txnkv: fix the issue that batch-get error might be ignored (#1733)

Signed-off-by: zyguan <zhongyangguan@gmail.com>

integration_tests/split_test.go

@@ -39,6 +39,7 @@ import (
 	"sync"
 	"testing"
 
+	"github.com/pingcap/failpoint"
 	"github.com/pingcap/kvproto/pkg/keyspacepb"
 	"github.com/pingcap/kvproto/pkg/meta_storagepb"
 	"github.com/pingcap/kvproto/pkg/metapb"
@@ -172,6 +173,13 @@ func (s *testSplitSuite) TestBatchGetUsingAsyncAPI() {
 	s.Equal([]byte("a"), m[string([]byte{'a'})])
 	s.Equal([]byte("c"), m[string([]byte{'c'})])
 	s.NotContains(m, string([]byte{'b'}))
+
+	// inject an error on sending request.
+	failpoint.Enable("tikvclient/tikvStoreSendReqResult", `1*return("timeout")`)
+	defer failpoint.Disable("tikvclient/tikvStoreSendReqResult")
+	txn = s.begin()
+	_, err = txn.GetSnapshot().BatchGet(context.TODO(), [][]byte{{'a'}, {'b'}, {'c'}})
+	s.Error(err)
 }
 
 func (s *testSplitSuite) TestStaleEpoch() {

internal/locate/region_request.go

@@ -470,6 +470,14 @@ func (s *RegionRequestSender) SendReqAsync(
 	cb async.Callback[*tikvrpc.ResponseExt],
 	opts ...StoreSelectorOption,
 ) {
+	if resp, err := failpointSendReqResult(req, tikvrpc.TiKV); err != nil || resp != nil {
+		var re *tikvrpc.ResponseExt
+		if resp != nil {
+			re = &tikvrpc.ResponseExt{Response: *resp}
+		}
+		cb.Invoke(re, err)
+		return
+	}
 	if err := s.validateReadTS(bo.GetCtx(), req); err != nil {
 		logutil.Logger(bo.GetCtx()).Error("validate read ts failed for request", zap.Stringer("reqType", req.Type), zap.Stringer("req", req.Req.(fmt.Stringer)), zap.Stringer("context", &req.Context), zap.Stack("stack"), zap.Error(err))
 		cb.Invoke(nil, err)

txnkv/txnsnapshot/snapshot_async.go

@@ -75,8 +75,8 @@ func (s *KVSnapshot) asyncBatchGetByRegions(
 		}))
 	}
 	for completed < len(batches) {
-		_, err = runloop.Exec(bo.GetCtx())
-		if err != nil {
+		if _, e := runloop.Exec(bo.GetCtx()); e != nil {
+			err = errors.WithStack(e)
 			break
 		}
 	}