retry.go

// Copyright 2024 Google LLC.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package gorm

import (
	"context"
	"database/sql"
	"math/rand"
	"time"

	"cloud.google.com/go/spanner"
	"github.com/googleapis/gax-go/v2"
	spannerdriver "github.com/googleapis/go-sql-spanner"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
	"gorm.io/gorm"
)

// RunTransaction executes a transaction on Spanner using the given
// gorm database, and retries the transaction if it is aborted by Spanner.
func RunTransaction(ctx context.Context, db *gorm.DB, fc func(tx *gorm.DB) error, opts ...*sql.TxOptions) error {
	// Disable internal (checksum-based) retries on the Spanner database/SQL connection.
	// Note: gorm also only uses the first option, so it is safe to pick just the first element in the slice.
	if len(opts) > 0 && opts[0] != nil {
		opts[0].Isolation = spannerdriver.WithDisableRetryAborts(opts[0].Isolation)
	}
	for {
		err := db.Transaction(fc, opts...)
		if err == nil {
			return nil
		}
		s, ok := status.FromError(err)
		if !ok || s.Code() != codes.Aborted {
			return err
		}
		delay, ok := spanner.ExtractRetryDelay(err)
		if !ok {
			// Use a random backoff time if no backoff time was included in the error.
			r := rand.New(rand.NewSource(time.Now().UnixNano()))
			delay = time.Duration(r.Intn(20)) * time.Millisecond
		}
		if err := gax.Sleep(ctx, delay); err != nil {
			return err
		}
	}
}