Files
tidb/kv/txn.go

111 lines
3.1 KiB
Go

// Copyright 2015 PingCAP, Inc.
//
// 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package kv
import (
"context"
"math"
"math/rand"
"sync/atomic"
"time"
"github.com/pingcap/errors"
"github.com/pingcap/parser/terror"
log "github.com/sirupsen/logrus"
)
// ContextKey is the type of context's key
type ContextKey string
// RunInNewTxn will run the f in a new transaction environment.
func RunInNewTxn(store Storage, retryable bool, f func(txn Transaction) error) error {
var (
err error
originalTxnTS uint64
txn Transaction
)
for i := uint(0); i < maxRetryCnt; i++ {
txn, err = store.Begin()
if err != nil {
log.Errorf("[kv] RunInNewTxn error - %v", err)
return errors.Trace(err)
}
// originalTxnTS is used to trace the original transaction when the function is retryable.
if i == 0 {
originalTxnTS = txn.StartTS()
}
err = f(txn)
if err != nil {
err1 := txn.Rollback()
terror.Log(errors.Trace(err1))
if retryable && IsRetryableError(err) {
log.Warnf("[kv] Retry txn %v original txn %v err %v", txn, originalTxnTS, err)
continue
}
return errors.Trace(err)
}
err = txn.Commit(context.Background())
if err == nil {
break
}
if retryable && IsRetryableError(err) {
log.Warnf("[kv] Retry txn %v original txn %v err %v", txn, originalTxnTS, err)
BackOff(i)
continue
}
return errors.Trace(err)
}
return errors.Trace(err)
}
var (
// maxRetryCnt represents maximum retry times in RunInNewTxn.
maxRetryCnt uint = 100
// retryBackOffBase is the initial duration, in microsecond, a failed transaction stays dormancy before it retries
retryBackOffBase = 1
// retryBackOffCap is the max amount of duration, in microsecond, a failed transaction stays dormancy before it retries
retryBackOffCap = 100
)
// BackOff Implements exponential backoff with full jitter.
// Returns real back off time in microsecond.
// See http://www.awsarchitectureblog.com/2015/03/backoff.html.
func BackOff(attempts uint) int {
upper := int(math.Min(float64(retryBackOffCap), float64(retryBackOffBase)*math.Pow(2.0, float64(attempts))))
sleep := time.Duration(rand.Intn(upper)) * time.Millisecond
time.Sleep(sleep)
return int(sleep)
}
// mockCommitErrorEnable uses to enable `mockCommitError` and only mock error once.
var mockCommitErrorEnable = int64(0)
// MockCommitErrorEnable exports for gofail testing.
func MockCommitErrorEnable() {
atomic.StoreInt64(&mockCommitErrorEnable, 1)
}
// MockCommitErrorDisable exports for gofail testing.
func MockCommitErrorDisable() {
atomic.StoreInt64(&mockCommitErrorEnable, 0)
}
// IsMockCommitErrorEnable exports for gofail testing.
func IsMockCommitErrorEnable() bool {
return atomic.LoadInt64(&mockCommitErrorEnable) == 1
}