AsynchronousInstruments.php

<?php

declare (strict_types=1);
namespace OpenTelemetry\SDK\Metrics;

use ArrayAccess;
use OpenTelemetry\API\Metrics\ObservableCallbackInterface;
use function OpenTelemetry\SDK\Common\Util\closure;
use function OpenTelemetry\SDK\Common\Util\weaken;
use OpenTelemetry\SDK\Metrics\MetricRegistry\MetricWriterInterface;

/**
 * @internal
 */
final class AsynchronousInstruments {
    
    /**
     * @param ArrayAccess<object, ObservableCallbackDestructor> $destructors
     * @param non-empty-list<Instrument> $instruments
     */
    public static function observe(MetricWriterInterface $writer, ArrayAccess $destructors, callable $callback, array $instruments, ReferenceCounterInterface $referenceCounter) : ObservableCallbackInterface {
        $target = null;
        $callback = weaken(closure($callback), $target);
        $callbackId = $writer->registerCallback($callback, ...$instruments);
        $referenceCounter->acquire();
        $destructor = null;
        if ($target) {
            $destructor = $destructors[$target] ??= new ObservableCallbackDestructor($destructors, $writer);
            $destructor->callbackIds[$callbackId] = $referenceCounter;
        }
        return new ObservableCallback($writer, $referenceCounter, $callbackId, $destructor, $target);
    }

}