1 files changed, 79 insertions, 0 deletions
diff --git a/third_party/rust/futures/tests/task_arc_wake.rs b/third_party/rust/futures/tests/task_arc_wake.rs
new file mode 100644
index 0000000000..aedc15bcb8
--- /dev/null
+++ b/third_party/rust/futures/tests/task_arc_wake.rs
@@ -0,0 +1,79 @@
+use futures::task::{self, ArcWake, Waker};
+use std::panic;
+use std::sync::{Arc, Mutex};
+
+struct CountingWaker {
+    nr_wake: Mutex<i32>,
+}
+
+impl CountingWaker {
+    fn new() -> Self {
+        Self { nr_wake: Mutex::new(0) }
+    }
+
+    fn wakes(&self) -> i32 {
+        *self.nr_wake.lock().unwrap()
+    }
+}
+
+impl ArcWake for CountingWaker {
+    fn wake_by_ref(arc_self: &Arc<Self>) {
+        let mut lock = arc_self.nr_wake.lock().unwrap();
+        *lock += 1;
+    }
+}
+
+#[test]
+fn create_from_arc() {
+    let some_w = Arc::new(CountingWaker::new());
+
+    let w1: Waker = task::waker(some_w.clone());
+    assert_eq!(2, Arc::strong_count(&some_w));
+    w1.wake_by_ref();
+    assert_eq!(1, some_w.wakes());
+
+    let w2 = w1.clone();
+    assert_eq!(3, Arc::strong_count(&some_w));
+
+    w2.wake_by_ref();
+    assert_eq!(2, some_w.wakes());
+
+    drop(w2);
+    assert_eq!(2, Arc::strong_count(&some_w));
+    drop(w1);
+    assert_eq!(1, Arc::strong_count(&some_w));
+}
+
+#[test]
+fn ref_wake_same() {
+    let some_w = Arc::new(CountingWaker::new());
+
+    let w1: Waker = task::waker(some_w.clone());
+    let w2 = task::waker_ref(&some_w);
+    let w3 = w2.clone();
+
+    assert!(w1.will_wake(&w2));
+    assert!(w2.will_wake(&w3));
+}
+
+#[test]
+fn proper_refcount_on_wake_panic() {
+    struct PanicWaker;
+
+    impl ArcWake for PanicWaker {
+        fn wake_by_ref(_arc_self: &Arc<Self>) {
+            panic!("WAKE UP");
+        }
+    }
+
+    let some_w = Arc::new(PanicWaker);
+
+    let w1: Waker = task::waker(some_w.clone());
+    assert_eq!(
+        "WAKE UP",
+        *panic::catch_unwind(|| w1.wake_by_ref()).unwrap_err().downcast::<&str>().unwrap()
+    );
+    assert_eq!(2, Arc::strong_count(&some_w)); // some_w + w1
+    drop(w1);
+    assert_eq!(1, Arc::strong_count(&some_w)); // some_w
+}