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ParentBasedSampler implements Sampler

Read onlyYes

FinalYes

Sampler that respects the parent span's sampling decision.

This sampler ensures sampling consistency across a trace:

If the parent was sampled, this span is sampled
If the parent was not sampled, this span is not sampled
For root spans (no parent), delegates to the configured root sampler

This is the recommended sampler for most production deployments as it ensures complete traces while maintaining sampling decisions made upstream.

Example usage:

$sampler = new ParentBasedSampler(
    new TraceIdRatioBasedSampler(0.01), // 1% for root spans
);
$result = $sampler->shouldSample($span);

Interfaces

Sampler: Interface for sampling decisions.

Methods

__construct() : mixed
__toString() : string: Get a string representation of this sampler for debugging.
shouldSample() : SamplingResult: Determine if a span should be sampled.

__construct()


    public
                    __construct(Sampler $rootSampler[, null|Sampler $remoteParentSampled = null ][, null|Sampler $remoteParentNotSampled = null ][, null|Sampler $localParentSampled = null ][, null|Sampler $localParentNotSampled = null ]) : mixed

Parameters

$rootSampler : Sampler: Sampler to use for root spans (no parent)
$remoteParentSampled : null|Sampler = null: Sampler for remote sampled parents (default: AlwaysOnSampler)
$remoteParentNotSampled : null|Sampler = null: Sampler for remote non-sampled parents (default: AlwaysOffSampler)
$localParentSampled : null|Sampler = null: Sampler for local sampled parents (default: AlwaysOnSampler)
$localParentNotSampled : null|Sampler = null: Sampler for local non-sampled parents (default: AlwaysOffSampler)

__toString()

Get a string representation of this sampler for debugging.


    public
                    __toString() : string

Examples:

"AlwaysOnSampler"
"TraceIdRatioBasedSampler{0.001}"
"ParentBased{root=AlwaysOnSampler}"

Return values

string

shouldSample()

Determine if a span should be sampled.


    public
                    shouldSample(Span $span) : SamplingResult

Parameters

$span : Span: The span to evaluate for sampling

Return values

SamplingResult —

The sampling decision