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<?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\StatsdClient;
use Liuggio\StatsdClient\Entity\StatsdData;
use Liuggio\StatsdClient\Entity\StatsdDataInterface;
/**
* A statsd client that applies the sampling rate to the data items before sending them.
*
* @since 1.26
*/
class SamplingStatsdClient extends StatsdClient {
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, 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;
}
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;
}
foreach ( $data as $message ) {
$written += $this->getSender()->write( $fp, $message );
}
$this->getSender()->close( $fp );
} catch ( Exception $e ) {
$this->throwException( $e );
}
return $written;
}
/**
* Throw away some of the data according to the sample rate.
* @param StatsdDataInterface[] $data
* @return StatsdDataInterface[]
* @throws LogicException
*/
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;
}
/**
* @inheritDoc
*/
protected function throwException( Exception $exception ) {
if ( !$this->getFailSilently() ) {
throw $exception;
}
}
}
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