WIP: Populate OM's created timestamps

Signed-off-by: Arthur Silva Sens <arthur.sens@coralogix.com>

examples/exemplars/main.go

@@ -66,4 +66,4 @@ func main() {
 	)
 	// To test: curl -H 'Accept: application/openmetrics-text' localhost:8080/metrics
 	log.Fatalln(http.ListenAndServe(":8080", nil))
-}
+}

go.mod

@@ -7,7 +7,7 @@ require (
 	github.com/cespare/xxhash/v2 v2.2.0
 	github.com/davecgh/go-spew v1.1.1
 	github.com/json-iterator/go v1.1.12
-	github.com/prometheus/client_model v0.3.0
+	github.com/prometheus/client_model v0.4.0
 	github.com/prometheus/common v0.42.0
 	github.com/prometheus/procfs v0.10.1
 	golang.org/x/sys v0.8.0
@@ -22,12 +22,15 @@ require (
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f // indirect
-	golang.org/x/net v0.7.0 // indirect
-	golang.org/x/oauth2 v0.5.0 // indirect
-	golang.org/x/text v0.7.0 // indirect
+	golang.org/x/net v0.10.0 // indirect
+	golang.org/x/oauth2 v0.8.0 // indirect
+	golang.org/x/text v0.9.0 // indirect
 	google.golang.org/appengine v1.6.7 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
 
 exclude github.com/prometheus/client_golang v1.12.1
+
+replace github.com/prometheus/common => github.com/ArthurSens/common v0.0.0-20230718212508-8ffc995a3589
+
+replace github.com/prometheus/client_model => github.com/ArthurSens/client_model v0.0.0-20230718164431-9a2bf3000d16

prometheus/counter.go

@@ -20,6 +20,7 @@ import (
 	"time"
 
 	dto "github.com/prometheus/client_model/go"
+	timestamppb "google.golang.org/protobuf/types/known/timestamppb"
 )
 
 // Counter is a Metric that represents a single numerical value that only ever
@@ -106,10 +107,11 @@ type counter struct {
 	selfCollector
 	desc *Desc
 
+	createdTs  *timestamppb.Timestamp
 	labelPairs []*dto.LabelPair
 	exemplar   atomic.Value // Containing nil or a *dto.Exemplar.
 
-	now func() time.Time // To mock out time.Now() for testing.
+	now            func() time.Time             // To mock out time.Now() for testing.
 }
 
 func (c *counter) Desc() *Desc {
@@ -121,6 +123,10 @@ func (c *counter) Add(v float64) {
 		panic(errors.New("counter cannot decrease in value"))
 	}
 
+	if c.createdTs == nil {
+		c.setCreatedTimestamp()
+	}
+
 	ival := uint64(v)
 	if float64(ival) == v {
 		atomic.AddUint64(&c.valInt, ival)
@@ -143,6 +149,13 @@ func (c *counter) AddWithExemplar(v float64, e Labels) {
 
 func (c *counter) Inc() {
 	atomic.AddUint64(&c.valInt, 1)
+	if c.createdTs == nil {
+		c.setCreatedTimestamp()
+	}
+}
+
+func (c *counter) setCreatedTimestamp() {
+	c.createdTs = timestamppb.New(c.now())
 }
 
 func (c *counter) get() float64 {
@@ -160,7 +173,7 @@ func (c *counter) Write(out *dto.Metric) error {
 	}
 	val := c.get()
 
-	return populateMetric(CounterValue, val, c.labelPairs, exemplar, out)
+	return populateMetric(CounterValue, val, c.labelPairs, exemplar, out, c.createdTs)
 }
 
 func (c *counter) updateExemplar(v float64, l Labels) {

prometheus/counter_test.go

@@ -273,3 +273,27 @@ func TestCounterExemplar(t *testing.T) {
 		t.Error("adding exemplar with oversized labels succeeded")
 	}
 }
+
+func TestCounterCreatedTimestamp(t *testing.T) {
+	now := time.Now()
+
+	counter := NewCounter(CounterOpts{
+		Name: "test",
+		Help: "test help",
+	}).(*counter)
+	counter.now = func() time.Time { return now }
+
+	ts := timestamppb.New(now)
+	if err := ts.CheckValid(); err != nil {
+		t.Fatal(err)
+	}
+
+	expectedCounter := &dto.Counter{
+		CreatedTimestamp: ts,
+	}
+
+	counter.Inc()
+	if counter.createdTs.AsTime() != expectedCounter.CreatedTimestamp.AsTime() {
+		t.Errorf("expected created timestamp %s, got %s", expectedCounter.CreatedTimestamp, counter.createdTs)
+	}
+}

prometheus/gauge.go

@@ -135,7 +135,7 @@ func (g *gauge) Sub(val float64) {
 
 func (g *gauge) Write(out *dto.Metric) error {
 	val := math.Float64frombits(atomic.LoadUint64(&g.valBits))
-	return populateMetric(GaugeValue, val, g.labelPairs, nil, out)
+	return populateMetric(GaugeValue, val, g.labelPairs, nil, out, nil)
 }
 
 // GaugeVec is a Collector that bundles a set of Gauges that all share the same

prometheus/histogram.go

@@ -25,6 +25,7 @@ import (
 	dto "github.com/prometheus/client_model/go"
 
 	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/known/timestamppb"
 )
 
 // nativeHistogramBounds for the frac of observed values. Only relevant for
@@ -694,6 +695,7 @@ type histogram struct {
 	counts [2]*histogramCounts
 
 	upperBounds                     []float64
+	createdTs                       *timestamppb.Timestamp
 	labelPairs                      []*dto.LabelPair
 	exemplars                       []atomic.Value // One more than buckets (to include +Inf), each a *dto.Exemplar.
 	nativeHistogramSchema           int32          // The initial schema. Set to math.MinInt32 if no sparse buckets are used.
@@ -742,9 +744,10 @@ func (h *histogram) Write(out *dto.Metric) error {
 	waitForCooldown(count, coldCounts)
 
 	his := &dto.Histogram{
-		Bucket:      make([]*dto.Bucket, len(h.upperBounds)),
-		SampleCount: proto.Uint64(count),
-		SampleSum:   proto.Float64(math.Float64frombits(atomic.LoadUint64(&coldCounts.sumBits))),
+		Bucket:           make([]*dto.Bucket, len(h.upperBounds)),
+		SampleCount:      proto.Uint64(count),
+		SampleSum:        proto.Float64(math.Float64frombits(atomic.LoadUint64(&coldCounts.sumBits))),
+		CreatedTimestamp: h.createdTs,
 	}
 	out.Histogram = his
 	out.Label = h.labelPairs
@@ -815,6 +818,13 @@ func (h *histogram) observe(v float64, bucket int) {
 	if doSparse {
 		h.limitBuckets(hotCounts, v, bucket)
 	}
+	if h.createdTs == nil {
+		h.setCreatedTimestamp()
+	}
+}
+
+func (h *histogram) setCreatedTimestamp() {
+	h.createdTs = timestamppb.New(h.now())
 }
 
 // limitBuckets applies a strategy to limit the number of populated sparse
@@ -1175,6 +1185,7 @@ type constHistogram struct {
 	count      uint64
 	sum        float64
 	buckets    map[float64]uint64
+	createdTS  *timestamppb.Timestamp
 	labelPairs []*dto.LabelPair
 }
 
@@ -1183,7 +1194,9 @@ func (h *constHistogram) Desc() *Desc {
 }
 
 func (h *constHistogram) Write(out *dto.Metric) error {
-	his := &dto.Histogram{}
+	his := &dto.Histogram{
+		CreatedTimestamp: h.createdTS,
+	}
 
 	buckets := make([]*dto.Bucket, 0, len(h.buckets))
 

prometheus/histogram_test.go

@@ -875,3 +875,28 @@ func TestGetLe(t *testing.T) {
 		}
 	}
 }
+
+func TestHistogramCreatedTimestamp(t *testing.T) {
+	now := time.Now()
+
+	histogram := NewHistogram(HistogramOpts{
+		Name:    "test",
+		Help:    "test help",
+		Buckets: []float64{1, 2, 3, 4},
+	}).(*histogram)
+	histogram.now = func() time.Time { return now }
+
+	ts := timestamppb.New(now)
+	if err := ts.CheckValid(); err != nil {
+		t.Fatal(err)
+	}
+	expectedHistogram := &dto.Histogram{
+		CreatedTimestamp: ts,
+	}
+
+	histogram.Observe(1.5)
+
+	if histogram.createdTs.AsTime() != expectedHistogram.CreatedTimestamp.AsTime() {
+		t.Errorf("expected created timestamp %s, got %s", expectedHistogram.CreatedTimestamp, histogram.createdTs)
+	}
+}

prometheus/summary.go

@@ -26,6 +26,7 @@ import (
 
 	"github.com/beorn7/perks/quantile"
 	"google.golang.org/protobuf/proto"
+	timestamppb "google.golang.org/protobuf/types/known/timestamppb"
 )
 
 // quantileLabel is used for the label that defines the quantile in a
@@ -244,6 +245,7 @@ func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary {
 		hotBuf:         make([]float64, 0, opts.BufCap),
 		coldBuf:        make([]float64, 0, opts.BufCap),
 		streamDuration: opts.MaxAge / time.Duration(opts.AgeBuckets),
+		now:            time.Now,
 	}
 	s.headStreamExpTime = time.Now().Add(s.streamDuration)
 	s.hotBufExpTime = s.headStreamExpTime
@@ -274,6 +276,7 @@ type summary struct {
 	objectives       map[float64]float64
 	sortedObjectives []float64
 
+	createdTs  *timestamppb.Timestamp
 	labelPairs []*dto.LabelPair
 
 	sum float64
@@ -286,6 +289,8 @@ type summary struct {
 	headStream                       *quantile.Stream
 	headStreamIdx                    int
 	headStreamExpTime, hotBufExpTime time.Time
+
+	now func() time.Time // To mock out time.Now() for testing.
 }
 
 func (s *summary) Desc() *Desc {
@@ -304,10 +309,19 @@ func (s *summary) Observe(v float64) {
 	if len(s.hotBuf) == cap(s.hotBuf) {
 		s.asyncFlush(now)
 	}
+	if s.createdTs == nil {
+		s.setCreatedTimestamp()
+	}
+}
+
+func (s *summary) setCreatedTimestamp() {
+	s.createdTs = timestamppb.New(s.now())
 }
 
 func (s *summary) Write(out *dto.Metric) error {
-	sum := &dto.Summary{}
+	sum := &dto.Summary{
+		CreatedTimestamp: s.createdTs,
+	}
 	qs := make([]*dto.Quantile, 0, len(s.objectives))
 
 	s.bufMtx.Lock()
@@ -439,7 +453,10 @@ type noObjectivesSummary struct {
 	// http://golang.org/pkg/sync/atomic/#pkg-note-BUG.
 	counts [2]*summaryCounts
 
+	createdTs  *timestamppb.Timestamp
 	labelPairs []*dto.LabelPair
+
+	now func() time.Time // To mock out time.Now() for testing.
 }
 
 func (s *noObjectivesSummary) Desc() *Desc {
@@ -463,6 +480,14 @@ func (s *noObjectivesSummary) Observe(v float64) {
 	// Increment count last as we take it as a signal that the observation
 	// is complete.
 	atomic.AddUint64(&hotCounts.count, 1)
+
+	if s.createdTs == nil {
+		s.setCreatedTimestamp()
+	}
+}
+
+func (s *noObjectivesSummary) setCreatedTimestamp() {
+	s.createdTs = timestamppb.New(s.now())
 }
 
 func (s *noObjectivesSummary) Write(out *dto.Metric) error {
@@ -490,8 +515,9 @@ func (s *noObjectivesSummary) Write(out *dto.Metric) error {
 	}
 
 	sum := &dto.Summary{
-		SampleCount: proto.Uint64(count),
-		SampleSum:   proto.Float64(math.Float64frombits(atomic.LoadUint64(&coldCounts.sumBits))),
+		SampleCount:      proto.Uint64(count),
+		SampleSum:        proto.Float64(math.Float64frombits(atomic.LoadUint64(&coldCounts.sumBits))),
+		CreatedTimestamp: s.createdTs,
 	}
 
 	out.Summary = sum

prometheus/summary_test.go

@@ -23,6 +23,7 @@ import (
 	"time"
 
 	dto "github.com/prometheus/client_model/go"
+	timestamppb "google.golang.org/protobuf/types/known/timestamppb"
 )
 
 func TestSummaryWithDefaultObjectives(t *testing.T) {
@@ -420,3 +421,40 @@ func getBounds(vars []float64, q, ε float64) (min, max float64) {
 	}
 	return
 }
+
+func TestSummaryCreatedTimestamp(t *testing.T) {
+	now := time.Now()
+
+	noObjSummary := NewSummary(SummaryOpts{
+		Name: "test",
+		Help: "test help",
+	}).(*noObjectivesSummary)
+	noObjSummary.now = func() time.Time { return now }
+
+	summary := NewSummary(SummaryOpts{
+		Name: "test2",
+		Help: "test2",
+		Objectives: map[float64]float64{
+			1.0: 1.0,
+		},
+	}).(*summary)
+	summary.now = func() time.Time { return now }
+
+	ts := timestamppb.New(now)
+	if err := ts.CheckValid(); err != nil {
+		t.Fatal(err)
+	}
+
+	expectedSummary := &dto.Summary{
+		CreatedTimestamp: ts,
+	}
+
+	noObjSummary.Observe(1.5)
+	summary.Observe(1.5)
+	if noObjSummary.createdTs.AsTime() != expectedSummary.CreatedTimestamp.AsTime() {
+		t.Errorf("expected created timestamp %s, got %s", expectedSummary.CreatedTimestamp, noObjSummary.createdTs)
+	}
+	if summary.createdTs.AsTime() != expectedSummary.CreatedTimestamp.AsTime() {
+		t.Errorf("expected created timestamp %s, got %s", expectedSummary.CreatedTimestamp, summary.createdTs)
+	}
+}

prometheus/value.go

@@ -91,7 +91,7 @@ func (v *valueFunc) Desc() *Desc {
 }
 
 func (v *valueFunc) Write(out *dto.Metric) error {
-	return populateMetric(v.valType, v.function(), v.labelPairs, nil, out)
+	return populateMetric(v.valType, v.function(), v.labelPairs, nil, out, nil)
 }
 
 // NewConstMetric returns a metric with one fixed value that cannot be
@@ -110,7 +110,7 @@ func NewConstMetric(desc *Desc, valueType ValueType, value float64, labelValues
 	}
 
 	metric := &dto.Metric{}
-	if err := populateMetric(valueType, value, MakeLabelPairs(desc, labelValues), nil, metric); err != nil {
+	if err := populateMetric(valueType, value, MakeLabelPairs(desc, labelValues), nil, metric, timestamppb.Now()); err != nil {
 		return nil, err
 	}
 
@@ -153,11 +153,12 @@ func populateMetric(
 	labelPairs []*dto.LabelPair,
 	e *dto.Exemplar,
 	m *dto.Metric,
+	cTs *timestamppb.Timestamp,
 ) error {
 	m.Label = labelPairs
 	switch t {
 	case CounterValue:
-		m.Counter = &dto.Counter{Value: proto.Float64(v), Exemplar: e}
+		m.Counter = &dto.Counter{Value: proto.Float64(v), Exemplar: e, CreatedTimestamp: cTs}
 	case GaugeValue:
 		m.Gauge = &dto.Gauge{Value: proto.Float64(v)}
 	case UntypedValue: