1 files changed, 70 insertions, 0 deletions
diff --git a/vendor/open-telemetry/sdk/Trace/Sampler/TraceIdRatioBasedSampler.php b/vendor/open-telemetry/sdk/Trace/Sampler/TraceIdRatioBasedSampler.php
new file mode 100644
index 000000000..c11a90d5d
--- /dev/null
+++ b/vendor/open-telemetry/sdk/Trace/Sampler/TraceIdRatioBasedSampler.php
@@ -0,0 +1,70 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\SDK\Trace\Sampler;
+
+use InvalidArgumentException;
+use OpenTelemetry\Context\ContextInterface;
+use OpenTelemetry\SDK\Common\Attribute\AttributesInterface;
+use OpenTelemetry\SDK\Trace\SamplerInterface;
+use OpenTelemetry\SDK\Trace\SamplingResult;
+use OpenTelemetry\SDK\Trace\Span;
+
+/**
+ * This implementation of the SamplerInterface records with given probability.
+ * Example:
+ * ```
+ * use OpenTelemetry\API\Trace\TraceIdRatioBasedSampler;
+ * $sampler = new TraceIdRatioBasedSampler(0.01);
+ * ```
+ */
+class TraceIdRatioBasedSampler implements SamplerInterface
+{
+    private float $probability;
+
+    /**
+     * TraceIdRatioBasedSampler constructor.
+     * @param float $probability Probability float value between 0.0 and 1.0.
+     */
+    public function __construct(float $probability)
+    {
+        if ($probability < 0.0 || $probability > 1.0) {
+            throw new InvalidArgumentException('probability should be be between 0.0 and 1.0.');
+        }
+        $this->probability = $probability;
+    }
+
+    /**
+     * Returns `SamplingResult` based on probability. Respects the parent `SampleFlag`
+     * {@inheritdoc}
+     */
+    public function shouldSample(
+        ContextInterface $parentContext,
+        string $traceId,
+        string $spanName,
+        int $spanKind,
+        AttributesInterface $attributes,
+        array $links
+    ): SamplingResult {
+        // TODO: Add config to adjust which spans get sampled (only default from specification is implemented)
+        $parentSpan = Span::fromContext($parentContext);
+        $parentSpanContext = $parentSpan->getContext();
+        $traceState = $parentSpanContext->getTraceState();
+
+        /**
+         * Since php can only store up to 63 bit positive integers
+         */
+        $traceIdLimit = (1 << 60) - 1;
+        $lowerOrderBytes = hexdec(substr($traceId, strlen($traceId) - 15, 15));
+        $traceIdCondition = $lowerOrderBytes < round($this->probability * $traceIdLimit);
+        $decision = $traceIdCondition ? SamplingResult::RECORD_AND_SAMPLE : SamplingResult::DROP;
+
+        return new SamplingResult($decision, [], $traceState);
+    }
+
+    public function getDescription(): string
+    {
+        return sprintf('%s{%.6F}', 'TraceIdRatioBasedSampler', $this->probability);
+    }
+}