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use super::{Compat, Future01CompatExt};
use crate::{
future::{FutureExt, TryFutureExt, UnitError},
task::SpawnExt,
};
use futures_01::future::{ExecuteError as ExecuteError01, Executor as Executor01};
use futures_01::Future as Future01;
use futures_task::{FutureObj, Spawn as Spawn03, SpawnError as SpawnError03};
/// A future that can run on a futures 0.1
/// [`Executor`](futures_01::future::Executor).
pub type Executor01Future = Compat<UnitError<FutureObj<'static, ()>>>;
/// Extension trait for futures 0.1 [`Executor`](futures_01::future::Executor).
pub trait Executor01CompatExt: Executor01<Executor01Future> + Clone + Send + 'static {
/// Converts a futures 0.1 [`Executor`](futures_01::future::Executor) into a
/// futures 0.3 [`Spawn`](futures_task::Spawn).
///
/// ```
/// # if cfg!(miri) { return; } // Miri does not support epoll
/// use futures::task::SpawnExt;
/// use futures::future::{FutureExt, TryFutureExt};
/// use futures_util::compat::Executor01CompatExt;
/// use tokio::executor::DefaultExecutor;
///
/// # let (tx, rx) = futures::channel::oneshot::channel();
///
/// let spawner = DefaultExecutor::current().compat();
/// let future03 = async move {
/// println!("Running on the pool");
/// spawner.spawn(async {
/// println!("Spawned!");
/// # tx.send(42).unwrap();
/// }).unwrap();
/// };
///
/// let future01 = future03.unit_error().boxed().compat();
///
/// tokio::run(future01);
/// # futures::executor::block_on(rx).unwrap();
/// ```
fn compat(self) -> Executor01As03<Self>
where
Self: Sized;
}
impl<Ex> Executor01CompatExt for Ex
where
Ex: Executor01<Executor01Future> + Clone + Send + 'static,
{
fn compat(self) -> Executor01As03<Self> {
Executor01As03 { executor01: self }
}
}
/// Converts a futures 0.1 [`Executor`](futures_01::future::Executor) into a
/// futures 0.3 [`Spawn`](futures_task::Spawn).
#[derive(Debug, Clone)]
pub struct Executor01As03<Ex> {
executor01: Ex,
}
impl<Ex> Spawn03 for Executor01As03<Ex>
where
Ex: Executor01<Executor01Future> + Clone + Send + 'static,
{
fn spawn_obj(&self, future: FutureObj<'static, ()>) -> Result<(), SpawnError03> {
let future = future.unit_error().compat();
self.executor01.execute(future).map_err(|_| SpawnError03::shutdown())
}
}
impl<Sp, Fut> Executor01<Fut> for Compat<Sp>
where
for<'a> &'a Sp: Spawn03,
Fut: Future01<Item = (), Error = ()> + Send + 'static,
{
fn execute(&self, future: Fut) -> Result<(), ExecuteError01<Fut>> {
(&self.inner)
.spawn(future.compat().map(|_| ()))
.expect("unable to spawn future from Compat executor");
Ok(())
}
}