[LiveComponent] Fix calculateFingerprint with big objects

[LunkLoafGrumble]

Q	A
Bug fix?	yes
New feature?	no
Tickets	N/A
License	MIT

This pull request will fix an issue for large objects (for example entities with a large relations) with in the FingerprintCalculator

While working with liveComponents I noticed my project getting slower and slower. After some digging I found out that in the calculateFingerprint function the data is serialized. When an entity with relations passes by it will serialize the entity and its child objects. This takes a considerable amount of time and is not needed.

[kevinmade]

I'm having the same issue.

[kbond]

Makes sense to me!

[weaverryan]

Great catch on this!

These fingerprints need to be a deterministic string that represents "the input passed into a component" -

ux/src/LiveComponent/src/Util/LiveControllerAttributesCreator.php

Line 68 in e45a8ed

$fingerprint = $this->fingerprintCalculator->calculateFingerprint($mounted->getInputProps());

- and they need to always return the same string for the same input.

If you pass an object (e.g. a Post entity) into a component, the spl_object_id() of that might be different the next time the component is re-rendered via an Ajax call, right?

I'm open to ideas on how to fix this. In practice, if we added some special code for entity objects that, if persisted, used their id instead of serializing them, that might solve things. For example, if one of the items in $data is a Post entity, then instead of serializing that or spl_object_id(), we use App\Entity\Post:{THE_ID}.

[kbond]

These fingerprints need to be a deterministic string that represents

Oops, didn't realize this. Could spl_object_hash() be used? I don't know if this would still have a perf problem.

[weaverryan]

I think spl_object_hash() has the same problem - not 100% certain on that, but pretty sure.

[kbond]

You're right. From php.net:

When an object is destroyed, its hash may be reused for other objects.

[kbond]

These fingerprints need to be a deterministic string that represents "the input passed into a component" -

We should have a test to prove this behaviour.

[kevinmade]

Perhaps it's an idea to add if (\is_object($value) && method_exists($value, 'getId')) { return $value->getId(); } instead of \is_object($value).

[kbond]

This is probably the best solution.

@LunkLoafGrumble does this method improve the speed in your app?

Could you add a basic integration test for FingerprintCalculator that proves the generated fingerprint is the same two different object instances that are equal?

[LunkLoafGrumble]

Using objectNormalizer greatly improves the performance over just serializing the object.

[kbond]

A few remaining minor things, then good to go by me!

[weaverryan]

Let's give this version a try - thanks @LunkLoafGrumble!

[weaverryan]

FYI - I'm reverting this in #832. But I'm hoping that it's not a problem anymore because usually zero LiveProps are used to calculate the fingerprint. But please tell me if you still have issues.