Sulu\Bundle\HttpCacheBundle\DependencyInjection\Compiler\HandlerPass::process PHP Method

    public function process(ContainerBuilder $container)
    {
        if (!$container->hasDefinition('sulu_http_cache.handler.aggregate')) {
            return;
        }
        $aggregateHandler = $container->getDefinition('sulu_http_cache.handler.aggregate');
        $taggedHandlers = $container->findTaggedServiceIds('sulu_http_cache.handler');
        $knownHandlers = [];
        foreach ($taggedHandlers as $id => $attributes) {
            if (!isset($attributes[0]['alias'])) {
                throw new \InvalidArgumentException(sprintf('No "alias" specified for cache handler service ID: "%s"', $id));
            }
            $alias = $attributes[0]['alias'];
            if (isset($knownHandlers[$alias])) {
                throw new \InvalidArgumentException(sprintf('Cache handler with alias "%s" has already been registered', $alias));
            }
            $this->validateHandler($container, $id);
            $knownHandlers[$alias] = $id;
        }
        $handlers = [];
        $configuredAliases = $container->getParameter('sulu_http_cache.handler.aggregate.handlers');
        foreach ($configuredAliases as $configuredAlias) {
            if (isset($knownHandlers[$configuredAlias])) {
                $handlers[] = new Reference($knownHandlers[$configuredAlias]);
            }
        }
        if (count($handlers) !== count($configuredAliases)) {
            throw new \InvalidArgumentException(sprintf('Could not find the following cache handlers: "%s"', implode('", "', array_diff($configuredAliases, array_keys($handlers)))));
        }
        $aggregateHandler->replaceArgument(0, array_values($handlers));
    }