lexi: Move old db if bad version.

Author: JoeGruffins

client/asset/btc/txdb.go

@@ -14,12 +14,14 @@ import (
 	"fmt"
 	"math"
 	"math/rand"
+	"os"
 	"sync"
 	"sync/atomic"
 	"time"
 
 	"decred.org/dcrdex/client/asset"
 	"decred.org/dcrdex/dex"
+	"decred.org/dcrdex/dex/lexi"
 	"github.com/dgraph-io/badger/v4"
 )
 
@@ -123,7 +125,22 @@ func (db *BadgerTxDB) Connect(ctx context.Context) (*sync.WaitGroup, error) {
 	var err error
 	db.DB, err = badger.Open(opts)
 	if err != nil {
-		return nil, err
+		if lexi.IsBadgerVersionError(err) {
+			db.log.Warnf("Detected incompatible database version at %s. "+
+				"Backing up old database and creating new one.", db.filePath)
+			backupPath := db.filePath + ".v1.bak"
+			if err := os.Rename(db.filePath, backupPath); err != nil {
+				return nil, fmt.Errorf("failed to backup old database: %w", err)
+			}
+			db.log.Infof("Old database backed up to %s", backupPath)
+			// Try opening again with a fresh directory
+			db.DB, err = badger.Open(opts)
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			return nil, err
+		}
 	}
 	db.ctx = ctx
 	db.seq, err = db.GetSequence([]byte("seq"), 10)

client/asset/eth/txdb_legacy.go

@@ -7,10 +7,12 @@ import (
 	"errors"
 	"fmt"
 	"math"
+	"os"
 	"sync"
 	"time"
 
 	"decred.org/dcrdex/dex"
+	"decred.org/dcrdex/dex/lexi"
 	"github.com/dgraph-io/badger/v4"
 	"github.com/ethereum/go-ethereum/common"
 )
@@ -100,7 +102,22 @@ func newBadgerTxDB(filePath string, log dex.Logger) (*badgerTxDB, error) {
 	var err error
 	bdb, err := badger.Open(opts)
 	if err != nil {
-		return nil, err
+		if lexi.IsBadgerVersionError(err) {
+			log.Warnf("Detected incompatible database version at %s. "+
+				"Backing up old database and creating new one.", filePath)
+			backupPath := filePath + ".v1.bak"
+			if err := os.Rename(filePath, backupPath); err != nil {
+				return nil, fmt.Errorf("failed to backup old database: %w", err)
+			}
+			log.Infof("Old database backed up to %s", backupPath)
+			// Try opening again with a fresh directory
+			bdb, err = badger.Open(opts)
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			return nil, err
+		}
 	}
 
 	db := &badgerTxDB{

client/asset/kvdb/kvdb.go

@@ -7,9 +7,12 @@ import (
 	"context"
 	"encoding"
 	"errors"
+	"fmt"
+	"os"
 	"time"
 
 	"decred.org/dcrdex/dex"
+	"decred.org/dcrdex/dex/lexi"
 	"github.com/dgraph-io/badger/v4"
 )
 
@@ -34,7 +37,22 @@ func NewFileDB(filePath string, log dex.Logger) (KeyValueDB, error) {
 	opts := badger.DefaultOptions(filePath).WithLogger(&badgerLoggerWrapper{log})
 	db, err := badger.Open(opts)
 	if err != nil {
-		return nil, err
+		if lexi.IsBadgerVersionError(err) {
+			log.Warnf("Detected incompatible database version at %s. "+
+				"Backing up old database and creating new one.", filePath)
+			backupPath := filePath + ".v1.bak"
+			if err := os.Rename(filePath, backupPath); err != nil {
+				return nil, fmt.Errorf("failed to backup old database: %w", err)
+			}
+			log.Infof("Old database backed up to %s", backupPath)
+			// Try opening again with a fresh directory
+			db, err = badger.Open(opts)
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			return nil, err
+		}
 	}
 
 	return &kvDB{db, log}, nil

dex/lexi/lexi.go

@@ -9,6 +9,8 @@ import (
 	"encoding/binary"
 	"errors"
 	"fmt"
+	"os"
+	"strings"
 	"sync"
 	"time"
 
@@ -46,12 +48,35 @@ type Config struct {
 	Log  dex.Logger
 }
 
+// IsBadgerVersionError checks if the error is due to an incompatible badger
+// database version (e.g., trying to open a v1 database with v4).
+func IsBadgerVersionError(err error) bool {
+	errStr := err.Error()
+	return strings.Contains(errStr, "manifest has unsupported version") ||
+		strings.Contains(errStr, "external magic number doesn't match")
+}
+
 // New constructs a new Lexi DB.
 func New(cfg *Config) (*DB, error) {
 	opts := badger.DefaultOptions(cfg.Path).WithLogger(&badgerLoggerWrapper{cfg.Log.SubLogger("BADG")})
 	bdb, err := badger.Open(opts)
 	if err != nil {
-		return nil, err
+		if IsBadgerVersionError(err) {
+			cfg.Log.Warnf("Detected incompatible database version at %s. "+
+				"Backing up old database and creating new one.", cfg.Path)
+			backupPath := cfg.Path + ".v1.bak"
+			if err := os.Rename(cfg.Path, backupPath); err != nil {
+				return nil, fmt.Errorf("failed to backup old database: %w", err)
+			}
+			cfg.Log.Infof("Old database backed up to %s", backupPath)
+			// Try opening again with a fresh directory
+			bdb, err = badger.Open(opts)
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			return nil, err
+		}
 	}
 	idSeq, err := bdb.GetSequence(prefixedKey(primarySequencePrefix, []byte{0x00}), 1000)
 	if err != nil {