symfony · derrabus · Dec 15, 2019
diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
@@ -88,6 +88,7 @@ public function getConfigTreeBuilder()
                ->scalarNode('error_controller')
                    ->defaultValue('error_controller')
                ->end()
+                ->booleanNode('freeze_kernel_events')->defaultValue(false)->end()
            ->end()
        ;


diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
@@ -69,6 +69,7 @@
 use Symfony\Component\HttpKernel\Controller\ArgumentValueResolverInterface;
 use Symfony\Component\HttpKernel\DataCollector\DataCollectorInterface;
 use Symfony\Component\HttpKernel\DependencyInjection\Extension;
+use Symfony\Component\HttpKernel\KernelEvents;
 use Symfony\Component\Lock\Lock;
 use Symfony\Component\Lock\LockFactory;
 use Symfony\Component\Lock\LockInterface;
@@ -223,6 +224,19 @@ public function load(array $configs, ContainerBuilder $container)
        $container->setParameter('kernel.trusted_hosts', $config['trusted_hosts']);
        $container->setParameter('kernel.default_locale', $config['default_locale']);
        $container->setParameter('kernel.error_controller', $config['error_controller']);
+        $container->setParameter(
+            'event_dispatcher.freeze_events',
+            $config['freeze_kernel_events'] ? [
+                KernelEvents::REQUEST,
+                KernelEvents::EXCEPTION,
+                KernelEvents::VIEW,
+                KernelEvents::CONTROLLER,
+                KernelEvents::CONTROLLER_ARGUMENTS,
+                KernelEvents::RESPONSE,
+                KernelEvents::TERMINATE,
+                KernelEvents::FINISH_REQUEST,
+            ] : []
+        );

        if (!$container->hasParameter('debug.file_link_format')) {
            $links = [

diff --git a/src/Symfony/Bundle/FrameworkBundle/Resources/config/schema/symfony-1.0.xsd b/src/Symfony/Bundle/FrameworkBundle/Resources/config/schema/symfony-1.0.xsd
@@ -41,6 +41,7 @@
        <xsd:attribute name="default-locale" type="xsd:string" />
        <xsd:attribute name="test" type="xsd:boolean" />
        <xsd:attribute name="error-controller" type="xsd:string" />
+        <xsd:attribute name="freeze-kernel-events" type="xsd:boolean" />
    </xsd:complexType>

    <xsd:complexType name="form">

diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/ConfigurationTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/ConfigurationTest.php
@@ -501,6 +501,7 @@ class_exists(SemaphoreStore::class) && SemaphoreStore::isSupported() ? 'semaphor
                'notification_on_failed_messages' => false,
            ],
            'error_controller' => 'error_controller',
+            'freeze_kernel_events' => false,
            'secrets' => [
                'enabled' => true,
                'vault_directory' => '%kernel.project_dir%/config/secrets/%kernel.environment%',

diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/php/freeze_events.php b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/php/freeze_events.php
@@ -0,0 +1,5 @@
+<?php
+
+$container->loadFromExtension('framework', [
+    'freeze_kernel_events' => true,
+]);
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/xml/freeze_events.xml b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/xml/freeze_events.xml
@@ -0,0 +1,10 @@
+<?xml version="1.0" ?>
+
+<container xmlns="http://symfony.com/schema/dic/services"
+           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+           xmlns:framework="http://symfony.com/schema/dic/symfony"
+           xsi:schemaLocation="http://symfony.com/schema/dic/services https://symfony.com/schema/dic/services/services-1.0.xsd
+                        http://symfony.com/schema/dic/symfony https://symfony.com/schema/dic/symfony/symfony-1.0.xsd">
+
+    <framework:config freeze-kernel-events="true" />
+</container>
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/yml/freeze_events.yml b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/yml/freeze_events.yml
@@ -0,0 +1,2 @@
+framework:
+    freeze_kernel_events: true
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/FrameworkExtensionTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/FrameworkExtensionTest.php
@@ -39,6 +39,7 @@
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\HttpClient\ScopingHttpClient;
 use Symfony\Component\HttpKernel\DependencyInjection\LoggerPass;
+use Symfony\Component\HttpKernel\KernelEvents;
 use Symfony\Component\Messenger\Transport\TransportFactory;
 use Symfony\Component\PropertyAccess\PropertyAccessor;
 use Symfony\Component\Serializer\Mapping\Loader\AnnotationLoader;
@@ -1384,6 +1385,32 @@ public function testMailerWithSpecificMessageBus(): void
        $this->assertEquals(new Reference('app.another_bus'), $container->getDefinition('mailer.mailer')->getArgument(1));
    }

+    public function testFreezeKernelEvents(): void
+    {
+        $container = $this->createContainerFromFile('freeze_events');
+
+        $this->assertSame(
+            [
+                KernelEvents::REQUEST,
+                KernelEvents::EXCEPTION,
+                KernelEvents::VIEW,
+                KernelEvents::CONTROLLER,
+                KernelEvents::CONTROLLER_ARGUMENTS,
+                KernelEvents::RESPONSE,
+                KernelEvents::TERMINATE,
+                KernelEvents::FINISH_REQUEST,
+            ],
+            $container->getParameter('event_dispatcher.freeze_events')
+        );
+    }
+
+    public function testDontFreezeKernelEventsByDefault(): void
+    {
+        $container = $this->createContainerFromFile('full');
+
+        $this->assertSame([], $container->getParameter('event_dispatcher.freeze_events'));
+    }
+
    protected function createContainer(array $data = [])
    {
        return new ContainerBuilder(new EnvPlaceholderParameterBag(array_merge([

diff --git a/src/Symfony/Bundle/FrameworkBundle/composer.json b/src/Symfony/Bundle/FrameworkBundle/composer.json
@@ -73,6 +73,7 @@
        "symfony/console": "<4.4",
        "symfony/dotenv": "<4.4",
        "symfony/dom-crawler": "<4.4",
+        "symfony/event-dispatcher": "<5.1",
        "symfony/http-client": "<4.4",
        "symfony/form": "<4.4",
        "symfony/lock": "<4.4",

diff --git a/src/Symfony/Component/EventDispatcher/Debug/TraceableEventDispatcher.php b/src/Symfony/Component/EventDispatcher/Debug/TraceableEventDispatcher.php
@@ -11,13 +11,15 @@

 namespace Symfony\Component\EventDispatcher\Debug;

+use Psr\EventDispatcher\ListenerProviderInterface;
 use Psr\EventDispatcher\StoppableEventInterface;
 use Psr\Log\LoggerInterface;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\RequestStack;
 use Symfony\Component\Stopwatch\Stopwatch;
+use Symfony\Contracts\EventDispatcher\ListenerProviderAwareInterface;
 use Symfony\Contracts\Service\ResetInterface;

 /**
@@ -27,7 +29,7 @@
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
-class TraceableEventDispatcher implements EventDispatcherInterface, ResetInterface
+class TraceableEventDispatcher implements EventDispatcherInterface, ListenerProviderAwareInterface, ResetInterface
 {
    protected $logger;
    protected $stopwatch;
@@ -47,6 +49,10 @@ public function __construct(EventDispatcherInterface $dispatcher, Stopwatch $sto
        $this->wrappedListeners = [];
        $this->orphanedEvents = [];
        $this->requestStack = $requestStack;
+
+        if (!$dispatcher instanceof ListenerProviderAwareInterface) {
+            @trigger_error(sprintf('Implementing %s without %s is deprecated since Symfony 5.1.', EventDispatcherInterface::class, ListenerProviderAwareInterface::class), E_USER_DEPRECATED);
+        }
    }

    /**
@@ -91,6 +97,14 @@ public function removeSubscriber(EventSubscriberInterface $subscriber)
        return $this->dispatcher->removeSubscriber($subscriber);
    }

+    /**
+     * {@inheritdoc}
+     */
+    public function setListenerProvider(string $eventName, ListenerProviderInterface $listenerProvider): void
+    {
+        $this->dispatcher->setListenerProvider($eventName, $listenerProvider);
+    }
+
    /**
     * {@inheritdoc}
     */

diff --git a/src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php b/src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php
@@ -14,11 +14,14 @@
 use Symfony\Component\DependencyInjection\Argument\ServiceClosureArgument;
 use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
 use Symfony\Component\DependencyInjection\Reference;
 use Symfony\Component\EventDispatcher\Event as LegacyEvent;
 use Symfony\Component\EventDispatcher\EventDispatcher;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+use Symfony\Component\EventDispatcher\ListenerProvider\LazyListenerProvider;
+use Symfony\Component\EventDispatcher\ListenerProvider\SimpleListenerProvider;
 use Symfony\Contracts\EventDispatcher\Event;

 /**
@@ -30,16 +33,18 @@ class RegisterListenersPass implements CompilerPassInterface
    protected $listenerTag;
    protected $subscriberTag;
    protected $eventAliasesParameter;
+    protected $freezeEventsParameter;

    private $hotPathEvents = [];
    private $hotPathTagName;

-    public function __construct(string $dispatcherService = 'event_dispatcher', string $listenerTag = 'kernel.event_listener', string $subscriberTag = 'kernel.event_subscriber', string $eventAliasesParameter = 'event_dispatcher.event_aliases')
+    public function __construct(string $dispatcherService = 'event_dispatcher', string $listenerTag = 'kernel.event_listener', string $subscriberTag = 'kernel.event_subscriber', string $eventAliasesParameter = 'event_dispatcher.event_aliases', string $freezeEventsParameter = 'event_dispatcher.freeze_events')
    {
        $this->dispatcherService = $dispatcherService;
        $this->listenerTag = $listenerTag;
        $this->subscriberTag = $subscriberTag;
        $this->eventAliasesParameter = $eventAliasesParameter;
+        $this->freezeEventsParameter = $freezeEventsParameter;
    }

    public function setHotPathEvents(array $hotPathEvents, $tagName = 'container.hot_path')
@@ -64,6 +69,13 @@ public function process(ContainerBuilder $container)
        }
        $definition = $container->findDefinition($this->dispatcherService);

+        $frozenEvents = [];
+        if ($container->hasParameter($this->freezeEventsParameter)) {
+            foreach ($container->getParameter($this->freezeEventsParameter) as $event) {
+                $frozenEvents[$event] = [];
+            }
+        }
+
        foreach ($container->findTaggedServiceIds($this->listenerTag, true) as $id => $events) {
            foreach ($events as $event) {
                $priority = isset($event['priority']) ? $event['priority'] : 0;
@@ -91,7 +103,11 @@ public function process(ContainerBuilder $container)
                    }
                }

-                $definition->addMethodCall('addListener', [$event['event'], [new ServiceClosureArgument(new Reference($id)), $event['method']], $priority]);
+                if (isset($frozenEvents[$event['event']])) {
+                    $frozenEvents[$event['event']][$priority][] = [new Reference($id), $event['method']];
+                } else {
+                    $definition->addMethodCall('addListener', [$event['event'], [new ServiceClosureArgument(new Reference($id)), $event['method']], $priority]);
+                }

                if (isset($this->hotPathEvents[$event['event']])) {
                    $container->getDefinition($id)->addTag($this->hotPathTagName);
@@ -119,8 +135,12 @@ public function process(ContainerBuilder $container)
            ExtractingEventDispatcher::$subscriber = $class;
            $extractingDispatcher->addSubscriber($extractingDispatcher);
            foreach ($extractingDispatcher->listeners as $args) {
-                $args[1] = [new ServiceClosureArgument(new Reference($id)), $args[1]];
-                $definition->addMethodCall('addListener', $args);
+                if (isset($frozenEvents[$args[0]])) {
+                    $frozenEvents[$args[0]][$args[2]][] = [new Reference($id), $args[1]];
+                } else {
+                    $args[1] = [new ServiceClosureArgument(new Reference($id)), $args[1]];
+                    $definition->addMethodCall('addListener', $args);
+                }

                if (isset($this->hotPathEvents[$args[0]])) {
                    $container->getDefinition($id)->addTag($this->hotPathTagName);
@@ -129,6 +149,15 @@ public function process(ContainerBuilder $container)
            $extractingDispatcher->listeners = [];
            ExtractingEventDispatcher::$aliases = [];
        }
+
+        foreach ($frozenEvents as $event => $listeners) {
+            krsort($listeners, SORT_NUMERIC);
+            $providerId = sprintf('__%s.listener_provider.%s', $this->dispatcherService, $event);
+            $container->register($providerId, SimpleListenerProvider::class)
+                ->setArguments([array_merge(...array_values($listeners))]);
+
+            $definition->addMethodCall('setListenerProvider', [$event, new Definition(LazyListenerProvider::class, [new ServiceClosureArgument(new Reference($providerId))])]);
+        }
    }

    private function getEventFromTypeDeclaration(ContainerBuilder $container, string $id, string $method): string

diff --git a/src/Symfony/Component/EventDispatcher/EventDispatcher.php b/src/Symfony/Component/EventDispatcher/EventDispatcher.php
@@ -11,8 +11,11 @@

 namespace Symfony\Component\EventDispatcher;

+use Psr\EventDispatcher\ListenerProviderInterface;
 use Psr\EventDispatcher\StoppableEventInterface;
 use Symfony\Component\EventDispatcher\Debug\WrappedListener;
+use Symfony\Component\EventDispatcher\Exception\RuntimeException;
+use Symfony\Contracts\EventDispatcher\ListenerProviderAwareInterface;

 /**
 * The EventDispatcherInterface is the central point of Symfony's event listener system.
@@ -29,11 +32,15 @@
 * @author Jordan Alliot <jordan.alliot@gmail.com>
 * @author Nicolas Grekas <p@tchwork.com>
 */
-class EventDispatcher implements EventDispatcherInterface
+class EventDispatcher implements EventDispatcherInterface, ListenerProviderAwareInterface
 {
    private $listeners = [];
    private $sorted = [];
    private $optimized;
+    /**
+     * @var ListenerProviderInterface[]
+     */
+    private $listenerProviders = [];

    public function __construct()
    {
@@ -49,7 +56,9 @@ public function dispatch(object $event, string $eventName = null): object
    {
        $eventName = $eventName ?? \get_class($event);

-        if (null !== $this->optimized && null !== $eventName) {
+        if (isset($this->listenerProviders[$eventName])) {
+            $listeners = $this->listenerProviders[$eventName]->getListenersForEvent($event);
+        } elseif (null !== $this->optimized && null !== $eventName) {
            $listeners = $this->optimized[$eventName] ?? (empty($this->listeners[$eventName]) ? [] : $this->optimizeListeners($eventName));
        } else {
            $listeners = $this->getListeners($eventName);
@@ -140,6 +149,10 @@ public function hasListeners(string $eventName = null)
     */
    public function addListener(string $eventName, $listener, int $priority = 0)
    {
+        if (isset($this->listenerProviders[$eventName])) {
+            throw new RuntimeException(sprintf('The "%s" event is frozen. You cannot attache listeners to it.', $eventName));
+        }
+
        $this->listeners[$eventName][$priority][] = $listener;
        unset($this->sorted[$eventName], $this->optimized[$eventName]);
    }
@@ -149,6 +162,10 @@ public function addListener(string $eventName, $listener, int $priority = 0)
     */
    public function removeListener(string $eventName, $listener)
    {
+        if (isset($this->listenerProviders[$eventName])) {
+            throw new RuntimeException(sprintf('The "%s" event is frozen. You cannot remove listeners from it.', $eventName));
+        }
+
        if (empty($this->listeners[$eventName])) {
            return;
        }
@@ -209,6 +226,18 @@ public function removeSubscriber(EventSubscriberInterface $subscriber)
        }
    }

+    /**
+     * {@inheritdoc}
+     */
+    public function setListenerProvider(string $eventName, ListenerProviderInterface $listenerProvider): void
+    {
+        if (isset($this->listeners[$eventName])) {
+            throw new RuntimeException(sprintf('There are already listeners attached to the "%s" event. You cannot set a listener provider for it.', $eventName));
+        }
+
+        $this->listenerProviders[$eventName] = $listenerProvider;
+    }
+
    /**
     * Triggers the listeners of an event.
     *

diff --git a/src/Symfony/Component/EventDispatcher/Exception/ExceptionInterface.php b/src/Symfony/Component/EventDispatcher/Exception/ExceptionInterface.php
@@ -0,0 +1,16 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\EventDispatcher\Exception;
+
+interface ExceptionInterface
+{
+}
diff --git a/src/Symfony/Component/EventDispatcher/Exception/RuntimeException.php b/src/Symfony/Component/EventDispatcher/Exception/RuntimeException.php
@@ -0,0 +1,16 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\EventDispatcher\Exception;
+
+final class RuntimeException extends \RuntimeException implements ExceptionInterface
+{
+}