CompositePropagator.php

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<?php
namespace Wikimedia\Telemetry;
 
use Wikimedia\Assert\Assert;
use Wikimedia\Assert\ParameterAssertionException;
 
class CompositePropagator implements ContextPropagatorInterface {
    private $propagators;
 
    public function __construct( array $propagators ) {
        Assert::parameter(
            count( $propagators ) > 0,
            '$propagators',
            'must not be empty'
        );
        $this->propagators = $propagators;
    }
 
    public function extract( array $carrier ): ?SpanContext {
        foreach ( $this->propagators as $propagator ) {
            $context = $propagator->extract( $carrier );
            if ( $context !== null ) {
                return $context;
            }
        }
        return null;
    }
 
    public function inject( ?SpanContext $context, array $carrier ): array {
        foreach ( $this->propagators as $propagator ) {
            $carrier = $propagator->inject( $context, $carrier );
        }
        return $carrier;
    }
}