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Unify fingerprinting aka signature calculation. 

This fixes https://github.com/prometheus/client_golang/issues/74 .

IT CHANGES THE FINGERPRINTING AND THEREFORE INVALIDATES EACH AND EVERY
PERSISTED FINGERPRINT (I.E. YOU HAVE TO WIPE THE STORAGE TO USE THIS).

This commit removes the LabelValuesToSignature function as it is used
nowhere (and broken in the way it is implemented right now).

Also, remove one more golint warning.
This commit is contained in:
beorn7 2015-03-03 13:23:11 +01:00
parent de5f7a2db9
commit af21d456db
5 changed files with 211 additions and 92 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
model/metric.go
View File

@ -14,10 +14,8 @@
package model
import (
"encoding/binary"
"encoding/json"
"fmt"
"hash/fnv"
"sort"
"strings"
)
@ -66,37 +64,7 @@ func (m Metric) String() string {
// Fingerprint returns a Metric's Fingerprint.
func (m Metric) Fingerprint() Fingerprint {
labelNames := make([]string, 0, len(m))
maxLength := 0
for labelName, labelValue := range m {
labelNames = append(labelNames, string(labelName))
if len(labelName) > maxLength {
maxLength = len(labelName)
}
if len(labelValue) > maxLength {
maxLength = len(labelValue)
}
}
sort.Strings(labelNames)
summer := fnv.New64a()
buf := make([]byte, maxLength)
for _, labelName := range labelNames {
labelValue := m[LabelName(labelName)]
copy(buf, labelName)
summer.Write(buf[:len(labelName)])
summer.Write(separator)
copy(buf, labelValue)
summer.Write(buf[:len(labelValue)])
}
return Fingerprint(binary.LittleEndian.Uint64(summer.Sum(nil)))
return metricToFingerprint(m)
}
// Clone returns a copy of the Metric.

14
model/metric_test.go
View File

@ -22,7 +22,7 @@ func testMetric(t testing.TB) {
}{
{
input: Metric{},
fingerprint: 2676020557754725067,
fingerprint: 14695981039346656037,
},
{
input: Metric{
@ -30,31 +30,27 @@ func testMetric(t testing.TB) {
"occupation": "robot",
"manufacturer": "westinghouse",
},
fingerprint: 13260944541294022935,
fingerprint: 11310079640881077873,
},
{
input: Metric{
"x": "y",
},
fingerprint: 1470933794305433534,
fingerprint: 13948396922932177635,
},
// The following two demonstrate a bug in fingerprinting. They
// should not have the same fingerprint with a sane
// fingerprinting function. See
// https://github.com/prometheus/client_golang/issues/74 .
{
input: Metric{
"a": "bb",
"b": "c",
},
fingerprint: 3734646176939799877,
fingerprint: 3198632812309449502,
},
{
input: Metric{
"a": "b",
"bb": "c",
},
fingerprint: 3734646176939799877,
fingerprint: 5774953389407657638,
},
}

74
model/signature.go
View File

@ -63,10 +63,10 @@ func LabelsToSignature(labels map[string]string) uint64 {
hb := getHashAndBuf()
defer putHashAndBuf(hb)
for k, v := range labels {
hb.b.WriteString(k)
for labelName, labelValue := range labels {
hb.b.WriteString(labelName)
hb.b.WriteByte(SeparatorByte)
hb.b.WriteString(v)
hb.b.WriteString(labelValue)
hb.h.Write(hb.b.Bytes())
result ^= hb.h.Sum64()
hb.h.Reset()
@ -75,10 +75,34 @@ func LabelsToSignature(labels map[string]string) uint64 {
return result
}
// LabelValuesToSignature returns a unique signature (i.e., fingerprint) for the
// values of a given label set.
func LabelValuesToSignature(labels map[string]string) uint64 {
if len(labels) == 0 {
// metricToFingerprint works exactly as LabelsToSignature but takes a Metric as
// parameter (rather than a label map) and returns a Fingerprint.
func metricToFingerprint(m Metric) Fingerprint {
if len(m) == 0 {
return Fingerprint(emptyLabelSignature)
}
var result uint64
hb := getHashAndBuf()
defer putHashAndBuf(hb)
for labelName, labelValue := range m {
hb.b.WriteString(string(labelName))
hb.b.WriteByte(SeparatorByte)
hb.b.WriteString(string(labelValue))
hb.h.Write(hb.b.Bytes())
result ^= hb.h.Sum64()
hb.h.Reset()
hb.b.Reset()
}
return Fingerprint(result)
}
// SignatureForLabels works like LabelsToSignature but takes a Metric as
// parameter (rather than a label map) and only includes the labels with the
// specified LabelNames into the signature calculation.
func SignatureForLabels(m Metric, labels LabelNames) uint64 {
if len(m) == 0 || len(labels) == 0 {
return emptyLabelSignature
}
@ -86,8 +110,10 @@ func LabelValuesToSignature(labels map[string]string) uint64 {
hb := getHashAndBuf()
defer putHashAndBuf(hb)
for _, v := range labels {
hb.b.WriteString(v)
for _, label := range labels {
hb.b.WriteString(string(label))
hb.b.WriteByte(SeparatorByte)
hb.b.WriteString(string(m[label]))
hb.h.Write(hb.b.Bytes())
result ^= hb.h.Sum64()
hb.h.Reset()
@ -95,3 +121,33 @@ func LabelValuesToSignature(labels map[string]string) uint64 {
}
return result
}
// SignatureWithoutLabels works like LabelsToSignature but takes a Metric as
// parameter (rather than a label map) and excludes the labels with any of the
// specified LabelNames from the signature calculation.
func SignatureWithoutLabels(m Metric, labels map[LabelName]struct{}) uint64 {
if len(m) == 0 {
return emptyLabelSignature
}
var result uint64
hb := getHashAndBuf()
defer putHashAndBuf(hb)
for labelName, labelValue := range m {
if _, exclude := labels[labelName]; exclude {
continue
}
hb.b.WriteString(string(labelName))
hb.b.WriteByte(SeparatorByte)
hb.b.WriteString(string(labelValue))
hb.h.Write(hb.b.Bytes())
result ^= hb.h.Sum64()
hb.h.Reset()
hb.b.Reset()
}
if result == 0 {
return emptyLabelSignature
}
return result
}

180
model/signature_test.go
View File

@ -18,7 +18,7 @@ import (
"testing"
)
func testLabelsToSignature(t testing.TB) {
func TestLabelsToSignature(t *testing.T) {
var scenarios = []struct {
in map[string]string
out uint64
@ -42,57 +42,112 @@ func testLabelsToSignature(t testing.TB) {
}
}
func TestLabelToSignature(t *testing.T) {
testLabelsToSignature(t)
}
func TestEmptyLabelSignature(t *testing.T) {
input := []map[string]string{nil, {}}
var ms runtime.MemStats
runtime.ReadMemStats(&ms)
alloc := ms.Alloc
for _, labels := range input {
LabelsToSignature(labels)
func TestMetricToFingerprint(t *testing.T) {
var scenarios = []struct {
in Metric
out Fingerprint
}{
{
in: Metric{},
out: 14695981039346656037,
},
{
in: Metric{"name": "garland, briggs", "fear": "love is not enough"},
out: 12952432476264840823,
},
}
runtime.ReadMemStats(&ms)
for i, scenario := range scenarios {
actual := metricToFingerprint(scenario.in)
if got := ms.Alloc; alloc != got {
t.Fatal("expected LabelsToSignature with empty labels not to perform allocations")
}
}
func BenchmarkLabelToSignature(b *testing.B) {
for i := 0; i < b.N; i++ {
testLabelsToSignature(b)
}
}
func benchmarkLabelValuesToSignature(b *testing.B, l map[string]string, e uint64) {
for i := 0; i < b.N; i++ {
if a := LabelValuesToSignature(l); a != e {
b.Fatalf("expected signature of %d for %s, got %d", e, l, a)
if actual != scenario.out {
t.Errorf("%d. expected %d, got %d", i, scenario.out, actual)
}
}
}
func BenchmarkLabelValuesToSignatureScalar(b *testing.B) {
benchmarkLabelValuesToSignature(b, nil, 14695981039346656037)
func TestSignatureForLabels(t *testing.T) {
var scenarios = []struct {
in Metric
labels LabelNames
out uint64
}{
{
in: Metric{},
labels: nil,
out: 14695981039346656037,
},
{
in: Metric{"name": "garland, briggs", "fear": "love is not enough"},
labels: LabelNames{"fear", "name"},
out: 12952432476264840823,
},
{
in: Metric{"name": "garland, briggs", "fear": "love is not enough", "foo": "bar"},
labels: LabelNames{"fear", "name"},
out: 12952432476264840823,
},
{
in: Metric{"name": "garland, briggs", "fear": "love is not enough"},
labels: LabelNames{},
out: 14695981039346656037,
},
{
in: Metric{"name": "garland, briggs", "fear": "love is not enough"},
labels: nil,
out: 14695981039346656037,
},
}
for i, scenario := range scenarios {
actual := SignatureForLabels(scenario.in, scenario.labels)
if actual != scenario.out {
t.Errorf("%d. expected %d, got %d", i, scenario.out, actual)
}
}
}
func BenchmarkLabelValuesToSignatureSingle(b *testing.B) {
benchmarkLabelValuesToSignature(b, map[string]string{"first-label": "first-label-value"}, 2653746141194979650)
}
func TestSignatureWithoutLabels(t *testing.T) {
var scenarios = []struct {
in Metric
labels map[LabelName]struct{}
out uint64
}{
{
in: Metric{},
labels: nil,
out: 14695981039346656037,
},
{
in: Metric{"name": "garland, briggs", "fear": "love is not enough"},
labels: map[LabelName]struct{}{"fear": struct{}{}, "name": struct{}{}},
out: 14695981039346656037,
},
{
in: Metric{"name": "garland, briggs", "fear": "love is not enough", "foo": "bar"},
labels: map[LabelName]struct{}{"foo": struct{}{}},
out: 12952432476264840823,
},
{
in: Metric{"name": "garland, briggs", "fear": "love is not enough"},
labels: map[LabelName]struct{}{},
out: 12952432476264840823,
},
{
in: Metric{"name": "garland, briggs", "fear": "love is not enough"},
labels: nil,
out: 12952432476264840823,
},
}
func BenchmarkLabelValuesToSignatureDouble(b *testing.B) {
benchmarkLabelValuesToSignature(b, map[string]string{"first-label": "first-label-value", "second-label": "second-label-value"}, 8893559499616767364)
}
for i, scenario := range scenarios {
actual := SignatureWithoutLabels(scenario.in, scenario.labels)
func BenchmarkLabelValuesToSignatureTriple(b *testing.B) {
benchmarkLabelValuesToSignature(b, map[string]string{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 1685970066862087833)
if actual != scenario.out {
t.Errorf("%d. expected %d, got %d", i, scenario.out, actual)
}
}
}
func benchmarkLabelToSignature(b *testing.B, l map[string]string, e uint64) {
@ -118,3 +173,46 @@ func BenchmarkLabelToSignatureDouble(b *testing.B) {
func BenchmarkLabelToSignatureTriple(b *testing.B) {
benchmarkLabelToSignature(b, map[string]string{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676)
}
func benchmarkMetricToFingerprint(b *testing.B, m Metric, e Fingerprint) {
for i := 0; i < b.N; i++ {
if a := metricToFingerprint(m); a != e {
b.Fatalf("expected signature of %d for %s, got %d", e, m, a)
}
}
}
func BenchmarkMetricToFingerprintScalar(b *testing.B) {
benchmarkMetricToFingerprint(b, nil, 14695981039346656037)
}
func BenchmarkMetricToFingerprintSingle(b *testing.B) {
benchmarkMetricToFingerprint(b, Metric{"first-label": "first-label-value"}, 5147259542624943964)
}
func BenchmarkMetricToFingerprintDouble(b *testing.B) {
benchmarkMetricToFingerprint(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value"}, 18269973311206963528)
}
func BenchmarkMetricToFingerprintTriple(b *testing.B) {
benchmarkMetricToFingerprint(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676)
}
func TestEmptyLabelSignature(t *testing.T) {
input := []map[string]string{nil, {}}
var ms runtime.MemStats
runtime.ReadMemStats(&ms)
alloc := ms.Alloc
for _, labels := range input {
LabelsToSignature(labels)
}
runtime.ReadMemStats(&ms)
if got := ms.Alloc; alloc != got {
t.Fatal("expected LabelsToSignature with empty labels not to perform allocations")
}
}

1
model/timestamp.go
View File

@ -88,6 +88,7 @@ func (t Timestamp) String() string {
return strconv.FormatFloat(float64(t)/float64(second), 'f', -1, 64)
}
// MarshalJSON implements the json.Marshaler interface.
func (t Timestamp) MarshalJSON() ([]byte, error) {
return []byte(t.String()), nil
}