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本文主要研究一下kingbus的DumpBinlogAt
DumpBinlogAt
kingbus/server/binlog_server.go
//DumpBinlogAt implements dump binlog event by slave executed gtid set
func (s *BinlogServer) DumpBinlogAt(ctx context.Context,
startRaftIndex uint64, slaveGtids *gomysql.MysqlGTIDSet,
eventC chan<- *storagepb.BinlogEvent, errorC chan<- error) error {
var inExcludeGroup = false
//new a binlog event reader from startRaftIndex, then send event to slave one by one
reader, err := s.store.NewEntryReaderAt(startRaftIndex)
if err != nil {
log.Log.Errorf("NewEntryReaderAt error,err:%s,raftIndex:%d", err, startRaftIndex)
return err
}
nextRaftIndex := reader.NextRaftIndex()
log.Log.Infof("DumpBinlogAt:raftIndex:%d,slaveGtids:%s", nextRaftIndex, slaveGtids.String())
go func() {
for {
//the next read raftIndex must be little than AppliedIndex
if nextRaftIndex <= s.kingbusInfo.AppliedIndex() {
raftEntry, err := reader.GetNext()
if err != nil {
log.Log.Errorf("reader.GetNext error,err:%s,nextRaftIndex:%d,AppliedIndex:%d",
err, nextRaftIndex, s.kingbusInfo.AppliedIndex())
select {
case errorC <- err:
default:
}
return //need quit
}
nextRaftIndex = reader.NextRaftIndex()
//this entry is not binlog event
if utils.IsBinlogEvent(raftEntry) == false {
continue
}
event := utils.DecodeBinlogEvent(raftEntry)
//filter the event in slave gtids,if the event has send to slave
inExcludeGroup = s.skipEvent(event, slaveGtids, inExcludeGroup)
if inExcludeGroup {
continue
}
select {
case eventC <- event:
case <-ctx.Done():
log.Log.Errorf("binlog server receive cancel, need quit,err:%s", ctx.Err())
select {
case errorC <- ctx.Err():
default:
}
return //need quit
}
} else {
select {
case <-s.broadcast.Receive():
break
case <-ctx.Done():
log.Log.Errorf("binlog server receive cancel, need quit,err:%s", ctx.Err())
select {
case errorC <- ctx.Err():
default:
}
return //need quit
}
}
}
}()
return nil
}
- DumpBinlogAt方法通过s.store.NewEntryReaderAt(startRaftIndex)获取reader,然后获取nextRaftIndex,之后通过utils.DecodeBinlogEvent(raftEntry)获取event,然后通过s.skipEvent(event, slaveGtids, inExcludeGroup)来判断是否该skip,之后将event写入到eventC
NewEntryReaderAt
kingbus/storage/disk_storage.go
//NewEntryReaderAt create a DiskEntryReader at raftIndex
func (s *DiskStorage) NewEntryReaderAt(raftIndex uint64) (EntryReader, error) {
err := s.checkRaftIndex(raftIndex)
if err != nil {
log.Log.Errorf("checkRaftIndex error,err:%s,raftIndex:%d", err, raftIndex)
return nil, err
}
reader := new(DiskEntryReader)
reader.indexReadAt = raftIndex
reader.store = s
return reader, nil
}
- NewEntryReaderAt方法先通过s.checkRaftIndex(raftIndex)校验一下index,然后创建DiskEntryReader,设置indexReadAt为raftIndex
skipEvent
kingbus/server/binlog_server.go
//skipEvent filter the event has been executed by slave
func (s *BinlogServer) skipEvent(event *storagepb.BinlogEvent, slaveGtids *gomysql.MysqlGTIDSet, inExcludeGroup bool) bool {
switch replication.EventType(event.Type) {
case replication.GTID_EVENT:
//remove header
eventBody := event.Data[replication.EventHeaderSize:]
//remove crc32
eventBody = eventBody[:len(eventBody)-replication.BinlogChecksumLength]
gtidEvent := &replication.GTIDEvent{}
if err := gtidEvent.Decode(eventBody); err != nil {
log.Log.Errorf("Decode gtid event error,err:%s", err)
return true
}
u, err := uuid.FromBytes(gtidEvent.SID)
if err != nil {
log.Log.Errorf("FromBytes error,err:%s,sid:%v", err, gtidEvent.SID)
return true
}
gtidStr := fmt.Sprintf("%s:%d", u.String(), gtidEvent.GNO)
currentGtidset, err := gomysql.ParseMysqlGTIDSet(gtidStr)
if err != nil {
log.Log.Errorf("ParseMysqlGTIDSet error,err:%s,gtid:%s", err, gtidStr)
return true
}
return slaveGtids.Contain(currentGtidset)
case replication.ROTATE_EVENT:
return false
}
return inExcludeGroup
}
- skipEvent方法根据replication.EventType(event.Type)类型来判断,对于能够取到currentGtidset的通过slaveGtids.Contain(currentGtidset)判断,对于replication.ROTATE_EVENT返回false
小结
DumpBinlogAt方法通过s.store.NewEntryReaderAt(startRaftIndex)获取reader,然后获取nextRaftIndex,之后通过utils.DecodeBinlogEvent(raftEntry)获取event,然后通过s.skipEvent(event, slaveGtids, inExcludeGroup)来判断是否该skip,之后将event写入到eventC
doc
来源:oschina
链接:https://my.oschina.net/go4it/blog/4318249