Struct OnceSlot 

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

A single-fire, wait-free async result cell.

The generalization of the PENDING-sentinel-AtomicI64 pattern used elsewhere in this crate, for results that aren’t a plain integer. See the module doc above for the exactly-once set contract.

Implementations

impl<T> OnceSlot<T>

pub const fn new() -> Self

An empty, not-yet-completed slot.

pub fn set(&self, value: T)

Complete this slot with value, waking whatever’s polling it. Must be called at most once per OnceSlot.

pub fn poll(&self, cx: &Context<'_>) -> Poll<T>

Poll for completion, registering cx’s waker if not yet complete.

Both checks swap the pointer out (not just load) before reconstructing the Box — polling again after an already-observed Ready is not something callers are expected to do (standard Future contract), but doing it anyway must not double-free, and a load-then-Box::from_raw on the fast path would leave a dangling non-null pointer behind for exactly that case.

Trait Implementations

impl<T> Default for OnceSlot<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T> Drop for OnceSlot<T>

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.

impl<T: Send> Send for OnceSlot<T>

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