index: Add Each() to MasterIndex

src/restic/checker/checker.go

@@ -142,7 +142,7 @@ func (c *Checker) LoadIndex(ctx context.Context) (hints []error, errs []error) {
 
 		debug.Log("process blobs")
 		cnt := 0
-		for blob := range res.Index.Each(done) {
+		for blob := range res.Index.Each(ctx) {
 			c.packs.Insert(blob.PackID)
 			c.blobs.Insert(blob.ID)
 			c.blobRefs.M[blob.ID] = 0

src/restic/fuse/snapshot.go

@@ -28,7 +28,7 @@ type BlobSizeCache struct {
 func NewBlobSizeCache(midx *repository.MasterIndex) *BlobSizeCache {
 	m := make(map[restic.ID]uint, 1000)
 	for _, idx := range midx.All() {
-		for pb := range idx.Each(nil) {
+		for pb := range idx.Each(context.TODO()) {
 			m[pb.ID] = pb.Length
 		}
 	}

src/restic/repository.go

@@ -58,4 +58,9 @@ type Index interface {
 	Has(ID, BlobType) bool
 	Lookup(ID, BlobType) ([]PackedBlob, error)
 	Count(BlobType) uint
+
+	// Each returns a channel that yields all blobs known to the index. When
+	// the context is cancelled, the background goroutine terminates. This
+	// blocks any modification of the index.
+	Each(ctx context.Context) <-chan PackedBlob
 }

src/restic/repository/index.go

@@ -206,10 +206,10 @@ func (idx *Index) AddToSupersedes(ids ...restic.ID) error {
 	return nil
 }
 
-// Each returns a channel that yields all blobs known to the index. If done is
-// closed, the background goroutine terminates. This blocks any modification of
-// the index.
-func (idx *Index) Each(done chan struct{}) <-chan restic.PackedBlob {
+// Each returns a channel that yields all blobs known to the index. When the
+// context is cancelled, the background goroutine terminates. This blocks any
+// modification of the index.
+func (idx *Index) Each(ctx context.Context) <-chan restic.PackedBlob {
 	idx.m.Lock()
 
 	ch := make(chan restic.PackedBlob)
@@ -223,7 +223,7 @@ func (idx *Index) Each(done chan struct{}) <-chan restic.PackedBlob {
 		for h, packs := range idx.pack {
 			for _, blob := range packs {
 				select {
-				case <-done:
+				case <-ctx.Done():
 					return
 				case ch <- restic.PackedBlob{
 					Blob: restic.Blob{

src/restic/repository/master_index.go

@@ -1,6 +1,7 @@
 package repository
 
 import (
+	"context"
 	"restic"
 	"sync"
 
@@ -188,6 +189,35 @@ func (mi *MasterIndex) All() []*Index {
 	return mi.idx
 }
 
+// Each returns a channel that yields all blobs known to the index. When the
+// context is cancelled, the background goroutine terminates. This blocks any
+// modification of the index.
+func (mi *MasterIndex) Each(ctx context.Context) <-chan restic.PackedBlob {
+	mi.idxMutex.RLock()
+
+	ch := make(chan restic.PackedBlob)
+
+	go func() {
+		defer mi.idxMutex.RUnlock()
+		defer func() {
+			close(ch)
+		}()
+
+		for _, idx := range mi.idx {
+			idxCh := idx.Each(ctx)
+			for pb := range idxCh {
+				select {
+				case <-ctx.Done():
+					return
+				case ch <- pb:
+				}
+			}
+		}
+	}()
+
+	return ch
+}
+
 // RebuildIndex combines all known indexes to a new index, leaving out any
 // packs whose ID is contained in packBlacklist. The new index contains the IDs
 // of all known indexes in the "supersedes" field.
@@ -198,13 +228,14 @@ func (mi *MasterIndex) RebuildIndex(packBlacklist restic.IDSet) (*Index, error)
 	debug.Log("start rebuilding index of %d indexes, pack blacklist: %v", len(mi.idx), packBlacklist)
 
 	newIndex := NewIndex()
-	done := make(chan struct{})
-	defer close(done)
+
+	ctx, cancel := context.WithCancel(context.TODO())
+	defer cancel()
 
 	for i, idx := range mi.idx {
 		debug.Log("adding index %d", i)
 
-		for pb := range idx.Each(done) {
+		for pb := range idx.Each(ctx) {
 			if packBlacklist.Has(pb.PackID) {
 				continue
 			}

src/restic/repository/repository_test.go

@@ -373,7 +373,7 @@ func TestRepositoryIncrementalIndex(t *testing.T) {
 		idx, err := repository.LoadIndex(context.TODO(), repo, id)
 		OK(t, err)
 
-		for pb := range idx.Each(nil) {
+		for pb := range idx.Each(context.TODO()) {
 			if _, ok := packEntries[pb.PackID]; !ok {
 				packEntries[pb.PackID] = make(map[restic.ID]struct{})
 			}