Fix Metadata Caching when it changes in EventListeners

[andrey-bondar-dron]

This PR fixed 2 bugs:

1. Using https://www.doctrine-project.org/projects/doctrine-orm/en/2.6/cookbook/resolve-target-entity-listener.html with metadata cache is not working, because ResolveTargetEntityListener calls setMetadataFor without any effect on generated cache.
2. Fallback metadata is not caching now.

I hope, it will be merged to version 1.0.2 and released ASAP.

[lcobucci]

Looking good, just some minor details

[lcobucci]

Can you also rebase your branch to organise your commits, please?

[alcaeus]

Apart from the issues highlighted by @lcobucci, LGTM! Thanks @andrey-bondar-dron!

[andrey-bondar-dron]

Hi! Guys, someone has already fixed all required changes, while I was absent. Thanks. :)

[Majkl578]

The change and refactoring looks good overall, but there is one issue that needs to be addressed (see inline comment).

Note that class aliases are to be removed in next major, but now they only cause troubles (like out-of-sync metadata during setMetadata() or in cache).

[Majkl578]

This particular change breaks in-memory caching ($this->loadedMetadata) for aliased classes, therefore breaking hot path at the top of this method for those:

public function testGettingAliasesOnlyFetchesFromCacheOnce() : void
{
    $loadedReflection = new ReflectionProperty(AbstractClassMetadataFactory::class, 'loadedMetadata');
    $loadedReflection->setAccessible(true);

    $this->cmf->getMetadataFor(RootEntity::class);
    self::assertArrayHasKey(RootEntity::class, $loadedReflection->getValue($this->cmf));
    self::assertArrayNotHasKey('Alias:RootEntity', $loadedReflection->getValue($this->cmf));

    $this->cmf->getMetadataFor('Alias:RootEntity');
    self::assertArrayHasKey(RootEntity::class, $loadedReflection->getValue($this->cmf));
    self::assertArrayHasKey('Alias:RootEntity', $loadedReflection->getValue($this->cmf));
}

It's because this condition has changed semantics and no longer does what the comment above says: "We do not have the alias name in the map, include it"

[andrey-bondar-dron]

@Majkl578 When it is needed to change metadata for some entity in EventListeners, we do not know about aliases that were used.
When I call setMetadataFor with real class name, AbstractClassMetadataFactory should replace metadata for all aliases in $loadedMetadata. And vise versa when I call setMetadataFor with alias.
For my opinion, it is normal when we will save only real classes in $loadedMetadata, because it prevent to have many problems with aliases.
On every call getMetadataFor with alias this code will be executed

// Check for namespace alias
        if (strpos($className, ':') !== false) {
            [$namespaceAlias, $simpleClassName] = explode(':', $className, 2);

            $realClassName = $this->getFqcnFromAlias($namespaceAlias, $simpleClassName);
        } else {
            $realClassName = $this->getRealClass($className);
        }

In order to prevent it I can create map for 'alias' => 'realClassName' and replace this code

        // Check for namespace alias
        if (strpos($className, ':') !== false) {
            [$namespaceAlias, $simpleClassName] = explode(':', $className, 2);

            $realClassName = $this->getFqcnFromAlias($namespaceAlias, $simpleClassName);
        } else {
            $realClassName = $this->getRealClass($className);
        }

with something like this

        switch (true) {
            case isset($this->aliasesMap[$className]):
                $realClassName = $this->aliasesMap[$className];
                break;
            case strpos($className, ':') !== false // Check for namespace alias
                [$namespaceAlias, $simpleClassName] = explode(':', $className, 2);
                $realClassName = $this->getFqcnFromAlias($namespaceAlias, $simpleClassName);
                $this->aliasesMap[$className] = $realClassName;
                break;
            default:
                $realClassName = $this->getRealClass($className);
        }

In this case AbstractClassMetadataFactory will not be too coupled with aliases in setMetadataFor/getMetadataFor methods.

[andrey-bondar-dron]

So, fixed.
For now in in-memory cache (also in MetadataCache) will be saved single value for all aliases.
Calling setMetadataFor and getMetadataFor with aliases or FQCN will same keys.

[andrey-bondar-dron]

@Majkl578 @lcobucci @alcaeus @malarzm Hi all! Give please your feedback.

[alcaeus]

Type hints are here to stay: there's no reason you should assume anything else than a string for $className.

[alcaeus]

We may also profit from making this method protected: class name resolution for proxy class names is currently more difficult in ODM 2.0 and ORM 3.0 (master) since moving away from the legacy proxies. Overriding this method would at least temporarily solve this problem. Opinions @lcobucci @Majkl578?