MetricUtils.php

Go to the documentation of this file.

<?php
declare( strict_types=1 );
 
namespace Wikimedia\Metrics;
 
use Wikimedia\Metrics\Exceptions\InvalidConfigurationException;
use Wikimedia\Metrics\Exceptions\InvalidLabelsException;
 
class MetricUtils {
 
    private const RE_VALID_NAME_AND_LABEL_NAME = '/^[a-zA-Z_][a-zA-Z0-9_]*$/';
 
    protected $prefix;
 
    protected $extension;
 
    protected $format;
 
    protected $name;
 
    protected $sampleRate;
 
    protected $labels;
 
    protected $samples = [];
 
    protected $typeIndicator;
 
    public function validateConfig( $config ) {
        $this->prefix = $config['prefix'];
        $this->extension = $config['extension'];
        $this->name = $config['name'];
        $this->sampleRate = $config['sampleRate'];
        $this->format = $config['format'];
        if ( !preg_match( self::RE_VALID_NAME_AND_LABEL_NAME, $this->name ) ) {
            throw new InvalidConfigurationException( "Invalid metric name: '" . $this->name . "'" );
        }
        $this->labels = $config['labels'];
        foreach ( $this->labels as $label ) {
            if ( !preg_match( self::RE_VALID_NAME_AND_LABEL_NAME, $label ) ) {
                throw new InvalidConfigurationException( "Invalid label name: '" . $label . "'" );
            }
        }
    }
 
    public function setTypeIndicator( string $typeIndicator ) {
        $this->typeIndicator = $typeIndicator;
    }
 
    public function addSample( Sample $sample ) {
        $this->samples[] = $sample;
    }
 
    public function render(): array {
        $output = [];
        switch ( $this->format ) {
            case 'dogstatsd':
                foreach ( $this->getFilteredSamples() as $sample ) {
                    $output[] = $this->renderDogStatsD( $sample );
                }
                break;
            case 'statsd':
                foreach ( $this->getFilteredSamples() as $sample ) {
                    $output[] = $this->renderStatsD( $sample );
                }
                break;
            default:  // "null"
                break;
        }
        return $output;
    }
 
    public function validateLabels( array $labels ): void {
        if ( count( $this->labels ) !== count( $labels ) ) {
            throw new InvalidLabelsException(
                'Not enough or too many labels provided to metric instance.'
                . 'Configured: ' . json_encode( $this->labels ) . ' Provided: ' . json_encode( $labels )
            );
        }
    }
 
    private function getFilteredSamples() {
        if ( $this->sampleRate === 1.0 ) {
            return $this->samples;
        }
        $output = [];
        $randMax = mt_getrandmax();
        foreach ( $this->samples as $sample ) {
            if ( mt_rand() / $randMax < $this->sampleRate ) {
                $output[] = $sample;
            }
        }
        return $output;
    }
 
    private function renderStatsD( Sample $sample ): string {
        $stat = implode( '.',
            array_merge( [ $this->prefix, $this->extension, $this->name ], $sample->getLabels() )
        );
        $value = ':' . $sample->getValue();
        $type = '|' . $this->typeIndicator;
        $sampleRate = $this->sampleRate !== 1.0 ? '|@' . $this->sampleRate : '';
 
        return $stat . $value . $type . $sampleRate;
    }
 
    private function renderDogStatsD( Sample $sample ): string {
        $stat = implode( '.', [ $this->prefix, $this->extension, $this->name ] );
        $sampleLabels = $sample->getLabels();
        $labels = [];
        foreach ( $this->labels as $i => $label ) {
            $labels[] = $label . ':' . $sampleLabels[$i];
        }
        $value = ':' . $sample->getValue();
        $type = '|' . $this->typeIndicator;
        $sampleRate = $this->sampleRate !== 1.0 ? '|@' . $this->sampleRate : '';
        $tags = $labels === [] ? '' : '|#' . implode( ',', $labels );
        return $stat . $value . $type . $sampleRate . $tags;
    }
 
}