log-backup: set gc disable when restore log

br/pkg/task/stream.go

@@ -458,6 +458,33 @@ func (s *streamMgr) checkStreamStartEnable(g glue.Glue) error {
 	return nil
 }
 
+type RestoreFunc func() error
+
+// KeepGcDisabled keeps GC disabled and return a function that used to gc enabled.
+// gc.ratio-threshold = "-1.0", which represents disable gc in TiKV.
+func KeepGcDisabled(g glue.Glue, store kv.Storage) (RestoreFunc, error) {
+	se, err := g.CreateSession(store)
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+
+	execCtx := se.GetSessionCtx().(sqlexec.RestrictedSQLExecutor)
+	oldRatio, err := utils.GetGcRatio(execCtx)
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+
+	newRatio := "-1.0"
+	err = utils.SetGcRatio(execCtx, newRatio)
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+
+	return func() error {
+		return utils.SetGcRatio(execCtx, oldRatio)
+	}, nil
+}
+
 // RunStreamCommand run all kinds of `stream task`
 func RunStreamCommand(
 	ctx context.Context,
@@ -1143,6 +1170,18 @@ func restoreStream(
 	// mode or emptied schedulers
 	defer restorePostWork(ctx, client, restoreSchedulers)
 
+	// It need disable GC in TiKV when PiTR.
+	// because the process of PITR is concurrent and kv events isn't sorted by tso.
+	restoreGc, err := KeepGcDisabled(g, mgr.GetStorage())
+	if err != nil {
+		return errors.Trace(err)
+	}
+	defer func() {
+		if err = restoreGc(); err != nil {
+			log.Info("failed to set gc enabled", zap.Error(err))
+		}
+	}()
+
 	err = client.InstallLogFileManager(ctx, cfg.StartTS, cfg.RestoreTS)
 	if err != nil {
 		return err

br/pkg/utils/db.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/pingcap/errors"
 	"github.com/pingcap/log"
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/sessionctx"
@@ -98,6 +99,39 @@ func IsLogBackupEnabled(ctx sqlexec.RestrictedSQLExecutor) (bool, error) {
 	return true, nil
 }
 
+func GetGcRatio(ctx sqlexec.RestrictedSQLExecutor) (string, error) {
+	valStr := "show config where name = 'log-backup.enable' and type = 'tikv'"
+	rows, fields, errSQL := ctx.ExecRestrictedSQL(
+		kv.WithInternalSourceType(context.Background(), kv.InternalTxnBR),
+		nil,
+		valStr,
+	)
+	if errSQL != nil {
+		return "", errSQL
+	}
+	if len(rows) == 0 {
+		// no rows mean not support log backup.
+		return "", nil
+	}
+
+	d := rows[0].GetDatum(3, &fields[3].Column.FieldType)
+	return d.ToString()
+}
+
+func SetGcRatio(ctx sqlexec.RestrictedSQLExecutor, ratio string) error {
+	_, _, err := ctx.ExecRestrictedSQL(
+		kv.WithInternalSourceType(context.Background(), kv.InternalTxnBR),
+		nil,
+		"set config tikv `gc.ratio-threshold`=%?",
+		ratio,
+	)
+	if err != nil {
+		return errors.Trace(err)
+	}
+	log.Info("set config tikv gc.ratio-threshold", zap.String("ratio", ratio))
+	return nil
+}
+
 // LogBackupTaskCountInc increases the count of log backup task.
 func LogBackupTaskCountInc() {
 	LogBackupTaskMutex.Lock()

br/pkg/utils/db_test.go

@@ -115,3 +115,37 @@ func TestCheckLogBackupTaskExist(t *testing.T) {
 	utils.LogBackupTaskCountDec()
 	require.False(t, utils.CheckLogBackupTaskExist())
 }
+
+func TestGc(t *testing.T) {
+	// config format:
+	// MySQL [(none)]> show config where name = 'gc.ratio-threshold';
+	// +------+-------------------+--------------------+-------+
+	// | Type | Instance          | Name               | Value |
+	// +------+-------------------+--------------------+-------+
+	// | tikv | 172.16.6.46:3460  | gc.ratio-threshold | 1.1   |
+	// | tikv | 172.16.6.47:3460  | gc.ratio-threshold | 1.1   |
+	// +------+-------------------+--------------------+-------+
+	fields := make([]*ast.ResultField, 4)
+	tps := []*types.FieldType{
+		types.NewFieldType(mysql.TypeString),
+		types.NewFieldType(mysql.TypeString),
+		types.NewFieldType(mysql.TypeString),
+		types.NewFieldType(mysql.TypeFloat),
+	}
+	for i := 0; i < len(tps); i++ {
+		rf := new(ast.ResultField)
+		rf.Column = new(model.ColumnInfo)
+		rf.Column.FieldType = *tps[i]
+		fields[i] = rf
+	}
+	rows := make([]chunk.Row, 0, 2)
+	row := chunk.MutRowFromValues("tikv", " 127.0.0.1:20161", "log-backup.enable", 1.1).ToRow()
+	rows = append(rows, row)
+	row = chunk.MutRowFromValues("tikv", " 127.0.0.1:20162", "log-backup.enable", 1.1).ToRow()
+	rows = append(rows, row)
+
+	s := &mockRestrictedSQLExecutor{rows: rows, fields: fields}
+	ratio, err := utils.GetGcRatio(s)
+	require.Nil(t, err)
+	require.Equal(t, ratio, 1.1)
+}