Function futures::future::always_ready
source · pub fn always_ready<T, F>(prod: F) -> AlwaysReady<T, F> ⓘwhere
F: Fn() -> T,
Expand description
Creates a future that is always immediately ready with a value.
This is particularly useful in avoiding a heap allocation when an API needs [Box<dyn Future<Output = T>>
],
as AlwaysReady
does not have to store a boolean for is_finished
.
§Examples
use std::mem::size_of_val;
use futures::future;
let a = future::always_ready(|| 1);
assert_eq!(size_of_val(&a), 0);
assert_eq!(a.await, 1);
assert_eq!(a.await, 1);