Add prw2 pool

Signed-off-by: SungJin1212 <[email protected]>

Author: SungJin1212

pkg/cortexpb/compat.go

@@ -20,7 +20,7 @@ import (
 
 // ToWriteRequest converts matched slices of Labels, Samples, Metadata and Histograms into a WriteRequest proto.
 // It gets timeseries from the pool, so ReuseSlice() should be called when done.
-func ToWriteRequest(lbls []labels.Labels, samples []Sample, metadata []*MetricMetadata, histograms []Histogram, source WriteRequest_SourceEnum) *WriteRequest {
+func ToWriteRequest(lbls []labels.Labels, samples []Sample, metadata []*MetricMetadata, histograms []Histogram, source SourceEnum) *WriteRequest {
 	req := &WriteRequest{
 		Timeseries: PreallocTimeseriesSliceFromPool(),
 		Metadata:   metadata,

pkg/cortexpb/compatv2.go

@@ -0,0 +1,22 @@
+package cortexpb
+
+import "github.com/prometheus/prometheus/model/labels"
+
+func (e *ExemplarV2) ToLabels(b *labels.ScratchBuilder, symbols []string) labels.Labels {
+	return desymbolizeLabels(b, e.GetLabelsRefs(), symbols)
+}
+
+func (t *TimeSeriesV2) ToLabels(b *labels.ScratchBuilder, symbols []string) labels.Labels {
+	return desymbolizeLabels(b, t.GetLabelsRefs(), symbols)
+}
+
+// desymbolizeLabels decodes label references, with given symbols to labels.
+// Copied from the Prometheus: https://github.com/prometheus/prometheus/blob/v3.5.0/prompb/io/prometheus/write/v2/symbols.go#L76
+func desymbolizeLabels(b *labels.ScratchBuilder, labelRefs []uint32, symbols []string) labels.Labels {
+	b.Reset()
+	for i := 0; i < len(labelRefs); i += 2 {
+		b.Add(symbols[labelRefs[i]], symbols[labelRefs[i+1]])
+	}
+	b.Sort()
+	return b.Labels()
+}