[#1334] metabase: Add upgrade from v2 to v3

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

cmd/frostfs-adm/internal/modules/metabase/root.go

@@ -0,0 +1,15 @@
+package metabase
+
+import "github.com/spf13/cobra"
+
+// RootCmd is a root command of config section.
+var RootCmd = &cobra.Command{
+	Use:   "metabase",
+	Short: "Section for metabase commands",
+}
+
+func init() {
+	RootCmd.AddCommand(UpgradeCmd)
+
+	initUpgradeCommand()
+}

cmd/frostfs-adm/internal/modules/metabase/upgrade.go

@@ -0,0 +1,44 @@
+package metabase
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	meta "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
+	"github.com/spf13/cobra"
+)
+
+const (
+	pathFlag      = "path"
+	noCompactFlag = "no-compact"
+)
+
+var path string
+
+var UpgradeCmd = &cobra.Command{
+	Use:   "upgrade",
+	Short: "Upgrade metabase to latest version",
+	RunE:  upgrade,
+}
+
+func upgrade(cmd *cobra.Command, _ []string) error {
+	path, _ := cmd.Flags().GetString(pathFlag)
+	noCompact, _ := cmd.Flags().GetBool(noCompactFlag)
+	if _, err := os.Stat(path); err != nil {
+		return fmt.Errorf("failed to check file: %w", err)
+	}
+	if err := meta.Upgrade(cmd.Context(), path, !noCompact, func(msg string) {
+		cmd.Println(fmt.Sprintf("%s:%s", time.Now().Format(time.RFC3339), msg))
+	}); err != nil {
+		return fmt.Errorf("failed to upgrade metabase: %w", err)
+	}
+	return nil
+}
+
+func initUpgradeCommand() {
+	flags := UpgradeCmd.Flags()
+	flags.StringVar(&path, pathFlag, "", "Path to metabase file")
+	_ = UpgradeCmd.MarkFlagRequired(pathFlag)
+	flags.Bool(noCompactFlag, false, "Do not compact upgraded metabase file")
+}

cmd/frostfs-adm/internal/modules/root.go

@@ -5,6 +5,7 @@ import (
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-adm/internal/commonflags"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-adm/internal/modules/config"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-adm/internal/modules/metabase"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-adm/internal/modules/morph"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-adm/internal/modules/storagecfg"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/misc"
@@ -41,6 +42,7 @@ func init() {
 	rootCmd.AddCommand(config.RootCmd)
 	rootCmd.AddCommand(morph.RootCmd)
 	rootCmd.AddCommand(storagecfg.RootCmd)
+	rootCmd.AddCommand(metabase.RootCmd)
 
 	rootCmd.AddCommand(autocomplete.Command("frostfs-adm"))
 	rootCmd.AddCommand(gendoc.Command(rootCmd, gendoc.Options{}))

pkg/local_object_storage/metabase/upgrade.go

@@ -0,0 +1,283 @@
+package meta
+
+import (
+	"bytes"
+	"context"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"os"
+	"strconv"
+	"time"
+
+	objectV2 "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/object"
+	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
+	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
+	"go.etcd.io/bbolt"
+	"golang.org/x/sync/errgroup"
+)
+
+var updates = map[uint64]func(ctx context.Context, db *bbolt.DB, log func(msg string)) error{
+	2: upgradeFromV2ToV3,
+}
+
+var errFailedToUpgradeDatabaseNotOpen = errors.New("failed to upgrade metabase: database not open")
+
+func Upgrade(ctx context.Context, path string, compact bool, log func(msg string)) error {
+	db, err := bbolt.Open(path, os.ModePerm, bbolt.DefaultOptions)
+	if err != nil {
+		return fmt.Errorf("failed to open metabase: %w", err)
+	}
+	var version uint64
+	if err := db.View(func(tx *bbolt.Tx) error {
+		var e error
+		version, e = currentVersion(tx)
+		return e
+	}); err != nil {
+		return err
+	}
+	updater, found := updates[version]
+	if !found {
+		return fmt.Errorf("unsupported version %d: no update available", version)
+	}
+	if err := updater(ctx, db, log); err != nil {
+		return fmt.Errorf("failed to update metabase schema: %w", err)
+	}
+	if compact {
+		log("compacting metabase...")
+		err := compactDB(db)
+		if err != nil {
+			return fmt.Errorf("failed to compact metabase: %w", err)
+		}
+		log("metabase compacted")
+	}
+	return db.Close()
+}
+
+func compactDB(db *bbolt.DB) error {
+	sourcePath := db.Path()
+	tmpFileName := sourcePath + "." + time.Now().Format(time.RFC3339)
+	f, err := os.Stat(sourcePath)
+	if err != nil {
+		return err
+	}
+	dst, err := bbolt.Open(tmpFileName, f.Mode(), &bbolt.Options{
+		Timeout: 100 * time.Millisecond,
+	})
+	if err != nil {
+		return fmt.Errorf("can't open new metabase to compact: %w", err)
+	}
+	if err := bbolt.Compact(dst, db, 256<<20); err != nil {
+		return fmt.Errorf("failed to compact metabase: %w", errors.Join(err, dst.Close(), os.Remove(tmpFileName)))
+	}
+	if err := dst.Close(); err != nil {
+		return fmt.Errorf("failed to close compacted metabase: %w", errors.Join(err, os.Remove(tmpFileName)))
+	}
+	if err := db.Close(); err != nil {
+		return fmt.Errorf("failed to close source metabase: %w", errors.Join(err, os.Remove(tmpFileName)))
+	}
+	if err := os.Rename(tmpFileName, sourcePath); err != nil {
+		return fmt.Errorf("failed to replace source metabase with compacted: %w", errors.Join(err, os.Remove(tmpFileName)))
+	}
+	return nil
+}
+
+func upgradeFromV2ToV3(ctx context.Context, db *bbolt.DB, log func(msg string)) error {
+	if err := createExpirationEpochBuckets(ctx, db, log); err != nil {
+		return err
+	}
+	if err := dropUserAttributes(ctx, db, log); err != nil {
+		return err
+	}
+	if err := dropOwnerIDIndex(ctx, db, log); err != nil {
+		return err
+	}
+	if err := dropPayloadChecksumIndex(ctx, db, log); err != nil {
+		return err
+	}
+	return db.Update(func(tx *bbolt.Tx) error {
+		return updateVersion(tx, version)
+	})
+}
+
+type objectIDToExpEpoch struct {
+	containerID     cid.ID
+	objectID        oid.ID
+	expirationEpoch uint64
+}
+
+func createExpirationEpochBuckets(ctx context.Context, db *bbolt.DB, log func(msg string)) error {
+	log("filling expiration epoch buckets...")
+	if err := db.Update(func(tx *bbolt.Tx) error {
+		_, err := tx.CreateBucketIfNotExists(expEpochToObjectBucketName)
+		return err
+	}); err != nil {
+		return err
+	}
+
+	objects := make(chan objectIDToExpEpoch, 1000)
+	defer func() {
+		close(objects)
+	}()
+
+	eg, ctx := errgroup.WithContext(ctx)
+	eg.Go(func() error {
+		return selectObjectsWithExpirationEpoch(ctx, db, objects)
+	})
+	eg.Go(func() error {
+		var count uint64
+		for {
+			if count++; count%1_000 == 0 {
+				log(fmt.Sprintf("expiration epoch filled for %d objects...", count-1))
+			}
+			select {
+			case <-ctx.Done():
+				return ctx.Err()
+			case obj := <-objects:
+				return db.Update(func(tx *bbolt.Tx) error {
+					if err := putUniqueIndexItem(tx, namedBucketItem{
+						name: expEpochToObjectBucketName,
+						key:  expirationEpochKey(obj.expirationEpoch, obj.containerID, obj.objectID),
+						val:  zeroValue,
+					}); err != nil {
+						return err
+					}
+					val := make([]byte, epochSize)
+					binary.LittleEndian.PutUint64(val, obj.expirationEpoch)
+					return putUniqueIndexItem(tx, namedBucketItem{
+						name: objectToExpirationEpochBucketName(obj.containerID, make([]byte, bucketKeySize)),
+						key:  objectKey(obj.objectID, make([]byte, objectKeySize)),
+						val:  val,
+					})
+				})
+			}
+		}
+	})
+	err := eg.Wait()
+	if err != nil {
+		log(fmt.Sprintf("expiration epoch buckets completed completed with error: %s", err.Error()))
+		return err
+
+	}
+	log("filling expiration epoch buckets completed successfully")
+	return nil
+}
+
+func selectObjectsWithExpirationEpoch(ctx context.Context, db *bbolt.DB, objects chan objectIDToExpEpoch) error {
+	prefix := []byte{userAttributePrefix}
+	return db.View(func(tx *bbolt.Tx) error {
+		userAttrCursor := tx.Cursor()
+		for userAttrKey, _ := userAttrCursor.Seek(prefix); userAttrKey != nil && bytes.HasPrefix(userAttrKey, prefix); userAttrKey, _ = userAttrCursor.Next() {
+			select {
+			case <-ctx.Done():
+				return ctx.Err()
+			default:
+			}
+
+			if len(userAttrKey) <= 1+cidSize {
+				continue
+			}
+			attributeKey := string(userAttrKey[1+cidSize:])
+			if attributeKey != objectV2.SysAttributeExpEpochNeoFS && attributeKey != objectV2.SysAttributeExpEpoch {
+				continue
+			}
+
+			var containerID cid.ID
+			if err := containerID.Decode(userAttrKey[1 : 1+cidSize]); err != nil {
+				return fmt.Errorf("failed to decode container id from user attribute bucket: %w", err)
+			}
+
+			b := tx.Bucket(userAttrKey)
+			return b.ForEachBucket(func(expKey []byte) error {
+				select {
+				case <-ctx.Done():
+					return ctx.Err()
+				default:
+				}
+
+				expirationEpoch, err := strconv.ParseUint(string(expKey), 10, 64)
+				if err != nil {
+					return fmt.Errorf("could not parse expiration epoch: %w", err)
+				}
+				expirationEpochBucket := b.Bucket(expKey)
+				return expirationEpochBucket.ForEach(func(k, _ []byte) error {
+					var objectID oid.ID
+					if err := objectID.Decode(k); err != nil {
+						return fmt.Errorf("failed to decode object id from container '%s' expiration epoch %d: %w", containerID, expirationEpoch, err)
+					}
+					select {
+					case <-ctx.Done():
+						return ctx.Err()
+					case objects <- objectIDToExpEpoch{
+						containerID:     containerID,
+						objectID:        objectID,
+						expirationEpoch: expirationEpoch,
+					}:
+						return nil
+					}
+				})
+			})
+		}
+		return nil
+	})
+}
+
+func dropUserAttributes(ctx context.Context, db *bbolt.DB, log func(msg string)) error {
+	return dropBucketsByPrefix(ctx, db, []byte{userAttributePrefix}, func(msg string) {
+		log(fmt.Sprintf("user attributes: %s", msg))
+	})
+}
+
+func dropOwnerIDIndex(ctx context.Context, db *bbolt.DB, log func(msg string)) error {
+	return dropBucketsByPrefix(ctx, db, []byte{ownerPrefix}, func(msg string) {
+		log(fmt.Sprintf("owner ID index: %s", msg))
+	})
+}
+
+func dropPayloadChecksumIndex(ctx context.Context, db *bbolt.DB, log func(msg string)) error {
+	return dropBucketsByPrefix(ctx, db, []byte{payloadHashPrefix}, func(msg string) {
+		log(fmt.Sprintf("payload checksum: %s", msg))
+	})
+}
+
+func dropBucketsByPrefix(ctx context.Context, db *bbolt.DB, prefix []byte, log func(msg string)) error {
+	log("deleting buckets...")
+	const batch = 100
+	var count uint64
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+		}
+		var keys [][]byte
+		if err := db.View(func(tx *bbolt.Tx) error {
+			c := tx.Cursor()
+			for k, _ := c.Seek(prefix); k != nil && bytes.HasPrefix(k, prefix) && len(keys) < batch; k, _ = c.Next() {
+				keys = append(keys, bytes.Clone(k))
+			}
+			return nil
+		}); err != nil {
+			log(fmt.Sprintf("deleting buckets completed with an error %s", err.Error()))
+			return err
+		}
+		if len(keys) == 0 {
+			log("deleting buckets completed successfully")
+			return nil
+		}
+		if err := db.Update(func(tx *bbolt.Tx) error {
+			for _, k := range keys {
+				if err := tx.DeleteBucket(k); err != nil {
+					return err
+				}
+			}
+			return nil
+		}); err != nil {
+			log(fmt.Sprintf("deleting buckets completed with an error %s", err.Error()))
+			return err
+		}
+		if count += uint64(len(keys)); count%10_000 == 0 {
+			log(fmt.Sprintf("deleted %d buckets", count))
+		}
+	}
+}

pkg/local_object_storage/metabase/upgrade_test.go

@@ -0,0 +1,207 @@
+//go:build integration
+
+package meta
+
+import (
+	"context"
+	"io"
+	"os"
+	"strconv"
+	"testing"
+	"time"
+
+	objectV2 "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/object"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/testutil"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger/test"
+	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
+	cidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id/test"
+	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
+	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
+	"github.com/stretchr/testify/require"
+	"golang.org/x/sync/errgroup"
+)
+
+const upgradeFilePath = "/path/to/metabase.v2"
+
+func TestUpgradeV2ToV3(t *testing.T) {
+	path := createTempCopy(t, upgradeFilePath)
+	defer func() {
+		require.NoError(t, os.Remove(path))
+	}()
+	db := New(WithPath(path), WithEpochState(epochState{e: 1000}), WithLogger(test.NewLogger(t)))
+	require.NoError(t, db.Open(context.Background(), mode.ReadWrite))
+	require.ErrorIs(t, db.Init(), ErrOutdatedVersion)
+	require.NoError(t, db.Close())
+	require.NoError(t, Upgrade(context.Background(), path, true, func(msg string) { t.Log(msg) }))
+	require.NoError(t, db.Open(context.Background(), mode.ReadWrite))
+	require.NoError(t, db.Init())
+	require.NoError(t, db.Close())
+}
+
+func createTempCopy(t *testing.T, path string) string {
+	src, err := os.Open(path)
+	require.NoError(t, err)
+
+	tmpPath := upgradeFilePath + time.Now().Format(time.RFC3339)
+	dest, err := os.Create(tmpPath)
+	require.NoError(t, err)
+
+	_, err = io.Copy(dest, src)
+	require.NoError(t, err)
+
+	require.NoError(t, src.Close())
+	require.NoError(t, dest.Close())
+
+	return tmpPath
+}
+
+func TestGenerateMetabaseFile(t *testing.T) {
+	t.Skip("for generating db")
+	// This test generates a metabase file with 2 million objects for 10 000 containers,
+	// of which
+	// 500 000 are simple objects,
+	// 500 000 are complex objects (total 1 million),
+	// 100 000 are deleted by gcMarks,
+	// 100 000 are deleted by tombstones (total 200 000),
+	// 100 000 million are locked (total 200 000).
+
+	db := New(WithPath(upgradeFilePath), WithEpochState(epochState{e: 1000}), WithLogger(test.NewLogger(t)),
+		WithMaxBatchDelay(100*time.Millisecond), WithMaxBatchSize(1000))
+	require.NoError(t, db.Open(context.Background(), mode.ReadWrite))
+	db.boltDB.AllocSize = 128 << 20
+	db.boltDB.NoSync = true
+	require.NoError(t, db.Init())
+	containers := make([]cid.ID, 10_000)
+	for i := range containers {
+		containers[i] = cidtest.ID()
+	}
+	oc, err := db.ObjectCounters()
+	require.NoError(t, err)
+	require.True(t, oc.IsZero())
+	eg, ctx := errgroup.WithContext(context.Background())
+	eg.SetLimit(10000)
+	// simple objects
+	for i := 0; i < 500_000; i++ {
+		i := i
+		eg.Go(func() error {
+			obj := testutil.GenerateObjectWithCID(containers[i%len(containers)])
+			testutil.AddAttribute(obj, "FileName", strconv.FormatInt(int64(i%1_000), 10))
+			testutil.AddAttribute(obj, objectV2.SysAttributeExpEpoch, strconv.FormatUint(uint64(i%1000+1000), 10))
+			_, err := db.Put(ctx, PutPrm{
+				obj: obj,
+				id:  []byte(strconv.FormatInt(int64(i%10), 10) + "/" + strconv.FormatInt(int64(i%10_000), 10)),
+			})
+			require.NoError(t, err)
+			return nil
+		})
+	}
+	require.NoError(t, eg.Wait())
+	db.log.Info("simple objects generated")
+	eg, ctx = errgroup.WithContext(context.Background())
+	eg.SetLimit(10000)
+	// complex objects
+	for i := 0; i < 500_000; i++ {
+		i := i
+		eg.Go(func() error {
+			parent := testutil.GenerateObjectWithCID(containers[i%len(containers)])
+			child := testutil.GenerateObjectWithCID(containers[i%len(containers)])
+			child.SetParent(parent)
+			idParent, _ := parent.ID()
+			child.SetParentID(idParent)
+			testutil.AddAttribute(child, "FileName", strconv.FormatInt(int64(i%1_000), 10))
+			testutil.AddAttribute(parent, "FileName", strconv.FormatInt(int64(i%1_000), 10))
+			testutil.AddAttribute(child, objectV2.SysAttributeExpEpoch, strconv.FormatUint(uint64(i%1000+1000), 10))
+			testutil.AddAttribute(parent, objectV2.SysAttributeExpEpoch, strconv.FormatUint(uint64(i%1000+1000), 10))
+			_, err := db.Put(ctx, PutPrm{
+				obj: child,
+			})
+			require.NoError(t, err)
+			return nil
+		})
+	}
+	require.NoError(t, eg.Wait())
+	db.log.Info("complex objects generated")
+	eg, ctx = errgroup.WithContext(context.Background())
+	eg.SetLimit(10000)
+	// simple objects deleted by gc marks
+	for i := 0; i < 100_000; i++ {
+		i := i
+		eg.Go(func() error {
+			obj := testutil.GenerateObjectWithCID(containers[i%len(containers)])
+			testutil.AddAttribute(obj, "FileName", strconv.FormatInt(int64(i%1_000), 10))
+			_, err := db.Put(ctx, PutPrm{
+				obj: obj,
+				id:  []byte(strconv.FormatInt(int64(i%10), 10) + "/" + strconv.FormatInt(int64(i%10_000), 10)),
+			})
+			require.NoError(t, err)
+			_, err = db.Inhume(ctx, InhumePrm{
+				target: []oid.Address{object.AddressOf(obj)},
+			})
+			require.NoError(t, err)
+			return nil
+		})
+	}
+	require.NoError(t, eg.Wait())
+	db.log.Info("simple objects deleted by gc marks generated")
+	eg, ctx = errgroup.WithContext(context.Background())
+	eg.SetLimit(10000)
+	// simple objects deleted by tombstones
+	for i := 0; i < 100_000; i++ {
+		i := i
+		eg.Go(func() error {
+			obj := testutil.GenerateObjectWithCID(containers[i%len(containers)])
+			testutil.AddAttribute(obj, "FileName", strconv.FormatInt(int64(i%1_000), 10))
+			_, err := db.Put(ctx, PutPrm{
+				obj: obj,
+				id:  []byte(strconv.FormatInt(int64(i%10), 10) + "/" + strconv.FormatInt(int64(i%10_000), 10)),
+			})
+			tomb := testutil.GenerateObjectWithCID(containers[i%len(containers)])
+			tomb.SetType(objectSDK.TypeTombstone)
+			_, err = db.Put(ctx, PutPrm{
+				obj: tomb,
+				id:  []byte(strconv.FormatInt(int64(i%10), 10) + "/" + strconv.FormatInt(int64(i%10_000), 10)),
+			})
+			require.NoError(t, err)
+			tombAddr := object.AddressOf(tomb)
+			_, err = db.Inhume(ctx, InhumePrm{
+				target: []oid.Address{object.AddressOf(obj)},
+				tomb:   &tombAddr,
+			})
+			require.NoError(t, err)
+			return nil
+		})
+	}
+	require.NoError(t, eg.Wait())
+	db.log.Info("simple objects deleted by tombstones generated")
+	eg, ctx = errgroup.WithContext(context.Background())
+	eg.SetLimit(10000)
+	// simple objects locked by locks
+	for i := 0; i < 100_000; i++ {
+		i := i
+		eg.Go(func() error {
+			obj := testutil.GenerateObjectWithCID(containers[i%len(containers)])
+			testutil.AddAttribute(obj, "FileName", strconv.FormatInt(int64(i%1_000), 10))
+			_, err := db.Put(ctx, PutPrm{
+				obj: obj,
+				id:  []byte(strconv.FormatInt(int64(i%10), 10) + "/" + strconv.FormatInt(int64(i%10_000), 10)),
+			})
+			lock := testutil.GenerateObjectWithCID(containers[i%len(containers)])
+			lock.SetType(objectSDK.TypeLock)
+			testutil.AddAttribute(lock, objectV2.SysAttributeExpEpoch, strconv.FormatUint(uint64(i%1000+1000), 10))
+			_, err = db.Put(ctx, PutPrm{
+				obj: lock,
+				id:  []byte(strconv.FormatInt(int64(i%10), 10) + "/" + strconv.FormatInt(int64(i%10_000), 10)),
+			})
+			require.NoError(t, err)
+			err = db.Lock(ctx, containers[i%len(containers)], object.AddressOf(lock).Object(), []oid.ID{object.AddressOf(obj).Object()})
+			require.NoError(t, err)
+			return nil
+		})
+	}
+	require.NoError(t, eg.Wait())
+	db.log.Info("simple objects locked by locks generated")
+	require.NoError(t, db.boltDB.Sync())
+	require.NoError(t, db.Close())
+}

pkg/local_object_storage/metabase/util.go

@@ -94,11 +94,13 @@ const (
 	// ownerPrefix was used for prefixing FKBT index buckets mapping owner to object IDs.
 	// Key: owner ID
 	// Value: bucket containing object IDs as keys
-	_
+	// removed in version 3
+	ownerPrefix
 	// userAttributePrefix was used for prefixing FKBT index buckets containing objects.
 	// Key: attribute value
 	// Value: bucket containing object IDs as keys
-	_
+	// removed in version 3
+	userAttributePrefix
 
 	// ====================
 	// List index buckets.
@@ -107,7 +109,8 @@ const (
 	// payloadHashPrefix was used for prefixing List index buckets mapping payload hash to a list of object IDs.
 	//  Key: payload hash
 	//  Value: list of object IDs
-	_
+	// removed in version 3
+	payloadHashPrefix
 	// parentPrefix is used for prefixing List index buckets mapping parent ID to a list of children IDs.
 	//  Key: parent ID
 	//  Value: list of object IDs

pkg/local_object_storage/metabase/version.go

@@ -2,6 +2,7 @@ package meta
 
 import (
 	"encoding/binary"
+	"errors"
 	"fmt"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/util/logicerr"
@@ -18,6 +19,8 @@ var versionKey = []byte("version")
 // the current code version.
 var ErrOutdatedVersion = logicerr.New("invalid version, resynchronization is required")
 
+var errVersionUndefinedNoInfoBucket = errors.New("version undefined: no info bucket")
+
 func checkVersion(tx *bbolt.Tx, initialized bool) error {
 	var knownVersion bool
 
@@ -59,3 +62,15 @@ func updateVersion(tx *bbolt.Tx, version uint64) error {
 	}
 	return b.Put(versionKey, data)
 }
+
+func currentVersion(tx *bbolt.Tx) (uint64, error) {
+	b := tx.Bucket(shardInfoBucket)
+	if b == nil {
+		return 0, errVersionUndefinedNoInfoBucket
+	}
+	data := b.Get(versionKey)
+	if len(data) != 8 {
+		return 0, fmt.Errorf("version undefined: invalid version data length %d", len(data))
+	}
+	return binary.LittleEndian.Uint64(data), nil
+}