Add extra arc_wake

Author: varkor

src/test/ui/async-await/auxiliary/arc_wake.rs

@@ -0,0 +1,64 @@
+// edition:2018
+
+use std::sync::Arc;
+use std::task::{
+    Waker, RawWaker, RawWakerVTable,
+};
+
+macro_rules! waker_vtable {
+    ($ty:ident) => {
+        &RawWakerVTable::new(
+            clone_arc_raw::<$ty>,
+            wake_arc_raw::<$ty>,
+            wake_by_ref_arc_raw::<$ty>,
+            drop_arc_raw::<$ty>,
+        )
+    };
+}
+
+pub trait ArcWake {
+    fn wake(self: Arc<Self>);
+
+    fn wake_by_ref(arc_self: &Arc<Self>) {
+        arc_self.clone().wake()
+    }
+
+    fn into_waker(wake: Arc<Self>) -> Waker where Self: Sized
+    {
+        let ptr = Arc::into_raw(wake) as *const ();
+
+        unsafe {
+            Waker::from_raw(RawWaker::new(ptr, waker_vtable!(Self)))
+        }
+    }
+}
+
+unsafe fn increase_refcount<T: ArcWake>(data: *const ()) {
+    // Retain Arc by creating a copy
+    let arc: Arc<T> = Arc::from_raw(data as *const T);
+    let arc_clone = arc.clone();
+    // Forget the Arcs again, so that the refcount isn't decrased
+    let _ = Arc::into_raw(arc);
+    let _ = Arc::into_raw(arc_clone);
+}
+
+unsafe fn clone_arc_raw<T: ArcWake>(data: *const ()) -> RawWaker {
+    increase_refcount::<T>(data);
+    RawWaker::new(data, waker_vtable!(T))
+}
+
+unsafe fn drop_arc_raw<T: ArcWake>(data: *const ()) {
+    // Drop Arc
+    let _: Arc<T> = Arc::from_raw(data as *const T);
+}
+
+unsafe fn wake_arc_raw<T: ArcWake>(data: *const ()) {
+    let arc: Arc<T> = Arc::from_raw(data as *const T);
+    ArcWake::wake(arc);
+}
+
+unsafe fn wake_by_ref_arc_raw<T: ArcWake>(data: *const ()) {
+    let arc: Arc<T> = Arc::from_raw(data as *const T);
+    ArcWake::wake_by_ref(&arc);
+    let _ = Arc::into_raw(arc);
+}