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Drop Weak<WaitableNativeActivityState> in on_destroy

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When we know we're done with the `Weak` reference that is associated with
the `NativeActivity` callbacks we make sure to drop the `Weak` reference
so that the underlying allocation for the `WaitableNativeActivityState`
can be freed.

This also updates `try_with_waitable_activity_ref` to be more careful
about converting the `Weak` ref back into a raw pointer _before_ calling
the handler, just in case the handler triggers a panic and unwinds
(where we wouldn't want to lose/Drop our weak ref).
This commit is contained in:
Robert Bragg
2026-03-12 21:34:09 +00:00
parent 9163368955
commit b042af60f2
1 changed files with 20 additions and 3 deletions
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android-activity/src/native_activity/glue.rs
+20 -3
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@@ -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();
@@ -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) {
@@ -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();
})
}