Struct FutureReader

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

Available on crate features runtime and component-model and component-model-async only.

Represents the readable end of a Component Model future.

Note that FutureReader instances must be disposed of using either read or close; otherwise the in-store representation will leak and the writer end will hang indefinitely. Consider using GuardedFutureReader to ensure that disposal happens automatically.

Implementations

impl<T> FutureReader<T>

pub async fn read(self, accessor: impl AsAccessor) -> Option<T>

where T: Lift + Send + 'static,

Read the value from this future.

The returned Future will yield Err if the guest has trapped before it could produce a result.

The [Accessor] provided can be acquired from Instance::run_concurrent or from within a host function for example.

Panics

Panics if the store that the [Accessor] is derived from does not own this future.

pub async fn watch_writer(&mut self, accessor: impl AsAccessor)

Wait for the write end of this future to be dropped.

The [Accessor] provided can be acquired from Instance::run_concurrent or from within a host function for example.

Panics

Panics if the store that the [Accessor] is derived from does not own this future.

pub fn into_val(self) -> Val

Convert this FutureReader into a Val.

pub fn from_val( store: impl AsContextMut<Data: Send>, instance: Instance, value: &Val, ) -> Result<Self>

Attempt to convert the specified Val to a FutureReader.

pub fn close(&mut self, store: impl AsContextMut)

Close this FutureReader, writing the default value.

Panics

Panics if the store that the [Accessor] is derived from does not own this future. Usage of this future after calling close will also cause a panic.

pub fn close_with(&mut self, accessor: impl AsAccessor)

Convenience method around Self::close.

pub fn guard<A>(self, accessor: A) -> GuardedFutureReader<T, A>

where A: AsAccessor,

Returns a GuardedFutureReader which will auto-close this future on drop and clean it up from the store.

Note that the accessor provided must own this future and is additionally transferred to the GuardedFutureReader return value.

Trait Implementations

impl<T> Debug for FutureReader<T>

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

Formats the value using the given formatter.

impl<T, A> From<GuardedFutureReader<T, A>> for FutureReader<T>

where A: AsAccessor,

fn from(guard: GuardedFutureReader<T, A>) -> Self

Converts to this type from the input type.

impl<T: Send + Sync> ComponentType for FutureReader<T>

impl<T: Send + Sync> Lift for FutureReader<T>

impl<T: Send + Sync> Lower for FutureReader<T>