Merge pull request #1650 from dmcgowan/fix-gc-race

gc: fix race and test failures

cmd/ctr/snapshot.go

@@ -28,6 +28,7 @@ var snapshotCommand = cli.Command{
 		mountSnapshotCommand,
 		commitSnapshotCommand,
 		infoSnapshotCommand,
+		labelSnapshotCommand,
 	},
 }
 
@@ -343,6 +344,58 @@ var infoSnapshotCommand = cli.Command{
 	},
 }
 
+var labelSnapshotCommand = cli.Command{
+	Name:        "label",
+	Usage:       "add labels to content",
+	ArgsUsage:   "[flags] <name> [<label>=<value> ...]",
+	Description: `Labels snapshots in the snapshotter`,
+	Flags:       []cli.Flag{},
+	Action: func(clicontext *cli.Context) error {
+		var (
+			key, labels = objectWithLabelArgs(clicontext)
+		)
+		ctx, cancel := appContext(clicontext)
+		defer cancel()
+
+		snapshotter, err := getSnapshotter(clicontext)
+		if err != nil {
+			return err
+		}
+
+		info := snapshot.Info{
+			Name:   key,
+			Labels: map[string]string{},
+		}
+
+		var paths []string
+		for k, v := range labels {
+			paths = append(paths, fmt.Sprintf("labels.%s", k))
+			if v != "" {
+				info.Labels[k] = v
+			}
+		}
+
+		// Nothing updated, do no clear
+		if len(paths) == 0 {
+			info, err = snapshotter.Stat(ctx, info.Name)
+		} else {
+			info, err = snapshotter.Update(ctx, info, paths...)
+		}
+		if err != nil {
+			return err
+		}
+
+		var labelStrings []string
+		for k, v := range info.Labels {
+			labelStrings = append(labelStrings, fmt.Sprintf("%s=%s", k, v))
+		}
+
+		fmt.Println(strings.Join(labelStrings, ","))
+
+		return nil
+	},
+}
+
 type snapshotTreeNode struct {
 	Name     string
 	Parent   string

metadata/db.go

@@ -37,8 +37,8 @@ const (
 // datastores for content and snapshots.
 type DB struct {
 	db *bolt.DB
-	ss map[string]snapshot.Snapshotter
+	ss map[string]*snapshotter
-	cs content.Store
+	cs *contentStore
 
 	// wlock is used to protect access to the data structures during garbage
 	// collection. While the wlock is held no writable transactions can be
@@ -60,12 +60,19 @@ type DB struct {
 // NewDB creates a new metadata database using the provided
 // bolt database, content store, and snapshotters.
 func NewDB(db *bolt.DB, cs content.Store, ss map[string]snapshot.Snapshotter) *DB {
-	return &DB{
+	m := &DB{
 		db:      db,
-		ss:      ss,
+		ss:      make(map[string]*snapshotter, len(ss)),
-		cs:      cs,
 		dirtySS: map[string]struct{}{},
 	}
+
+	// Initialize data stores
+	m.cs = newContentStore(m, cs)
+	for name, sn := range ss {
+		m.ss[name] = newSnapshotter(m, name, sn)
+	}
+
+	return m
 }
 
 // Init ensures the database is at the correct version
@@ -158,7 +165,7 @@ func (m *DB) ContentStore() content.Store {
 	if m.cs == nil {
 		return nil
 	}
-	return newContentStore(m, m.cs)
+	return m.cs
 }
 
 // Snapshotter returns a namespaced content store for
@@ -168,7 +175,7 @@ func (m *DB) Snapshotter(name string) snapshot.Snapshotter {
 	if !ok {
 		return nil
 	}
-	return newSnapshotter(m, name, sn)
+	return sn
 }
 
 // View runs a readonly transaction on the metadata store.
@@ -292,7 +299,7 @@ func (m *DB) cleanupSnapshotter(name string) {
 		return
 	}
 
-	err := newSnapshotter(m, name, sn).garbageCollect(ctx)
+	err := sn.garbageCollect(ctx)
 	if err != nil {
 		log.G(ctx).WithError(err).WithField("snapshotter", name).Warn("garbage collection failed")
 	}