+
+ #[test]
+ fn test_future_callbacks() {
+ let future = Future {
+ state: Arc::new(Mutex::new(FutureState {
+ callbacks: Vec::new(),
+ complete: false,
+ }))
+ };
+ let callback = Arc::new(AtomicBool::new(false));
+ let callback_ref = Arc::clone(&callback);
+ future.register_callback(Box::new(move || assert!(!callback_ref.fetch_or(true, Ordering::SeqCst))));
+
+ assert!(!callback.load(Ordering::SeqCst));
+ future.state.lock().unwrap().complete();
+ assert!(callback.load(Ordering::SeqCst));
+ future.state.lock().unwrap().complete();
+ }
+
+ #[test]
+ fn test_pre_completed_future_callbacks() {
+ let future = Future {
+ state: Arc::new(Mutex::new(FutureState {
+ callbacks: Vec::new(),
+ complete: false,
+ }))
+ };
+ future.state.lock().unwrap().complete();
+
+ let callback = Arc::new(AtomicBool::new(false));
+ let callback_ref = Arc::clone(&callback);
+ future.register_callback(Box::new(move || assert!(!callback_ref.fetch_or(true, Ordering::SeqCst))));
+
+ assert!(callback.load(Ordering::SeqCst));
+ assert!(future.state.lock().unwrap().callbacks.is_empty());
+ }
+
+ // Rather annoyingly, there's no safe way in Rust std to construct a Waker despite it being
+ // totally possible to construct from a trait implementation (though somewhat less effecient
+ // compared to a raw VTable). Instead, we have to write out a lot of boilerplate to build a
+ // waker, which we do here with a trivial Arc<AtomicBool> data element to track woke-ness.
+ const WAKER_V_TABLE: RawWakerVTable = RawWakerVTable::new(waker_clone, wake, wake_by_ref, drop);
+ unsafe fn wake_by_ref(ptr: *const ()) { let p = ptr as *const Arc<AtomicBool>; assert!(!(*p).fetch_or(true, Ordering::SeqCst)); }
+ unsafe fn drop(ptr: *const ()) { let p = ptr as *mut Arc<AtomicBool>; let _freed = Box::from_raw(p); }
+ unsafe fn wake(ptr: *const ()) { wake_by_ref(ptr); drop(ptr); }
+ unsafe fn waker_clone(ptr: *const ()) -> RawWaker {
+ let p = ptr as *const Arc<AtomicBool>;
+ RawWaker::new(Box::into_raw(Box::new(Arc::clone(&*p))) as *const (), &WAKER_V_TABLE)
+ }
+
+ fn create_waker() -> (Arc<AtomicBool>, Waker) {
+ let a = Arc::new(AtomicBool::new(false));
+ let waker = unsafe { Waker::from_raw(waker_clone((&a as *const Arc<AtomicBool>) as *const ())) };
+ (a, waker)
+ }
+
+ #[test]
+ fn test_future() {
+ let mut future = Future {
+ state: Arc::new(Mutex::new(FutureState {
+ callbacks: Vec::new(),
+ complete: false,
+ }))
+ };
+ let mut second_future = Future { state: Arc::clone(&future.state) };
+
+ let (woken, waker) = create_waker();
+ assert_eq!(Pin::new(&mut future).poll(&mut Context::from_waker(&waker)), Poll::Pending);
+ assert!(!woken.load(Ordering::SeqCst));
+
+ let (second_woken, second_waker) = create_waker();
+ assert_eq!(Pin::new(&mut second_future).poll(&mut Context::from_waker(&second_waker)), Poll::Pending);
+ assert!(!second_woken.load(Ordering::SeqCst));
+
+ future.state.lock().unwrap().complete();
+ assert!(woken.load(Ordering::SeqCst));
+ assert!(second_woken.load(Ordering::SeqCst));
+ assert_eq!(Pin::new(&mut future).poll(&mut Context::from_waker(&waker)), Poll::Ready(()));
+ assert_eq!(Pin::new(&mut second_future).poll(&mut Context::from_waker(&second_waker)), Poll::Ready(()));
+ }