feature #31334 [Messenger] Add clear Entity Manager middleware (Koc)

This PR was merged into the 4.4 branch.

Discussion
----------

[Messenger] Add clear Entity Manager middleware

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #29662
| License       | MIT
| Doc PR        | TBD

General purpose of this middleware:
* avoid memory leaks during messages handling
* prevent unexpected side effects when entities that already stored in identity map not refreshed between messages

Commits
-------

6e690a6078 Add clear Entity Manager middleware (closes #29662)

src/Symfony/Bridge/Doctrine/CHANGELOG.md

@@ -1,6 +1,12 @@
 CHANGELOG
 =========
 
+4.4.0
+-----
+
+ * added `DoctrineClearEntityManagerMiddleware`
+
+
 4.3.0
 -----
 

src/Symfony/Bridge/Doctrine/Messenger/DoctrineClearEntityManagerMiddleware.php

@@ -0,0 +1,53 @@
+<?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\Bridge\Doctrine\Messenger;
+
+use Doctrine\Common\Persistence\ManagerRegistry;
+use Symfony\Component\Messenger\Envelope;
+use Symfony\Component\Messenger\Exception\UnrecoverableMessageHandlingException;
+use Symfony\Component\Messenger\Middleware\MiddlewareInterface;
+use Symfony\Component\Messenger\Middleware\StackInterface;
+
+/**
+ * Clears entity manager after calling all handlers.
+ *
+ * @author Konstantin Myakshin <molodchick@gmail.com>
+ */
+class DoctrineClearEntityManagerMiddleware implements MiddlewareInterface
+{
+    private $managerRegistry;
+    private $entityManagerName;
+
+    public function __construct(ManagerRegistry $managerRegistry, string $entityManagerName = null)
+    {
+        $this->managerRegistry = $managerRegistry;
+        $this->entityManagerName = $entityManagerName;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function handle(Envelope $envelope, StackInterface $stack): Envelope
+    {
+        try {
+            $entityManager = $this->managerRegistry->getManager($this->entityManagerName);
+        } catch (\InvalidArgumentException $e) {
+            throw new UnrecoverableMessageHandlingException($e->getMessage(), 0, $e);
+        }
+
+        try {
+            return $stack->next()->handle($envelope, $stack);
+        } finally {
+            $entityManager->clear();
+        }
+    }
+}

src/Symfony/Bridge/Doctrine/Tests/Messenger/DoctrineClearEntityManagerMiddlewareTest.php

@@ -0,0 +1,54 @@
+<?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\Bridge\Doctrine\Tests\Messenger;
+
+use Doctrine\Common\Persistence\ManagerRegistry;
+use Doctrine\ORM\EntityManagerInterface;
+use Symfony\Bridge\Doctrine\Messenger\DoctrineClearEntityManagerMiddleware;
+use Symfony\Component\Messenger\Envelope;
+use Symfony\Component\Messenger\Exception\UnrecoverableMessageHandlingException;
+use Symfony\Component\Messenger\Test\Middleware\MiddlewareTestCase;
+
+class DoctrineClearEntityManagerMiddlewareTest extends MiddlewareTestCase
+{
+    public function testMiddlewareClearEntityManager()
+    {
+        $entityManager = $this->createMock(EntityManagerInterface::class);
+        $entityManager->expects($this->once())
+            ->method('clear');
+
+        $managerRegistry = $this->createMock(ManagerRegistry::class);
+        $managerRegistry
+            ->method('getManager')
+            ->with('default')
+            ->willReturn($entityManager);
+
+        $middleware = new DoctrineClearEntityManagerMiddleware($managerRegistry, 'default');
+
+        $middleware->handle(new Envelope(new \stdClass()), $this->getStackMock());
+    }
+
+    public function testInvalidEntityManagerThrowsException()
+    {
+        $managerRegistry = $this->createMock(ManagerRegistry::class);
+        $managerRegistry
+            ->method('getManager')
+            ->with('unknown_manager')
+            ->will($this->throwException(new \InvalidArgumentException()));
+
+        $middleware = new DoctrineClearEntityManagerMiddleware($managerRegistry, 'unknown_manager');
+
+        $this->expectException(UnrecoverableMessageHandlingException::class);
+
+        $middleware->handle(new Envelope(new \stdClass()), $this->getStackMock(false));
+    }
+}