includes/libs/SamplingStatsdClient.php

   1 <?php
   2 /**
   3  * Copyright 2015
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22
  23 use Liuggio\StatsdClient\StatsdClient;
  24 use Liuggio\StatsdClient\Entity\StatsdData;
  25 use Liuggio\StatsdClient\Entity\StatsdDataInterface;
  26
  27 /**
  28  * A statsd client that applies the sampling rate to the data items before sending them.
  29  *
  30  * @since 1.26
  31  */
  32 class SamplingStatsdClient extends StatsdClient {
  33         /**
  34          * Sets sampling rate for all items in $data.
  35          * The sample rate specified in a StatsdData entity overrides the sample rate specified here.
  36          *
  37          * {@inheritDoc}
  38          */
  39         public function appendSampleRate( $data, $sampleRate = 1 ) {
  40                 if ( $sampleRate < 1 ) {
  41                         array_walk( $data, function( $item ) use ( $sampleRate ) {
  42                                 /** @var $item StatsdData */
  43                                 if ( $item->getSampleRate() === 1 ) {
  44                                         $item->setSampleRate( $sampleRate );
  45                                 }
  46                         } );
  47                 }
  48
  49                 return $data;
  50         }
  51
  52         /*
  53          * Send the metrics over UDP
  54          * Sample the metrics according to their sample rate and send the remaining ones.
  55          *
  56          * @param StatsdDataInterface|StatsdDataInterface[] $data message(s) to sent
  57          *        strings are not allowed here as sampleData requires a StatsdDataInterface
  58          * @param int $sampleRate
  59          *
  60          * @return integer the data sent in bytes
  61          */
  62         public function send( $data, $sampleRate = 1 ) {
  63                 if ( !is_array( $data ) ) {
  64                         $data = array( $data );
  65                 }
  66                 if ( !$data ) {
  67                         return;
  68                 }
  69                 foreach ( $data as $item ) {
  70                         if ( !( $item instanceof StatsdDataInterface ) ) {
  71                                 throw new InvalidArgumentException(
  72                                         'SamplingStatsdClient does not accept stringified messages' );
  73                         }
  74                 }
  75
  76                 // add sampling
  77                 if ( $sampleRate < 1 ) {
  78                         $data = $this->appendSampleRate( $data, $sampleRate );
  79                 }
  80                 $data = $this->sampleData( $data );
  81
  82                 $data = array_map( 'strval', $data );
  83
  84                 // reduce number of packets
  85                 if ( $this->getReducePacket() ) {
  86                         $data = $this->reduceCount( $data );
  87                 }
  88
  89                 // failures in any of this should be silently ignored if ..
  90                 $written = 0;
  91                 try {
  92                         $fp = $this->getSender()->open();
  93                         if ( !$fp ) {
  94                                 return;
  95                         }
  96                         foreach ( $data as $message ) {
  97                                 $written += $this->getSender()->write( $fp, $message );
  98                         }
  99                         $this->getSender()->close( $fp );
 100                 } catch ( Exception $e ) {
 101                         $this->throwException( $e );
 102                 }
 103
 104                 return $written;
 105         }
 106
 107         /**
 108          * Throw away some of the data according to the sample rate.
 109          * @param StatsdDataInterface[] $data
 110          * @return StatsdDataInterface[]
 111          * @throws LogicException
 112          */
 113         protected function sampleData( $data ) {
 114                 $newData = array();
 115                 $mt_rand_max = mt_getrandmax();
 116                 foreach ( $data as $item ) {
 117                         $samplingRate = $item->getSampleRate();
 118                         if ( $samplingRate <= 0.0 || $samplingRate > 1.0 ) {
 119                                 throw new LogicException( 'Sampling rate shall be within ]0, 1]' );
 120                         }
 121                         if (
 122                                 $samplingRate === 1 ||
 123                                 ( mt_rand() / $mt_rand_max <= $samplingRate )
 124                         ) {
 125                                 $newData[] = $item;
 126                         }
 127                 }
 128                 return $newData;
 129         }
 130
 131         /**
 132          * {@inheritDoc}
 133          */
 134         protected function throwException( Exception $exception ) {
 135                 if ( !$this->getFailSilently() ) {
 136                         throw $exception;
 137                 }
 138         }
 139 }