<?php
# src/EventSubscriber/StopWorkerOnSigquitSignalSubscriber.php

namespace App\EventSubscriber;

use Psr\Log\LoggerInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\Messenger\Event\WorkerStartedEvent;

/**
 * Listens to SIGQUIT signal in order to shut down the Messenger worker gracefully,
 * since the PHP-FPM Docker images use SIGQUIT instead of SIGTERM to signal process termination.
 *
 * @see https://github.com/symfony/symfony/issues/43866
 * @see https://github.com/docker-library/php/blob/8007237246d31766d78fb25a4590d289cac545ca/8.1/alpine3.16/fpm/Dockerfile#L251-L253
 */
class StopWorkerOnSigquitSignalSubscriber implements EventSubscriberInterface
{
    public function __construct(
        private readonly LoggerInterface $logger,
    ) {
    }

    public function onWorkerStarted(WorkerStartedEvent $event): void
    {
        pcntl_signal(\SIGQUIT, function () use ($event) {
            $this->logger?->info('Received SIGQUIT signal.', [
                'transport_names' => $event->getWorker()->getMetadata()->getTransportNames(),
            ]);

            $event->getWorker()->stop();
        });
    }

    public static function getSubscribedEvents(): array
    {
        if (!\function_exists('pcntl_signal')) {
            return [];
        }

        return [
            WorkerStartedEvent::class => ['onWorkerStarted', 100],
        ];
    }
}