exemplar

Documentation

Overview

Package exemplar provides an implementation of the OpenTelemetry exemplar reservoir to be used in metric collection pipelines.

Index

• type Reservoir
  • func Drop[N int64 | float64]() Reservoir[N]
  • func FixedSize[N int64 | float64](k int) Reservoir[N]
  • func Histogram[N int64 | float64](bounds []float64) Reservoir[N]
  • func SampledFilter[N int64 | float64](r Reservoir[N]) Reservoir[N]

Types

type Reservoir

type Reservoir[N int64 | float64] interface {
	// Offer accepts the parameters associated with a measurement. The
	// parameters will be stored as an exemplar if the Reservoir decides to
	// sample the measurement.
	//
	// The passed ctx needs to contain any baggage or span that were active
	// when the measurement was made. This information may be used by the
	// Reservoir in making a sampling decision.
	//
	// The time t is the time when the measurement was made. The val and attr
	// parameters are the value and dropped (filtered) attributes of the
	// measurement respectively.
	Offer(ctx context.Context, t time.Time, val N, attr []attribute.KeyValue)

	// Collect returns all the held exemplars.
	//
	// The Reservoir state is preserved after this call.
	Collect(dest *[]metricdata.Exemplar[N])
}

Reservoir holds the sampled exemplar of measurements made.

func Drop

func Drop[N int64 | float64]() Reservoir[N]

Drop returns a Reservoir that drops all measurements it is offered.

func FixedSize

func FixedSize[N int64 | float64](k int) Reservoir[N]

FixedSize returns a Reservoir that samples at most k exemplars. If there are k or less measurements made, the Reservoir will sample each one. If there are more than k, the Reservoir will then randomly sample all additional measurement with a decreasing probability.

func Histogram

func Histogram[N int64 | float64](bounds []float64) Reservoir[N]

Histogram returns a Reservoir that samples the last measurement that falls within a histogram bucket. The histogram bucket upper-boundaries are define by bounds.

The passed bounds will be sorted by this function.

func SampledFilter

func SampledFilter[N int64 | float64](r Reservoir[N]) Reservoir[N]

SampledFilter returns a Reservoir wrapping r that will only offer measurements to r if the passed context associated with the measurement contains a sampled go.opentelemetry.io/otel/trace.SpanContext.