71 lines
2.3 KiB
PHP
71 lines
2.3 KiB
PHP
<?php
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declare(strict_types=1);
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namespace OpenTelemetry\SDK\Trace\Sampler;
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use InvalidArgumentException;
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use OpenTelemetry\Context\ContextInterface;
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use OpenTelemetry\SDK\Common\Attribute\AttributesInterface;
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use OpenTelemetry\SDK\Trace\SamplerInterface;
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use OpenTelemetry\SDK\Trace\SamplingResult;
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use OpenTelemetry\SDK\Trace\Span;
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/**
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* This implementation of the SamplerInterface records with given probability.
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* Example:
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* ```
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* use OpenTelemetry\API\Trace\TraceIdRatioBasedSampler;
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* $sampler = new TraceIdRatioBasedSampler(0.01);
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* ```
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*/
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class TraceIdRatioBasedSampler implements SamplerInterface
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{
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private float $probability;
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/**
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* TraceIdRatioBasedSampler constructor.
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* @param float $probability Probability float value between 0.0 and 1.0.
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*/
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public function __construct(float $probability)
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{
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if ($probability < 0.0 || $probability > 1.0) {
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throw new InvalidArgumentException('probability should be be between 0.0 and 1.0.');
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}
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$this->probability = $probability;
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}
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/**
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* Returns `SamplingResult` based on probability. Respects the parent `SampleFlag`
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* {@inheritdoc}
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*/
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public function shouldSample(
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ContextInterface $parentContext,
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string $traceId,
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string $spanName,
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int $spanKind,
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AttributesInterface $attributes,
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array $links
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): SamplingResult {
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// TODO: Add config to adjust which spans get sampled (only default from specification is implemented)
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$parentSpan = Span::fromContext($parentContext);
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$parentSpanContext = $parentSpan->getContext();
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$traceState = $parentSpanContext->getTraceState();
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/**
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* Since php can only store up to 63 bit positive integers
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*/
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$traceIdLimit = (1 << 60) - 1;
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$lowerOrderBytes = hexdec(substr($traceId, strlen($traceId) - 15, 15));
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$traceIdCondition = $lowerOrderBytes < round($this->probability * $traceIdLimit);
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$decision = $traceIdCondition ? SamplingResult::RECORD_AND_SAMPLE : SamplingResult::DROP;
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return new SamplingResult($decision, [], $traceState);
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}
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public function getDescription(): string
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{
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return sprintf('%s{%.6F}', 'TraceIdRatioBasedSampler', $this->probability);
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}
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}
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