dm: reduce gSet.String() usage by using zeroGSet for checking empty (#9944)

dm/pkg/binlog/event/common.go

@@ -19,6 +19,7 @@ import (
 
 	gmysql "github.com/go-mysql-org/go-mysql/mysql"
 	"github.com/go-mysql-org/go-mysql/replication"
+	"github.com/pingcap/tiflow/dm/pkg/gtid"
 	"github.com/pingcap/tiflow/dm/pkg/terror"
 )
 
@@ -172,7 +173,7 @@ func GTIDIncrease(flavor string, gSet gmysql.GTIDSet) (gmysql.GTIDSet, error) {
 
 // verifySingleGTID verifies gSet whether only containing a single valid GTID.
 func verifySingleGTID(flavor string, gSet gmysql.GTIDSet) (interface{}, error) {
-	if gSet == nil || len(gSet.String()) == 0 {
+	if gtid.IsZeroGTIDSet(gSet) {
 		return nil, terror.ErrBinlogEmptyGTID.Generate()
 	}
 

dm/pkg/binlog/event/event.go

@@ -22,6 +22,7 @@ import (
 
 	gmysql "github.com/go-mysql-org/go-mysql/mysql"
 	"github.com/go-mysql-org/go-mysql/replication"
+	"github.com/pingcap/tiflow/dm/pkg/gtid"
 	"github.com/pingcap/tiflow/dm/pkg/terror"
 )
 
@@ -717,7 +718,7 @@ func GenXIDEvent(header *replication.EventHeader, latestPos uint32, xid uint64)
 // GenMariaDBGTIDListEvent generates a MariadbGTIDListEvent.
 // ref: https://mariadb.com/kb/en/library/gtid_list_event/
 func GenMariaDBGTIDListEvent(header *replication.EventHeader, latestPos uint32, gSet gmysql.GTIDSet) (*replication.BinlogEvent, error) {
-	if gSet == nil || len(gSet.String()) == 0 {
+	if gtid.IsZeroGTIDSet(gSet) {
 		return nil, terror.ErrBinlogEmptyGTID.Generate()
 	}
 

dm/pkg/binlog/position.go

@@ -366,8 +366,8 @@ func IsFreshPosition(location Location, flavor string, cmpGTID bool) bool {
 //
 // but if can't compare gSet1 and gSet2, will returns 0, false.
 func CompareGTID(gSet1, gSet2 gmysql.GTIDSet) (int, bool) {
-	gSetIsEmpty1 := gSet1 == nil || len(gSet1.String()) == 0
-	gSetIsEmpty2 := gSet2 == nil || len(gSet2.String()) == 0
+	gSetIsEmpty1 := gtid.IsZeroGTIDSet(gSet1)
+	gSetIsEmpty2 := gtid.IsZeroGTIDSet(gSet2)
 
 	switch {
 	case gSetIsEmpty1 && gSetIsEmpty2:

dm/pkg/gtid/gtid.go

@@ -21,6 +21,11 @@ import (
 	"github.com/pingcap/tiflow/dm/pkg/terror"
 )
 
+var (
+	zeroMySQLGTIDSet   = MustZeroGTIDSet(mysql.MySQLFlavor)
+	zeroMariaDBGTIDSet = MustZeroGTIDSet(mysql.MariaDBFlavor)
+)
+
 // ParserGTID parses GTID from string. If the flavor is not specified, it will
 // try mysql GTID first and then MariaDB GTID.
 func ParserGTID(flavor, gtidStr string) (mysql.GTIDSet, error) {
@@ -42,7 +47,11 @@ func ParserGTID(flavor, gtidStr string) (mysql.GTIDSet, error) {
 			gtid, err = mysql.ParseGTIDSet(fla, gtidStr)
 		}
 	case mysql.MariaDBFlavor:
-		gtid, err = mysql.ParseGTIDSet(fla, gtidStr)
+		if IsZeroMariaDBGTIDSet(gtidStr) {
+			gtid, err = mysql.ParseGTIDSet(fla, "")
+		} else {
+			gtid, err = mysql.ParseGTIDSet(fla, gtidStr)
+		}
 	case "":
 		fla = mysql.MySQLFlavor
 		gtid, err = mysql.ParseGTIDSet(fla, gtidStr)
@@ -74,9 +83,6 @@ func MustZeroGTIDSet(flavor string) mysql.GTIDSet {
 // IsZeroMySQLGTIDSet is used to meet this usage: when user wants to start binlog
 // replication from scratch, a "uuid:0" (MySQL flavor) or "0-0-0" (mariaDB) GTID
 // set must be written, in order to distinguish that user forgets to write it.
-//
-// For above two flavor, only "uuid:0" is illegal, so we use IsZeroMySQLGTIDSet
-// to handle it.
 func IsZeroMySQLGTIDSet(gStr string) bool {
 	sp := strings.Split(gStr, ",")
 	if len(sp) != 1 {
@@ -90,3 +96,28 @@ func IsZeroMySQLGTIDSet(gStr string) bool {
 	interval := strings.TrimSpace(sep[1])
 	return interval == "0"
 }
+
+// IsZeroMariaDBGTIDSet is used to meet this usage: when user wants to start binlog
+// replication from scratch, a "uuid:0" (MySQL flavor) or "0-0-0" (mariaDB) GTID
+// set must be written, in order to distinguish that user forgets to write it.
+//
+// For MariaDB, the GTID set like "0-0-0" will confuse IsZeroGTIDSet function,
+// so we also need to check the interval part.
+func IsZeroMariaDBGTIDSet(gStr string) bool {
+	sp := strings.Split(gStr, ",")
+	if len(sp) != 1 {
+		return false
+	}
+
+	sep := strings.Split(sp[0], "-")
+	if len(sep) != 3 {
+		return false
+	}
+	interval := strings.TrimSpace(sep[2])
+	return interval == "0"
+}
+
+// IsZeroGTIDSet is used to check whether a GTID set is zero.
+func IsZeroGTIDSet(gSet mysql.GTIDSet) bool {
+	return gSet == nil || zeroMySQLGTIDSet.Equal(gSet) || zeroMariaDBGTIDSet.Equal(gSet)
+}

dm/pkg/gtid/gtid_test.go

@@ -67,7 +67,7 @@ func TestParseGTIDNoFlavor(t *testing.T) {
 	require.Error(t, err)
 }
 
-func TestIsNilGTIDSet(t *testing.T) {
+func TestIsNilMySQLGTIDSet(t *testing.T) {
 	t.Parallel()
 
 	require.False(t, IsZeroMySQLGTIDSet(""))
@@ -79,6 +79,17 @@ func TestIsNilGTIDSet(t *testing.T) {
 	require.True(t, IsZeroMySQLGTIDSet(" xxxxx:0 "))
 }
 
+func TestIsNilMariaDBGTIDSet(t *testing.T) {
+	t.Parallel()
+
+	require.False(t, IsZeroMariaDBGTIDSet(""))
+	require.False(t, IsZeroMariaDBGTIDSet("xxxxx"))
+	require.False(t, IsZeroMariaDBGTIDSet("a-b-0,c-d:0"))
+	require.False(t, IsZeroMariaDBGTIDSet("xxxxx:1"))
+	require.True(t, IsZeroMariaDBGTIDSet("x-y-0"))
+	require.True(t, IsZeroMariaDBGTIDSet(" x-y-0 "))
+}
+
 func TestParseZeroAsEmptyGTIDSet(t *testing.T) {
 	t.Parallel()
 
@@ -94,3 +105,50 @@ func TestParseZeroAsEmptyGTIDSet(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, "", gset.String())
 }
+
+func TestIsZeroGTIDSet(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		gsetStr string
+		isZero  bool
+		flavor  string
+	}{
+		{
+			"",
+			true,
+			mysql.MySQLFlavor,
+		},
+		{
+			"",
+			true,
+			mysql.MariaDBFlavor,
+		},
+		{
+			"3ccc475b-2343-11e7-be21-6c0b84d59f30:0",
+			true,
+			mysql.MySQLFlavor,
+		},
+		{
+			"0-0-0",
+			true,
+			mysql.MariaDBFlavor,
+		},
+		{
+			"3ccc475b-2343-11e7-be21-6c0b84d59f30:1-14",
+			false,
+			mysql.MySQLFlavor,
+		},
+		{
+			"1-2-3",
+			false,
+			mysql.MariaDBFlavor,
+		},
+	}
+	for i, testCase := range testCases {
+		t.Logf("test case %d", i)
+		gset, err := ParserGTID(testCase.flavor, testCase.gsetStr)
+		require.NoError(t, err)
+		require.Equal(t, testCase.isZero, IsZeroGTIDSet(gset))
+	}
+}