Struct OnceLock 

pub struct OnceLock<T> { /* private fields */ }

A synchronization primitive for one-time initialization.

Uses a three-state atomic with compare_exchange to ensure exactly one thread performs initialization.

Implementations

impl<T> OnceLock<T>

pub const fn new() -> Self

Creates a new empty OnceLock.

pub fn get(&self) -> Option<&T>

Returns Some(&value) if initialized, None otherwise.

pub fn set(&self, value: T) -> Result<(), T>

Initializes the cell with value if not yet initialized.

pub fn get_or_init<F>(&self, f: F) -> &T

where F: FnOnce() -> T,

Initializes the cell with the result of f if not yet initialized, then returns a reference to the value.

Trait Implementations

impl<T> Default for OnceLock<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T: Send> Send for OnceLock<T>

impl<T: Send> Sync for OnceLock<T>