blob: 509556e219885de42f8214492b5a541a2177e42b [file] [log] [blame]
use futures_core::task::{LocalSpawn, Spawn};
if_std! {
use crate::future::{FutureExt, RemoteHandle};
use futures_core::future::{Future, FutureObj, LocalFutureObj};
use futures_core::task::SpawnError;
}
impl<Sp: ?Sized> SpawnExt for Sp where Sp: Spawn {}
impl<Sp: ?Sized> LocalSpawnExt for Sp where Sp: LocalSpawn {}
/// Extension trait for `Spawn`.
pub trait SpawnExt: Spawn {
/// Spawns a task that polls the given future with output `()` to
/// completion.
///
/// This method returns a [`Result`] that contains a [`SpawnError`] if
/// spawning fails.
///
/// You can use [`spawn_with_handle`](SpawnExt::spawn_with_handle) if
/// you want to spawn a future with output other than `()` or if you want
/// to be able to await its completion.
///
/// Note this method will eventually be replaced with the upcoming
/// `Spawn::spawn` method which will take a `dyn Future` as input.
/// Technical limitations prevent `Spawn::spawn` from being implemented
/// today. Feel free to use this method in the meantime.
///
/// ```
/// #![feature(async_await, await_macro, futures_api)]
/// use futures::executor::ThreadPool;
/// use futures::task::SpawnExt;
///
/// let mut executor = ThreadPool::new().unwrap();
///
/// let future = async { /* ... */ };
/// executor.spawn(future).unwrap();
/// ```
#[cfg(feature = "std")]
fn spawn<Fut>(&mut self, future: Fut) -> Result<(), SpawnError>
where
Fut: Future<Output = ()> + Send + 'static,
{
self.spawn_obj(FutureObj::new(Box::new(future)))
}
/// Spawns a task that polls the given future to completion and returns a
/// future that resolves to the spawned future's output.
///
/// This method returns a [`Result`] that contains a [`RemoteHandle`], or, if
/// spawning fails, a [`SpawnError`]. [`RemoteHandle`] is a future that
/// resolves to the output of the spawned future.
///
/// ```
/// #![feature(async_await, await_macro, futures_api)]
/// use futures::executor::ThreadPool;
/// use futures::future;
/// use futures::task::SpawnExt;
///
/// let mut executor = ThreadPool::new().unwrap();
///
/// let future = future::ready(1);
/// let join_handle_fut = executor.spawn_with_handle(future).unwrap();
/// assert_eq!(executor.run(join_handle_fut), 1);
/// ```
#[cfg(feature = "std")]
fn spawn_with_handle<Fut>(
&mut self,
future: Fut
) -> Result<RemoteHandle<Fut::Output>, SpawnError>
where
Fut: Future + Send + 'static,
Fut::Output: Send,
{
let (future, handle) = future.remote_handle();
self.spawn(future)?;
Ok(handle)
}
}
/// Extension trait for `LocalSpawn`.
pub trait LocalSpawnExt: LocalSpawn {
/// Spawns a task that polls the given future with output `()` to
/// completion.
///
/// This method returns a [`Result`] that contains a [`SpawnError`] if
/// spawning fails.
///
/// You can use [`spawn_with_handle`](SpawnExt::spawn_with_handle) if
/// you want to spawn a future with output other than `()` or if you want
/// to be able to await its completion.
///
/// Note this method will eventually be replaced with the upcoming
/// `Spawn::spawn` method which will take a `dyn Future` as input.
/// Technical limitations prevent `Spawn::spawn` from being implemented
/// today. Feel free to use this method in the meantime.
///
/// ```
/// #![feature(async_await, await_macro, futures_api)]
/// use futures::executor::LocalPool;
/// use futures::task::LocalSpawnExt;
///
/// let executor = LocalPool::new();
/// let mut spawner = executor.spawner();
///
/// let future = async { /* ... */ };
/// spawner.spawn_local(future).unwrap();
/// ```
#[cfg(feature = "std")]
fn spawn_local<Fut>(&mut self, future: Fut) -> Result<(), SpawnError>
where
Fut: Future<Output = ()> + 'static,
{
self.spawn_local_obj(LocalFutureObj::new(Box::new(future)))
}
/// Spawns a task that polls the given future to completion and returns a
/// future that resolves to the spawned future's output.
///
/// This method returns a [`Result`] that contains a [`RemoteHandle`], or, if
/// spawning fails, a [`SpawnError`]. [`RemoteHandle`] is a future that
/// resolves to the output of the spawned future.
///
/// ```
/// #![feature(async_await, await_macro, futures_api)]
/// use futures::executor::LocalPool;
/// use futures::future;
/// use futures::task::LocalSpawnExt;
///
/// let mut executor = LocalPool::new();
/// let mut spawner = executor.spawner();
///
/// let future = future::ready(1);
/// let join_handle_fut = spawner.spawn_local_with_handle(future).unwrap();
/// assert_eq!(executor.run_until(join_handle_fut), 1);
/// ```
#[cfg(feature = "std")]
fn spawn_local_with_handle<Fut>(
&mut self,
future: Fut
) -> Result<RemoteHandle<Fut::Output>, SpawnError>
where
Fut: Future + 'static,
{
let (future, handle) = future.remote_handle();
self.spawn_local(future)?;
Ok(handle)
}
}