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Litarnus wants to merge 7 commits into from
+509 −142
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Transaction sampler #2118

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8c35756
feat(scopes): add new scopes
Litarnus Jun 10, 2026
ecfa38b
feat(scopes): add clients to scopes
Litarnus Jun 10, 2026
8b22eac
fix
Litarnus Jun 10, 2026
914e278
Merge remote-tracking branch 'origin/scopes-client' into scopes-client
Litarnus Jun 11, 2026
5615917
feat(scopes): extract transaction sampling logic into TransactionSampler
Litarnus Jun 11, 2026
f28ee44
make TransactionSampler static
Litarnus Jun 11, 2026
0ab8198
Revert "make TransactionSampler static"
Litarnus Jun 11, 2026
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144 changes: 2 additions & 142 deletions src/State/Hub.php
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Original file line number Diff line number Diff line change
Expand Up @@ -16,10 +16,10 @@
use Sentry\MonitorConfig;
use Sentry\NoOpClient;
use Sentry\Severity;
use Sentry\Tracing\SamplingContext;
use Sentry\Tracing\Span;
use Sentry\Tracing\Transaction;
use Sentry\Tracing\TransactionContext;
use Sentry\Tracing\TransactionSampler;

/**
* This class is a basic implementation of the {@see HubInterface} interface.
Expand Down Expand Up @@ -237,103 +237,8 @@ public function getIntegration(string $className): ?IntegrationInterface
public function startTransaction(TransactionContext $context, array $customSamplingContext = []): Transaction
{
$transaction = new Transaction($context, $this);
$options = $this->getClient()->getOptions();
$logger = $options->getLoggerOrNullLogger();

if (!$options->isTracingEnabled()) {
$transaction->setSampled(false);

$logger->warning(\sprintf('Transaction [%s] was started but tracing is not enabled.', (string) $transaction->getTraceId()), ['context' => $context]);

return $transaction;
}

$samplingContext = SamplingContext::getDefault($context);
$samplingContext->setAdditionalContext($customSamplingContext);

$sampleSource = 'context';
$sampleRand = $context->getMetadata()->getSampleRand();

if ($transaction->getSampled() === null) {
$tracesSampler = $options->getTracesSampler();

if ($tracesSampler !== null) {
$sampleRate = $tracesSampler($samplingContext);
$sampleSource = 'config:traces_sampler';
} else {
$parentSampleRate = $context->getMetadata()->getParentSamplingRate();
if ($parentSampleRate !== null) {
$sampleRate = $parentSampleRate;
$sampleSource = 'parent:sample_rate';
} else {
$sampleRate = $this->getSampleRate(
$samplingContext->getParentSampled(),
$options->getTracesSampleRate() ?? 0
);
$sampleSource = $samplingContext->getParentSampled() !== null ? 'parent:sampling_decision' : 'config:traces_sample_rate';
}
}

if (!$this->isValidSampleRate($sampleRate)) {
$transaction->setSampled(false);

$logger->warning(\sprintf('Transaction [%s] was started but not sampled because sample rate (decided by %s) is invalid.', (string) $transaction->getTraceId(), $sampleSource), ['context' => $context]);

return $transaction;
}

$transaction->getMetadata()->setSamplingRate($sampleRate);

// Always overwrite the sample_rate in the DSC
$dynamicSamplingContext = $context->getMetadata()->getDynamicSamplingContext();
if ($dynamicSamplingContext !== null) {
$dynamicSamplingContext->set('sample_rate', (string) $sampleRate, true);
}

if ($sampleRate === 0.0) {
$transaction->setSampled(false);

$logger->info(\sprintf('Transaction [%s] was started but not sampled because sample rate (decided by %s) is %s.', (string) $transaction->getTraceId(), $sampleSource, $sampleRate), ['context' => $context]);

return $transaction;
}

$transaction->setSampled($sampleRand < $sampleRate);
}

if (!$transaction->getSampled()) {
$logger->info(\sprintf('Transaction [%s] was started but not sampled, decided by %s.', (string) $transaction->getTraceId(), $sampleSource), ['context' => $context]);

return $transaction;
}

$logger->info(\sprintf('Transaction [%s] was started and sampled, decided by %s.', (string) $transaction->getTraceId(), $sampleSource), ['context' => $context]);

$transaction->initSpanRecorder();

$profilesSampleSource = 'config:profiles_sample_rate';
$profilesSampler = $options->getProfilesSampler();

if ($profilesSampler !== null) {
$profilesSampleRate = $profilesSampler($samplingContext);
$profilesSampleSource = 'config:profiles_sampler';
} else {
$profilesSampleRate = $options->getProfilesSampleRate();
}

if ($profilesSampleRate === null) {
$logger->info(\sprintf('Transaction [%s] is not profiling because neither `profiles_sample_rate` nor `profiles_sampler` option is set.', (string) $transaction->getTraceId()));
} elseif (!$this->isValidSampleRate($profilesSampleRate)) {
$logger->warning(\sprintf('Transaction [%s] is not profiling because profile sample rate (decided by %s) is invalid.', (string) $transaction->getTraceId(), $profilesSampleSource));
} elseif ($this->sample($profilesSampleRate)) {
$logger->info(\sprintf('Transaction [%s] started profiling because it was sampled.', (string) $transaction->getTraceId()));

$transaction->initProfiler()->start();
} else {
$logger->info(\sprintf('Transaction [%s] is not profiling because it was not sampled.', (string) $transaction->getTraceId()));
}

return $transaction;
return (new TransactionSampler($this->getClient()->getOptions()))->startTransaction($transaction, $context, $customSamplingContext);
}

/**
Expand Down Expand Up @@ -377,49 +282,4 @@ private function getStackTop(): Layer
{
return $this->stack[\count($this->stack) - 1];
}

private function getSampleRate(?bool $hasParentBeenSampled, float $fallbackSampleRate): float
{
if ($hasParentBeenSampled === true) {
return 1.0;
}

if ($hasParentBeenSampled === false) {
return 0.0;
}

return $fallbackSampleRate;
}

/**
* @param mixed $sampleRate
*/
private function sample($sampleRate): bool
{
if ($sampleRate === 0.0 || $sampleRate === null) {
return false;
}

if ($sampleRate === 1.0) {
return true;
}

return mt_rand(0, mt_getrandmax() - 1) / mt_getrandmax() < $sampleRate;
}

/**
* @param mixed $sampleRate
*/
private function isValidSampleRate($sampleRate): bool
{
if (!\is_float($sampleRate) && !\is_int($sampleRate)) {
return false;
}

if ($sampleRate < 0 || $sampleRate > 1) {
return false;
}

return true;
}
}
177 changes: 177 additions & 0 deletions src/Tracing/TransactionSampler.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,177 @@
<?php

declare(strict_types=1);

namespace Sentry\Tracing;

use Sentry\Options;

/**
* Applies tracing and profiling sampling decisions to transactions.
*
* @internal
*/
final class TransactionSampler
{
/**
* @var Options
*/
private $options;

public function __construct(Options $options)
{
$this->options = $options;
}

/**
* @param array<string, mixed> $customSamplingContext Additional context that will be passed to the {@see SamplingContext}
*/
public function startTransaction(Transaction $transaction, TransactionContext $context, array $customSamplingContext = []): Transaction
{
$logger = $this->options->getLoggerOrNullLogger();

if (!$this->options->isTracingEnabled()) {
$transaction->setSampled(false);

$logger->warning(\sprintf('Transaction [%s] was started but tracing is not enabled.', (string) $transaction->getTraceId()), ['context' => $context]);

return $transaction;
}

$samplingContext = SamplingContext::getDefault($context);
$samplingContext->setAdditionalContext($customSamplingContext);

$sampleSource = 'context';
$sampleRand = $context->getMetadata()->getSampleRand() ?? 0.0;

if ($transaction->getSampled() === null) {
$tracesSampler = $this->options->getTracesSampler();

if ($tracesSampler !== null) {
$sampleRate = $tracesSampler($samplingContext);
$sampleSource = 'config:traces_sampler';
} else {
$parentSampleRate = $context->getMetadata()->getParentSamplingRate();
if ($parentSampleRate !== null) {
$sampleRate = $parentSampleRate;
$sampleSource = 'parent:sample_rate';
} else {
$sampleRate = $this->getSampleRate(
$samplingContext->getParentSampled(),
$this->options->getTracesSampleRate() ?? 0
);
$sampleSource = $samplingContext->getParentSampled() !== null ? 'parent:sampling_decision' : 'config:traces_sample_rate';
}
}

if (!$this->isValidSampleRate($sampleRate)) {
$transaction->setSampled(false);

$logger->warning(\sprintf('Transaction [%s] was started but not sampled because sample rate (decided by %s) is invalid.', (string) $transaction->getTraceId(), $sampleSource), ['context' => $context]);

return $transaction;
}

$transaction->getMetadata()->setSamplingRate($sampleRate);

// Always overwrite the sample_rate in the DSC
$dynamicSamplingContext = $context->getMetadata()->getDynamicSamplingContext();
if ($dynamicSamplingContext !== null) {
$dynamicSamplingContext->set('sample_rate', (string) $sampleRate, true);
}

if ($sampleRate === 0.0) {
$transaction->setSampled(false);

$logger->info(\sprintf('Transaction [%s] was started but not sampled because sample rate (decided by %s) is %s.', (string) $transaction->getTraceId(), $sampleSource, $sampleRate), ['context' => $context]);

return $transaction;
}

$transaction->setSampled($sampleRand < $sampleRate);
}

if (!$transaction->getSampled()) {
$logger->info(\sprintf('Transaction [%s] was started but not sampled, decided by %s.', (string) $transaction->getTraceId(), $sampleSource), ['context' => $context]);

return $transaction;
}

$logger->info(\sprintf('Transaction [%s] was started and sampled, decided by %s.', (string) $transaction->getTraceId(), $sampleSource), ['context' => $context]);

$transaction->initSpanRecorder();

$profilesSampleSource = 'config:profiles_sample_rate';
$profilesSampler = $this->options->getProfilesSampler();

if ($profilesSampler !== null) {
$profilesSampleRate = $profilesSampler($samplingContext);
$profilesSampleSource = 'config:profiles_sampler';
} else {
$profilesSampleRate = $this->options->getProfilesSampleRate();
}

if ($profilesSampleRate === null) {
$logger->info(\sprintf('Transaction [%s] is not profiling because neither `profiles_sample_rate` nor `profiles_sampler` option is set.', (string) $transaction->getTraceId()));
} elseif (!$this->isValidSampleRate($profilesSampleRate)) {
$logger->warning(\sprintf('Transaction [%s] is not profiling because profile sample rate (decided by %s) is invalid.', (string) $transaction->getTraceId(), $profilesSampleSource));
} elseif ($this->sampleRate($profilesSampleRate)) {
$logger->info(\sprintf('Transaction [%s] started profiling because it was sampled.', (string) $transaction->getTraceId()));

$transaction->initProfiler()->start();
} else {
$logger->info(\sprintf('Transaction [%s] is not profiling because it was not sampled.', (string) $transaction->getTraceId()));
}

return $transaction;
}

private function getSampleRate(?bool $hasParentBeenSampled, float $fallbackSampleRate): float
{
if ($hasParentBeenSampled === true) {
return 1.0;
}

if ($hasParentBeenSampled === false) {
return 0.0;
}

return $fallbackSampleRate;
}

/**
* @param mixed $sampleRate
*/
private function sampleRate($sampleRate): bool
{
if (!\is_float($sampleRate) && !\is_int($sampleRate)) {
return false;
}

if ($sampleRate === 0.0) {
return false;
}

if ($sampleRate === 1.0) {
return true;
}

return mt_rand(0, mt_getrandmax() - 1) / mt_getrandmax() < (float) $sampleRate;
}

/**
* @param mixed $sampleRate
*/
private function isValidSampleRate($sampleRate): bool
{
if (!\is_float($sampleRate) && !\is_int($sampleRate)) {
return false;
}

if ($sampleRate < 0 || $sampleRate > 1) {
return false;
}

return true;
}
}
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