Locking is broken when ClassMetadata is cached

[buffcode]

Bug Report

Q	A
BC Break	no
Version	all

Summary

Lock functionality is broken as soon as a non-volatile ClassMetadata cache is used.

Current behavior

When a metadata_cache_driver is defined, Doctrine MongoDB caches the ClassMetadata using the given driver by serializing all relevant fields. The fields isLockable and lockField are not serialized.

On a second request (or after the cache has been warmed), ClassMetadata has no information about locking-behaviour anymore and calls to ->lock(...) will fail with undefined index, as $this->class->lockField is empty [1] and there is no field mapping for this empty value.

#0 vendor/doctrine/mongodb-odm/lib/Doctrine/ODM/MongoDB/UnitOfWork.php(2325): Doctrine\ODM\MongoDB\Persisters\DocumentPersister->lock(Object(MyDocument), 4)
#1 vendor/doctrine/mongodb-odm/lib/Doctrine/ODM/MongoDB/DocumentManager.php(501): Doctrine\ODM\MongoDB\UnitOfWork->lock(Object(MyDocument), 4, NULL)

How to reproduce

1. Configure a persistent metadata cache driver:

# config/packages/doctrine_mongodb.yaml 
services:
    app.doctrine_mongodb.redis.cache:
        class: Doctrine\Common\Cache\PredisCache
        arguments:
            - "@app.doctrine_mongodb.redis.inner"

    app.doctrine_mongodb.redis.inner:
        class: Predis\Client
        arguments:
           - "%env(REDIS_URL)%"

doctrine_mongodb:
    document_managers:
        default:
            auto_mapping: true
            metadata_cache_driver:
                type: service
                id:   app.doctrine_mongodb.redis.cache

2. Warm cache (cache:warmup or trigger application)
3. Try to lock the document by calling

$documentManager->lock($myDocument, LockMode::PESSIMISTIC_WRITE);

4. Notice is thrown, no locking occurs.

Expected behavior

Lock functionality should work, even when ClassMetadata is cached.

Solution

Include isLockable and lockField in serialization (PRs incoming).

[malarzm]

Forgot to link issues before, closing as #2281 was merged