feat: fix failure when calling SavePolicy within the Transaction meth…

…od (#251)

Co-authored-by: junfengxu <junfeng.xu@takuad.com>

adapter.go

@@ -707,18 +707,17 @@ func (a *Adapter) Transaction(e casbin.IEnforcer, fc func(casbin.IEnforcer) erro
 	a.transactionMu.Lock()
 	defer a.transactionMu.Unlock()
 	var err error
-	oriAdapter := a.db
 	// reload policy from database to sync with the transaction
 	defer func() {
-		e.SetAdapter(&Adapter{db: oriAdapter, transactionMu: a.transactionMu})
+		e.SetAdapter(a.Copy())
 		err = e.LoadPolicy()
 		if err != nil {
 			panic(err)
 		}
 	}()
 	copyDB := *a.db
 	tx := copyDB.Begin(opts...)
-	b := &Adapter{db: tx, transactionMu: a.transactionMu}
+	b := a.Copy()
 	// copy enforcer to set the new adapter with transaction tx
 	copyEnforcer := e
 	copyEnforcer.SetAdapter(b)
@@ -946,6 +945,21 @@ func (a *Adapter) UpdateFilteredPolicies(sec string, ptype string, newPolicies [
 	return oldPolicies, tx.Commit().Error
 }
 
+func (a *Adapter) Copy() *Adapter {
+	oriAdapter := a.db
+	return &Adapter{
+		db:             oriAdapter,
+		transactionMu:  a.transactionMu,
+		driverName:     a.driverName,
+		dataSourceName: a.dataSourceName,
+		databaseName:   a.databaseName,
+		tablePrefix:    a.tablePrefix,
+		tableName:      a.tableName,
+		dbSpecified:    a.dbSpecified,
+		isFiltered:     a.isFiltered,
+	}
+}
+
 // Preview Pre-checking to avoid causing partial load success and partial failure deep
 func (a *Adapter) Preview(rules *[]CasbinRule, model model.Model) error {
 	j := 0

adapter_test.go

@@ -766,3 +766,33 @@ func TestTransactionRace(t *testing.T) {
 		require.True(t, e.HasPolicy("jack", fmt.Sprintf("data%d", i), "write"))
 	}
 }
+
+func TestTransactionWithSavePolicy(t *testing.T) {
+	a := initAdapter(t, "mysql", "root:@tcp(127.0.0.1:3306)/", "casbin", "casbin_rule")
+	e, _ := casbin.NewEnforcer("examples/rbac_model.conf", a)
+	defer func() {
+		e.ClearPolicy()
+		err := e.SavePolicy()
+		if err != nil {
+			t.Fatalf("save policy err %v", err)
+		}
+	}()
+	err := e.GetAdapter().(*Adapter).Transaction(e, func(e casbin.IEnforcer) error {
+		_, err := e.AddPolicy("jack", "data1", "write")
+		if err != nil {
+			return err
+		}
+		_, err = e.AddPolicy("jack", "data2", "write")
+		if err != nil {
+			return err
+		}
+		err = e.SavePolicy()
+		if err != nil {
+			return err
+		}
+		return nil
+	})
+	if err != nil {
+		return
+	}
+}