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          * Sample the metrics according to their sample rate and send the remaining ones.
  54          *
  55          * {@inheritDoc}
  56          */
  57         public function send( $data, $sampleRate = 1 ) {
  58                 if ( !is_array( $data ) ) {
  59                         $data = array( $data );
  60                 }
  61                 if ( !$data ) {
  62                         return;
  63                 }
  64                 foreach ( $data as $item ) {
  65                         if ( !( $item instanceof StatsdDataInterface ) ) {
  66                                 throw new InvalidArgumentException(
  67                                         'SamplingStatsdClient does not accept stringified messages' );
  68                         }
  69                 }
  70
  71                 // add sampling
  72                 if ( $sampleRate < 1 ) {
  73                         $data = $this->appendSampleRate( $data, $sampleRate );
  74                 }
  75                 $data = $this->sampleData( $data );
  76
  77                 $messages = array_map( 'strval', $data );
  78
  79                 // reduce number of packets
  80                 if ( $this->getReducePacket() ) {
  81                         $data = $this->reduceCount( $data );
  82                 }
  83                 //failures in any of this should be silently ignored if ..
  84                 $written = 0;
  85                 try {
  86                         $fp = $this->getSender()->open();
  87                         if ( !$fp ) {
  88                                 return;
  89                         }
  90                         foreach ( $messages as $message ) {
  91                                 $written += $this->getSender()->write( $fp, $message );
  92                         }
  93                         $this->getSender()->close( $fp );
  94                 } catch ( Exception $e ) {
  95                         $this->throwException( $e );
  96                 }
  97
  98                 return $written;
  99         }
 100
 101         /**
 102          * Throw away some of the data according to the sample rate.
 103          * @param StatsdDataInterface[] $data
 104          * @return array
 105          * @throws LogicException
 106          */
 107         protected function sampleData( $data ) {
 108                 $newData = array();
 109                 $mt_rand_max = mt_getrandmax();
 110                 foreach ( $data as $item ) {
 111                         $samplingRate = $item->getSampleRate();
 112                         if ( $samplingRate <= 0.0 || $samplingRate > 1.0 ) {
 113                                 throw new LogicException( 'Sampling rate shall be within ]0, 1]' );
 114                         }
 115                         if (
 116                                 $samplingRate === 1 ||
 117                                 ( mt_rand() / $mt_rand_max <= $samplingRate )
 118                         ) {
 119                                 $newData[] = $item;
 120                         }
 121                 }
 122                 return $newData;
 123         }
 124
 125         /**
 126          * {@inheritDoc}
 127          */
 128         protected function throwException( Exception $exception ) {
 129                 if ( !$this->getFailSilently() ) {
 130                         throw $exception;
 131                 }
 132         }
 133 }