Struct OnceState

pub struct OnceState { /* private fields */ }

Available on crate feature std only.

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

Implementations

impl OnceState

pub fn is_poisoned(&self) -> bool

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

Examples

A poisoned Once:

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.is_poisoned());
});

An unpoisoned Once:

use std::sync::Once;

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

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

Trait Implementations

impl Debug for OnceState

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.