From 28fffdfcc7241cb28aacfaebba6c50b62e3d0d98 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@victoriametrics.com>
Date: Wed, 7 Feb 2024 21:33:18 +0200
Subject: [PATCH] lib/protoparser/datadogsketches: add more permalinks to the
original source code
These permalinks should help verifying the correctness of the code
This is a follow-up after 07213f4e0cc140a4f37f5b045afdfe7caf5728e0
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5775
---
lib/protoparser/datadogsketches/parser.go | 39 +++++++++++--------
.../datadogsketches/parser_test.go | 4 +-
2 files changed, 24 insertions(+), 19 deletions(-)
diff --git a/lib/protoparser/datadogsketches/parser.go b/lib/protoparser/datadogsketches/parser.go
index c9242bc576..ec2b212686 100644
--- a/lib/protoparser/datadogsketches/parser.go
+++ b/lib/protoparser/datadogsketches/parser.go
@@ -9,11 +9,11 @@ import (
)
var (
- // https://github.com/DataDog/opentelemetry-mapping-go/blob/48d52eeea60d28da2e14c154a24557c4d290c6e2/pkg/quantile/config.go
- epsillon = 1.0 / 128
- gamma = 1 + 2*epsillon
- gammaLn = math.Log(gamma)
- defaultMin = 0.981e-9
+ // These constants were obtained from https://github.com/DataDog/opentelemetry-mapping-go/blob/48d52eeea60d28da2e14c154a24557c4d290c6e2/pkg/quantile/config.go
+ eps = 1.0 / 128
+ gamma = 1 + 2*eps
+ gammaLn = math.Log1p(2 * eps)
+ defaultMin = 1e-9
bias = 1 - int(math.Floor(math.Log(defaultMin)/gammaLn))
quantiles = []float64{0.5, 0.75, 0.9, 0.95, 0.99}
)
@@ -174,7 +174,7 @@ func (s *Sketch) ToSummary() []*Metric {
timestamp := d.Ts * 1000
points[j] = Point{
Timestamp: timestamp,
- Value: d.valueForQuantile(q),
+ Value: d.quantile(q),
}
sumPoints[j] = Point{
Timestamp: timestamp,
@@ -285,7 +285,8 @@ func (d *Dogsketch) unmarshalProtobuf(src []byte) (err error) {
return nil
}
-func (d *Dogsketch) valueForQuantile(q float64) float64 {
+// This function has been copied from https://github.com/DataDog/opentelemetry-mapping-go/blob/48d52eeea60d28da2e14c154a24557c4d290c6e2/pkg/quantile/sparse.go#L92
+func (d *Dogsketch) quantile(q float64) float64 {
switch {
case d.Cnt == 0:
return 0
@@ -312,10 +313,7 @@ func (d *Dogsketch) valueForQuantile(q float64) float64 {
weight := (cnt - rank) / float64(n)
vLow := f64(ks[i])
vHigh := vLow * gamma
- switch i {
- case len(ns):
- vHigh = d.Max
- case 0:
+ if i == 0 {
vLow = d.Min
}
return vLow*weight + vHigh*(1-weight)
@@ -323,15 +321,22 @@ func (d *Dogsketch) valueForQuantile(q float64) float64 {
return d.Max
}
+// This function has been copied from https://github.com/DataDog/opentelemetry-mapping-go/blob/48d52eeea60d28da2e14c154a24557c4d290c6e2/pkg/quantile/config.go#L54
func f64(k int32) float64 {
- switch {
- case k < 0:
- return -f64(-k)
- case k == math.MaxInt16 || k == math.MinInt16:
- return math.Inf(int(k))
- case k == 0:
+ // See https://github.com/DataDog/opentelemetry-mapping-go/blob/48d52eeea60d28da2e14c154a24557c4d290c6e2/pkg/quantile/key.go#L14
+ if k <= -((1 << 15) - 1) {
+ return math.Inf(-1)
+ }
+ if k >= ((1 << 15) - 1) {
+ return math.Inf(1)
+ }
+ if k == 0 {
return 0
}
+ if k < 0 {
+ return -f64(-k)
+ }
+
exp := float64(int(k) - bias)
return math.Pow(gamma, exp)
}
diff --git a/lib/protoparser/datadogsketches/parser_test.go b/lib/protoparser/datadogsketches/parser_test.go
index 94c3bf0f10..161f073ef5 100644
--- a/lib/protoparser/datadogsketches/parser_test.go
+++ b/lib/protoparser/datadogsketches/parser_test.go
@@ -5,10 +5,10 @@ import (
"testing"
)
-func TestPointsForQuantile(t *testing.T) {
+func TestDogsketchQuantile(t *testing.T) {
f := func(d *Dogsketch, q float64, vExpected float64) {
t.Helper()
- v := d.valueForQuantile(q)
+ v := d.quantile(q)
if math.Abs(v-vExpected) > 0.4 {
t.Fatalf("unexpected value; got %v; want %v", v, vExpected)
}