bug #36103 [DI] fix preloading script generation (nicolas-grekas)

This PR was merged into the 4.4 branch.

Discussion
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[DI] fix preloading script generation

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

(fabbot failure is a false positive)

On master, we should work on being able to preload more classes (esp. all cache-warmup artifacts).

But for 4.4, this is good enough. Submitted as a bug fix because 1. the current code that deals with preloading kinda-works, but only on "dev" mode... and 2. fixing it provides a nice boost!

Small bench on a hello world:
- before: 380 req/s
- after: 580 req/s

That's +50%!

Pro-tip: adding a few `class_exists()` as done in this PR for the classes that are always used in the implementations (e.g. `new Foo()` in the constructor) will help the preload-script generator to work optimally. Without them, it will discover the symbols to preload only if they're found on methods.

Some of those `class_exists()` are mandatory, in relation to anonymous classes and https://bugs.php.net/79349

Commits
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a10fc4da5d [DI] fix preloading script generation

Author: fabpot

FrameworkBundle.php

@@ -23,6 +23,11 @@
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\TestServiceContainerWeakRefPass;
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\UnusedTagsPass;
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\WorkflowGuardListenerPass;
+use Symfony\Component\Cache\Adapter\ApcuAdapter;
+use Symfony\Component\Cache\Adapter\ArrayAdapter;
+use Symfony\Component\Cache\Adapter\ChainAdapter;
+use Symfony\Component\Cache\Adapter\PhpArrayAdapter;
+use Symfony\Component\Cache\Adapter\PhpFilesAdapter;
 use Symfony\Component\Cache\DependencyInjection\CacheCollectorPass;
 use Symfony\Component\Cache\DependencyInjection\CachePoolClearerPass;
 use Symfony\Component\Cache\DependencyInjection\CachePoolPass;
@@ -32,6 +37,7 @@
 use Symfony\Component\DependencyInjection\Compiler\PassConfig;
 use Symfony\Component\DependencyInjection\Compiler\RegisterReverseContainerPass;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\Dotenv\Dotenv;
 use Symfony\Component\ErrorHandler\ErrorHandler;
 use Symfony\Component\EventDispatcher\DependencyInjection\RegisterListenersPass;
 use Symfony\Component\Form\DependencyInjection\FormPass;
@@ -58,6 +64,19 @@
 use Symfony\Component\Validator\DependencyInjection\AddAutoMappingConfigurationPass;
 use Symfony\Component\Validator\DependencyInjection\AddConstraintValidatorsPass;
 use Symfony\Component\Validator\DependencyInjection\AddValidatorInitializersPass;
+use Symfony\Component\VarExporter\Internal\Hydrator;
+use Symfony\Component\VarExporter\Internal\Registry;
+
+// Help opcache.preload discover always-needed symbols
+class_exists(ApcuAdapter::class);
+class_exists(ArrayAdapter::class);
+class_exists(ChainAdapter::class);
+class_exists(PhpArrayAdapter::class);
+class_exists(PhpFilesAdapter::class);
+class_exists(Dotenv::class);
+class_exists(ErrorHandler::class);
+class_exists(Hydrator::class);
+class_exists(Registry::class);
 
 /**
  * Bundle.

Routing/Router.php

@@ -20,10 +20,15 @@
 use Symfony\Component\DependencyInjection\Exception\ParameterNotFoundException;
 use Symfony\Component\DependencyInjection\Exception\RuntimeException;
 use Symfony\Component\HttpKernel\CacheWarmer\WarmableInterface;
+use Symfony\Component\Routing\Annotation\Route;
 use Symfony\Component\Routing\RequestContext;
 use Symfony\Component\Routing\RouteCollection;
 use Symfony\Component\Routing\Router as BaseRouter;
 
+// Help opcache.preload discover always-needed symbols
+class_exists(RedirectableCompiledUrlMatcher::class);
+class_exists(Route::class);
+
 /**
  * This Router creates the Loader only when the cache is empty.
  *