StatsdFormatter.php

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<?php
declare( strict_types=1 );
 
namespace Wikimedia\Stats\Formatters;
 
use Wikimedia\Stats\Metrics\MetricInterface;
 
class StatsdFormatter implements FormatterInterface {
    public function getFormattedSamples( string $prefix, MetricInterface $metric ): array {
        $output = [];
 
        // append component to prefix if set
        if ( $metric->getComponent() !== '' ) {
            $prefix .= ".{$metric->getComponent()}";
        }
 
        // Metrics used in HistogramMetrics are not compatible with StatsD
        if ( $metric->isHistogram() ) {
            return [];
        }
 
        foreach ( $metric->getSamples() as $sample ) {
            // dot-separate prefix, component, name, and label values `prefix.component.name.value1.value2`
            $stat = implode( '.', [ $prefix, $metric->getName(), ...$sample->getLabelValues() ] );
 
            // merge value with separator `:42`
            $value = ':' . $sample->getValue();
 
            // merge type indicator with separator `|c`
            $type = '|' . $metric->getTypeIndicator();
 
            // blank string if samplerate is 1.0, otherwise add samplerate indicator `|@0.5`
            $sampleRate = $metric->getSampleRate() !== 1.0 ? '|@' . $metric->getSampleRate() : '';
 
            // combine and append to output `prefix.component.name.value1.value2:42|c|@0.5`
            $output[] = $stat . $value . $type . $sampleRate;
        }
        return $output;
    }
}