check set key exist

Signed-off-by: Ben Ye <[email protected]>

pkg/queryfrontend/metadata_codec.go

@@ -4,21 +4,20 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
-	"io/ioutil"
-	"net/http"
-	"net/url"
-	"sort"
-	"strconv"
-	"strings"
-
 	"github.com/cortexproject/cortex/pkg/querier/queryrange"
 	cortexutil "github.com/cortexproject/cortex/pkg/util"
 	"github.com/cortexproject/cortex/pkg/util/spanlogger"
 	"github.com/opentracing/opentracing-go"
 	otlog "github.com/opentracing/opentracing-go/log"
-	"github.com/weaveworks/common/httpgrpc"
-
 	queryv1 "github.com/thanos-io/thanos/pkg/api/query"
+	"github.com/weaveworks/common/httpgrpc"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
 )
 
 type metadataCodec struct {
@@ -47,7 +46,9 @@ func (c metadataCodec) MergeResponse(responses ...queryrange.Response) (queryran
 
 		for _, res := range responses {
 			for _, value := range res.(*ThanosLabelsResponse).Data {
-				set[value] = struct{}{}
+				if _, ok := set[value]; !ok {
+					set[value] = struct{}{}
+				}
 			}
 		}
 		labels := make([]string, 0, len(set))
@@ -69,6 +70,7 @@ func (c metadataCodec) MergeResponse(responses ...queryrange.Response) (queryran
 
 		return &ThanosSeriesResponse{
 			Status: queryrange.StatusSuccess,
+			// TODO: fix this
 			Data:   metadataResponses[0].Data,
 		}, nil
 	default:
@@ -261,6 +263,7 @@ func (c metadataCodec) parseLabelsRequest(r *http.Request, op string) (queryrang
 			break
 		}
 	}
+	time.Now().UnixNano()
 
 	return &result, nil
 }