--- /dev/null
+<?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 {
+ /**
+ * 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 ) {
+ if ( $sampleRate < 1 ) {
+ array_walk( $data, function( $item ) use ( $sampleRate ) {
+ /** @var $item StatsdData */
+ if ( $item->getSampleRate() === 1 ) {
+ $item->setSampleRate( $sampleRate );
+ }
+ });
+ }
+
+ return $data;
+ }
+
+ /**
+ * Sample the metrics according to their sample rate and send the remaining ones.
+ *
+ * {@inheritDoc}
+ */
+ public function send( $data, $sampleRate = 1 ) {
+ if ( !is_array( $data ) ) {
+ $data = array( $data );
+ }
+ if ( !$data ) {
+ return;
+ }
+ foreach ( $data as $item ) {
+ if ( !( $item instanceof StatsdDataInterface ) ) {
+ throw new InvalidArgumentException(
+ 'SamplingStatsdClient does not accept stringified messages' );
+ }
+ }
+
+ // add sampling
+ if ( $sampleRate < 1 ) {
+ $data = $this->appendSampleRate( $data, $sampleRate );
+ }
+ $data = $this->sampleData( $data );
+
+ $messages = 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 ( $messages 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 array
+ * @throws LogicException
+ */
+ protected function sampleData( $data ) {
+ $newData = array();
+ $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;
+ }
+ }
+}
--- /dev/null
+<?php
+
+use Liuggio\StatsdClient\Entity\StatsdData;
+
+class SamplingStatsdClientTest extends PHPUnit_Framework_TestCase {
+ /**
+ * @dataProvider samplingDataProvider
+ */
+ public function testSampling( $data, $sampleRate, $seed, $expectWrite ) {
+ $sender = $this->getMock( 'Liuggio\StatsdClient\Sender\SenderInterface' );
+ $sender->expects( $this->any() )->method( 'open' )->will( $this->returnValue( true ) );
+ if ( $expectWrite ) {
+ $sender->expects( $this->once() )->method( 'write' )
+ ->with( $this->anything(), $this->equalTo( $data ) );
+ } else {
+ $sender->expects( $this->never() )->method( 'write' );
+ }
+ mt_srand( $seed );
+ $client = new SamplingStatsdClient( $sender );
+ $client->send( $data, $sampleRate );
+ }
+
+ public function samplingDataProvider() {
+ $unsampled = new StatsdData();
+ $unsampled->setKey( 'foo' );
+ $unsampled->setValue( 1 );
+
+ $sampled = new StatsdData();
+ $sampled->setKey( 'foo' );
+ $sampled->setValue( 1 );
+ $sampled->setSampleRate( '0.1' );
+
+ return array(
+ // $data, $sampleRate, $seed, $expectWrite
+ array( $unsampled, 1, 0 /*0.44*/, $unsampled ),
+ array( $sampled, 1, 0 /*0.44*/, null ),
+ array( $sampled, 1, 4 /*0.03*/, $sampled ),
+ array( $unsampled, 0.1, 4 /*0.03*/, $sampled ),
+ array( $sampled, 0.5, 0 /*0.44*/, null ),
+ array( $sampled, 0.5, 4 /*0.03*/, $sampled ),
+ );
+ }
+}