bug symfony#30907 [Serializer] Respect ignored attributes in cache key of normalizer (dbu)

This PR was squashed before being merged into the 3.4 branch (closes symfony#30907).

Discussion
----------

[Serializer] Respect ignored attributes in cache key of normalizer

EUFOSSA

| Q             | A
| ------------- | ---
| Branch       | 3.4
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Do not share the attributes cache in object normalizer when using a different setting for the ignoredAttributes setting.

In Symfony 4.2, the setter is deprecated in favor of the ignored_attibutes option in the $context. When merging this up, we will however still need to respect the field as well for BC, the cache key does not look at the default context (apart from the deprecated modifiers, the default context is immutable)

There might be performance regression for some use cases, but also could be a performance improvement when using 'attributes' in the context with lists of objects of the same class.

Commits
-------

926d228 [Serializer] Respect ignored attributes in cache key of normalizer

Author: fabpot

src/Symfony/Component/Serializer/Normalizer/AbstractNormalizer.php

@@ -397,7 +397,7 @@ protected function denormalizeParameter(\ReflectionClass $class, \ReflectionPara
                 }
                 $parameterClass = $parameter->getClass()->getName();
 
-                return $this->serializer->denormalize($parameterData, $parameterClass, $format, $this->createChildContext($context, $parameterName));
+                return $this->serializer->denormalize($parameterData, $parameterClass, $format, $this->createChildContext($context, $parameterName, $format));
             }
 
             return $parameterData;
@@ -407,14 +407,15 @@ protected function denormalizeParameter(\ReflectionClass $class, \ReflectionPara
     }
 
     /**
-     * @param array  $parentContext
-     * @param string $attribute
+     * @param array       $parentContext
+     * @param string      $attribute     Attribute name
+     * @param string|null $format
      *
      * @return array
      *
      * @internal
      */
-    protected function createChildContext(array $parentContext, $attribute)
+    protected function createChildContext(array $parentContext, $attribute/*, string $format = null */)
     {
         if (isset($parentContext[self::ATTRIBUTES][$attribute])) {
             $parentContext[self::ATTRIBUTES] = $parentContext[self::ATTRIBUTES][$attribute];

src/Symfony/Component/Serializer/Normalizer/AbstractObjectNormalizer.php

@@ -94,7 +94,7 @@ public function normalize($object, $format = null, array $context = [])
                 throw new LogicException(sprintf('Cannot normalize attribute "%s" because the injected serializer is not a normalizer', $attribute));
             }
 
-            $data = $this->updateData($data, $attribute, $this->serializer->normalize($attributeValue, $format, $this->createChildContext($context, $attribute)));
+            $data = $this->updateData($data, $attribute, $this->serializer->normalize($attributeValue, $format, $this->createChildContext($context, $attribute, $format)));
         }
 
         return $data;
@@ -128,15 +128,13 @@ protected function getAttributes($object, $format = null, array $context)
             return $allowedAttributes;
         }
 
-        if (isset($context['attributes'])) {
-            return $this->extractAttributes($object, $format, $context);
-        }
+        $attributes = $this->extractAttributes($object, $format, $context);
 
-        if (isset($this->attributesCache[$class])) {
-            return $this->attributesCache[$class];
+        if ($context['cache_key']) {
+            $this->attributesCache[$key] = $attributes;
         }
 
-        return $this->attributesCache[$class] = $this->extractAttributes($object, $format, $context);
+        return $attributes;
     }
 
     /**
@@ -276,7 +274,7 @@ private function validateAndDenormalize($currentClass, $attribute, $data, $forma
                     throw new LogicException(sprintf('Cannot denormalize attribute "%s" for class "%s" because injected serializer is not a denormalizer', $attribute, $class));
                 }
 
-                $childContext = $this->createChildContext($context, $attribute);
+                $childContext = $this->createChildContext($context, $attribute, $format);
                 if ($this->serializer->supportsDenormalization($data, $class, $format, $childContext)) {
                     return $this->serializer->denormalize($data, $class, $format, $childContext);
                 }
@@ -373,7 +371,32 @@ private function isMaxDepthReached(array $attributesMetadata, $class, $attribute
     }
 
     /**
-     * Gets the cache key to use.
+     * Overwritten to update the cache key for the child.
+     *
+     * We must not mix up the attribute cache between parent and children.
+     *
+     * {@inheritdoc}
+     */
+    protected function createChildContext(array $parentContext, $attribute/*, string $format = null */)
+    {
+        if (\func_num_args() >= 3) {
+            $format = \func_get_arg(2);
+        } else {
+            // will be deprecated in version 4
+            $format = null;
+        }
+
+        $context = parent::createChildContext($parentContext, $attribute, $format);
+        // format is already included in the cache_key of the parent.
+        $context['cache_key'] = $this->getCacheKey($format, $context);
+
+        return $context;
+    }
+
+    /**
+     * Builds the cache key for the attributes cache.
+     *
+     * The key must be different for every option in the context that could change which attributes should be handled.
      *
      * @param string|null $format
      * @param array       $context
@@ -382,8 +405,13 @@ private function isMaxDepthReached(array $attributesMetadata, $class, $attribute
      */
     private function getCacheKey($format, array $context)
     {
+        unset($context['cache_key']); // avoid artificially different keys
         try {
-            return md5($format.serialize($context));
+            return md5($format.serialize([
+                'context' => $context,
+                'ignored' => $this->ignoredAttributes,
+                'camelized' => $this->camelizedAttributes,
+            ]));
         } catch (\Exception $exception) {
             // The context cannot be serialized, skip the cache
             return false;

src/Symfony/Component/Serializer/Tests/Normalizer/ObjectNormalizerTest.php

@@ -380,6 +380,16 @@ public function testIgnoredAttributes()
             ['fooBar' => 'foobar'],
             $this->normalizer->normalize($obj, 'any')
         );
+
+        $this->normalizer->setIgnoredAttributes(['foo', 'baz', 'camelCase', 'object']);
+
+        $this->assertEquals(
+            [
+                'fooBar' => 'foobar',
+                'bar' => 'bar',
+            ],
+            $this->normalizer->normalize($obj, 'any')
+        );
     }
 
     public function testIgnoredAttributesDenormalize()