Struct OnceLock 

pub(crate) struct OnceLock<T> {
    once: Once,
    value: UnsafeCell<MaybeUninit<T>>,
}

Fields

once: Once

value: UnsafeCell<MaybeUninit<T>>

Implementations

impl<T> OnceLock<T>

pub(crate) const fn new() -> Self

Creates a new empty cell.

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

where F: FnOnce() -> T,

Gets the contents of the cell, initializing it with f if the cell was empty.

Many threads may call get_or_init concurrently with different initializing functions, but it is guaranteed that only one function will be executed.

Panics

If f panics, the panic is propagated to the caller, and the cell remains uninitialized.

It is an error to reentrantly initialize the cell from f. The exact outcome is unspecified. Current implementation deadlocks, but this may be changed to a panic in the future.

fn initialize<F>(&self, f: F)

where F: FnOnce() -> T,

unsafe fn get_unchecked(&self) -> &T

Safety

The value must be initialized

Trait Implementations

impl<T> Drop for OnceLock<T>

fn drop(&mut self)

Executes the destructor for this type.

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

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