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StatsFactory.php
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StatsFactory.php
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<?php
/**
* @license GPL-2.0-or-later
* @file
*/
declare( strict_types=1 );
namespace Wikimedia\Stats;
use InvalidArgumentException;
use Psr\Log\LoggerInterface;
use Psr\Log\NullLogger;
use TypeError;
use Wikimedia\Stats\Emitters\EmitterInterface;
use Wikimedia\Stats\Emitters\NullEmitter;
use Wikimedia\Stats\Exceptions\InvalidConfigurationException;
use Wikimedia\Stats\Metrics\BaseMetric;
use Wikimedia\Stats\Metrics\CounterMetric;
use Wikimedia\Stats\Metrics\GaugeMetric;
use Wikimedia\Stats\Metrics\HistogramMetric;
use Wikimedia\Stats\Metrics\NullMetric;
use Wikimedia\Stats\Metrics\TimingMetric;
/**
* This is the primary interface for validating metrics definitions,
* caching defined metrics, and returning metric instances from cache
* if previously defined.
*
* @author Cole White
* @since 1.41
*/
class StatsFactory {
private string $component = '';
private StatsCache $cache;
private EmitterInterface $emitter;
private LoggerInterface $logger;
private ?IBufferingStatsdDataFactory $statsdDataFactory = null;
/**
* StatsFactory builds, configures, and caches Metrics.
*/
public function __construct(
StatsCache $cache,
EmitterInterface $emitter,
LoggerInterface $logger,
?string $component = null
) {
if ( $component !== null ) {
$this->component = StatsUtils::normalizeString( $component );
}
$this->cache = $cache;
$this->emitter = $emitter;
$this->logger = $logger;
}
/**
* Returns a new StatsFactory instance prefixed by component.
*
* @param string $component
* @return StatsFactory
*/
public function withComponent( string $component ): StatsFactory {
$statsFactory = new StatsFactory( $this->cache, $this->emitter, $this->logger, $component );
return $statsFactory->withStatsdDataFactory( $this->statsdDataFactory );
}
/**
* This function existed to support the Graphite->Prometheus transition and is no longer needed.
* @deprecated since 1.45, see: https://www.mediawiki.org/wiki/Manual:Stats
*/
public function withStatsdDataFactory( ?IBufferingStatsdDataFactory $statsdDataFactory ): StatsFactory {
// TODO: remove this and all other copyToStatsdAt() usage and implementation
//$this->statsdDataFactory = $statsdDataFactory;
return $this;
}
/**
* Makes a new CounterMetric or fetches one from cache.
*
* If a collision occurs, returns a NullMetric to suppress exceptions.
*
* @param string $name
* @return CounterMetric|NullMetric
*/
public function getCounter( string $name ) {
return $this->getMetric( $name, CounterMetric::class );
}
/**
* Makes a new GaugeMetric or fetches one from cache.
*
* If a collision occurs, returns a NullMetric to suppress exceptions.
*
* @param string $name
* @return GaugeMetric|NullMetric
*/
public function getGauge( string $name ) {
return $this->getMetric( $name, GaugeMetric::class );
}
/**
* Makes a new TimingMetric or fetches one from cache.
*
* The timing data should be in the range [5ms, 60s]; use
* ::getHistogram() if you need a different range.
*
* This range limitation is a consequence of the recommended
* setup with prometheus/statsd_exporter (as dogstatsd target)
* and Prometheus (as time series database), with
* `statsd_exporter::histogram_buckets` set to a 5ms-60s range.
*
* If a collision occurs, returns a NullMetric to suppress exceptions.
*
* @param string $name
* @return TimingMetric|NullMetric
*/
public function getTiming( string $name ) {
return $this->getMetric( $name, TimingMetric::class );
}
/**
* Makes a new HistogramMetric from a list of buckets.
*
* Beware: this is for storing non-time data in histograms, like byte
* sizes, or time data outside of the range [5ms, 60s].
*
* Avoid changing the bucket list once a metric has been
* deployed. When bucket list changes are unavoidable, change the metric
* name and handle the transition in PromQL.
*
* @param string $name
* @param array<int|float> $buckets
* @return HistogramMetric
*/
public function getHistogram( string $name, array $buckets ) {
$name = StatsUtils::normalizeString( $name );
StatsUtils::validateMetricName( $name );
return new HistogramMetric( $this, $name, $buckets );
}
/**
* Send all buffered metrics to the target and destroy the cache.
*/
public function flush(): void {
$cacheSize = $this->getCacheCount();
// Optimization: To encourage long-running scripts to frequently yield
// and flush (T181385), it is important that we don't do any work here
// unless new stats were added to the cache since the last flush.
if ( $cacheSize > 0 ) {
$this->getCounter( 'stats_buffered_total' )
->copyToStatsdAt( 'stats.statslib.buffered' )
->incrementBy( $cacheSize );
$this->emitter->send();
$this->cache->clear();
}
}
/**
* Get a total of the number of samples in cache.
*/
private function getCacheCount(): int {
$accumulator = 0;
foreach ( $this->cache->getAllMetrics() as $metric ) {
$accumulator += $metric->getSampleCount();
}
return $accumulator;
}
/**
* Fetches a metric from cache or makes a new metric.
*
* If a metric name collision occurs, returns a NullMetric to suppress runtime exceptions.
*
* @param string $name
* @param class-string $className
* @return CounterMetric|TimingMetric|GaugeMetric|NullMetric
*/
private function getMetric( string $name, string $className ) {
$name = StatsUtils::normalizeString( $name );
StatsUtils::validateMetricName( $name );
try {
$metric = $this->cache->get( $this->component, $name, $className );
} catch ( TypeError | InvalidArgumentException | InvalidConfigurationException $ex ) {
// Log the condition and give the caller something that will absorb calls.
trigger_error( "Stats: {$name}: {$ex->getMessage()}", E_USER_WARNING );
return new NullMetric;
}
if ( $metric === null ) {
$baseMetric = new BaseMetric( $this->component, $name );
$metric = new $className( $baseMetric->withStatsdDataFactory( $this->statsdDataFactory ), $this->logger );
$this->cache->set( $this->component, $name, $metric );
}
return $metric->fresh();
}
/**
* Create a no-op StatsFactory.
*
* Use this as the default in a service that takes an optional StatsFactory,
* or as null implementation in PHPUnit tests, where we don't need to send
* output to an actual network service.
*
* @since 1.42
* @return self
*/
public static function newNull(): self {
return new self( new StatsCache(), new NullEmitter(), new NullLogger() );
}
/**
* Create a stats helper for use in PHPUnit tests.
*
* Example:
*
* ```php
* $statsHelper = StatsFactory::newUnitTestingHelper();
*
* $x = new MySubject( $statsHelper->getStatsFactory() );
* $x->execute();
*
* // Assert full (emitting more is unexpected)
* $this->assertSame(
* [
* 'example_executions_total:1|c|#foo:bar'
* ],
* $statsHelper->consumeAllFormatted()
* );
*
* // Assert partially (at least this should be emitted)
* $this->assertSame( 1, $statsHelper->count( 'example_executions_total{foo="bar"}' ) );
* ```
*
* @since 1.44
* @return UnitTestingHelper
*/
public static function newUnitTestingHelper() {
return new UnitTestingHelper();
}
}

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