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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
}