com.newrelic.agent.tracing.samplers

Class ProbabilityBasedSampler

java.lang.Object

com.newrelic.agent.tracing.samplers.ProbabilityBasedSampler

All Implemented Interfaces:

Sampler

public class ProbabilityBasedSampler
extends java.lang.Object
implements Sampler

Probability based sampler that utilizes the hex encoded trace id string as a deterministic source of randomness.
The sampler is seeded with a float value that represents the sampling probability target. The threshold (T) is calculated via:

     (1 - samplingProbability) * 2^56
 

When the sampler is presented with the hex encoded trace id, a deterministic random value (R) is derived by extracting the last 7 bytes (14 characters) of the id and converting into a long value.
If this value is greater than or equal to T, we return a priority of 2.0 which will mark this trace for sampling.

Constructor Summary

Constructors

Constructor and Description
ProbabilityBasedSampler(SamplerConfig samplerConfig) Construct a new ProbabilityBasedSampler with the desired probability supplied as a float value in the SamplerConfig instance.

Method Summary

Modifier and Type	Method and Description
float	calculatePriority(Transaction tx) Calculate the priority of a trace.
long	getRejectionThreshold() Retrieve the current rejection threshold value
java.lang.String	getType() Get the description/name of this Sampler

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.newrelic.agent.tracing.samplers.Sampler

isValidTraceRatio, traceIdFromTransaction

Constructor Detail

ProbabilityBasedSampler

public ProbabilityBasedSampler(SamplerConfig samplerConfig)

Construct a new ProbabilityBasedSampler with the desired probability supplied as a float value in the SamplerConfig instance.

Parameters:

samplerConfig - the agent's finalized sampler configuration

Method Detail

calculatePriority

public float calculatePriority(Transaction tx)

Description copied from interface: Sampler

Calculate the priority of a trace. The value returned must be in the range of 0.0f - 2.0f.

Specified by:

calculatePriority in interface Sampler

Parameters:

tx - the transaction to calculate the priority for

Returns:

a priority value between 0.0f - 2.0f, inclusive

getType

public java.lang.String getType()

Description copied from interface: Sampler

Get the description/name of this Sampler

Specified by:

getType in interface Sampler

Returns:

the current Sampler's description

getRejectionThreshold

public long getRejectionThreshold()

Retrieve the current rejection threshold value

Returns:

the calculated rejection threshold