Support for wasm32-unknown-unknown

Cargo.toml

@@ -13,7 +13,15 @@ Timeouts for futures.
 """
 
 [dependencies]
+gloo-timers = { version = "0.2.0", features = ["futures"], optional = true }
+send_wrapper = { version = "0.4.0", optional = true }
 
 [dev-dependencies]
 async-std = { version = "1.0.1", features = ["attributes"] }
 futures = "0.3.1"
+
+[features]
+wasm-bindgen = [
+	"gloo-timers",
+	"send_wrapper"
+]

src/delay.rs

@@ -25,7 +25,6 @@ use crate::{ScheduledTimer, TimerHandle};
 /// at.
 pub struct Delay {
     state: Option<Arc<Node<ScheduledTimer>>>,
-    when: Instant,
 }
 
 impl Delay {
@@ -38,25 +37,14 @@ impl Delay {
         Delay::new_handle(Instant::now() + dur, Default::default())
     }
 
-    /// Return the `Instant` when this delay will fire.
-    #[inline]
-    pub fn when(&self) -> Instant {
-        self.when
-    }
-
     /// Creates a new future which will fire at the time specified by `at`.
     ///
     /// The returned instance of `Delay` will be bound to the timer specified by
     /// the `handle` argument.
     pub(crate) fn new_handle(at: Instant, handle: TimerHandle) -> Delay {
         let inner = match handle.inner.upgrade() {
             Some(i) => i,
-            None => {
-                return Delay {
-                    state: None,
-                    when: at,
-                }
-            }
+            None => return Delay { state: None },
         };
         let state = Arc::new(Node::new(ScheduledTimer {
             at: Mutex::new(Some(at)),
@@ -70,30 +58,23 @@ impl Delay {
         // timer, meaning that we'll want to immediately return an error from
         // `poll`.
         if inner.list.push(&state).is_err() {
-            return Delay {
-                state: None,
-                when: at,
-            };
+            return Delay { state: None };
         }
 
         inner.waker.wake();
-        Delay {
-            state: Some(state),
-            when: at,
-        }
+        Delay { state: Some(state) }
     }
 
     /// Resets this timeout to an new timeout which will fire at the time
     /// specified by `at`.
     #[inline]
-    pub fn reset(&mut self, at: Instant) {
-        self.when = at;
-        if self._reset(self.when).is_err() {
+    pub fn reset(&mut self, delay: Duration) {
+        if self._reset(delay).is_err() {
             self.state = None
         }
     }
 
-    fn _reset(&mut self, at: Instant) -> Result<(), ()> {
+    fn _reset(&mut self, delay: Duration) -> Result<(), ()> {
         let state = match self.state {
             Some(ref state) => state,
             None => return Err(()),
@@ -111,7 +92,7 @@ impl Delay {
                     Err(s) => bits = s,
                 }
             }
-            *state.at.lock().unwrap() = Some(at);
+            *state.at.lock().unwrap() = Some(Instant::now() + delay);
             // If we fail to push our node then we've become an inert timer, so
             // we'll want to clear our `state` field accordingly
             timeouts.list.push(state)?;
@@ -165,6 +146,6 @@ impl Drop for Delay {
 
 impl fmt::Debug for Delay {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-        f.debug_struct("Delay").field("when", &self.when).finish()
+        f.debug_struct("Delay").finish()
     }
 }

src/delay_wasm.rs

@@ -0,0 +1,36 @@
+//! A version of `Delay` that works on wasm.
+
+use gloo_timers::future::TimeoutFuture;
+use send_wrapper::SendWrapper;
+use std::{
+    future::Future,
+    pin::Pin,
+    task::{Context, Poll},
+    time::Duration,
+};
+
+/// A version of `Delay` that works on wasm.
+#[derive(Debug)]
+pub struct Delay(SendWrapper<TimeoutFuture>);
+
+impl Delay {
+    /// Creates a new future which will fire at `dur` time into the future.
+    #[inline]
+    pub fn new(dur: Duration) -> Delay {
+        Self(SendWrapper::new(TimeoutFuture::new(dur.as_millis() as u32)))
+    }
+
+    /// Resets the timeout. Panics on wasm.
+    #[inline]
+    pub fn reset(&mut self, at: Duration) {
+        *self = Delay::new(at);
+    }
+}
+
+impl Future for Delay {
+    type Output = ();
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
+        Pin::new(&mut *Pin::into_inner(self).0).poll(cx)
+    }
+}

src/lib.rs

@@ -18,7 +18,10 @@
 
 mod arc_list;
 mod atomic_waker;
+#[cfg(not(all(target_arch = "wasm32", feature = "wasm-bindgen")))]
 mod delay;
+#[cfg(all(target_arch = "wasm32", feature = "wasm-bindgen"))]
+mod delay_wasm;
 mod global;
 mod heap;
 mod heap_timer;
@@ -30,4 +33,7 @@ use heap::{Heap, Slot};
 use heap_timer::HeapTimer;
 use timer::{ScheduledTimer, Timer, TimerHandle};
 
+#[cfg(not(all(target_arch = "wasm32", feature = "wasm-bindgen")))]
 pub use self::delay::Delay;
+#[cfg(all(target_arch = "wasm32", feature = "wasm-bindgen"))]
+pub use self::delay_wasm::Delay;

tests/smoke.rs

@@ -24,7 +24,7 @@ async fn reset() -> Result<(), Box<dyn Error + Send + Sync + 'static>> {
     assert!(i.elapsed() > dur);
 
     let i = Instant::now();
-    d.reset(Instant::now() + dur);
+    d.reset(dur);
     d.await;
     assert!(i.elapsed() > dur);
     Ok(())