SamplingStatsdClient.php

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<?php
use Liuggio\StatsdClient\StatsdClient;
use Liuggio\StatsdClient\Entity\StatsdData;
use Liuggio\StatsdClient\Entity\StatsdDataInterface;

class SamplingStatsdClient extends StatsdClient {
    protected $samplingRates = [];

    public function setSamplingRates( array $samplingRates ) {
        $this->samplingRates = $samplingRates;
    }

    public function appendSampleRate( $data, $sampleRate = 1 ) {
        $samplingRates = $this->samplingRates;
        if ( !$samplingRates && $sampleRate !== 1 ) {
            $samplingRates = [ '*' => $sampleRate ];
        }
        if ( $samplingRates ) {
            array_walk( $data, function( $item ) use ( $samplingRates ) {
                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 integer 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;
    }

    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;
    }

    protected function throwException( Exception $exception ) {
        if ( !$this->getFailSilently() ) {
            throw $exception;
        }
    }
}