[#231] metabase: Add container lister

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/local_object_storage/metabase/v2/containers.go

@@ -0,0 +1,49 @@
+package meta
+
+import (
+	"strings"
+
+	"github.com/nspcc-dev/neofs-api-go/pkg/container"
+	"go.etcd.io/bbolt"
+)
+
+func (db *DB) Containers() (list []*container.ID, err error) {
+	err = db.boltDB.View(func(tx *bbolt.Tx) error {
+		list, err = db.containers(tx)
+
+		return err
+	})
+
+	return list, err
+}
+
+func (db *DB) containers(tx *bbolt.Tx) ([]*container.ID, error) {
+	result := make([]*container.ID, 0)
+
+	err := tx.ForEach(func(name []byte, _ *bbolt.Bucket) error {
+		id, err := parseContainerID(name)
+		if err != nil {
+			return err
+		}
+
+		if id != nil {
+			result = append(result, id)
+		}
+
+		return nil
+	})
+
+	return result, err
+}
+
+func parseContainerID(name []byte) (*container.ID, error) {
+	strName := string(name)
+
+	if strings.Contains(strName, "_") {
+		return nil, nil
+	}
+
+	id := container.NewID()
+
+	return id, id.Parse(strName)
+}

pkg/local_object_storage/metabase/v2/containers_test.go

@@ -0,0 +1,36 @@
+package meta_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestDB_Containers(t *testing.T) {
+	db := newDB(t)
+	defer releaseDB(db)
+
+	const N = 10
+
+	cids := make(map[string]int, N)
+
+	for i := 0; i < N; i++ {
+		obj := generateRawObject(t)
+
+		cids[obj.ContainerID().String()] = 0
+
+		err := db.Put(obj.Object(), nil)
+		require.NoError(t, err)
+	}
+
+	lst, err := db.Containers()
+	require.NoError(t, err)
+
+	for _, cid := range lst {
+		i, ok := cids[cid.String()]
+		require.True(t, ok)
+		require.Equal(t, 0, i)
+
+		cids[cid.String()] = 1
+	}
+}