Struct std::sync::OnceState

pub struct OnceState { /* fields omitted */ }

🔬 This is a nightly-only experimental API. (once_poison #33577)

State yielded to call_once_force’s closure parameter. The state can be used to query the poison status of the Once.

Methods

impl OnceState

pub fn poisoned(&self) -> bool

🔬 This is a nightly-only experimental API. (once_poison #33577)

Returns true if the associated Once was poisoned prior to the invocation of the closure passed to call_once_force.

Examples

A poisoned Once:

#![feature(once_poison)]

use std::sync::Once;
use std::thread;

static INIT: Once = Once::new();

// poison the once
let handle = thread::spawn(|| {
    INIT.call_once(|| panic!());
});
assert!(handle.join().is_err());

INIT.call_once_force(|state| {
    assert!(state.poisoned());
});

An unpoisoned Once:

#![feature(once_poison)]

use std::sync::Once;

static INIT: Once = Once::new();

INIT.call_once_force(|state| {
    assert!(!state.poisoned());
});

Trait Implementations

impl Debug for OnceState

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.