobs
+// aren't used any more.
+func NewRepacker(src, dst *repository.Repository, unusedBlobs []backend.ID) *Repacker {
+	return &Repacker{
+		src:         src,
+		dst:         dst,
+		unusedBlobs: unusedBlobs,
+	}
+}
+
+// Repack runs the process of finding still used blobs in packs with unused
+// blobs, extracts them and creates new packs with just the still-in-use blobs.
+func (r *Repacker) Repack() error {
+	debug.Log("Repacker.Repack", "searching packs for %v", r.unusedBlobs)
+	packs, err := FindPacksforBlobs(r.src, r.unusedBlobs)
+	if err != nil {
+		return err
+	}
+
+	debug.Log("Repacker.Repack", "found packs: %v", packs)
+
+	return nil
+}
+
+// FindPacksforBlobs returns the set of packs that contain the blobs.
+func FindPacksforBlobs(repo *repository.Repository, blobs []backend.ID) (backend.IDSet, error) {
+	packs := backend.NewIDSet()
+	idx := repo.Index()
+	for _, id := range blobs {
+		blob, err := idx.Lookup(id)
+		if err != nil {
+			return nil, err
+		}
+
+		packs.Insert(blob.PackID)
+	}
+
+	return packs, nil
+}
+
+// repackBlob loads a single blob from src and saves it in dst.
+func repackBlob(src, dst *repository.Repository, id backend.ID) error {
+	blob, err := src.Index().Lookup(id)
+	if err != nil {
+		return err
+	}
+
+	debug.Log("RepackBlobs", "repacking blob %v, len %v", id.Str(), blob.PlaintextLength())
+
+	buf := make([]byte, 0, blob.PlaintextLength())
+	buf, err = src.LoadBlob(blob.Type, id, buf)
+	if err != nil {
+		return err
+	}
+
+	if uint(len(buf)) != blob.PlaintextLength() {
+		debug.Log("RepackBlobs", "repack blob %v: len(buf) isn't equal to length: %v = %v", id.Str(), len(buf), blob.PlaintextLength())
+		return errors.New("LoadBlob returned wrong data, len() doesn't match")
+	}
+
+	_, err = dst.SaveAndEncrypt(blob.Type, buf, &id)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// RepackBlobs reads all blobs in blobIDs from src and saves them into new pack
+// files in dst. Source and destination repo may be the same.
+func RepackBlobs(src, dst *repository.Repository, blobIDs backend.IDs) (err error) {
+	for _, id := range blobIDs {
+		err = repackBlob(src, dst, id)
+		if err != nil {
+			return err
+		}
+	}
+
+	err = dst.Flush()
+	if err != nil {
+		return err
+	}
+
+	err = dst.SaveIndex()
+	if err != nil {
+		return err
+	}
+
+	return nil
+}