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

This PR was merged into the 4.4 branch.

Discussion
----------

[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
-------

a10fc4da5d [DI] fix preloading script generation

Author: fabpot

Container.php

@@ -11,6 +11,8 @@
 
 namespace Symfony\Component\DependencyInjection;
 
+use Symfony\Component\DependencyInjection\Argument\RewindableGenerator;
+use Symfony\Component\DependencyInjection\Argument\ServiceLocator as ArgumentServiceLocator;
 use Symfony\Component\DependencyInjection\Exception\EnvNotFoundException;
 use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
 use Symfony\Component\DependencyInjection\Exception\ParameterCircularReferenceException;
@@ -22,6 +24,10 @@
 use Symfony\Component\DependencyInjection\ParameterBag\ParameterBagInterface;
 use Symfony\Contracts\Service\ResetInterface;
 
+// Help opcache.preload discover always-needed symbols
+class_exists(RewindableGenerator::class);
+class_exists(ArgumentServiceLocator::class);
+
 /**
  * Container is a dependency injection container.
  *

Dumper/PhpDumper.php

@@ -81,6 +81,7 @@ class PhpDumper extends Dumper
     private $inlinedRequires = [];
     private $circularReferences = [];
     private $singleUsePrivateIds = [];
+    private $preload = [];
     private $addThrow = false;
     private $addGetService = false;
     private $locatedIds = [];
@@ -142,6 +143,7 @@ public function dump(array $options = [])
             'hot_path_tag' => 'container.hot_path',
             'inline_factories_parameter' => 'container.dumper.inline_factories',
             'inline_class_loader_parameter' => 'container.dumper.inline_class_loader',
+            'preload_classes' => [],
             'service_locator_tag' => 'container.service_locator',
             'build_time' => time(),
         ], $options);
@@ -226,8 +228,12 @@ public function dump(array $options = [])
 
         $proxyClasses = $this->inlineFactories ? $this->generateProxyClasses() : null;
 
+        if ($options['preload_classes']) {
+            $this->preload = array_combine($options['preload_classes'], $options['preload_classes']);
+        }
+
         $code =
-            $this->startClass($options['class'], $baseClass, $preload).
+            $this->startClass($options['class'], $baseClass).
             $this->addServices($services).
             $this->addDeprecatedAliases().
             $this->addDefaultParametersMethod()
@@ -302,7 +308,7 @@ public function dump(array $options = [])
             $id = hash('crc32', $hash.$time);
             $this->asFiles = false;
 
-            if ($preload && null !== $autoloadFile = $this->getAutoloadFile()) {
+            if ($this->preload && null !== $autoloadFile = $this->getAutoloadFile()) {
                 $autoloadFile = substr($this->export($autoloadFile), 2, -1);
 
                 $code[$options['class'].'.preload.php'] = <<<EOF
@@ -320,8 +326,13 @@ public function dump(array $options = [])
 
 EOF;
 
-                foreach ($preload as $class) {
-                    $code[$options['class'].'.preload.php'] .= sprintf("\$classes[] = '%s';\n", $class);
+                foreach ($this->preload as $class) {
+                    if (!$class || false !== strpos($class, '$')) {
+                        continue;
+                    }
+                    if (!(class_exists($class, false) || interface_exists($class, false) || trait_exists($class, false)) || (new \ReflectionClass($class))->isUserDefined()) {
+                        $code[$options['class'].'.preload.php'] .= sprintf("\$classes[] = '%s';\n", $class);
+                    }
                 }
 
                 $code[$options['class'].'.preload.php'] .= <<<'EOF'
@@ -367,6 +378,7 @@ public function dump(array $options = [])
         $this->circularReferences = [];
         $this->locatedIds = [];
         $this->exportedVariables = [];
+        $this->preload = [];
 
         $unusedEnvs = [];
         foreach ($this->container->getEnvCounters() as $env => $use) {
@@ -542,8 +554,10 @@ private function addServiceInclude(string $cId, Definition $definition): string
         if ($this->inlineRequires && (!$this->isHotPath($definition) || $this->getProxyDumper()->isProxyCandidate($definition))) {
             $lineage = [];
             foreach ($this->inlinedDefinitions as $def) {
-                if (!$def->isDeprecated() && \is_string($class = \is_array($factory = $def->getFactory()) && \is_string($factory[0]) ? $factory[0] : $def->getClass())) {
-                    $this->collectLineage($class, $lineage);
+                if (!$def->isDeprecated()) {
+                    foreach ($this->getClasses($def) as $class) {
+                        $this->collectLineage($class, $lineage);
+                    }
                 }
             }
 
@@ -552,9 +566,10 @@ private function addServiceInclude(string $cId, Definition $definition): string
                     && ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE !== $behavior
                     && $this->container->has($id)
                     && $this->isTrivialInstance($def = $this->container->findDefinition($id))
-                    && \is_string($class = \is_array($factory = $def->getFactory()) && \is_string($factory[0]) ? $factory[0] : $def->getClass())
                 ) {
-                    $this->collectLineage($class, $lineage);
+                    foreach ($this->getClasses($def) as $class) {
+                        $this->collectLineage($class, $lineage);
+                    }
                 }
             }
 
@@ -804,6 +819,12 @@ protected function {$methodName}($lazyInitialization)
 
             if ($definition->isDeprecated()) {
                 $code .= sprintf("        @trigger_error(%s, E_USER_DEPRECATED);\n\n", $this->export($definition->getDeprecationMessage($id)));
+            } else {
+                foreach ($this->inlinedDefinitions as $def) {
+                    foreach ($this->getClasses($def) as $class) {
+                        $this->preload[$class] = $class;
+                    }
+                }
             }
 
             if ($this->getProxyDumper()->isProxyCandidate($definition)) {
@@ -960,7 +981,15 @@ private function addServices(array &$services = null): string
         $definitions = $this->container->getDefinitions();
         ksort($definitions);
         foreach ($definitions as $id => $definition) {
-            $services[$id] = $definition->isSynthetic() ? null : $this->addService($id, $definition);
+            if (!$definition->isSynthetic()) {
+                $services[$id] = $this->addService($id, $definition);
+            } else {
+                $services[$id] = null;
+
+                foreach ($this->getClasses($definition) as $class) {
+                    $this->preload[$class] = $class;
+                }
+            }
         }
 
         foreach ($definitions as $id => $definition) {
@@ -1061,7 +1090,7 @@ private function addNewInstance(Definition $definition, string $return = '', str
         return $return.sprintf('new %s(%s)', $this->dumpLiteralClass($this->dumpValue($class)), implode(', ', $arguments)).$tail;
     }
 
-    private function startClass(string $class, string $baseClass, ?array &$preload): string
+    private function startClass(string $class, string $baseClass): string
     {
         $namespaceLine = !$this->asFiles && $this->namespace ? "\nnamespace {$this->namespace};\n" : '';
 
@@ -1124,7 +1153,7 @@ public function __construct()
         $code .= $this->addMethodMap();
         $code .= $this->asFiles && !$this->inlineFactories ? $this->addFileMap() : '';
         $code .= $this->addAliases();
-        $code .= $this->addInlineRequires($preload);
+        $code .= $this->addInlineRequires();
         $code .= <<<EOF
     }
 
@@ -1324,7 +1353,7 @@ protected function {$methodNameAlias}()
         return $code;
     }
 
-    private function addInlineRequires(?array &$preload): string
+    private function addInlineRequires(): string
     {
         if (!$this->hotPathTag || !$this->inlineRequires) {
             return '';
@@ -1342,8 +1371,7 @@ private function addInlineRequires(?array &$preload): string
             $inlinedDefinitions = $this->getDefinitionsFromArguments([$definition]);
 
             foreach ($inlinedDefinitions as $def) {
-                if (\is_string($class = \is_array($factory = $def->getFactory()) && \is_string($factory[0]) ? $factory[0] : $def->getClass())) {
-                    $preload[$class] = $class;
+                foreach ($this->getClasses($def) as $class) {
                     $this->collectLineage($class, $lineage);
                 }
             }
@@ -2065,4 +2093,29 @@ private function getAutoloadFile(): ?string
 
         return null;
     }
+
+    private function getClasses(Definition $definition): array
+    {
+        $classes = [];
+
+        while ($definition instanceof Definition) {
+            $classes[] = trim($definition->getClass(), '\\');
+            $factory = $definition->getFactory();
+
+            if (!\is_array($factory)) {
+                $factory = [$factory];
+            }
+
+            if (\is_string($factory[0])) {
+                if (false !== $i = strrpos($factory[0], '::')) {
+                    $factory[0] = substr($factory[0], 0, $i);
+                }
+                $classes[] = trim($factory[0], '\\');
+            }
+
+            $definition = $factory[0];
+        }
+
+        return array_filter($classes);
+    }
 }

Tests/Fixtures/php/services9_as_files.txt

@@ -531,6 +531,24 @@ class ProjectServiceContainer extends Container
     }
 }
 
+    [ProjectServiceContainer.preload.php] => <?php
+%A
+
+$classes = [];
+$classes[] = 'Bar\FooClass';
+$classes[] = 'Baz';
+$classes[] = 'ConfClass';
+$classes[] = 'Bar';
+$classes[] = 'BazClass';
+$classes[] = 'Foo';
+$classes[] = 'LazyContext';
+$classes[] = 'FooBarBaz';
+$classes[] = 'FactoryClass';
+$classes[] = 'Request';
+$classes[] = 'Symfony\Component\DependencyInjection\ContainerInterface';
+
+%A
+
     [ProjectServiceContainer.php] => <?php
 
 // This file has been auto-generated by the Symfony Dependency Injection Component for internal use.

Tests/Fixtures/php/services9_inlined_factories.txt

@@ -536,6 +536,16 @@ class ProjectServiceContainer extends Container
 
 $classes = [];
 $classes[] = 'Bar\FooClass';
+$classes[] = 'Baz';
+$classes[] = 'ConfClass';
+$classes[] = 'Bar';
+$classes[] = 'BazClass';
+$classes[] = 'Foo';
+$classes[] = 'LazyContext';
+$classes[] = 'FooBarBaz';
+$classes[] = 'FactoryClass';
+$classes[] = 'Request';
+$classes[] = 'Symfony\Component\DependencyInjection\ContainerInterface';
 
 %A
 

Tests/Fixtures/php/services9_lazy_inlined_factories.txt

@@ -165,6 +165,16 @@ class FooClass_%s extends \Bar\FooClass implements \ProxyManager\Proxy\VirtualPr
 %A
 }
 
+    [ProjectServiceContainer.preload.php] => <?php
+%A
+
+$classes = [];
+$classes[] = 'Bar\FooClass';
+$classes[] = 'Bar\FooLazyClass';
+$classes[] = 'Symfony\Component\DependencyInjection\ContainerInterface';
+
+%A
+
     [ProjectServiceContainer.php] => <?php
 
 // This file has been auto-generated by the Symfony Dependency Injection Component for internal use.

Tests/Fixtures/php/services_non_shared_lazy_as_files.txt

@@ -83,6 +83,15 @@ class ProjectServiceContainer extends Container
     }
 }
 
+    [ProjectServiceContainer.preload.php] => <?php
+%A
+
+$classes = [];
+$classes[] = 'Bar\FooLazyClass';
+$classes[] = 'Symfony\Component\DependencyInjection\ContainerInterface';
+
+%A
+
     [ProjectServiceContainer.php] => <?php
 
 // This file has been auto-generated by the Symfony Dependency Injection Component for internal use.