Merge pull request #354 from restic/fix-index

Save new packs in index atomically

repository/index.go

@@ -109,6 +109,22 @@ func (idx *Index) Store(blob PackedBlob) {
 	idx.store(blob)
 }
 
+// StoreBlobs saves information about the blobs to the index in one atomic transaction.
+func (idx *Index) StoreBlobs(blobs []PackedBlob) {
+	idx.m.Lock()
+	defer idx.m.Unlock()
+
+	if idx.final {
+		panic("store new item in finalized index")
+	}
+
+	debug.Log("Index.StoreBlobs", "stored %d blobs", len(blobs))
+
+	for _, blob := range blobs {
+		idx.store(blob)
+	}
+}
+
 // Lookup queries the index for the blob ID and returns a PackedBlob.
 func (idx *Index) Lookup(id backend.ID) (pb PackedBlob, err error) {
 	idx.m.Lock()

repository/repository.go

@@ -268,9 +268,9 @@ func (r *Repository) savePacker(p *pack.Packer) error {
 	debug.Log("Repo.savePacker", "saved as %v", sid.Str())
 
 	// update blobs in the index
+	var packedBlobs []PackedBlob
 	for _, b := range p.Blobs() {
-		debug.Log("Repo.savePacker", "  updating blob %v to pack %v", b.ID.Str(), sid.Str())
-		r.idx.Current().Store(PackedBlob{
+		packedBlobs = append(packedBlobs, PackedBlob{
 			Type:   b.Type,
 			ID:     b.ID,
 			PackID: sid,
@@ -279,6 +279,7 @@ func (r *Repository) savePacker(p *pack.Packer) error {
 		})
 		r.idx.RemoveFromInFlight(b.ID)
 	}
+	r.idx.Current().StoreBlobs(packedBlobs)
 
 	return nil
 }