diff options
Diffstat (limited to 'vendor/github.com/prometheus/client_golang/prometheus/histogram.go')
| -rw-r--r-- | vendor/github.com/prometheus/client_golang/prometheus/histogram.go | 147 |
1 files changed, 104 insertions, 43 deletions
diff --git a/vendor/github.com/prometheus/client_golang/prometheus/histogram.go b/vendor/github.com/prometheus/client_golang/prometheus/histogram.go index 9719e8fac..331783a75 100644 --- a/vendor/github.com/prometheus/client_golang/prometheus/histogram.go +++ b/vendor/github.com/prometheus/client_golang/prometheus/histogram.go @@ -126,23 +126,16 @@ type HistogramOpts struct { // string. Help string - // ConstLabels are used to attach fixed labels to this - // Histogram. Histograms with the same fully-qualified name must have the - // same label names in their ConstLabels. + // ConstLabels are used to attach fixed labels to this metric. Metrics + // with the same fully-qualified name must have the same label names in + // their ConstLabels. // - // Note that in most cases, labels have a value that varies during the - // lifetime of a process. Those labels are usually managed with a - // HistogramVec. ConstLabels serve only special purposes. One is for the - // special case where the value of a label does not change during the - // lifetime of a process, e.g. if the revision of the running binary is - // put into a label. Another, more advanced purpose is if more than one - // Collector needs to collect Histograms with the same fully-qualified - // name. In that case, those Summaries must differ in the values of - // their ConstLabels. See the Collector examples. - // - // If the value of a label never changes (not even between binaries), - // that label most likely should not be a label at all (but part of the - // metric name). + // ConstLabels are only used rarely. In particular, do not use them to + // attach the same labels to all your metrics. Those use cases are + // better covered by target labels set by the scraping Prometheus + // server, or by one specific metric (e.g. a build_info or a + // machine_role metric). See also + // https://prometheus.io/docs/instrumenting/writing_exporters/#target-labels,-not-static-scraped-labels ConstLabels Labels // Buckets defines the buckets into which observations are counted. Each @@ -287,12 +280,11 @@ func (h *histogram) Write(out *dto.Metric) error { // (e.g. HTTP request latencies, partitioned by status code and method). Create // instances with NewHistogramVec. type HistogramVec struct { - *MetricVec + *metricVec } // NewHistogramVec creates a new HistogramVec based on the provided HistogramOpts and -// partitioned by the given label names. At least one label name must be -// provided. +// partitioned by the given label names. func NewHistogramVec(opts HistogramOpts, labelNames []string) *HistogramVec { desc := NewDesc( BuildFQName(opts.Namespace, opts.Subsystem, opts.Name), @@ -301,47 +293,116 @@ func NewHistogramVec(opts HistogramOpts, labelNames []string) *HistogramVec { opts.ConstLabels, ) return &HistogramVec{ - MetricVec: newMetricVec(desc, func(lvs ...string) Metric { + metricVec: newMetricVec(desc, func(lvs ...string) Metric { return newHistogram(desc, opts, lvs...) }), } } -// GetMetricWithLabelValues replaces the method of the same name in -// MetricVec. The difference is that this method returns a Histogram and not a -// Metric so that no type conversion is required. -func (m *HistogramVec) GetMetricWithLabelValues(lvs ...string) (Histogram, error) { - metric, err := m.MetricVec.GetMetricWithLabelValues(lvs...) +// GetMetricWithLabelValues returns the Histogram for the given slice of label +// values (same order as the VariableLabels in Desc). If that combination of +// label values is accessed for the first time, a new Histogram is created. +// +// It is possible to call this method without using the returned Histogram to only +// create the new Histogram but leave it at its starting value, a Histogram without +// any observations. +// +// Keeping the Histogram for later use is possible (and should be considered if +// performance is critical), but keep in mind that Reset, DeleteLabelValues and +// Delete can be used to delete the Histogram from the HistogramVec. In that case, the +// Histogram will still exist, but it will not be exported anymore, even if a +// Histogram with the same label values is created later. See also the CounterVec +// example. +// +// An error is returned if the number of label values is not the same as the +// number of VariableLabels in Desc (minus any curried labels). +// +// Note that for more than one label value, this method is prone to mistakes +// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as +// an alternative to avoid that type of mistake. For higher label numbers, the +// latter has a much more readable (albeit more verbose) syntax, but it comes +// with a performance overhead (for creating and processing the Labels map). +// See also the GaugeVec example. +func (v *HistogramVec) GetMetricWithLabelValues(lvs ...string) (Observer, error) { + metric, err := v.metricVec.getMetricWithLabelValues(lvs...) if metric != nil { - return metric.(Histogram), err + return metric.(Observer), err } return nil, err } -// GetMetricWith replaces the method of the same name in MetricVec. The -// difference is that this method returns a Histogram and not a Metric so that no -// type conversion is required. -func (m *HistogramVec) GetMetricWith(labels Labels) (Histogram, error) { - metric, err := m.MetricVec.GetMetricWith(labels) +// GetMetricWith returns the Histogram for the given Labels map (the label names +// must match those of the VariableLabels in Desc). If that label map is +// accessed for the first time, a new Histogram is created. Implications of +// creating a Histogram without using it and keeping the Histogram for later use +// are the same as for GetMetricWithLabelValues. +// +// An error is returned if the number and names of the Labels are inconsistent +// with those of the VariableLabels in Desc (minus any curried labels). +// +// This method is used for the same purpose as +// GetMetricWithLabelValues(...string). See there for pros and cons of the two +// methods. +func (v *HistogramVec) GetMetricWith(labels Labels) (Observer, error) { + metric, err := v.metricVec.getMetricWith(labels) if metric != nil { - return metric.(Histogram), err + return metric.(Observer), err } return nil, err } // WithLabelValues works as GetMetricWithLabelValues, but panics where -// GetMetricWithLabelValues would have returned an error. By not returning an -// error, WithLabelValues allows shortcuts like +// GetMetricWithLabelValues would have returned an error. Not returning an +// error allows shortcuts like // myVec.WithLabelValues("404", "GET").Observe(42.21) -func (m *HistogramVec) WithLabelValues(lvs ...string) Histogram { - return m.MetricVec.WithLabelValues(lvs...).(Histogram) +func (v *HistogramVec) WithLabelValues(lvs ...string) Observer { + h, err := v.GetMetricWithLabelValues(lvs...) + if err != nil { + panic(err) + } + return h +} + +// With works as GetMetricWith but panics where GetMetricWithLabels would have +// returned an error. Not returning an error allows shortcuts like +// myVec.With(prometheus.Labels{"code": "404", "method": "GET"}).Observe(42.21) +func (v *HistogramVec) With(labels Labels) Observer { + h, err := v.GetMetricWith(labels) + if err != nil { + panic(err) + } + return h } -// With works as GetMetricWith, but panics where GetMetricWithLabels would have -// returned an error. By not returning an error, With allows shortcuts like -// myVec.With(Labels{"code": "404", "method": "GET"}).Observe(42.21) -func (m *HistogramVec) With(labels Labels) Histogram { - return m.MetricVec.With(labels).(Histogram) +// CurryWith returns a vector curried with the provided labels, i.e. the +// returned vector has those labels pre-set for all labeled operations performed +// on it. The cardinality of the curried vector is reduced accordingly. The +// order of the remaining labels stays the same (just with the curried labels +// taken out of the sequence – which is relevant for the +// (GetMetric)WithLabelValues methods). It is possible to curry a curried +// vector, but only with labels not yet used for currying before. +// +// The metrics contained in the HistogramVec are shared between the curried and +// uncurried vectors. They are just accessed differently. Curried and uncurried +// vectors behave identically in terms of collection. Only one must be +// registered with a given registry (usually the uncurried version). The Reset +// method deletes all metrics, even if called on a curried vector. +func (v *HistogramVec) CurryWith(labels Labels) (ObserverVec, error) { + vec, err := v.curryWith(labels) + if vec != nil { + return &HistogramVec{vec}, err + } + return nil, err +} + +// MustCurryWith works as CurryWith but panics where CurryWith would have +// returned an error. +func (v *HistogramVec) MustCurryWith(labels Labels) ObserverVec { + vec, err := v.CurryWith(labels) + if err != nil { + panic(err) + } + return vec } type constHistogram struct { @@ -401,8 +462,8 @@ func NewConstHistogram( buckets map[float64]uint64, labelValues ...string, ) (Metric, error) { - if len(desc.variableLabels) != len(labelValues) { - return nil, errInconsistentCardinality + if err := validateLabelValues(labelValues, len(desc.variableLabels)); err != nil { + return nil, err } return &constHistogram{ desc: desc, |