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Drop Weak<WaitableNativeActivityState> in on_destroy #237

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Merged
rib merged 1 commit into from
Mar 19, 2026
Merged

Drop Weak<WaitableNativeActivityState> in on_destroy #237

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23 changes: 20 additions & 3 deletions android-activity/src/native_activity/glue.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -328,7 +328,7 @@ impl NativeActivityState {

impl Drop for WaitableNativeActivityState {
fn drop(&mut self) {
log::debug!("WaitableNativeActivityState::drop!");
log::info!("WaitableNativeActivityState::drop!");
unsafe {
let mut guard = self.mutex.lock().unwrap();
guard.detach_input_queue_from_looper();
Expand Down Expand Up @@ -670,12 +670,19 @@ unsafe fn try_with_waitable_activity_ref(
assert!(!(*activity).instance.is_null());
let weak_ptr: *const WaitableNativeActivityState = (*activity).instance.cast();
let weak_ref = Weak::from_raw(weak_ptr);
if let Some(waitable_activity) = weak_ref.upgrade() {
let maybe_upgraded = weak_ref.upgrade();

// Make sure we don't Drop the Weak reference (even if we failed to upgrade it
// and also considering the possibility that we unwind due to a panic in `closure()`)
// (The raw weak pointer associated with activity->instance must remain valid
// until `on_destroy` is called).
let _ = weak_ref.into_raw();

if let Some(waitable_activity) = maybe_upgraded {
closure(waitable_activity);
} else {
log::error!("Ignoring spurious JVM callback after last activity reference was dropped!")
}
let _ = weak_ref.into_raw();
}

unsafe extern "C" fn on_destroy(activity: *mut ndk_sys::ANativeActivity) {
Expand All @@ -684,6 +691,16 @@ unsafe extern "C" fn on_destroy(activity: *mut ndk_sys::ANativeActivity) {
try_with_waitable_activity_ref(activity, |waitable_activity| {
waitable_activity.notify_destroyed()
});

// Once we return from here the `ANativeActivity` will be deleted via an
// `unloadNativeCode` native method and so we can't get any more
// callbacks and we can release the `Weak<WaitableNativeActivityState>`
// reference we have associated with `activity->instance`

assert!(!(*activity).instance.is_null());
let weak_ptr: *const WaitableNativeActivityState = (*activity).instance.cast();
let _drop_weak_ref = Weak::from_raw(weak_ptr);
(*activity).instance = std::ptr::null_mut();
})
}

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