relay: align with MySQL when using GTID (#1390)

_utils/terror_gen/errors_release.txt

@@ -127,6 +127,7 @@ ErrNoUUIDDirMatchGTID,[code=11120:class=functional:scope=internal:level=high], "
 ErrNoRelayPosMatchGTID,[code=11121:class=functional:scope=internal:level=high], "Message: no relay pos match gtid %s"
 ErrReaderReachEndOfFile,[code=11122:class=functional:scope=internal:level=low]
 ErrMetadataNoBinlogLoc,[code=11123:class=functional:scope=upstream:level=low], "Message: didn't found binlog location in dumped metadata file %s, Workaround: Please check log of dump unit, there maybe errors when read upstream binlog status"
+ErrPreviousGTIDNotExist,[code=11124:class=functional:scope=internal:level=high], "Message: no previous gtid event from binlog %s"
 ErrConfigCheckItemNotSupport,[code=20001:class=config:scope=internal:level=medium], "Message: checking item %s is not supported\n%s, Workaround: Please check `ignore-checking-items` config in task configuration file, which can be set including `all`/`dump_privilege`/`replication_privilege`/`version`/`binlog_enable`/`binlog_format`/`binlog_row_image`/`table_schema`/`schema_of_shard_tables`/`auto_increment_ID`."
 ErrConfigTomlTransform,[code=20002:class=config:scope=internal:level=medium], "Message: %s, Workaround: Please check the configuration file has correct TOML format."
 ErrConfigYamlTransform,[code=20003:class=config:scope=internal:level=medium], "Message: %s, Workaround: Please check the configuration file has correct YAML format."

chaos/cases/conf/source3.yaml

@@ -1,5 +1,5 @@
 source-id: "replica-03"
-enable-gtid: false
+enable-gtid: true
 enable-relay: true
 
 from:

errors.toml

@@ -772,6 +772,12 @@ description = ""
 workaround = "Please check log of dump unit, there maybe errors when read upstream binlog status"
 tags = ["upstream", "low"]
 
+[error.DM-functional-11124]
+message = "no previous gtid event from binlog %s"
+description = ""
+workaround = ""
+tags = ["internal", "high"]
+
 [error.DM-config-20001]
 message = "checking item %s is not supported\n%s"
 description = ""

pkg/binlog/event/event.go

@@ -851,3 +851,19 @@ func GenDummyEvent(header *replication.EventHeader, latestPos uint32, eventSize
 	ev, err := GenQueryEvent(&headerClone, latestPos, 0, 0, 0, nil, nil, queryBytes)
 	return ev, err
 }
+
+// GenHeartbeatEvent generates a heartbeat event.
+// ref: https://dev.mysql.com/doc/internals/en/heartbeat-event.html
+func GenHeartbeatEvent(header *replication.EventHeader) *replication.BinlogEvent {
+	// modify header
+	headerClone := *header // do a copy
+	headerClone.Flags = 0
+	headerClone.EventSize = 39
+	headerClone.Timestamp = 0
+	headerClone.EventType = replication.HEARTBEAT_EVENT
+
+	eventBytes := make([]byte, 39)
+	ev := &replication.BinlogEvent{Header: &headerClone, Event: &replication.GenericEvent{Data: eventBytes}}
+
+	return ev
+}

pkg/binlog/reader/util.go

@@ -140,3 +140,39 @@ func GetGTIDsForPos(ctx context.Context, r Reader, endPos gmysql.Position) (gtid
 		}
 	}
 }
+
+// GetPreviousGTIDFromGTIDSet tries to get previous GTID sets from Previous_GTID_EVENT GTID for the specified GITD Set.
+// events should be [fake_rotate_event,format_description_event,previous_gtids_event/mariadb_gtid_list_event]
+func GetPreviousGTIDFromGTIDSet(ctx context.Context, r Reader, gset gtid.Set) (gtid.Set, error) {
+	err := r.StartSyncByGTID(gset)
+	if err != nil {
+		return nil, err
+	}
+	defer r.Close()
+
+	for {
+		var e *replication.BinlogEvent
+		e, err = r.GetEvent(ctx)
+		if err != nil {
+			return nil, err
+		}
+
+		switch e.Header.EventType {
+		case replication.ROTATE_EVENT:
+			if e.Header.Timestamp == 0 || e.Header.LogPos == 0 { // fake rotate event
+				continue
+			}
+			return nil, terror.ErrPreviousGTIDNotExist.Generate(gset.String())
+		case replication.FORMAT_DESCRIPTION_EVENT:
+			continue
+		case replication.PREVIOUS_GTIDS_EVENT:
+			previousGset, err := event.GTIDsFromPreviousGTIDsEvent(e)
+			return previousGset, err
+		case replication.MARIADB_GTID_LIST_EVENT:
+			previousGset, err := event.GTIDsFromMariaDBGTIDListEvent(e)
+			return previousGset, err
+		default:
+			return nil, terror.ErrPreviousGTIDNotExist.Generate(gset.String())
+		}
+	}
+}

pkg/binlog/reader/util_test.go

@@ -62,3 +62,32 @@ func (t *testTCPReaderSuite) TestGetGTIDsForPos(c *C) {
 	c.Assert(err, ErrorMatches, ".*invalid position .* or GTID not enabled in upstream.*")
 	c.Assert(gs, IsNil)
 }
+
+// added to testTCPReaderSuite to re-use DB connection.
+func (t *testTCPReaderSuite) TestGetPreviousGTIDFromGTIDSet(c *C) {
+	var (
+		cfg = replication.BinlogSyncerConfig{
+			ServerID:       serverIDs[1],
+			Flavor:         flavor,
+			Host:           t.host,
+			Port:           uint16(t.port),
+			User:           t.user,
+			Password:       t.password,
+			UseDecimal:     true,
+			VerifyChecksum: true,
+		}
+		ctx, cancel = context.WithTimeout(context.Background(), utils.DefaultDBTimeout)
+	)
+	defer cancel()
+
+	_, endGS, err := utils.GetMasterStatus(ctx, t.db, flavor)
+	c.Assert(err, IsNil)
+
+	r1 := NewTCPReader(cfg)
+	c.Assert(r1, NotNil)
+	defer r1.Close()
+
+	gs, err := GetPreviousGTIDFromGTIDSet(ctx, r1, endGS)
+	c.Assert(err, IsNil)
+	c.Assert(endGS.Contain(gs), IsTrue)
+}