Package io.opencensus.trace.samplers

Class ProbabilitySampler

java.lang.Object

io.opencensus.trace.Sampler

io.opencensus.trace.samplers.ProbabilitySampler

Direct Known Subclasses:

AutoValue_ProbabilitySampler

@Immutable
abstract class ProbabilitySampler
extends Sampler

We assume the lower 64 bits of the traceId's are randomly distributed around the whole (long) range. We convert an incoming probability into an upper bound on that value, such that we can just compare the absolute value of the id and the bound to see if we are within the desired probability range. Using the low bits of the traceId also ensures that systems that only use 64 bit ID's will also work with this sampler.

Constructor Summary

Constructors

Constructor	Description
ProbabilitySampler()

Method Summary

Modifier and Type	Method	Description
(package private) static ProbabilitySampler	create(double probability)	Returns a new ProbabilitySampler.
java.lang.String	getDescription()	Returns the description of this Sampler.
(package private) abstract long	getIdUpperBound()
(package private) abstract double	getProbability()
boolean	shouldSample(SpanContext parentContext, java.lang.Boolean hasRemoteParent, TraceId traceId, SpanId spanId, java.lang.String name, java.util.List<Span> parentLinks)	Called during Span creation to make a sampling decision.

Methods inherited from class java.lang.Object

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

Constructor Detail

ProbabilitySampler

ProbabilitySampler()

Method Detail

getProbability

abstract double getProbability()

getIdUpperBound

abstract long getIdUpperBound()

create

static ProbabilitySampler create(double probability)

Returns a new ProbabilitySampler. The probability of sampling a trace is equal to that of the specified probability.

Parameters:

probability - The desired probability of sampling. Must be within [0.0, 1.0].

Returns:

a new ProbabilitySampler.

Throws:

java.lang.IllegalArgumentException - if probability is out of range

shouldSample

public final boolean shouldSample(@Nullable
                                  SpanContext parentContext,
                                  @Nullable
                                  java.lang.Boolean hasRemoteParent,
                                  TraceId traceId,
                                  SpanId spanId,
                                  java.lang.String name,
                                  @Nullable
                                  java.util.List<Span> parentLinks)

Description copied from class: Sampler

Called during Span creation to make a sampling decision.

Specified by:

shouldSample in class Sampler

Parameters:

parentContext - the parent span's SpanContext. null if this is a root span.

hasRemoteParent - true if the parent Span is remote. null if this is a root span.

traceId - the TraceId for the new Span. This will be identical to that in the parentContext, unless this is a root span.

spanId - the SpanId for the new Span.

name - the name of the new Span.

parentLinks - the parentLinks associated with the new Span.

Returns:

true if the Span is sampled.

getDescription

public final java.lang.String getDescription()

Description copied from class: Sampler

Returns the description of this Sampler. This may be displayed on debug pages or in the logs.

Example: "ProbabilitySampler{0.000100}"

Specified by:

getDescription in class Sampler

Returns:

the description of this Sampler.