wikimedia/mediawiki-core

<?php
/**
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 * @file
 */

declare( strict_types=1 );

namespace Wikimedia\Stats\Metrics;

use InvalidArgumentException;
use Psr\Log\LoggerInterface;
use Wikimedia\Stats\Exceptions\IllegalOperationException;
use Wikimedia\Stats\Sample;

/**
 * Timing Metric Implementation
 *
 * Timing metrics track duration data which can be broken into histograms.
 * They are identified by type "ms".
 *
 * @author Cole White
 * @since 1.38
 */
class TimingMetric implements MetricInterface {

    /**
     * The StatsD protocol type indicator:
     * https://github.com/statsd/statsd/blob/v0.9.0/docs/metric_types.md
     * https://docs.datadoghq.com/developers/dogstatsd/datagram_shell/?tab=metrics
     *
     * @var string
     */
    private const TYPE_INDICATOR = "ms";

    /** @var BaseMetricInterface */
    private BaseMetricInterface $baseMetric;

    /** @var LoggerInterface */
    private LoggerInterface $logger;

    /** @var float|null */
    private ?float $startTime = null;

    /** @inheritDoc */
    public function __construct( $baseMetric, $logger ) {
        $this->baseMetric = $baseMetric;
        $this->logger = $logger;
    }

    /**
     * Starts a timer.
     *
     * @return void
     */
    public function start(): void {
        $this->startTime = hrtime( true );
    }

    /**
     * Stops a running timer.
     *
     * @return void
     */
    public function stop(): void {
        if ( $this->startTime === null ) {
            trigger_error( "Stats: stop() called before start() for metric '{$this->getName()}'", E_USER_WARNING );
            return;
        }
        $value = ( hrtime( true ) - $this->startTime ) * 1e-6; // convert nanoseconds to milliseconds
        $this->observe( $value );
        $this->startTime = null;
    }

    /**
     * Records a previously calculated observation.
     *
     * Expects values in milliseconds.
     *
     * @param float $value milliseconds
     * @return void
     */
    public function observe( float $value ): void {
        foreach ( $this->baseMetric->getStatsdNamespaces() as $namespace ) {
            $this->baseMetric->getStatsdDataFactory()->timing( $namespace, $value );
        }

        try {
            $this->baseMetric->addSample( new Sample( $this->baseMetric->getLabelValues(), $value ) );
        } catch ( IllegalOperationException $ex ) {
            // Log the condition and give the caller something that will absorb calls.
            trigger_error( $ex->getMessage(), E_USER_WARNING );
        }
    }

    /** @inheritDoc */
    public function getName(): string {
        return $this->baseMetric->getName();
    }

    /** @inheritDoc */
    public function getComponent(): string {
        return $this->baseMetric->getComponent();
    }

    /** @inheritDoc */
    public function getTypeIndicator(): string {
        return self::TYPE_INDICATOR;
    }

    /** @inheritDoc */
    public function getSamples(): array {
        return $this->baseMetric->getSamples();
    }

    /** @inheritDoc */
    public function getSampleCount(): int {
        return $this->baseMetric->getSampleCount();
    }

    /** @inheritDoc */
    public function getSampleRate(): float {
        return $this->baseMetric->getSampleRate();
    }

    /** @inheritDoc */
    public function setSampleRate( float $sampleRate ) {
        try {
            $this->baseMetric->setSampleRate( $sampleRate );
        } catch ( IllegalOperationException | InvalidArgumentException $ex ) {
            // Log the condition and give the caller something that will absorb calls.
            trigger_error( $ex->getMessage(), E_USER_WARNING );
            return new NullMetric;
        }
        return $this;
    }

    /** @inheritDoc */
    public function getLabelKeys(): array {
        return $this->baseMetric->getLabelKeys();
    }

    /** @inheritDoc */
    public function setLabel( string $key, string $value ) {
        try {
            $this->baseMetric->addLabel( $key, $value );
        } catch ( IllegalOperationException | InvalidArgumentException $ex ) {
            // Log the condition and give the caller something that will absorb calls.
            trigger_error( $ex->getMessage(), E_USER_WARNING );
            return new NullMetric;
        }
        return $this;
    }

    /** @inheritDoc */
    public function copyToStatsdAt( $statsdNamespaces ) {
        try {
            $this->baseMetric->setStatsdNamespaces( $statsdNamespaces );
        } catch ( InvalidArgumentException $ex ) {
            // Log the condition and give the caller something that will absorb calls.
            trigger_error( $ex->getMessage(), E_USER_WARNING );
            return new NullMetric;
        }
        return $this;
    }

    /** @inheritDoc */
    public function fresh(): TimingMetric {
        $this->baseMetric->clearLabels();
        return $this;
    }
}