Add `smol` async runtime

5 files changed, 70 insertions, 3 deletions

diff --git a/futures/Cargo.toml b/futures/Cargo.toml
index 92b504a6..c42cc603 100644
--- a/futures/Cargo.toml
+++ b/futures/Cargo.toml
@@ -36,6 +36,10 @@ version = "1.0"
 optional = true
 features = ["unstable"]
 
+[target.'cfg(not(target_arch = "wasm32"))'.dependencies.smol]
+version = "1.0"
+optional = true
+
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 wasm-bindgen-futures = "0.4"
 
diff --git a/futures/src/executor.rs b/futures/src/executor.rs
index fa87216a..b35b5bc1 100644
--- a/futures/src/executor.rs
+++ b/futures/src/executor.rs
@@ -13,6 +13,9 @@ mod tokio_old;
 #[cfg(all(not(target_arch = "wasm32"), feature = "async-std"))]
 mod async_std;
 
+#[cfg(all(not(target_arch = "wasm32"), feature = "smol"))]
+mod smol;
+
 #[cfg(target_arch = "wasm32")]
 mod wasm_bindgen;
 
@@ -30,6 +33,9 @@ pub use self::tokio_old::TokioOld;
 #[cfg(all(not(target_arch = "wasm32"), feature = "async-std"))]
 pub use self::async_std::AsyncStd;
 
+#[cfg(all(not(target_arch = "wasm32"), feature = "smol"))]
+pub use self::smol::Smol;
+
 #[cfg(target_arch = "wasm32")]
 pub use wasm_bindgen::WasmBindgen;
 
diff --git a/futures/src/executor/smol.rs b/futures/src/executor/smol.rs
new file mode 100644
index 00000000..deafd43a
--- /dev/null
+++ b/futures/src/executor/smol.rs
@@ -0,0 +1,18 @@
+use crate::Executor;
+
+use futures::Future;
+
+/// A `smol` runtime.
+#[cfg_attr(docsrs, doc(cfg(feature = "smol")))]
+#[derive(Debug)]
+pub struct Smol;
+
+impl Executor for Smol {
+    fn new() -> Result<Self, futures::io::Error> {
+        Ok(Self)
+    }
+
+    fn spawn(&self, future: impl Future<Output = ()> + Send + 'static) {
+        smol::spawn(future).detach();
+    }
+}
diff --git a/futures/src/lib.rs b/futures/src/lib.rs
index c7c6fd3a..01cf5c89 100644
--- a/futures/src/lib.rs
+++ b/futures/src/lib.rs
@@ -17,10 +17,22 @@ pub mod executor;
 pub mod subscription;
 
 #[cfg(all(
-    any(feature = "tokio", feature = "tokio_old", feature = "async-std"),
+    any(
+        feature = "tokio",
+        feature = "tokio_old",
+        feature = "async-std",
+        feature = "smol"
+    ),
     not(target_arch = "wasm32")
 ))]
-#[cfg_attr(docsrs, doc(cfg(any(feature = "tokio", feature = "async-std"))))]
+#[cfg_attr(
+    docsrs,
+    doc(cfg(any(
+        feature = "tokio",
+        feature = "async-std",
+        feature = "smol"
+    )))
+)]
 pub mod time;
 
 pub use command::Command;
diff --git a/futures/src/time.rs b/futures/src/time.rs
index d015d2f0..86b4a4e7 100644
--- a/futures/src/time.rs
+++ b/futures/src/time.rs
@@ -13,6 +13,33 @@ pub fn every<H: std::hash::Hasher, E>(
 
 struct Every(std::time::Duration);
 
+#[cfg(all(
+    not(any(feature = "tokio_old", feature = "tokio", feature = "async-std")),
+    feature = "smol"
+))]
+impl<H, E> subscription::Recipe<H, E> for Every
+where
+    H: std::hash::Hasher,
+{
+    type Output = std::time::Instant;
+
+    fn hash(&self, state: &mut H) {
+        use std::hash::Hash;
+
+        std::any::TypeId::of::<Self>().hash(state);
+        self.0.hash(state);
+    }
+
+    fn stream(
+        self: Box<Self>,
+        _input: futures::stream::BoxStream<'static, E>,
+    ) -> futures::stream::BoxStream<'static, Self::Output> {
+        use futures::stream::StreamExt;
+
+        smol::Timer::interval(self.0).boxed()
+    }
+}
+
 #[cfg(feature = "async-std")]
 impl<H, E> subscription::Recipe<H, E> for Every
 where
@@ -41,7 +68,7 @@ where
 
 #[cfg(all(
     any(feature = "tokio", feature = "tokio_old"),
-    not(feature = "async-std")
+    not(any(feature = "async-std", feature = "smol"))
 ))]
 impl<H, E> subscription::Recipe<H, E> for Every
 where