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use futures::future::FutureExt;
use std::alloc::Layout;
use std::future::Future;
use std::marker::PhantomPinned;
use std::pin::Pin;
use std::rc::Rc;
use std::task::{Context, Poll};
use tokio_util::sync::ReusableBoxFuture;
#[test]
// Clippy false positive; it's useful to be able to test the trait impls for any lifetime
#[allow(clippy::extra_unused_lifetimes)]
fn traits<'a>() {
fn assert_traits<T: Send + Sync + Unpin>() {}
// Use a type that is !Unpin
assert_traits::<ReusableBoxFuture<'a, PhantomPinned>>();
// Use a type that is !Send + !Sync
assert_traits::<ReusableBoxFuture<'a, Rc<()>>>();
}
#[test]
fn test_different_futures() {
let fut = async move { 10 };
// Not zero sized!
assert_eq!(Layout::for_value(&fut).size(), 1);
let mut b = ReusableBoxFuture::new(fut);
assert_eq!(b.get_pin().now_or_never(), Some(10));
b.try_set(async move { 20 })
.unwrap_or_else(|_| panic!("incorrect size"));
assert_eq!(b.get_pin().now_or_never(), Some(20));
b.try_set(async move { 30 })
.unwrap_or_else(|_| panic!("incorrect size"));
assert_eq!(b.get_pin().now_or_never(), Some(30));
}
#[test]
fn test_different_sizes() {
let fut1 = async move { 10 };
let val = [0u32; 1000];
let fut2 = async move { val[0] };
let fut3 = ZeroSizedFuture {};
assert_eq!(Layout::for_value(&fut1).size(), 1);
assert_eq!(Layout::for_value(&fut2).size(), 4004);
assert_eq!(Layout::for_value(&fut3).size(), 0);
let mut b = ReusableBoxFuture::new(fut1);
assert_eq!(b.get_pin().now_or_never(), Some(10));
b.set(fut2);
assert_eq!(b.get_pin().now_or_never(), Some(0));
b.set(fut3);
assert_eq!(b.get_pin().now_or_never(), Some(5));
}
struct ZeroSizedFuture {}
impl Future for ZeroSizedFuture {
type Output = u32;
fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<u32> {
Poll::Ready(5)
}
}
#[test]
fn test_zero_sized() {
let fut = ZeroSizedFuture {};
// Zero sized!
assert_eq!(Layout::for_value(&fut).size(), 0);
let mut b = ReusableBoxFuture::new(fut);
assert_eq!(b.get_pin().now_or_never(), Some(5));
assert_eq!(b.get_pin().now_or_never(), Some(5));
b.try_set(ZeroSizedFuture {})
.unwrap_or_else(|_| panic!("incorrect size"));
assert_eq!(b.get_pin().now_or_never(), Some(5));
assert_eq!(b.get_pin().now_or_never(), Some(5));
}
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