ConfigCacheTag::onSave

public ConfigCacheTag::onSave(ConfigCrudEvent $event)

public function onSave(ConfigCrudEvent $event) {
  // Changing the site settings may mean a different route is selected for the
  // front page. Additionally a change to the site name or similar must
  // invalidate the render cache since this could be used anywhere.
  if ($event->getConfig()->getName() === 'system.site') {
    $this->cacheTagsInvalidator->invalidateTags(['route_match', 'rendered']);
  }

  // Theme configuration and global theme settings.
  if (in_array($event->getConfig()->getName(), ['system.theme', 'system.theme.global'], TRUE)) {
    $this->cacheTagsInvalidator->invalidateTags(['rendered']);
  }

  // Theme-specific settings, check if this matches a theme settings
  // configuration object, in that case, clear the rendered cache tag.
  foreach (array_keys($this->themeHandler->listInfo()) as $theme_name) {
    if ($theme_name == $event->getConfig()->getName()) {
      $this->cacheTagsInvalidator->invalidateTags(['rendered']);
      break;
    }
  }
}