Implementing destructors for Kotlin callbacks #682
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| @@ -67,7 +68,11 @@ internal class DiplomatCallback_MyNativeStruct_test_multi_arg_callback_diplomatC | |||
| } | |||
| } | |||
| @JvmField | |||
| internal var destructor: Pointer = Pointer(0L); | |||
| internal var destructor: Callback = object : Callback { | |||
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Do you need to produce an extra Callback layer here? Is there any reason we can't just assign destroy_rust_jvm_cookie to this directly? Having two layers of indirection seems weird unless this is actually mandatory.
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I've tried this but it doesn't seem to work -- as I understand this, i'ts because the Callback is a JNA construct, and also you don't seem to be able to assign functions directly to variables in Kotlin 😢
But I'm not a Kotlin expert, maybe I'm missing something
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If we can figure out how to return a function pointer to the Rust function, from Rust, then we can probably have the destructor be a Pointer instead?
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This seems correct to me, I'd like @maurer to also approve this
feature_tests/kotlin/somelib/src/main/kotlin/dev/diplomattest/somelib/CallbackWrapper.kt
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This makes sense to me. I'm not the biggest fan of the extra layers of indirection and the inversion of GC vs owned environment maintenance, but it's simple, it avoids extra build system work, it doesn't modify the ABI, and it works, so seems fine.
(Above assumes you fix the link error showing up in ci, but since I've seen this working on your machine I assume that won't be hard.)
Probably worth filing a followup issue about this to try and improve the situation? |
Adding support for proper memory management of callbacks passed to Rust from Kotlin -- now, they are stopped from being freed in Rust by a JNI
GlobalRefto the callback wrapper object on the Kotlin side. TheGlobalRefis removed in a finalizer on the Kotlin side.This is addressing issue #648