wikimedia/mediawiki-core

<?php
/**
 * Copyright 2015
 *
 * 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
 */

use Liuggio\StatsdClient\Entity\StatsdData;
use Liuggio\StatsdClient\Entity\StatsdDataInterface;
use Liuggio\StatsdClient\StatsdClient;
use Wikimedia\RequestTimeout\TimeoutException;

/**
 * A statsd client that applies the sampling rate to the data items before sending them.
 *
 * @deprecated since 1.43 No longer used after $wgSamplingStatsdClient was removed.
 * @since 1.26
 */
class SamplingStatsdClient extends StatsdClient {
    /** @var array */
    protected $samplingRates = [];

    /**
     * Sampling rates as an associative array of patterns and rates.
     * Patterns are Unix shell patterns (e.g. 'MediaWiki.api.*').
     * Rates are sampling probabilities (e.g. 0.1 means 1 in 10 events are sampled).
     * @param array $samplingRates
     * @since 1.28
     */
    public function setSamplingRates( array $samplingRates ) {
        $this->samplingRates = $samplingRates;
    }

    /**
     * Sets sampling rate for all items in $data.
     * The sample rate specified in a StatsdData entity overrides the sample rate specified here.
     *
     * @inheritDoc
     */
    public function appendSampleRate( $data, $sampleRate = 1 ) {
        $samplingRates = $this->samplingRates;
        if ( !$samplingRates && $sampleRate !== 1 ) {
            $samplingRates = [ '*' => $sampleRate ];
        }
        if ( $samplingRates ) {
            array_walk( $data, static function ( $item ) use ( $samplingRates ) {
                /** @var StatsdData $item */
                foreach ( $samplingRates as $pattern => $rate ) {
                    if ( fnmatch( $pattern, $item->getKey(), FNM_NOESCAPE ) ) {
                        $item->setSampleRate( $item->getSampleRate() * $rate );
                        break;
                    }
                }
            } );
        }

        return $data;
    }

    /**
     * Send the metrics over UDP
     * Sample the metrics according to their sample rate and send the remaining ones.
     *
     * @param StatsdDataInterface|StatsdDataInterface[] $data message(s) to sent
     *        strings are not allowed here as sampleData requires a StatsdDataInterface
     * @param int $sampleRate
     *
     * @return int the data sent in bytes
     */
    public function send( $data, $sampleRate = 1 ) {
        if ( !is_array( $data ) ) {
            $data = [ $data ];
        }
        if ( !$data ) {
            return 0;
        }
        foreach ( $data as $item ) {
            if ( !( $item instanceof StatsdDataInterface ) ) {
                throw new InvalidArgumentException(
                    'SamplingStatsdClient does not accept stringified messages' );
            }
        }

        // add sampling
        $data = $this->appendSampleRate( $data, $sampleRate );
        $data = $this->sampleData( $data );

        $data = array_map( 'strval', $data );

        // reduce number of packets
        if ( $this->getReducePacket() ) {
            $data = $this->reduceCount( $data );
        }

        // failures in any of this should be silently ignored if ..
        $written = 0;
        try {
            $fp = $this->getSender()->open();
            if ( !$fp ) {
                return 0;
            }
            foreach ( $data as $message ) {
                $written += $this->getSender()->write( $fp, $message );
            }
            $this->getSender()->close( $fp );
        } catch ( TimeoutException $e ) {
            throw $e;
        } catch ( Exception $e ) {
            $this->throwException( $e );
        }

        return $written;
    }

    /**
     * Throw away some of the data according to the sample rate.
     * @param StatsdDataInterface[] $data
     * @return StatsdDataInterface[]
     */
    protected function sampleData( $data ) {
        $newData = [];
        $mt_rand_max = mt_getrandmax();
        foreach ( $data as $item ) {
            $samplingRate = $item->getSampleRate();
            if ( $samplingRate <= 0.0 || $samplingRate > 1.0 ) {
                throw new LogicException( 'Sampling rate shall be within ]0, 1]' );
            }
            if (
                $samplingRate === 1 ||
                ( mt_rand() / $mt_rand_max <= $samplingRate )
            ) {
                $newData[] = $item;
            }
        }
        return $newData;
    }

    /**
     * Ideally this would override parent::throwException(), but that is private,
     * not protected.
     *
     * @param Exception $exception
     */
    private function throwException( Exception $exception ) {
        if ( !$this->getFailSilently() ) {
            throw $exception;
        }
    }
}