feat: improve garbage collection for injected types & implement finalizer support & stop leaking memory where we can avoid it. #216

soqb · 2025-06-26T14:46:31Z

New way to track instances of injected classes, allowing injected finalizers to run properly, and fix the memory leaks which the documentation warns of.
Consolidate Il2CppObjectBase initialization (and related IL generation) into one cohesive method.
See the new documentation for the procedural overview.
This also fixes a bug/is a breaking change: the lifetime of managed injected instances is now shorter, meaning that non-injected fields might now be dropped earlier than expected.~
Open question: currently, this PR has some trickery to make the managed object's finalizer itself (~Foo()) be the method which is overriden, should we instead make this some public override void Il2CppFinalize() dummy method instead? It likely would make our implementation burden a little easier, and maybe elide the SuppressFinalize trickery, but would be an ergonomics hit.

ds5678 · 2025-06-27T01:34:52Z

Hello 👋

I don't normally work on runtime stuff, so I'm not sure I feel comfortable reviewing your pull request, but it did not go unnoticed.

FYI I'm currently working on the v2 rewrite, which could cause issues for your pull request. I'm looking at getting an implementation for the generation changes pushed soon.

soqb · 2025-06-28T08:43:43Z

exciting! could you point me to your work (if available online, no worries if not) so i can see how we intersect?

Il2CppInterop.Runtime/Runtime/Il2CppObjectPool.cs

ds5678 · 2025-06-28T19:15:26Z

exciting! could you point me to your work (if available online, no worries if not) so i can see how we intersect?

Not yet available. I'm going to make a pull request when I push.

… robust#

ds5678 · 2025-09-01T20:28:22Z

exciting! could you point me to your work (if available online, no worries if not) so i can see how we intersect?

https://github.com/ds5678/Il2CppInterop/tree/v2-rewrite

ds5678

Hello! I'm excited for your pull request and want to see it be part of v2.

ds5678 · 2025-09-02T04:21:58Z

Il2CppInterop.Runtime/DelegateSupport.cs

-        public IntPtr MethodInfo;
-        public Delegate ReferencedDelegate;


I'm very happy to see this. One of the things in v2 that was bothering me is that I wasn't sure what to do with these fields. I'm introducing a breaking change that injected classes can't have managed state.

yeah i think breaking change is the only way to fix the semantics. i have a branch somewhere for bepinex which fixes it there.

ds5678 · 2025-09-02T04:29:11Z

Documentation/Class-Injection.md

+        ClassInjector.DerivedConstructorBody(this);
+    }
+
+    private void Il2CppFinalize()


v2 replaces [HideFromIl2Cpp] with an opt-in system. The user indicator for this would be:

[Il2CppMethod(Name = "Finalize")]

not exactly, i think the attribute does make sense for consistency but it would still need special-casing and the injected class' Finalize method would not directly translate to the one defined here.

The Name property applies in any situation where an Il2Cpp name differs from the generated name in managed code. In the case of finalizers, the v2 generator appends underscores, which is approximately the same as what you're doing.

ds5678 · 2025-09-02T04:31:22Z

Il2CppInterop.Runtime/Injection/ClassInjector.cs

    public Il2CppInterfaceCollection? Interfaces { get; init; } = null;
 }

+internal record FinalizerChain(Delegate finalizer, FinalizerChain? next)


I feel like this should just use a primary constructor rather than be a record.

ds5678 · 2025-09-02T04:36:53Z

Il2CppInterop.Runtime/InteropTypes/Il2CppObjectBase.cs


 namespace Il2CppInterop.Runtime.InteropTypes;

 public class Il2CppObjectBase


Il2CppObjectBase is being removed in v2 in lieu of injecting code directly into Il2CppSystem.Object. As much code as possible should be implemented with extension methods or other helper classes.

what's wrong with Il2CppObjectBase 😭? where will the new Il2CppSystem.Object be defined? will it still have behaviour i can configure (like the finalizer, and initialisation)?

It's not a real type.

Il2Cppmscorlib

Your capabilities should not change.

soqb · 2025-09-02T09:24:30Z

i'm a little confused on what the roadmap is with v2. is there an issue or something which lays it out? as a downstream user, i need to know if v2 is "coming soon" or not; are we at that stage of saying "nothing gets merged until v2 because that's top priority"? if so, i can rebase on top of your branch, but if not, i'm also willing to rebase yours on mine once this is merged.

i want to make this as easy a merge as possible for you.

ds5678 · 2025-09-02T16:24:54Z

i'm a little confused on what the roadmap is with v2. is there an issue or something which lays it out?

There's a milestone, which includes most of the v2 changes.

as a downstream user, i need to know if v2 is "coming soon" or not

Yes, I'm making a WIP pull request sometime this week.

are we at that stage of saying "nothing gets merged until v2 because that's top priority"?

Yes, that will likely be the next merge. 1.5.1 was released as the "last commit before the massively breaking changes of v2."

if so, i can rebase on top of your branch, but if not, i'm also willing to rebase yours on mine once this is merged.

i want to make this as easy a merge as possible for you.

I still need to:

Rebase my branch on the recent commits from 1.5.1
Make some generation changes
Tidy up my branch
Make a pull request

At that point, my branch will still need additional runtime changes, but it'll be safe for you to rebase your changes and make a pull request onto my branch.

soqb · 2025-09-03T21:33:25Z

thank you so much.

soqb added 2 commits June 26, 2025 15:39

feat: support for finalizers and stop leaking injected objects

6f43413

feat: support for finalizers and stop leaking injected objects (ii)

4d87b31

ds5678 reviewed Jun 28, 2025

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Il2CppInterop.Runtime/Runtime/Il2CppObjectPool.cs Outdated Show resolved Hide resolved

soqb added 5 commits September 1, 2025 09:13

fix(gc): revert cache flag publicization

d905c92

feat(gc): use dedicated private method for finalizers. made much more…

a29f0f6

… robust#

fix(gc): adjust documentation and move resurrection method.

4a4ce64

fix(gc): harden finalizer search

2e48c74

fix(gc): how did that get there?

bba83b3

soqb mentioned this pull request Sep 1, 2025

Fix "Handle is not initialized" for Unity 2021.2.x games #232

Merged

ds5678 reviewed Sep 2, 2025

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ds5678 added this to the 2.0.0 milestone Sep 2, 2025

Kein mentioned this pull request Oct 9, 2025

[Bug] Stack crash failure on Unity 6.1.x IL2CPP yukieiji/UnityExplorer#72

Closed

		public IntPtr MethodInfo;
		public Delegate ReferencedDelegate;


		namespace Il2CppInterop.Runtime.InteropTypes;

		public class Il2CppObjectBase

feat: improve garbage collection for injected types & implement finalizer support & stop leaking memory where we can avoid it. #216

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feat: improve garbage collection for injected types & implement finalizer support & stop leaking memory where we can avoid it. #216

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soqb commented Jun 26, 2025 •

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