From e463d717e6b21101cc4dcd39f3ffa1fef319f008 Mon Sep 17 00:00:00 2001
From: Christian Simon <simon@swine.de>
Date: Wed, 12 Jun 2024 15:21:53 +0100
Subject: [PATCH] profilecli: Add a label values cardinality subcommand

---
 cmd/profilecli/main.go  |  7 ++++
 cmd/profilecli/query.go | 76 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 83 insertions(+)

diff --git a/cmd/profilecli/main.go b/cmd/profilecli/main.go
index 124b160cff..7fa6c563e4 100644
--- a/cmd/profilecli/main.go
+++ b/cmd/profilecli/main.go
@@ -70,6 +70,8 @@ func main() {
 	queryMergeParams := addQueryMergeParams(queryMergeCmd)
 	querySeriesCmd := queryCmd.Command("series", "Request series labels.")
 	querySeriesParams := addQuerySeriesParams(querySeriesCmd)
+	queryLabelValuesCardinalityCmd := queryCmd.Command("label-values-cardinality", "Request label values cardinality.")
+	queryLabelValuesCardinalityParams := addQueryLabelValuesCardinalityParams(queryLabelValuesCardinalityCmd)
 
 	queryTracerCmd := app.Command("query-tracer", "Analyze query traces.")
 	queryTracerParams := addQueryTracerParams(queryTracerCmd)
@@ -116,6 +118,11 @@ func main() {
 			os.Exit(checkError(err))
 		}
 
+	case queryLabelValuesCardinalityCmd.FullCommand():
+		if err := queryLabelValuesCardinality(ctx, queryLabelValuesCardinalityParams); err != nil {
+			os.Exit(checkError(err))
+		}
+
 	case queryTracerCmd.FullCommand():
 		if err := queryTracer(ctx, queryTracerParams); err != nil {
 			os.Exit(checkError(err))
diff --git a/cmd/profilecli/query.go b/cmd/profilecli/query.go
index aff60f16a3..e986e67550 100644
--- a/cmd/profilecli/query.go
+++ b/cmd/profilecli/query.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"sort"
 	"strings"
 	"time"
 
@@ -26,6 +27,7 @@ import (
 	"github.com/klauspost/compress/gzip"
 	"github.com/mattn/go-isatty"
 	"github.com/pkg/errors"
+	"golang.org/x/sync/errgroup"
 )
 
 const (
@@ -261,3 +263,77 @@ func querySeries(ctx context.Context, params *querySeriesParams) (err error) {
 	return nil
 
 }
+
+type queryLabelValuesCardinalityParams struct {
+	*queryParams
+	TopN uint64
+}
+
+func addQueryLabelValuesCardinalityParams(queryCmd commander) *queryLabelValuesCardinalityParams {
+	params := new(queryLabelValuesCardinalityParams)
+	params.queryParams = addQueryParams(queryCmd)
+	queryCmd.Flag("top-n", "Show the top N high cardinality label values").Default("20").Uint64Var(&params.TopN)
+	return params
+}
+
+func queryLabelValuesCardinality(ctx context.Context, params *queryLabelValuesCardinalityParams) (err error) {
+	from, to, err := params.parseFromTo()
+	if err != nil {
+		return err
+	}
+
+	level.Info(logger).Log("msg", "query label names", "url", params.URL, "from", from, "to", to, "labelNames", fmt.Sprintf("%q"))
+
+	qc := params.phlareClient.queryClient()
+	resp, err := qc.LabelNames(ctx, connect.NewRequest(&typesv1.LabelNamesRequest{
+		Start:    from.UnixMilli(),
+		End:      to.UnixMilli(),
+		Matchers: []string{params.Query},
+	}))
+	if err != nil {
+		return errors.Wrap(err, "failed to query")
+	}
+
+	level.Info(logger).Log("msg", fmt.Sprintf("received %d label names", len(resp.Msg.Names)))
+
+	g, gctx := errgroup.WithContext(ctx)
+	g.SetLimit(16)
+	result := make([]int, len(resp.Msg.Names))
+
+	for idx := range resp.Msg.Names {
+		idx := idx
+		g.Go(func() error {
+			name := resp.Msg.Names[idx]
+			resp, err := qc.LabelValues(gctx, connect.NewRequest(&typesv1.LabelValuesRequest{
+				Name:     name,
+				Start:    from.UnixMilli(),
+				End:      to.UnixMilli(),
+				Matchers: []string{params.Query},
+			}))
+			if err != nil {
+				return fmt.Errorf("failed to query label values for %s: %w", name, err)
+			}
+
+			result[idx] = len(resp.Msg.Names)
+
+			return nil
+		})
+	}
+	if err := g.Wait(); err != nil {
+		return err
+	}
+
+	// sort the result
+	sort.Slice(resp.Msg.Names, func(i, j int) bool {
+		return result[i] > result[j]
+	})
+	sort.Slice(result, func(i, j int) bool {
+		return result[i] > result[j]
+	})
+
+	for idx := range resp.Msg.Names[:params.TopN] {
+		fmt.Println(resp.Msg.Names[idx], result[idx])
+	}
+
+	return nil
+}