dtm/dtmsvr/cron.go

/*
 * Copyright (c) 2021 yedf. All rights reserved.
 * Use of this source code is governed by a BSD-style
 * license that can be found in the LICENSE file.
 */

package dtmsvr

import (
	"fmt"
	"math/rand"
	"runtime/debug"
	"time"

	"github.com/yedf/dtm/dtmcli/dtmimp"
)

// NowForwardDuration will be set in test, trans may be timeout
var NowForwardDuration time.Duration = time.Duration(0)

// CronForwardDuration will be set in test. cron will fetch trans which expire in CronForwardDuration
var CronForwardDuration time.Duration = time.Duration(0)

// CronTransOnce cron expired trans. use expireIn as expire time
func CronTransOnce() (gid string) {
	defer handlePanic(nil)
	trans := lockOneTrans(CronForwardDuration)
	if trans == nil {
		return
	}
	gid = trans.Gid
	trans.WaitResult = true
	trans.Process(dbGet())
	return
}

// CronExpiredTrans cron expired trans, num == -1 indicate for ever
func CronExpiredTrans(num int) {
	for i := 0; i < num || num == -1; i++ {
		gid := CronTransOnce()
		if gid == "" && num != 1 {
			sleepCronTime()
		}
	}
}

func lockOneTrans(expireIn time.Duration) *TransGlobal {
	trans := TransGlobal{}
	owner := GenGid()
	db := dbGet()
	getTime := dtmimp.GetDBSpecial().TimestampAdd
	expire := int(expireIn / time.Second)
	whereTime := fmt.Sprintf("next_cron_time < %s and update_time < %s", getTime(expire), getTime(expire-3))
	// 这里next_cron_time需要限定范围，否则数据量累计之后，会导致查询变慢
	// 限定update_time < now - 3，否则会出现刚被这个应用取出，又被另一个取出
	dbr := db.Must().Model(&trans).
		Where(whereTime+"and status in ('prepared', 'aborting', 'submitted')").Limit(1).Update("owner", owner)
	if dbr.RowsAffected == 0 {
		return nil
	}
	dbr = db.Must().Where("owner=?", owner).Find(&trans)
	updates := trans.setNextCron(cronKeep)
	db.Must().Model(&trans).Select(updates).Updates(&trans)
	return &trans
}

func handlePanic(perr *error) {
	if err := recover(); err != nil {
		dtmimp.LogRedf("----recovered panic %v\n%s", err, string(debug.Stack()))
		if perr != nil {
			*perr = fmt.Errorf("dtm panic: %v", err)
		}
	}
}

func sleepCronTime() {
	normal := time.Duration((float64(config.TransCronInterval) - rand.Float64()) * float64(time.Second))
	interval := dtmimp.If(CronForwardDuration > 0, 1*time.Millisecond, normal).(time.Duration)
	dtmimp.Logf("sleeping for %v milli", interval/time.Microsecond)
	time.Sleep(interval)
}