Fix wrong deallocation management for JSClosure with FinalizationRegistry #393
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…stry In FinalizationRegistry mode, the `swjs_free_host_function` should be called with the Swift heap object ID, not the JS closure object ID. The wrong argument was causing: - Swift closures to be leaked, because FinalizationRegistry attempted to release a JS object ID that was never registered as a Swift closure. - Unintended deallocation of unrelated closures when a reused JS object ID happened to match a valid Swift closure ID by coincidence. This eventually led to crashes with `The JSClosure has been already released by Swift side.`
JSOneshotClosure manages its lifetime by itself, so it doesn't require nondeterministic FinalizationRegistry. Additionally, use of FinalizationRegistry was unsafe for the case: 1. JSOneshotClosure C1 is created 2. C1 is called, and destroyed 3. JSOneshotClosure C2 is created at the same address of C1 4. C1's finalizer callback is called
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lowkahonn
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Aug 4, 2025
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In FinalizationRegistry mode, the
swjs_free_host_functionshould be called with the Swift heap object ID, not the JS closure object ID.The wrong argument was causing:
The JSClosure has been already released by Swift side.Stop managing JSOneshotClosure by FinalizationRegistry
JSOneshotClosure manages its lifetime by itself, so it doesn't require
nondeterministic FinalizationRegistry. Additionally, use of FinalizationRegistry
was unsafe for the case: