Struct UniqueArc

pub struct UniqueArc<T: ?Sized>(/* private fields */);

An Arc that is known to be uniquely owned

When Arcs are constructed, they are known to be uniquely owned. In such a case it is safe to mutate the contents of the Arc. Normally, one would just handle this by mutating the data on the stack before allocating the Arc, however it’s possible the data is large or unsized and you need to heap-allocate it earlier in such a way that it can be freely converted into a regular Arc once you’re done.

UniqueArc exists for this purpose, when constructed it performs the same allocations necessary for an Arc, however it allows mutable access. Once the mutation is finished, you can call .shareable() and get a regular Arc out of it.

let data = [1, 2, 3, 4, 5];
let mut x = UniqueArc::new(data);
x[4] = 7; // mutate!
let y = x.shareable(); // y is an Arc<T>

Implementations

impl<T> UniqueArc<T>

pub fn new(data: T) -> Self

Construct a new UniqueArc

pub fn new_uninit() -> UniqueArc<MaybeUninit<T>>

Construct an uninitialized arc

pub fn into_inner(this: Self) -> T

Gets the inner value of the unique arc

impl<T: ?Sized> UniqueArc<T>

pub fn shareable(self) -> Arc<T>

Convert to a shareable Arc<T> once we’re done mutating it

impl<T> UniqueArc<MaybeUninit<T>>

pub fn write(&mut self, val: T) -> &mut T

Calls MaybeUninit::write on the contained value.

pub fn as_mut_ptr(&mut self) -> *mut MaybeUninit<T>

Obtain a mutable pointer to the stored MaybeUninit<T>.

pub unsafe fn assume_init(this: Self) -> UniqueArc<T>

Convert to an initialized Arc.

Safety

This function is equivalent to MaybeUninit::assume_init and has the same safety requirements. You are responsible for ensuring that the T has actually been initialized before calling this method.

impl<T> UniqueArc<[MaybeUninit<T>]>

pub fn new_uninit_slice(len: usize) -> Self

Create an Arc contains an array [MaybeUninit<T>] of len.

pub unsafe fn assume_init_slice(Self: Self) -> UniqueArc<[T]>

Safety

Must initialize all fields before calling this function.

impl<H, T> UniqueArc<HeaderSlice<H, [MaybeUninit<T>]>>

pub fn from_header_and_uninit_slice(header: H, len: usize) -> Self

Creates an Arc for a HeaderSlice using the given header struct and allocated space for an unitialized slice of length len.

pub unsafe fn assume_init_slice_with_header( self, ) -> UniqueArc<HeaderSlice<H, [T]>>

Safety

Must initialize all fields before calling this function.

Trait Implementations

impl<T: ?Sized> Deref for UniqueArc<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T: ?Sized> DerefMut for UniqueArc<T>

fn deref_mut(&mut self) -> &mut T

Mutably dereferences the value.

impl<A> FromIterator<A> for UniqueArc<[A]>

fn from_iter<T: IntoIterator<Item = A>>(iter: T) -> Self

Creates a value from an iterator.

impl<T: ?Sized> TryFrom<Arc<T>> for UniqueArc<T>

type Error = Arc<T>

The type returned in the event of a conversion error.

fn try_from(arc: Arc<T>) -> Result<Self, Self::Error>

Performs the conversion.

impl<T: ?Sized + Send> Send for UniqueArc<T>

impl<T: ?Sized + Sync> Sync for UniqueArc<T>