std::sync::OnceState - Rust
Description: API documentation for the Rust `OnceState` struct in crate `std`.
Keywords: rust, rustlang, rust-lang, OnceState

# Struct std::sync::OnceState[−][src]

    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`

[src]

####

`pub fn poisoned(&self) -> bool`

[src]

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

Returns whether 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());
    });Run

An unpoisoned `Once`:

    #![feature(once_poison)]

    use std::sync::Once;

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

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

## Trait Implementations

###

`impl Debug for OnceState`

[src]

####

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

[src]

Formats the value using the given formatter. Read more

## Auto Trait Implementations

###

`impl Send for OnceState`

###

`impl Sync for OnceState`

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