*: support recover relay log file with a subset of metadata (pingcap#530

)

_utils/terror_gen/errors_release.txt

@@ -95,7 +95,7 @@ ErrBinlogWriterGetFileStat,[code=11088:class=functional:scope=internal:level=hig
 ErrBinlogWriterWriteDataLen,[code=11089:class=functional:scope=internal:level=high],"data length %d"
 ErrBinlogWriterFileNotOpened,[code=11090:class=functional:scope=internal:level=high],"file %s not opened"
 ErrBinlogWriterFileSync,[code=11091:class=functional:scope=internal:level=high],"sync file"
-ErrBinlogPrevGTIDEvNotValid,[code=11092:class=functional:scope=internal:level=high],"PreviousGTIDsEvent should be a GenericEvent in go-mysql, but got %T"
+ErrBinlogPrevGTIDEvNotValid,[code=11092:class=functional:scope=internal:level=high],"the event should be a PreviousGTIDsEvent in go-mysql, but got %T"
 ErrBinlogDecodeMySQLGTIDSet,[code=11093:class=functional:scope=internal:level=high],"decode from % X"
 ErrBinlogNeedMariaDBGTIDSet,[code=11094:class=functional:scope=internal:level=high],"the event should be a MariadbGTIDListEvent, but got %T"
 ErrBinlogParseMariaDBGTIDSet,[code=11095:class=functional:scope=internal:level=high],"parse MariaDB GTID set"

go.mod

@@ -47,7 +47,7 @@ require (
 	github.com/shopspring/decimal v0.0.0-20191125035519-b054a8dfd10d // indirect
 	github.com/siddontang/go v0.0.0-20180604090527-bdc77568d726
 	github.com/siddontang/go-log v0.0.0-20190221022429-1e957dd83bed // indirect
-	github.com/siddontang/go-mysql v0.0.0-20191009015310-f66c8b344478
+	github.com/siddontang/go-mysql v0.0.0-20200222075837-12e89848f047
 	github.com/soheilhy/cmux v0.1.4
 	github.com/spaolacci/murmur3 v1.1.0 // indirect
 	github.com/spf13/cobra v0.0.5

go.sum

@@ -360,8 +360,8 @@ github.com/siddontang/go-log v0.0.0-20180807004314-8d05993dda07 h1:oI+RNwuC9jF2g
 github.com/siddontang/go-log v0.0.0-20180807004314-8d05993dda07/go.mod h1:yFdBgwXP24JziuRl2NMUahT7nGLNOKi1SIiFxMttVD4=
 github.com/siddontang/go-log v0.0.0-20190221022429-1e957dd83bed h1:KMgQoLJGCq1IoZpLZE3AIffh9veYWoVlsvA4ib55TMM=
 github.com/siddontang/go-log v0.0.0-20190221022429-1e957dd83bed/go.mod h1:yFdBgwXP24JziuRl2NMUahT7nGLNOKi1SIiFxMttVD4=
-github.com/siddontang/go-mysql v0.0.0-20191009015310-f66c8b344478 h1:pfx6pRovM/9/GGA3bAnJu3vlIqLuWwqEo56WXPrN6o4=
-github.com/siddontang/go-mysql v0.0.0-20191009015310-f66c8b344478/go.mod h1:+W4RCzesQDI11HvIkaDjS8yM36SpAnGNQ7jmTLn5BnU=
+github.com/siddontang/go-mysql v0.0.0-20200222075837-12e89848f047 h1:boyJ8EgQN/aC3grvx8QUoJrptt7RvneezSJSCbW25a4=
+github.com/siddontang/go-mysql v0.0.0-20200222075837-12e89848f047/go.mod h1:+W4RCzesQDI11HvIkaDjS8yM36SpAnGNQ7jmTLn5BnU=
 github.com/sirupsen/logrus v1.0.5/go.mod h1:pMByvHTf9Beacp5x1UXfOR9xyW/9antXMhjMPG0dEzc=
 github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
 github.com/sirupsen/logrus v1.4.1/go.mod h1:ni0Sbl8bgC9z8RoU9G6nDWqqs/fq4eDPysMBDgk/93Q=

pkg/binlog/event/common.go

@@ -50,7 +50,7 @@ func GenCommonFileHeader(flavor string, serverID uint32, gSet gtid.Set) ([]*repl
 			Flags:     defaultHeaderFlags,
 		}
 		latestPos   = uint32(len(replication.BinLogFileHeader))
-		prevGTIDsEv *replication.BinlogEvent // for MySQL, this will be a GenericEvent
+		prevGTIDsEv *replication.BinlogEvent
 	)
 
 	formatDescEv, err := GenFormatDescriptionEvent(header, latestPos)

pkg/binlog/event/common_test.go

@@ -14,7 +14,6 @@
 package event
 
 import (
-	"bytes"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -60,26 +59,12 @@ func (t *testCommonSuite) TestGenCommonFileHeader(c *C) {
 	var count = 0
 	onEventFunc := func(e *replication.BinlogEvent) error {
 		count++
-		switch count {
-		case 1: // FormatDescriptionEvent
-			c.Assert(e.Header, DeepEquals, events[0].Header)
-			c.Assert(e.Event, DeepEquals, events[0].Event)
-			c.Assert(e.RawData, DeepEquals, events[0].RawData)
-		case 2: // PreviousGTIDsEvent
-			switch flavor {
-			case gmysql.MySQLFlavor:
-				c.Assert(e.Header.EventType, Equals, replication.PREVIOUS_GTIDS_EVENT)
-				c.Assert(bytes.Contains(data, e.RawData), IsTrue)
-			case gmysql.MariaDBFlavor:
-				c.Assert(e.Header, DeepEquals, events[1].Header)
-				c.Assert(e.Event, DeepEquals, events[1].Event)
-				c.Assert(e.RawData, DeepEquals, events[1].RawData)
-			default:
-				c.Fatalf("invalid flavor %s", flavor)
-			}
-		default:
+		if count > 2 {
 			c.Fatalf("too many binlog events got, current is %+v", e.Header)
 		}
+		c.Assert(e.Header, DeepEquals, events[count-1].Header)
+		c.Assert(e.Event, DeepEquals, events[count-1].Event)
+		c.Assert(e.RawData, DeepEquals, events[count-1].RawData)
 		return nil
 	}
 

pkg/binlog/event/event.go

@@ -196,7 +196,6 @@ func GenRotateEvent(header *replication.EventHeader, latestPos uint32, nextLogNa
 }
 
 // GenPreviousGTIDsEvent generates a PreviousGTIDsEvent.
-// go-mysql has no PreviousGTIDsEvent struct defined, so return a GenericEvent instead.
 // MySQL has no internal doc for PREVIOUS_GTIDS_EVENT.
 // we ref:
 //   a. https://github.com/vitessio/vitess/blob/28e7e5503a6c3d3b18d4925d95f23ebcb6f25c8e/go/mysql/binlog_event_mysql56.go#L56
@@ -215,7 +214,7 @@ func GenPreviousGTIDsEvent(header *replication.EventHeader, latestPos uint32, gS
 	payload := origin.Encode()
 
 	buf := new(bytes.Buffer)
-	event := &replication.GenericEvent{} // no PreviousGTIDsEvent struct defined, so use a GenericEvent instead.
+	event := &replication.PreviousGTIDsEvent{}
 	ev, err := assembleEvent(buf, event, false, *header, replication.PREVIOUS_GTIDS_EVENT, latestPos, nil, payload)
 	return ev, err
 }

pkg/binlog/event/event_test.go

@@ -160,7 +160,6 @@ func (t *testEventSuite) TestGenPreviousGTIDsEvent(c *C) {
 		str              = "9f61c5f9-1eef-11e9-b6cf-0242ac140003:1-5"
 	)
 
-	// go-mysql has no PreviousGTIDsEvent struct defined, so we try to parse a binlog file.
 	// always needing a FormatDescriptionEvent in the binlog file.
 	formatDescEv, err := GenFormatDescriptionEvent(header, latestPos)
 	c.Assert(err, IsNil)
@@ -202,7 +201,8 @@ func (t *testEventSuite) TestGenPreviousGTIDsEvent(c *C) {
 			c.Assert(e.Event, DeepEquals, formatDescEv.Event)
 			c.Assert(e.RawData, DeepEquals, formatDescEv.RawData)
 		case 2: // PreviousGTIDsEvent
-			c.Assert(e.Header.EventType, Equals, replication.PREVIOUS_GTIDS_EVENT)
+			c.Assert(e.Header, DeepEquals, previousGTIDsEv.Header)
+			c.Assert(e.Event, DeepEquals, previousGTIDsEv.Event)
 			c.Assert(e.RawData, DeepEquals, previousGTIDsEv.RawData)
 		default:
 			c.Fatalf("too many binlog events got, current is %+v", e.Header)
@@ -319,7 +319,8 @@ func (t *testEventSuite) TestGenGTIDEvent(c *C) {
 			c.Assert(e.Event, DeepEquals, formatDescEv.Event)
 			c.Assert(e.RawData, DeepEquals, formatDescEv.RawData)
 		case 2: // PreviousGTIDsEvent
-			c.Assert(e.Header.EventType, Equals, replication.PREVIOUS_GTIDS_EVENT)
+			c.Assert(e.Header, DeepEquals, previousGTIDsEv.Header)
+			c.Assert(e.Event, DeepEquals, previousGTIDsEv.Event)
 			c.Assert(e.RawData, DeepEquals, previousGTIDsEv.RawData)
 		case 3: // GTIDEvent
 			c.Assert(e.Header.EventType, Equals, replication.GTID_EVENT)

pkg/binlog/event/generator_test.go

@@ -294,9 +294,7 @@ func (t *testGeneratorSuite) testGenerate(c *C, flavor string, serverID uint32,
 	var count = 0
 	onEventFunc := func(e *replication.BinlogEvent) error {
 		c.Assert(e.Header.EventType, Equals, allEventTypes[count])
-		if count != 1 { // allEvents[1] is nil for PreviousGTIDsEvent
-			c.Assert(e.RawData, DeepEquals, allEvents[count].RawData)
-		}
+		c.Assert(e.RawData, DeepEquals, allEvents[count].RawData)
 		count++
 		return nil
 	}

pkg/binlog/event/helper.go

@@ -23,34 +23,15 @@ import (
 
 // GTIDsFromPreviousGTIDsEvent get GTID set from a PreviousGTIDsEvent.
 func GTIDsFromPreviousGTIDsEvent(e *replication.BinlogEvent) (gtid.Set, error) {
-	var payload []byte
+	var gSetStr string
 	switch ev := e.Event.(type) {
-	case *replication.GenericEvent:
-		payload = ev.Data
+	case *replication.PreviousGTIDsEvent:
+		gSetStr = ev.GTIDSets
 	default:
 		return nil, terror.ErrBinlogPrevGTIDEvNotValid.Generate(e.Event)
 	}
 
-	if e.Header.EventType != replication.PREVIOUS_GTIDS_EVENT {
-		return nil, terror.ErrBinlogEventTypeNotValid.Generatef("invalid event type %d, expect %d", e.Header.EventType, replication.PREVIOUS_GTIDS_EVENT)
-	}
-
-	set, err := gmysql.DecodeMysqlGTIDSet(payload)
-	if err != nil {
-		return nil, terror.ErrBinlogDecodeMySQLGTIDSet.Delegate(err, payload)
-	}
-
-	// always MySQL for PreviousGTIDsEvent
-	gSet, err := gtid.ParserGTID(gmysql.MySQLFlavor, "")
-	if err != nil {
-		return nil, terror.ErrBinlogEmptyGTID.Delegate(err)
-	}
-	err = gSet.Set(set)
-	if err != nil {
-		return nil, terror.Annotatef(err, "replace GTID set with set %v", set)
-	}
-
-	return gSet, nil
+	return gtid.ParserGTID(gmysql.MySQLFlavor, gSetStr)
 }
 
 // GTIDsFromMariaDBGTIDListEvent get GTID set from a MariaDBGTIDListEvent.

pkg/binlog/event/helper_test.go

@@ -21,6 +21,7 @@ import (
 	"github.com/siddontang/go-mysql/replication"
 
 	"github.com/pingcap/dm/pkg/gtid"
+	"github.com/pingcap/dm/pkg/terror"
 )
 
 var _ = Suite(&testHelperSuite{})
@@ -41,14 +42,7 @@ func (t *testHelperSuite) TestGTIDsFromPreviousGTIDsEvent(c *C) {
 	queryEv, err := GenQueryEvent(header, latestPos, 0, 0, 0, nil, []byte("schema"), []byte("BEGIN"))
 	c.Assert(err, IsNil)
 	gSet, err := GTIDsFromPreviousGTIDsEvent(queryEv)
-	c.Assert(err, ErrorMatches, ".*should be a GenericEvent in go-mysql.*")
-	c.Assert(gSet, IsNil)
-
-	// invalid binlog type, USER_VAR_EVENT
-	userVarEv, err := GenDummyEvent(header, latestPos, MinUserVarEventLen)
-	c.Assert(err, IsNil)
-	gSet, err = GTIDsFromPreviousGTIDsEvent(userVarEv)
-	c.Assert(err, ErrorMatches, ".*invalid event type.*")
+	c.Assert(terror.ErrBinlogPrevGTIDEvNotValid.Equal(err), IsTrue)
 	c.Assert(gSet, IsNil)
 
 	// valid MySQL GTIDs

pkg/terror/error_list.go

@@ -642,7 +642,7 @@ var (
 	ErrBinlogWriterWriteDataLen      = New(codeBinlogWriterWriteDataLen, ClassFunctional, ScopeInternal, LevelHigh, "data length %d")
 	ErrBinlogWriterFileNotOpened     = New(codeBinlogWriterFileNotOpened, ClassFunctional, ScopeInternal, LevelHigh, "file %s not opened")
 	ErrBinlogWriterFileSync          = New(codeBinlogWriterFileSync, ClassFunctional, ScopeInternal, LevelHigh, "sync file")
-	ErrBinlogPrevGTIDEvNotValid      = New(codeBinlogPrevGTIDEvNotValid, ClassFunctional, ScopeInternal, LevelHigh, "PreviousGTIDsEvent should be a GenericEvent in go-mysql, but got %T")
+	ErrBinlogPrevGTIDEvNotValid      = New(codeBinlogPrevGTIDEvNotValid, ClassFunctional, ScopeInternal, LevelHigh, "the event should be a PreviousGTIDsEvent in go-mysql, but got %T")
 	ErrBinlogDecodeMySQLGTIDSet      = New(codeBinlogDecodeMySQLGTIDSet, ClassFunctional, ScopeInternal, LevelHigh, "decode from % X")
 	ErrBinlogNeedMariaDBGTIDSet      = New(codeBinlogNeedMariaDBGTIDSet, ClassFunctional, ScopeInternal, LevelHigh, "the event should be a MariadbGTIDListEvent, but got %T")
 	ErrBinlogParseMariaDBGTIDSet     = New(codeBinlogParseMariaDBGTIDSet, ClassFunctional, ScopeInternal, LevelHigh, "parse MariaDB GTID set")

relay/relay.go

@@ -378,7 +378,11 @@ func (r *Relay) tryRecoverLatestFile(parser2 *parser.Parser) error {
 		if result.Recovered {
 			r.tctx.L().Warn("relay log file recovered",
 				zap.Stringer("from position", latestPos), zap.Stringer("to position", result.LatestPos), log.WrapStringerField("from GTID set", latestGTID), log.WrapStringerField("to GTID set", result.LatestGTIDs))
-			if err = latestGTID.Truncate(result.LatestGTIDs); err != nil {
+			if !result.LatestGTIDs.Equal(latestGTID) && result.LatestGTIDs.Contain(latestGTID) {
+				r.tctx.L().Warn("some GTIDs are missing in the meta data, this is usually due to the process was interrupted while writing the meta data. force to update GTIDs",
+					log.WrapStringerField("from GTID set", latestGTID), log.WrapStringerField("to GTID set", result.LatestGTIDs))
+				latestGTID = result.LatestGTIDs.Clone()
+			} else if err = latestGTID.Truncate(result.LatestGTIDs); err != nil {
 				return err
 			}
 			err = r.meta.Save(result.LatestPos, latestGTID)

relay/relay_test.go

@@ -36,8 +36,8 @@ import (
 	"github.com/pingcap/dm/pkg/binlog"
 	"github.com/pingcap/dm/pkg/binlog/event"
 	"github.com/pingcap/dm/pkg/gtid"
+	"github.com/pingcap/dm/pkg/log"
 	"github.com/pingcap/dm/pkg/streamer"
-	"github.com/pingcap/dm/pkg/terror"
 	"github.com/pingcap/dm/pkg/utils"
 	"github.com/pingcap/dm/relay/reader"
 	"github.com/pingcap/dm/relay/retry"
@@ -54,6 +54,10 @@ func TestSuite(t *testing.T) {
 type testRelaySuite struct {
 }
 
+func (t *testRelaySuite) SetUpSuite(c *C) {
+	log.InitLogger(&log.Config{})
+}
+
 func getDBConfigForTest() config.DBConfig {
 	host := os.Getenv("MYSQL_HOST")
 	if host == "" {
@@ -198,16 +202,6 @@ func (t *testRelaySuite) TestTryRecoverLatestFile(c *C) {
 	c.Assert(err, IsNil)
 	f.Close()
 
-	// GTID sets in meta data does not contain the GTID sets in relay log, invalid
-	c.Assert(terror.ErrGTIDTruncateInvalid.Equal(r.tryRecoverLatestFile(parser2)), IsTrue)
-
-	// write some invalid data into the relay log file again
-	f, err = os.OpenFile(filepath.Join(r.meta.Dir(), filename), os.O_WRONLY|os.O_APPEND, 0600)
-	c.Assert(err, IsNil)
-	_, err = f.Write([]byte("invalid event data"))
-	c.Assert(err, IsNil)
-	f.Close()
-
 	// write a greater GTID sets in meta
 	greaterGITDSet, err := gtid.ParserGTID(relayCfg.Flavor, greaterGITDSetStr)
 	c.Assert(err, IsNil)
@@ -231,6 +225,72 @@ func (t *testRelaySuite) TestTryRecoverLatestFile(c *C) {
 	c.Assert(latestGTIDs.Contain(g.LatestGTID), IsTrue)
 }
 
+func (t *testRelaySuite) TestTryRecoverMeta(c *C) {
+	var (
+		uuid               = "24ecd093-8cec-11e9-aa0d-0242ac170002"
+		previousGTIDSetStr = "3ccc475b-2343-11e7-be21-6c0b84d59f30:1-14,53bfca22-690d-11e7-8a62-18ded7a37b78:1-495,406a3f61-690d-11e7-87c5-6c92bf46f384:123-456"
+		latestGTIDStr1     = "3ccc475b-2343-11e7-be21-6c0b84d59f30:14"
+		latestGTIDStr2     = "53bfca22-690d-11e7-8a62-18ded7a37b78:495"
+		genGTIDSetStr      = "3ccc475b-2343-11e7-be21-6c0b84d59f30:1-17,53bfca22-690d-11e7-8a62-18ded7a37b78:1-505,406a3f61-690d-11e7-87c5-6c92bf46f384:123-456"
+		filename           = "mysql-bin.000001"
+		startPos           = gmysql.Position{Name: filename, Pos: 123}
+
+		parser2  = parser.New()
+		relayCfg = &Config{
+			RelayDir: c.MkDir(),
+			Flavor:   gmysql.MySQLFlavor,
+		}
+		r = NewRelay(relayCfg).(*Relay)
+	)
+
+	genGTIDSet, err := gtid.ParserGTID(relayCfg.Flavor, genGTIDSetStr)
+	c.Assert(err, IsNil)
+
+	c.Assert(r.meta.AddDir(uuid, &startPos, nil), IsNil)
+	c.Assert(r.meta.Load(), IsNil)
+
+	// use a generator to generate some binlog events
+	previousGTIDSet, err := gtid.ParserGTID(relayCfg.Flavor, previousGTIDSetStr)
+	c.Assert(err, IsNil)
+	latestGTID1, err := gtid.ParserGTID(relayCfg.Flavor, latestGTIDStr1)
+	c.Assert(err, IsNil)
+	latestGTID2, err := gtid.ParserGTID(relayCfg.Flavor, latestGTIDStr2)
+	c.Assert(err, IsNil)
+	g, _, data := genBinlogEventsWithGTIDs(c, relayCfg.Flavor, previousGTIDSet, latestGTID1, latestGTID2)
+
+	// write events into relay log file
+	err = ioutil.WriteFile(filepath.Join(r.meta.Dir(), filename), data, 0600)
+	c.Assert(err, IsNil)
+	// write some invalid data into the relay log file to trigger a recover.
+	f, err := os.OpenFile(filepath.Join(r.meta.Dir(), filename), os.O_WRONLY|os.O_APPEND, 0600)
+	c.Assert(err, IsNil)
+	_, err = f.Write([]byte("invalid event data"))
+	c.Assert(err, IsNil)
+	f.Close()
+
+	// recover with empty GTIDs.
+	c.Assert(r.tryRecoverLatestFile(parser2), IsNil)
+	_, latestPos := r.meta.Pos()
+	c.Assert(latestPos, DeepEquals, gmysql.Position{Name: filename, Pos: g.LatestPos})
+	_, latestGTIDs := r.meta.GTID()
+	c.Assert(latestGTIDs.Equal(genGTIDSet), IsTrue)
+
+	// write some invalid data into the relay log file again.
+	f, err = os.OpenFile(filepath.Join(r.meta.Dir(), filename), os.O_WRONLY|os.O_APPEND, 0600)
+	c.Assert(err, IsNil)
+	_, err = f.Write([]byte("invalid event data"))
+	c.Assert(err, IsNil)
+	f.Close()
+
+	// recover with the subset of GTIDs (previous GTID set).
+	c.Assert(r.meta.Save(startPos, previousGTIDSet), IsNil)
+	c.Assert(r.tryRecoverLatestFile(parser2), IsNil)
+	_, latestPos = r.meta.Pos()
+	c.Assert(latestPos, DeepEquals, gmysql.Position{Name: filename, Pos: g.LatestPos})
+	_, latestGTIDs = r.meta.GTID()
+	c.Assert(latestGTIDs.Equal(genGTIDSet), IsTrue)
+}
+
 // genBinlogEventsWithGTIDs generates some binlog events used by testFileUtilSuite and testFileWriterSuite.
 // now, its generated events including 3 DDL and 10 DML.
 func genBinlogEventsWithGTIDs(c *C, flavor string, previousGTIDSet, latestGTID1, latestGTID2 gtid.Set) (*event.Generator, []*replication.BinlogEvent, []byte) {

relay/writer/file_util.go

@@ -227,6 +227,17 @@ func getTxnPosGTIDs(filename string, p *parser.Parser) (int64, gtid.Set, error)
 			// learn from: https://github.com/siddontang/go-mysql/blob/c6ab05a85eb86dc51a27ceed6d2f366a32874a24/replication/binlogsyncer.go#L745
 			GTID := ev.GTID
 			nextGTIDStr = fmt.Sprintf("%d-%d-%d", GTID.DomainID, GTID.ServerID, GTID.SequenceNumber)
+		case *replication.PreviousGTIDsEvent:
+			// if GTID enabled, we can get a PreviousGTIDEvent after the FormatDescriptionEvent
+			// ref: https://github.com/mysql/mysql-server/blob/8cc757da3d87bf4a1f07dcfb2d3c96fed3806870/sql/binlog.cc#L4549
+			// ref: https://github.com/mysql/mysql-server/blob/8cc757da3d87bf4a1f07dcfb2d3c96fed3806870/sql/binlog.cc#L5161
+			var gSet gtid.Set
+			gSet, err = gtid.ParserGTID(gmysql.MySQLFlavor, ev.GTIDSets)
+			if err != nil {
+				return 0, nil, err
+			}
+			latestGSet = gSet.Origin()
+			flavor = gmysql.MySQLFlavor
 		case *replication.MariadbGTIDListEvent:
 			// a MariadbGTIDListEvent logged in every binlog to record the current replication state if GTID enabled
 			// ref: https://mariadb.com/kb/en/library/gtid_list_event/
@@ -236,18 +247,6 @@ func getTxnPosGTIDs(filename string, p *parser.Parser) (int64, gtid.Set, error)
 			}
 			latestGSet = gSet.Origin()
 			flavor = gmysql.MariaDBFlavor
-		case *replication.GenericEvent:
-			if e.Header.EventType == replication.PREVIOUS_GTIDS_EVENT {
-				// if GTID enabled, we can get a PreviousGTIDEvent after the FormatDescriptionEvent
-				// ref: https://github.com/mysql/mysql-server/blob/8cc757da3d87bf4a1f07dcfb2d3c96fed3806870/sql/binlog.cc#L4549
-				// ref: https://github.com/mysql/mysql-server/blob/8cc757da3d87bf4a1f07dcfb2d3c96fed3806870/sql/binlog.cc#L5161
-				gSet, err2 := event.GTIDsFromPreviousGTIDsEvent(e)
-				if err2 != nil {
-					return 0, nil, terror.Annotatef(err2, "get GTID set from PreviousGTIDsEvent %+v", e.Header)
-				}
-				latestGSet = gSet.Origin()
-				flavor = gmysql.MySQLFlavor
-			}
 		}
 	}