1 use super::{Compat, Future01CompatExt};
2 use crate::{
3     future::{FutureExt, TryFutureExt, UnitError},
4     task::SpawnExt,
5 };
6 use futures_01::future::{ExecuteError as ExecuteError01, Executor as Executor01};
7 use futures_01::Future as Future01;
8 use futures_task::{FutureObj, Spawn as Spawn03, SpawnError as SpawnError03};
9 
10 /// A future that can run on a futures 0.1
11 /// [`Executor`](futures_01::future::Executor).
12 pub type Executor01Future = Compat<UnitError<FutureObj<'static, ()>>>;
13 
14 /// Extension trait for futures 0.1 [`Executor`](futures_01::future::Executor).
15 pub trait Executor01CompatExt: Executor01<Executor01Future> + Clone + Send + 'static {
16     /// Converts a futures 0.1 [`Executor`](futures_01::future::Executor) into a
17     /// futures 0.3 [`Spawn`](futures_task::Spawn).
18     ///
19     /// ```
20     /// use futures::task::SpawnExt;
21     /// use futures::future::{FutureExt, TryFutureExt};
22     /// use futures_util::compat::Executor01CompatExt;
23     /// use tokio::executor::DefaultExecutor;
24     ///
25     /// # let (tx, rx) = futures::channel::oneshot::channel();
26     ///
27     /// let spawner = DefaultExecutor::current().compat();
28     /// let future03 = async move {
29     ///     println!("Running on the pool");
30     ///     spawner.spawn(async {
31     ///         println!("Spawned!");
32     ///         # tx.send(42).unwrap();
33     ///     }).unwrap();
34     /// };
35     ///
36     /// let future01 = future03.unit_error().boxed().compat();
37     ///
38     /// tokio::run(future01);
39     /// # futures::executor::block_on(rx).unwrap();
40     /// ```
compat(self) -> Executor01As03<Self> where Self: Sized41     fn compat(self) -> Executor01As03<Self>
42     where
43         Self: Sized;
44 }
45 
46 impl<Ex> Executor01CompatExt for Ex
47 where
48     Ex: Executor01<Executor01Future> + Clone + Send + 'static,
49 {
compat(self) -> Executor01As03<Self>50     fn compat(self) -> Executor01As03<Self> {
51         Executor01As03 { executor01: self }
52     }
53 }
54 
55 /// Converts a futures 0.1 [`Executor`](futures_01::future::Executor) into a
56 /// futures 0.3 [`Spawn`](futures_task::Spawn).
57 #[derive(Debug, Clone)]
58 pub struct Executor01As03<Ex> {
59     executor01: Ex,
60 }
61 
62 impl<Ex> Spawn03 for Executor01As03<Ex>
63 where
64     Ex: Executor01<Executor01Future> + Clone + Send + 'static,
65 {
spawn_obj(&self, future: FutureObj<'static, ()>) -> Result<(), SpawnError03>66     fn spawn_obj(&self, future: FutureObj<'static, ()>) -> Result<(), SpawnError03> {
67         let future = future.unit_error().compat();
68 
69         self.executor01.execute(future).map_err(|_| SpawnError03::shutdown())
70     }
71 }
72 
73 #[allow(single_use_lifetimes)] // https://github.com/rust-lang/rust/issues/55058
74 impl<Sp, Fut> Executor01<Fut> for Compat<Sp>
75 where
76     for<'a> &'a Sp: Spawn03,
77     Fut: Future01<Item = (), Error = ()> + Send + 'static,
78 {
execute(&self, future: Fut) -> Result<(), ExecuteError01<Fut>>79     fn execute(&self, future: Fut) -> Result<(), ExecuteError01<Fut>> {
80         (&self.inner)
81             .spawn(future.compat().map(|_| ()))
82             .expect("unable to spawn future from Compat executor");
83         Ok(())
84     }
85 }
86