Struct OnceNonZeroUsize 

pub struct OnceNonZeroUsize { /* private fields */ }

A thread-safe cell which can be written to only once.

Implementations

impl OnceNonZeroUsize

pub const fn new() -> OnceNonZeroUsize

Creates a new empty cell.

pub fn get(&self) -> Option<NonZero<usize>>

Gets the underlying value.

pub unsafe fn get_unchecked(&self) -> NonZero<usize>

Get the reference to the underlying value, without checking if the cell is initialized.

Safety

Caller must ensure that the cell is in initialized state, and that the contents are acquired by (synchronized to) this thread.

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

Sets the contents of this cell to value.

Returns Ok(()) if the cell was empty and Err(()) if it was full.

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

where F: FnOnce() -> NonZero<usize>,

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

If several threads concurrently run get_or_init, more than one f can be called. However, all threads will return the same value, produced by some f.

pub fn get_or_try_init<F, E>(&self, f: F) -> Result<NonZero<usize>, E>

where F: FnOnce() -> Result<NonZero<usize>, E>,

Gets the contents of the cell, initializing it with f if the cell was empty. If the cell was empty and f failed, an error is returned.

If several threads concurrently run get_or_init, more than one f can be called. However, all threads will return the same value, produced by some f.

Trait Implementations

impl Debug for OnceNonZeroUsize

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

Formats the value using the given formatter.

impl Default for OnceNonZeroUsize

fn default() -> OnceNonZeroUsize

Returns the “default value” for a type.