Struct Once

pub struct Once { /* private fields */ }

A low-level synchronization primitive for one-time global execution.

Useful for one-time initialization for FFI or related functionality. This type can only be constructed with Once::new().

Examples

use vexide::core::sync::Once;

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

START.call_once(|| {
    // run initialization here
});

Implementations

impl Once

pub const fn new() -> Self

Create a new uncompleted Once

pub fn is_completed(&self) -> bool

Returns true if call_once has been run.

pub async fn call_once<F: FnOnce()>(&self, fun: F)

Runs a closure if and only if this is the first time that call_once or try_call_once has been run.

This is useful for making sure that expensive initialization is only run once. This will block if another task is running a different initialization routine.

pub fn try_call_once<F: FnOnce()>(&self, fun: F) -> Result<(), TryCallOnceError>

Runs a closure if and only if this is the first time that call_once or try_call_once has been run.

Unlike call_once, this function will return an error rather than waiting for initialization.

Errors

This method will return TryCallOnceError if recursively called during the execution of F. This can only happen if F explicitly tries to call itself, or if using block_on to execute async code from within the function.

Trait Implementations

impl Debug for Once

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

Formats the value using the given formatter.