ConfigCacheInvalidator.php

<?php

namespace Drupal\subpathauto\EventSubscriber;

use Drupal\Core\Cache\CacheTagsInvalidatorInterface;
use Drupal\Core\Config\ConfigCrudEvent;
use Drupal\Core\Config\ConfigEvents;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

/**
 * A subscriber invalidating cache tags when subpathauto config is saved.
 */
class ConfigCacheInvalidator implements EventSubscriberInterface {
    
    /**
     * The cache tags invalidator.
     *
     * @var \Drupal\Core\Cache\CacheTagsInvalidatorInterface
     */
    protected $cacheTagsInvalidator;
    
    /**
     * Constructs a SubPathautoSettingsCacheInvalidator object.
     *
     * @param \Drupal\Core\Cache\CacheTagsInvalidatorInterface $cache_tags_invalidator
     *   The cache tags invalidator.
     */
    public function __construct(CacheTagsInvalidatorInterface $cache_tags_invalidator) {
        $this->cacheTagsInvalidator = $cache_tags_invalidator;
    }
    
    /**
     * Invalidate the 'rendered' cache tag whenever the settings are modified.
     *
     * @param \Drupal\Core\Config\ConfigCrudEvent $event
     *   The Event to process.
     */
    public function onSave(ConfigCrudEvent $event) {
        // Changing the Subpathauto settings means that any cached page might
        // result in a different response, so we need to invalidate them all.
        if ($event->getConfig()
            ->getName() === 'subpathauto.settings') {
            $this->cacheTagsInvalidator
                ->invalidateTags([
                'rendered',
            ]);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public static function getSubscribedEvents() {
        $events[ConfigEvents::SAVE][] = [
            'onSave',
        ];
        return $events;
    }

}