Flow PHP

Sampler

Interface for sampling decisions.

Samplers determine whether a span should be recorded and/or exported. This allows controlling the volume of telemetry data while maintaining the ability to trace complete transactions.

Following OpenTelemetry, the sampling decision receives the parent Context (carrying the active span and the tracing-suppression bit) alongside the span to be created.

Example usage:

$sampler = new TraceIdRatioBasedSampler(0.1); // 10% sampling

$result = $sampler->shouldSample($context, $span);

if ($result->decision->isRecording()) {
    // Record the span
}

Methods

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

__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(Context $parentContext, Span $span) : SamplingResult

Parameters

$parentContext : Context: The parent context of the span to be created
$span : Span: The span to evaluate for sampling

Return values

SamplingResult —

The sampling decision