此数据是否被另一个组件覆盖？答案

【问题标题】：Is this data being overwritten by another component?此数据是否被另一个组件覆盖？
【发布时间】：2017-06-23 19:27:46
【问题描述】：

我正在使用 symfony 组件在 Silex 中进行一些编程，我想我发现了 symfony/serializer 和 symfony/validator 组件的错误。

首先让我解释一下我训练要实现的目标，然后我们来看代码。我的目标是用序列化指令和验证指令等信息来注释一个类。由于读取这些注释可能会消耗很少的 CPU，因此我喜欢将它们缓存在内存中。为此，我在 Doctrine/Common/Cache 包中使用了 memcache 包装器。

我面临的问题是symfony/serializer 和symfony/validator 都使用类名作为键将元数据写入缓存。当他们稍后尝试检索元数据时，他们会抛出异常，因为缓存中有无效的元数据，Symfony\Component\Validator\Mapping\ClassMetadata 或 Symfony\Component\Serializer\Mapping\ClassMetadataInterface 的实例。

以下是一个可复制的示例（对不起，如果它很大，我试图尽可能小）：

use Symfony\Component\Serializer\Annotation\Groups;
use Symfony\Component\Validator\Constraints as Assert;

class Foo
{
    /**
     * @var int
     * @Assert\NotBlank(message="This field cannot be empty")
     */
    private $someProperty;

    /**
     * @return int
     * @Groups({"some_group"})
     */
    public function getSomeProperty() {
        return $this->someProperty;
    }
}


use Doctrine\Common\Annotations\AnnotationReader;
use \Memcache as MemcachePHP;
use Doctrine\Common\Cache\MemcacheCache as MemcacheWrapper;

$loader = require_once __DIR__ . '/../vendor/autoload.php';

\Doctrine\Common\Annotations\AnnotationRegistry::registerLoader([$loader, 'loadClass']);

$memcache = new MemcachePHP();

if (! $memcache->connect('localhost', '11211')) {
    throw new \Exception('Unable to connect to memcache server');
}

$cacheDriver = new MemcacheWrapper();
$cacheDriver->setMemcache($memcache);

$app = new \Silex\Application();

$app->register(new Silex\Provider\SerializerServiceProvider());

$app['serializer.normalizers'] = function () use ($app, $cacheDriver) {
    $classMetadataFactory = new Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactory(
        new Symfony\Component\Serializer\Mapping\Loader\AnnotationLoader(new AnnotationReader()), $cacheDriver);

    return [new Symfony\Component\Serializer\Normalizer\GetSetMethodNormalizer($classMetadataFactory) ];
};

$app->register(new Silex\Provider\ValidatorServiceProvider(), [
    'validator.mapping.class_metadata_factory' =>
        new \Symfony\Component\Validator\Mapping\Factory\LazyLoadingMetadataFactory(
            new \Symfony\Component\Validator\Mapping\Loader\AnnotationLoader(new AnnotationReader()),
            new \Symfony\Component\Validator\Mapping\Cache\DoctrineCache($cacheDriver)
        )
]);

$app->get('/', function(\Silex\Application $app) {
    $foo = new Foo();

    $app['validator']->validate($foo);
    $json = $app['serializer']->serialize($foo, 'json');

    return new \Symfony\Component\HttpFoundation\JsonResponse($json, \Symfony\Component\HttpFoundation\Response::HTTP_OK, [], true);
});

$app->error(function (\Exception $e, \Symfony\Component\HttpFoundation\Request $request, $code) {
    return new \Symfony\Component\HttpFoundation\Response('We are sorry, but something went terribly wrong.' . $e->getMessage());
});

$app->run();

运行此示例后，您会遇到致命错误。谁能确认我在这里没有犯严重的错误？

目前我的解决方法是重写DoctrineCache 类，使用缓存键的命名空间。它可以工作，但我认为它很丑。

【问题讨论】：

标签： php validation symfony silex serialization

【解决方案1】：

我认为你需要做的是两个独立的CacheDrivers。请参阅 https://github.com/doctrine/cache/blob/master/lib/Doctrine/Common/Cache/CacheProvider.php 了解如何使用命名空间。

你可以：

$validatorCacheDriver = new MemcacheWrapper();
$validatorCacheDriver->setMemcache($memcache);
$validatorCacheDriver->setNamespace('symfony_validator');

$serializerCacheDriver = new MemcacheWrapper();
$serializerCacheDriver->setMemcache($memcache);
$serializerCacheDriver->setNamespace('symfony_serializer');

// note that the two drivers are using the same memcache instance, 
// so only one connection will be used.

$app['serializer.normalizers'] = function () use ($app, $serializerCacheDriver) {
    $classMetadataFactory = new Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactory(
        new Symfony\Component\Serializer\Mapping\Loader\AnnotationLoader(new AnnotationReader()), $serializerCacheDriver);

    return [new Symfony\Component\Serializer\Normalizer\GetSetMethodNormalizer($classMetadataFactory) ];
};

$app->register(new Silex\Provider\ValidatorServiceProvider(), [
    'validator.mapping.class_metadata_factory' =>
        new \Symfony\Component\Validator\Mapping\Factory\LazyLoadingMetadataFactory(
            new \Symfony\Component\Validator\Mapping\Loader\AnnotationLoader(new AnnotationReader()),
            new \Symfony\Component\Validator\Mapping\Cache\DoctrineCache($validatorCacheDriver)
        )
]);

我已经修剪了代码，只显示在解决方案中发挥作用的部分。我希望这会有所帮助！

【讨论】：