Merge pull request #115 from prometheus/beorn7/const-summaries-histograms
Make it possible to create constant summaries and histograms from static values.
This commit is contained in:
commit
6efaf95d98
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@ -455,6 +455,56 @@ func ExampleSummaryVec() {
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// ]
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}
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func ExampleConstSummary() {
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desc := prometheus.NewDesc(
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"http_request_duration_seconds",
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"A summary of the HTTP request durations.",
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[]string{"code", "method"},
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prometheus.Labels{"owner": "example"},
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)
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// Create a constant summary from values we got from a 3rd party telemetry system.
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s := prometheus.MustNewConstSummary(
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desc,
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4711, 403.34,
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map[float64]float64{0.5: 42.3, 0.9: 323.3},
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"200", "get",
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)
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// Just for demonstration, let's check the state of the summary by
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// (ab)using its Write method (which is usually only used by Prometheus
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// internally).
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metric := &dto.Metric{}
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s.Write(metric)
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fmt.Println(proto.MarshalTextString(metric))
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// Output:
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// label: <
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// name: "code"
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// value: "200"
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// >
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// label: <
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// name: "method"
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// value: "get"
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// >
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// label: <
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// name: "owner"
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// value: "example"
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// >
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// summary: <
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// sample_count: 4711
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// sample_sum: 403.34
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// quantile: <
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// quantile: 0.5
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// value: 42.3
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// >
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// quantile: <
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// quantile: 0.9
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// value: 323.3
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// >
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// >
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}
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func ExampleHistogram() {
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temps := prometheus.NewHistogram(prometheus.HistogramOpts{
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Name: "pond_temperature_celsius",
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@ -501,6 +551,64 @@ func ExampleHistogram() {
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// >
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}
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func ExampleConstHistogram() {
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desc := prometheus.NewDesc(
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"http_request_duration_seconds",
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"A histogram of the HTTP request durations.",
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[]string{"code", "method"},
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prometheus.Labels{"owner": "example"},
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)
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// Create a constant histogram from values we got from a 3rd party telemetry system.
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h := prometheus.MustNewConstHistogram(
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desc,
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4711, 403.34,
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map[float64]uint64{25: 121, 50: 2403, 100: 3221, 200: 4233},
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"200", "get",
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)
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// Just for demonstration, let's check the state of the histogram by
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// (ab)using its Write method (which is usually only used by Prometheus
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// internally).
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metric := &dto.Metric{}
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h.Write(metric)
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fmt.Println(proto.MarshalTextString(metric))
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// Output:
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// label: <
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// name: "code"
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// value: "200"
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// >
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// label: <
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// name: "method"
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// value: "get"
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// >
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// label: <
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// name: "owner"
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// value: "example"
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// >
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// histogram: <
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// sample_count: 4711
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// sample_sum: 403.34
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// bucket: <
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// cumulative_count: 121
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// upper_bound: 25
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// >
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// bucket: <
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// cumulative_count: 2403
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// upper_bound: 50
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// >
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// bucket: <
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// cumulative_count: 3221
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// upper_bound: 100
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// >
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// bucket: <
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// cumulative_count: 4233
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// upper_bound: 200
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// >
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// >
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}
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func ExamplePushCollectors() {
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hostname, _ := os.Hostname()
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completionTime := prometheus.NewGauge(prometheus.GaugeOpts{
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@ -342,3 +342,102 @@ func (m *HistogramVec) WithLabelValues(lvs ...string) Histogram {
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func (m *HistogramVec) With(labels Labels) Histogram {
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return m.MetricVec.With(labels).(Histogram)
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}
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type constHistogram struct {
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desc *Desc
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count uint64
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sum float64
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buckets map[float64]uint64
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labelPairs []*dto.LabelPair
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}
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func (h *constHistogram) Desc() *Desc {
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return h.desc
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}
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func (h *constHistogram) Write(out *dto.Metric) error {
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his := &dto.Histogram{}
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buckets := make([]*dto.Bucket, 0, len(h.buckets))
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his.SampleCount = proto.Uint64(h.count)
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his.SampleSum = proto.Float64(h.sum)
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for upperBound, count := range h.buckets {
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buckets = append(buckets, &dto.Bucket{
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CumulativeCount: proto.Uint64(count),
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UpperBound: proto.Float64(upperBound),
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})
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}
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if len(buckets) > 0 {
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sort.Sort(buckSort(buckets))
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}
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his.Bucket = buckets
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out.Histogram = his
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out.Label = h.labelPairs
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return nil
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}
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// NewConstHistogram returns a metric representing a Prometheus histogram with
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// fixed values for the count, sum, and bucket counts. As those parameters
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// cannot be changed, the returned value does not implement the Histogram
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// interface (but only the Metric interface). Users of this package will not
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// have much use for it in regular operations. However, when implementing custom
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// Collectors, it is useful as a throw-away metric that is generated on the fly
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// to send it to Prometheus in the Collect method.
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//
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// buckets is a map of upper bounds to cumulative counts, excluding the +Inf
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// bucket.
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//
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// NewConstHistogram returns an error if the length of labelValues is not
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// consistent with the variable labels in Desc.
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func NewConstHistogram(
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desc *Desc,
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count uint64,
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sum float64,
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buckets map[float64]uint64,
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labelValues ...string,
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) (Metric, error) {
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if len(desc.variableLabels) != len(labelValues) {
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return nil, errInconsistentCardinality
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}
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return &constHistogram{
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desc: desc,
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count: count,
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sum: sum,
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buckets: buckets,
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labelPairs: makeLabelPairs(desc, labelValues),
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}, nil
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}
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// MustNewConstHistogram is a version of NewConstHistogram that panics where
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// NewConstMetric would have returned an error.
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func MustNewConstHistogram(
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desc *Desc,
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count uint64,
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sum float64,
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buckets map[float64]uint64,
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labelValues ...string,
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) Metric {
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m, err := NewConstHistogram(desc, count, sum, buckets, labelValues...)
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if err != nil {
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panic(err)
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}
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return m
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}
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type buckSort []*dto.Bucket
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func (s buckSort) Len() int {
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return len(s)
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}
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func (s buckSort) Swap(i, j int) {
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s[i], s[j] = s[j], s[i]
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}
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func (s buckSort) Less(i, j int) bool {
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return s[i].GetUpperBound() < s[j].GetUpperBound()
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}
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@ -448,3 +448,89 @@ func (m *SummaryVec) WithLabelValues(lvs ...string) Summary {
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func (m *SummaryVec) With(labels Labels) Summary {
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return m.MetricVec.With(labels).(Summary)
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}
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type constSummary struct {
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desc *Desc
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count uint64
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sum float64
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quantiles map[float64]float64
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labelPairs []*dto.LabelPair
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}
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func (s *constSummary) Desc() *Desc {
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return s.desc
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}
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func (s *constSummary) Write(out *dto.Metric) error {
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sum := &dto.Summary{}
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qs := make([]*dto.Quantile, 0, len(s.quantiles))
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sum.SampleCount = proto.Uint64(s.count)
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sum.SampleSum = proto.Float64(s.sum)
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for rank, q := range s.quantiles {
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qs = append(qs, &dto.Quantile{
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Quantile: proto.Float64(rank),
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Value: proto.Float64(q),
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})
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}
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if len(qs) > 0 {
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sort.Sort(quantSort(qs))
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}
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sum.Quantile = qs
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out.Summary = sum
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out.Label = s.labelPairs
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return nil
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}
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// NewConstSummary returns a metric representing a Prometheus summary with fixed
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// values for the count, sum, and quantiles. As those parameters cannot be
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// changed, the returned value does not implement the Summary interface (but
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// only the Metric interface). Users of this package will not have much use for
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// it in regular operations. However, when implementing custom Collectors, it is
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// useful as a throw-away metric that is generated on the fly to send it to
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// Prometheus in the Collect method.
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//
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// quantiles maps ranks to quantile values. For example, a median latency of
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// 0.23s and a 99th percentile latency of 0.56s would be expressed as:
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// map[float64]float64{0.5: 0.23, 0.99: 0.56}
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//
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// NewConstSummary returns an error if the length of labelValues is not
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// consistent with the variable labels in Desc.
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func NewConstSummary(
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desc *Desc,
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count uint64,
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sum float64,
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quantiles map[float64]float64,
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labelValues ...string,
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) (Metric, error) {
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if len(desc.variableLabels) != len(labelValues) {
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return nil, errInconsistentCardinality
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}
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return &constSummary{
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desc: desc,
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count: count,
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sum: sum,
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quantiles: quantiles,
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labelPairs: makeLabelPairs(desc, labelValues),
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}, nil
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}
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// MustNewConstSummary is a version of NewConstSummary that panics where
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// NewConstMetric would have returned an error.
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func MustNewConstSummary(
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desc *Desc,
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count uint64,
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sum float64,
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quantiles map[float64]float64,
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labelValues ...string,
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) Metric {
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m, err := NewConstSummary(desc, count, sum, quantiles, labelValues...)
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if err != nil {
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panic(err)
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}
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return m
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}
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