store: fix stringlabel build errors for prometheus store api (thanos-…

…io#6861)

Signed-off-by: Michael Hoffmann <[email protected]>

pkg/store/prometheus.go

@@ -121,12 +121,11 @@ func (p *PrometheusStore) Info(_ context.Context, _ *storepb.InfoRequest) (*stor
 	mint, maxt := p.timestamps()
 
 	res := &storepb.InfoResponse{
-		Labels:    make([]labelpb.ZLabel, 0, len(lset)),
+		Labels:    labelpb.ZLabelsFromPromLabels(lset),
 		StoreType: p.component.ToProto(),
 		MinTime:   mint,
 		MaxTime:   maxt,
 	}
-	res.Labels = append(res.Labels, labelpb.ZLabelsFromPromLabels(lset)...)
 
 	// Until we deprecate the single labels in the reply, we just duplicate
 	// them here for migration/compatibility purposes.
@@ -194,7 +193,7 @@ func (p *PrometheusStore) Series(r *storepb.SeriesRequest, s storepb.Store_Serie
 			return err
 		}
 		for _, lbm := range labelMaps {
-			lset := make([]labelpb.ZLabel, 0, len(lbm)+len(finalExtLset))
+			lset := make([]labelpb.ZLabel, 0, len(lbm)+finalExtLset.Len())
 			for k, v := range lbm {
 				lset = append(lset, labelpb.ZLabel{Name: k, Value: v})
 			}
@@ -293,19 +292,18 @@ func (p *PrometheusStore) queryPrometheus(
 	}
 
 	externalLbls := rmLabels(p.externalLabelsFn().Copy(), extLsetToRemove)
+	b := labels.NewScratchBuilder(16)
 	for _, vector := range matrix {
-		seriesLbls := labels.Labels(make([]labels.Label, 0, len(vector.Metric)))
+		b.Reset()
 
 		// Attach labels from samples.
 		for k, v := range vector.Metric {
-			seriesLbls = append(seriesLbls, labels.FromStrings(string(k), string(v))...)
+			b.Add(string(k), string(v))
 		}
-		sort.Slice(seriesLbls, func(i, j int) bool {
-			return seriesLbls.Less(i, j)
-		})
-		// Attach external labels for compatibility with remote read.
-		finalLbls := labelpb.ExtendSortedLabels(seriesLbls, externalLbls)
-		finalLbls = append(finalLbls, dedup.PushdownMarker)
+		b.Add(dedup.PushdownMarker.Name, dedup.PushdownMarker.Value)
+		b.Sort()
+
+		finalLbls := labelpb.ExtendSortedLabels(b.Labels(), externalLbls)
 
 		series := &prompb.TimeSeries{
 			Labels:  labelpb.ZLabelsFromPromLabels(finalLbls),
@@ -606,7 +604,7 @@ func matchesExternalLabels(ms []storepb.LabelMatcher, externalLabels labels.Labe
 		return false, nil, err
 	}
 
-	if len(externalLabels) == 0 {
+	if externalLabels.IsEmpty() {
 		return true, tms, nil
 	}
 
@@ -683,9 +681,9 @@ func (p *PrometheusStore) LabelNames(ctx context.Context, r *storepb.LabelNamesR
 	}
 
 	if len(lbls) > 0 {
-		for _, extLbl := range extLset {
-			lbls = append(lbls, extLbl.Name)
-		}
+		extLset.Range(func(l labels.Label) {
+			lbls = append(lbls, l.Name)
+		})
 		sort.Strings(lbls)
 	}
 
@@ -761,10 +759,7 @@ func (p *PrometheusStore) LabelValues(ctx context.Context, r *storepb.LabelValue
 }
 
 func (p *PrometheusStore) LabelSet() []labelpb.ZLabelSet {
-	lset := p.externalLabelsFn()
-
-	labels := make([]labelpb.ZLabel, 0, len(lset))
-	labels = append(labels, labelpb.ZLabelsFromPromLabels(lset)...)
+	labels := labelpb.ZLabelsFromPromLabels(p.externalLabelsFn())
 
 	labelset := []labelpb.ZLabelSet{}
 	if len(labels) > 0 {

pkg/store/storepb/testutil/series.go

@@ -136,8 +136,8 @@ func ReadSeriesFromBlock(t testing.TB, h tsdb.BlockReader, extLabels labels.Labe
 	all := allPostings(t, ir)
 	for all.Next() {
 		testutil.Ok(t, ir.Series(all.At(), &builder, &chunkMetas))
-		lset := builder.Labels()
-		expected = append(expected, &storepb.Series{Labels: labelpb.ZLabelsFromPromLabels(append(extLabels.Copy(), lset...))})
+		lset := labelpb.ExtendSortedLabels(builder.Labels(), extLabels)
+		expected = append(expected, &storepb.Series{Labels: labelpb.ZLabelsFromPromLabels(lset)})
 
 		if skipChunks {
 			continue
@@ -189,7 +189,7 @@ func appendFloatSamples(t testing.TB, app storage.Appender, tsLabel int, opts He
 	testutil.Ok(t, err)
 
 	for is := 1; is < opts.SamplesPerSeries; is++ {
-		_, err := app.Append(ref, nil, int64(tsLabel+is)*opts.ScrapeInterval.Milliseconds(), opts.Random.Float64())
+		_, err := app.Append(ref, labels.EmptyLabels(), int64(tsLabel+is)*opts.ScrapeInterval.Milliseconds(), opts.Random.Float64())
 		testutil.Ok(t, err)
 	}
 }
@@ -211,7 +211,7 @@ func appendHistogramSamples(t testing.TB, app storage.Appender, tsLabel int, opt
 	testutil.Ok(t, err)
 
 	for i, h := range histograms[1:] {
-		_, err := app.AppendHistogram(ref, nil, int64(tsLabel+i+1)*opts.ScrapeInterval.Milliseconds(), h, nil)
+		_, err := app.AppendHistogram(ref, labels.EmptyLabels(), int64(tsLabel+i+1)*opts.ScrapeInterval.Milliseconds(), h, nil)
 		testutil.Ok(t, err)
 	}
 }