From a0574d7daa6d81215749196e348762da54f65dc0 Mon Sep 17 00:00:00 2001
From: Justin Lei <lei.justin@gmail.com>
Date: Fri, 26 Apr 2024 10:56:21 -0700
Subject: [PATCH] Scripts to find discrepancies in aggregated histograms

---
 cmd/foobar/main.go | 185 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 185 insertions(+)
 create mode 100644 cmd/foobar/main.go

diff --git a/cmd/foobar/main.go b/cmd/foobar/main.go
new file mode 100644
index 00000000000..0d1fef196f3
--- /dev/null
+++ b/cmd/foobar/main.go
@@ -0,0 +1,185 @@
+package main
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"net/url"
+	"os"
+	"time"
+
+	commonconfig "github.com/prometheus/common/config"
+	"github.com/prometheus/common/model"
+
+	"github.com/prometheus/prometheus/config"
+	"github.com/prometheus/prometheus/prompb"
+	"github.com/prometheus/prometheus/storage/remote"
+	"github.com/prometheus/prometheus/tsdb/chunkenc"
+)
+
+const (
+	rawURL                 = "http://localhost:8080/prometheus/api/v1/read"
+	tenantID               = "10428"
+	histogramBasesFilepath = "/Users/leizor/tmp/science/20240409/histogram_bases.out"
+)
+
+func main() {
+	histogramBases, err := readHistogramBases()
+	if err != nil {
+		panic(err)
+	}
+
+	client, err := initializeReadClient()
+	if err != nil {
+		panic(err)
+	}
+
+	now := time.Now().Truncate(time.Hour)
+
+	for _, hb := range histogramBases {
+		// Start at the 12-hour mark and go backwards from there to avoid querying against the ingesters.
+		for i := 12; i < 24; i++ {
+			hourOffset := time.Duration((i+2)*-1) * time.Hour
+			start := now.Add(hourOffset)
+
+			ts, err := checkHistogram(client, hb, start)
+			if err != nil {
+				panic(err)
+			}
+
+			if ts > 0 {
+				fmt.Printf("Found! %s at %s\n", hb, time.UnixMilli(ts).UTC().String())
+
+				fmt.Printf(`sum({__aggregation__="%s_bucket:sum:counter",le="+Inf"})`, hb)
+				fmt.Println()
+				fmt.Printf(`sum({__aggregation__="%s_count:sum:counter"})`, hb)
+				fmt.Println()
+				fmt.Printf("Start: %s, End: %s\n", start.UTC().String(), start.Add(time.Hour).UTC().String())
+				fmt.Println()
+			}
+		}
+	}
+}
+
+func readHistogramBases() ([]string, error) {
+	f, err := os.Open(histogramBasesFilepath)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = f.Close() }()
+
+	var histogramBases []string
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		hb := scanner.Text()
+		histogramBases = append(histogramBases, hb)
+	}
+	if err = scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	return histogramBases, nil
+}
+
+func initializeReadClient() (remote.ReadClient, error) {
+	u, err := url.Parse(rawURL)
+	if err != nil {
+		return nil, err
+	}
+
+	return remote.NewReadClient("foobar", &remote.ClientConfig{
+		URL: &commonconfig.URL{URL: u},
+		Headers: map[string]string{
+			"x-scope-orgid": tenantID,
+		},
+		Timeout:          model.Duration(5 * time.Minute),
+		ChunkedReadLimit: config.DefaultChunkedReadLimit,
+	})
+}
+
+func checkHistogram(client remote.ReadClient, histogramBase string, hourStart time.Time) (int64, error) {
+	startTimestampMs := hourStart.UnixMilli()
+	endTimestampMs := hourStart.Add(time.Hour).UnixMilli()
+
+	queries := []*prompb.Query{
+		{
+			StartTimestampMs: startTimestampMs,
+			EndTimestampMs:   endTimestampMs,
+			Matchers: []*prompb.LabelMatcher{
+				{
+					Type:  prompb.LabelMatcher_EQ,
+					Name:  "__aggregation__",
+					Value: fmt.Sprintf("%s_count:sum:counter", histogramBase),
+				},
+			},
+		},
+		{
+			StartTimestampMs: startTimestampMs,
+			EndTimestampMs:   endTimestampMs,
+			Matchers: []*prompb.LabelMatcher{
+				{
+					Type:  prompb.LabelMatcher_EQ,
+					Name:  "__aggregation__",
+					Value: fmt.Sprintf("%s_bucket:sum:counter", histogramBase),
+				},
+				{
+					Type:  prompb.LabelMatcher_EQ,
+					Name:  "le",
+					Value: "+Inf",
+				},
+			},
+		},
+	}
+
+	res := []map[int64]float64{
+		make(map[int64]float64),
+		make(map[int64]float64),
+	}
+
+	for i, q := range queries {
+		ss, err := client.Read(context.Background(), q, false)
+		if err != nil {
+			return -1, err
+		}
+
+		for ss.Next() {
+			if err = ss.Err(); err != nil {
+				return -1, err
+			}
+
+			series := ss.At()
+			it := series.Iterator(nil)
+
+			for vt := it.Next(); vt != chunkenc.ValNone; vt = it.Next() {
+				if err = it.Err(); err != nil {
+					return -1, fmt.Errorf("error iterating through %v: %w", series.Labels(), err)
+				}
+				if vt != chunkenc.ValFloat {
+					return -1, fmt.Errorf("expected float result for query '%v', got %s", q, vt.String())
+				}
+
+				ts, v := it.At()
+
+				if _, ok := res[i][ts]; !ok {
+					res[i][ts] = v
+				} else {
+					res[i][ts] += v
+				}
+			}
+		}
+	}
+
+	if len(res[0]) != len(res[1]) {
+		return -1, fmt.Errorf("result sets different lengths, %v != %v", len(res[0]), len(res[1]))
+	}
+
+	for ts, v0 := range res[0] {
+		v1 := res[1][ts]
+		if v0 != v1 {
+			return ts, nil
+		}
+	}
+
+	return 0, nil
+}