package meta import ( "encoding/binary" "fmt" "go.etcd.io/bbolt" ) // version contains current metabase version. const version = 0 var versionKey = []byte("version") func checkVersion(tx *bbolt.Tx, initialized bool) error { b := tx.Bucket(shardInfoBucket) if b != nil { data := b.Get(versionKey) if len(data) == 8 { stored := binary.LittleEndian.Uint64(data) if stored != version { return fmt.Errorf("invalid version: expected=%d, stored=%d", version, stored) } } } if !initialized { // new database, write version return updateVersion(tx, version) } return nil // return error here after the first version increase } func updateVersion(tx *bbolt.Tx, version uint64) error { data := make([]byte, 8) binary.LittleEndian.PutUint64(data, version) b, err := tx.CreateBucketIfNotExists(shardInfoBucket) if err != nil { return fmt.Errorf("can't create auxilliary bucket: %w", err) } return b.Put(versionKey, data) }