pub struct LazyLock<T, F = fn() -> T> { /* private fields */ }
Expand description
A value which is initialized on the first access.
This type is a thread-safe Lazy
, and can be used in statics.
Examples
#![feature(once_cell)]
use std::collections::HashMap;
use std::sync::LazyLock;
static HASHMAP: LazyLock<HashMap<i32, String>> = LazyLock::new(|| {
println!("initializing");
let mut m = HashMap::new();
m.insert(13, "Spica".to_string());
m.insert(74, "Hoyten".to_string());
m
});
fn main() {
println!("ready");
std::thread::spawn(|| {
println!("{:?}", HASHMAP.get(&13));
}).join().unwrap();
println!("{:?}", HASHMAP.get(&74));
// Prints:
// ready
// initializing
// Some("Spica")
// Some("Hoyten")
}
RunImplementations
Trait Implementations
impl<T, F: UnwindSafe> RefUnwindSafe for LazyLock<T, F> where
OnceLock<T>: RefUnwindSafe,
impl<T, F: Send> Sync for LazyLock<T, F> where
OnceLock<T>: Sync,
impl<T, F: UnwindSafe> UnwindSafe for LazyLock<T, F> where
OnceLock<T>: UnwindSafe,
Auto Trait Implementations
impl<T, F> Send for LazyLock<T, F> where
F: Send,
T: Send,
impl<T, F> Unpin for LazyLock<T, F> where
F: Unpin,
T: Unpin,
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more