Class DefaultExemplarSampler

java.lang.Object

io.prometheus.client.exemplars.DefaultExemplarSampler

All Implemented Interfaces:

CounterExemplarSampler, ExemplarSampler, HistogramExemplarSampler

public class DefaultExemplarSampler
extends Object
implements ExemplarSampler

Default Exemplar sampler.

Keeps each Exemplar for a minimum of ~7 seconds, then samples a new one.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static interface	DefaultExemplarSampler.Clock
(package private) static class	DefaultExemplarSampler.SystemClock

Field Summary

Fields

Modifier and Type	Field	Description
private final DefaultExemplarSampler.Clock	clock
private final long	minRetentionIntervalMs
private static final String	SPAN_ID
private final SpanContextSupplier	spanContextSupplier
private static final String	TRACE_ID

Constructor Summary

Constructors

Constructor	Description
DefaultExemplarSampler(SpanContextSupplier spanContextSupplier)
DefaultExemplarSampler(SpanContextSupplier spanContextSupplier, DefaultExemplarSampler.Clock clock)

Method Summary

Modifier and Type	Method	Description
private Exemplar	doSample(double value, Exemplar previous)
Exemplar	sample(double value, double bucketFrom, double bucketTo, Exemplar previous)
Exemplar	sample(double increment, Exemplar previous)

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

SPAN_ID

private static final String SPAN_ID

See Also:

• Constant Field Values

TRACE_ID

private static final String TRACE_ID

See Also:

• Constant Field Values

spanContextSupplier

private final SpanContextSupplier spanContextSupplier

minRetentionIntervalMs

private final long minRetentionIntervalMs

See Also:

• Constant Field Values

clock

private final DefaultExemplarSampler.Clock clock

Constructor Details

DefaultExemplarSampler

public DefaultExemplarSampler(SpanContextSupplier spanContextSupplier)

DefaultExemplarSampler

DefaultExemplarSampler(SpanContextSupplier spanContextSupplier,
 DefaultExemplarSampler.Clock clock)

Method Details

sample

public Exemplar sample(double increment,
 Exemplar previous)

Specified by:

sample in interface CounterExemplarSampler

Parameters:

increment - the value added to the counter on this event

previous - the previously sampled exemplar, or null if there is none.

Returns:

an Exemplar to be sampled, or null if the previous exemplar does not need to be updated. Returning null and returning previous is equivalent.

sample

public Exemplar sample(double value,
 double bucketFrom,
 double bucketTo,
 Exemplar previous)

Specified by:

sample in interface HistogramExemplarSampler

Parameters:

value - the value to be observed.

bucketFrom - upper boundary of the previous bucket in the histogram. Will be Double.NEGATIVE_INFINITY if there is no previous bucket.

bucketTo - upper boundary of this histogram bucket. Will be Double.POSITIVE_INFINITY if this is the last bucket.

previous - the previously sampled exemplar, or null if there is none.

Returns:

an Exemplar to be sampled, or null if the previous exemplar does not need to be updated. Returning null and returning previous is equivalent.

doSample

private Exemplar doSample(double value,
 Exemplar previous)