聊聊kingbus的binlogprogressgo

序

本文主要研究一下 kingbus 的 binlog_progress.go

BinlogProgress

kingbus/server/binlog_progress.go

//BinlogProgress is the progress of receiving binlog
type BinlogProgress struct {
    currentGtid  *atomic.String
    lastSaveGtid string
    //for heartbeat event
    lastBinlogFile     *atomic.String
    lastFilePosition   *atomic.Uint32
    executedGtidSetStr *atomic.String

    trxBoundaryParser *mysql.TransactionBoundaryParser

    persistentTime         time.Time
    persistentAppliedIndex uint64
    executedGtidSet        gomysql.GTIDSet
    store                  storage.Storage
}

• BinlogProgress 定义了 currentGtid、lastSaveGtid、lastBinlogFile、lastFilePosition、executedGtidSetStr、trxBoundaryParser、persistentTime、persistentAppliedIndex、executedGtidSet、store 属性

newBinlogProgress

kingbus/server/binlog_progress.go

func newBinlogProgress(store storage.Storage) (*BinlogProgress, error) {
    var err error
    p := new(BinlogProgress)

    p.trxBoundaryParser = new(mysql.TransactionBoundaryParser)
    p.trxBoundaryParser.Reset()

    p.currentGtid = atomic.NewString("")
    p.lastBinlogFile = atomic.NewString("")
    p.lastFilePosition = atomic.NewUint32(0)

    p.persistentAppliedIndex = 0
    p.persistentTime = time.Unix(0, 0)

    //get executed gtid_set
    //This value may be old, but resetBinlogProgress will update it to the latest
    p.executedGtidSet, err = store.GetGtidSet(gomysql.MySQLFlavor, storage.ExecutedGtidSetKey)
    if err != nil {log.Log.Errorf("newBinlogProgress:get executedGtidSet error,err:%s", err)
        return nil, err
    }
    p.executedGtidSetStr = atomic.NewString(p.executedGtidSet.String())
    p.store = store

    return p, nil
}

• newBinlogProgress 方法创建了 BinlogProgress 及 mysql.TransactionBoundaryParser，之后通过 store.GetGtidSet(gomysql.MySQLFlavor, storage.ExecutedGtidSetKey) 获取 executedGtidSet

updateProcess

kingbus/server/binlog_progress.go

//updateProcess update and save executedGtid set
func (s *BinlogProgress) updateProcess(raftIndex uint64, eventRawData []byte) error {
    var err error

    //parse event header
    h := new(replication.EventHeader)
    err = h.Decode(eventRawData)
    if err != nil {log.Log.Errorf("Decode error,err:%s,buf:%v", err, eventRawData)
        return err
    }
    //set the heartbeat info
    s.lastFilePosition.Store(h.LogPos)

    //remove header
    eventRawData = eventRawData[replication.EventHeaderSize:]
    eventLen := int(h.EventSize) - replication.EventHeaderSize
    if len(eventRawData) != eventLen {
        return fmt.Errorf("invalid data size %d in event %s, less event length %d",
            len(eventRawData), h.EventType, eventLen)
    }
    //remove crc32
    eventRawData = eventRawData[:len(eventRawData)-replication.BinlogChecksumLength]

    //the eventRawData maybe the first divided packet, but must not be query event
    //so don't worry
    eventBoundaryType, err := s.trxBoundaryParser.GetEventBoundaryType(h, eventRawData)
    if err != nil {
        log.Log.Errorf("GetEventBoundaryType error,err:%s,header:%v",
            err, *h)
        return err
    }
    //ignore updateState error, maybe a partial trx
    err = s.trxBoundaryParser.UpdateState(eventBoundaryType)
    if err != nil {log.Log.Warnf("trxBoundaryParser UpdateState error,err:%s,header:%v", err, *h)
        s.trxBoundaryParser.Reset()
        s.currentGtid.Store("")
        return nil
    }

    currentGtidStr := s.currentGtid.Load()
    if s.trxBoundaryParser.IsNotInsideTransaction() &&
        len(currentGtidStr) != 0 && s.lastSaveGtid != currentGtidStr {

        log.Log.Debugf("current gtid is :%s,add into executedGtidSet:%s",
            currentGtidStr, s.executedGtidSet.String())
        //update executedGtidSet
        err = s.executedGtidSet.Update(currentGtidStr)
        if err != nil {return err}
        s.lastSaveGtid = currentGtidStr
        s.executedGtidSetStr.Store(s.executedGtidSet.String())

        //save the raftIndex and executedGtidSet at the same time
        if raftIndex-s.persistentAppliedIndex > persistentCount ||
            time.Now().Sub(s.persistentTime) > persistentTimeInterval {err = s.store.SetBinlogProgress(raftIndex, s.executedGtidSet)
            if err != nil {
                log.Log.Errorf("SetGtidSet error,err:%s,key:%s,value:%s",
                    err, storage.ExecutedGtidSetKey, s.executedGtidSet.String())
                return err
            }

            s.persistentAppliedIndex = raftIndex
            s.persistentTime = time.Now()}
    }
    return nil
}

• updateProcess 方法会解析 eventRawData 为 replication.EventHeader，然后存储 h.LogPos；之后通过 s.trxBoundaryParser.GetEventBoundaryType(h, eventRawData) 获取 eventBoundaryType，然后通过 s.trxBoundaryParser.UpdateState(eventBoundaryType) 更新；之后通过 s.executedGtidSet.Update(currentGtidStr) 更新 currentGtidStr；最后通过 s.store.SetBinlogProgress(raftIndex, s.executedGtidSet) 更新 binlogProgress

小结

kingbus 的 binlog_progress.go 提供了 newBinlogProgress、updateProcess 方法用于存储 binglogProgress

doc

• binlog_progress