Package zipkin2.collector

Class CollectorSampler

java.lang.Object

zipkin2.collector.CollectorSampler

public abstract class CollectorSampler
extends Object

CollectorSampler decides if a particular trace should be "sampled", i.e. recorded in permanent storage. This involves a consistent decision based on the span's trace ID with one notable exception: Debug spans are always stored.

Implementation

Accepts a percentage of trace ids by comparing their absolute value against a potentially dynamic boundary. eg isSampled == abs(traceId) <= boundary

While idempotent, this implementation's sample rate won't exactly match the input rate because trace ids are not perfectly distributed across 64bits. For example, tests have shown an error rate of 3% when 100K trace ids are random.

Field Summary

Fields

Modifier and Type	Field	Description
static CollectorSampler	ALWAYS_SAMPLE

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	CollectorSampler()

Method Summary

Modifier and Type	Method	Description
protected abstract long	boundary()
static CollectorSampler	create(float rate)	Returns a trace ID sampler with the indicated rate.
boolean	isSampled(String hexTraceId, boolean debug)	Returns true if spans with this trace ID should be recorded to storage.
String	toString()

Methods inherited from class java.lang.Object

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

Field Details

ALWAYS_SAMPLE

public static final CollectorSampler ALWAYS_SAMPLE

Constructor Details

CollectorSampler

protected CollectorSampler()

Method Details

create

public static CollectorSampler create(float rate)

Returns a trace ID sampler with the indicated rate.

Parameters:

rate - minimum sample rate is 0.0001, or 0.01% of traces

boundary

protected abstract long boundary()

isSampled

public boolean isSampled(String hexTraceId, boolean debug)

Returns true if spans with this trace ID should be recorded to storage.

Zipkin v1 allows storage-layer sampling, which can help prevent spikes in traffic from overloading the system. Debug spans are always stored.

This uses only the lower 64 bits of the trace ID as instrumentation still send mixed trace ID width.

Parameters:

hexTraceId - the lower 64 bits of the span's trace ID are checked against the boundary

debug - when true, always passes sampling

toString

public String toString()

Overrides:

toString in class Object