UDPEmitter.php

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<?php
declare( strict_types=1 );
 
namespace Wikimedia\Stats\Emitters;
 
use InvalidArgumentException;
use UDPTransport;
use Wikimedia\Stats\Formatters\FormatterInterface;
use Wikimedia\Stats\Metrics\NullMetric;
use Wikimedia\Stats\StatsCache;
use Wikimedia\Stats\StatsUtils;
 
class UDPEmitter implements EmitterInterface {
 
    private string $prefix;
 
    private StatsCache $cache;
 
    private FormatterInterface $formatter;
 
    private ?UDPTransport $transport;
 
    private int $payloadSize;
 
    public function __construct( string $prefix, StatsCache $cache, FormatterInterface $formatter, ?string $target ) {
        $this->prefix = $this->normalizePrefix( $prefix );
        $this->cache = $cache;
        $this->formatter = $formatter;
        $this->transport = $target ? UDPTransport::newFromString( $target ) : null;
        $this->payloadSize = UDPTransport::MAX_PAYLOAD_SIZE;
    }
 
    public function withPayloadSize( int $payloadSize ): UDPEmitter {
        $this->payloadSize = $payloadSize;
        return $this;
    }
 
    public function withTransport( UDPTransport $transport ): UDPEmitter {
        $this->transport = $transport;
        return $this;
    }
 
    private function normalizePrefix( string $prefix ): string {
        if ( $prefix === '' ) {
            throw new InvalidArgumentException( 'UDPEmitter: Prefix cannot be empty.' );
        }
        return StatsUtils::normalizeString( $prefix );
    }
 
    private function render(): array {
        $output = [];
        foreach ( $this->cache->getAllMetrics() as $metric ) {
            // Skip NullMetric instances.
            if ( get_class( $metric ) === NullMetric::class ) {
                continue;
            }
            foreach ( $this->formatter->getFormattedSamples( $this->prefix, $metric ) as $formatted ) {
                $output[] = $formatted;
            }
        }
        return $output;
    }
 
    private function batch( array $samples, int $payloadSize ): void {
        $payload = '';
        foreach ( $samples as $sample ) {
            if ( strlen( $payload ) + strlen( $sample ) + 1 < $payloadSize ) {
                $payload .= $sample . "\n";
            } else {
                // Send this payload and make a new one
                $this->transport->emit( $payload );
                $payload = '';
            }
        }
        // Send what is left in the payload
        if ( strlen( $payload ) > 0 ) {
            $this->transport->emit( $payload );
        }
    }
 
    public function send(): void {
        $this->batch( $this->render(), $this->payloadSize );
    }
}