Hide Metal drawables from Kotlin runtime

[elijah-semyonov]

Explicitly manage lifetime of metal drawables by hiding them from Kotlin runtime.

Fixes a memory spike when quickly resizing metal layer as in a scenario reported in the issue

Otherwise associated drawable pools are retained until next GC, which can happen after inadequate amount of drawables with new sizes are allocated

Before:

After:

Testing

Resize the popup with ComposeUIViewController to different detents inside Demo IosBugs/PopupStretching
Requires either patch:

Index: compose/ui/ui/src/uikitMain/kotlin/androidx/compose/ui/scene/ComposeSceneMediator.uikit.kt
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/compose/ui/ui/src/uikitMain/kotlin/androidx/compose/ui/scene/ComposeSceneMediator.uikit.kt b/compose/ui/ui/src/uikitMain/kotlin/androidx/compose/ui/scene/ComposeSceneMediator.uikit.kt
--- a/compose/ui/ui/src/uikitMain/kotlin/androidx/compose/ui/scene/ComposeSceneMediator.uikit.kt	(revision 39d436a845d0cbe9526a6c24933268aacf83b2eb)
+++ b/compose/ui/ui/src/uikitMain/kotlin/androidx/compose/ui/scene/ComposeSceneMediator.uikit.kt	(date 1717747754590)
@@ -558,6 +558,7 @@
                 asDpRect().toRect()
             }
         }
+        onComposeSceneInvalidate()
         scene.size = IntSize(
             width = boundsInPx.width.roundToInt(),
             height = boundsInPx.height.roundToInt()

Or #1387

Release Notes

Fixes - iOS

• Fixed a memory spike when continuously resizing the ComposeUIViewController (such as when used in modal sheet presentation context with different detents)

[ASalavei]

Comments?

[elijah-semyonov]

Oops, removed

[ASalavei]

Just thinking about slightly more generic solution.
What do you think about creating analog of "Manual Reference Counter" that can wrap various classes and hide them from Kotlin GC?
Or maybe even play a bit with NSProxy to provide sufficient interface for Kotlin.

[elijah-semyonov]

I tried to model this approach in my head, but didn't succeed. Do you have proof-of-concept available?

[ASalavei]

please check copyright

[elijah-semyonov]

Fixed!

[MatkovIvan]

Can we just nullify it?

[elijah-semyonov]

It's a smart cast val, doing so will require to put force-unwraps everywhere

[elijah-semyonov]

The particular web tests were reported to be flaky and are unrelevant to the PR, merging ignoring the failure.

[chrisjenx]

Do you reckon this is related? JetBrains/compose-multiplatform#4852