store/copr: error on fulltext retry

Author: wshwsh12

pkg/store/copr/batch_coprocessor.go

@@ -1407,6 +1407,11 @@ func (b *batchCopIterator) handleTask(ctx context.Context, bo *Backoffer, task *
 
 // Merge all ranges and request again.
 func (b *batchCopIterator) retryBatchCopTask(ctx context.Context, bo *backoff.Backoffer, batchTask *batchCopTask) ([]*batchCopTask, error) {
+	// FullText batch cop tasks contain TableShardInfos only. They don't have regionInfos/PartitionTableRegions, so we
+	// cannot retry by rebuilding tasks with regions; return an error instead of silently producing an empty task set.
+	if batchTask.TableShardInfos != nil {
+		return nil, errors.New("tiflash_fts node is unavailable")
+	}
 	if batchTask.regionInfos != nil {
 		var ranges []kv.KeyRange
 		for _, ri := range batchTask.regionInfos {

pkg/store/copr/batch_coprocessor_test.go

@@ -25,6 +25,7 @@ import (
 
 	"github.com/pingcap/errors"
 	"github.com/pingcap/failpoint"
+	"github.com/pingcap/kvproto/pkg/coprocessor"
 	"github.com/pingcap/kvproto/pkg/metapb"
 	"github.com/pingcap/tidb/pkg/kv"
 	"github.com/pingcap/tidb/pkg/store/driver/backoff"
@@ -138,6 +139,18 @@ func TestBalanceBatchCopTaskWithEmptyTaskSet(t *testing.T) {
 	}
 }
 
+func TestRetryBatchCopTaskForFullTextReturnsError(t *testing.T) {
+	it := &batchCopIterator{}
+	bo := backoff.NewBackofferWithVars(context.Background(), 1, nil)
+	task := &batchCopTask{
+		TableShardInfos: []*coprocessor.TableShardInfos{{}},
+	}
+	ret, err := it.retryBatchCopTask(context.Background(), bo, task)
+	require.Nil(t, ret)
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "tiflash_fts node is unavailable")
+}
+
 func TestDeepCopyStoreTaskMap(t *testing.T) {
 	storeTasks1 := buildStoreTaskMap(10)
 	for _, task := range storeTasks1 {