-
Notifications
You must be signed in to change notification settings - Fork 63
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Add support for timers on web platforms
This commit adds support for async-io on wasm32-unknown-unknown. Not all features of async-io can be ported to WASM; for instance: - Async<T> can't be ported over as WASM doesn't really have a reactor. WASI could eventually be supported here, but that is dependent on smol-rs/polling#102 - block_on() can't be ported over, as blocking isn't allowed on the web. The only thing left is Timer, which can be implemented using setTimeout and setInterval. So that's what's been done: when the WASM target family is enabled, Async<T> and block_on() will be disabled and Timer will switch to an implementation that uses web timeouts. This is not a breaking change, as this crate previously failed to compile on web platforms anyways. This functionality currently does not support Node.js. Signed-off-by: John Nunley <dev@notgull.net>
- Loading branch information
Showing
8 changed files
with
331 additions
and
20 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,212 @@ | ||
| //! Timers for web targets. | ||
| //! | ||
| //! These use the `setTimeout` function on the web to handle timing. | ||
|
|
||
| use std::convert::TryInto; | ||
| use std::sync::atomic::{AtomicUsize, Ordering}; | ||
| use std::sync::Arc; | ||
| use std::task::{Context, Poll}; | ||
| use std::time::Duration; | ||
|
|
||
| use atomic_waker::AtomicWaker; | ||
| use wasm_bindgen::closure::Closure; | ||
| use wasm_bindgen::JsCast; | ||
|
|
||
| /// A timer for non-Web platforms. | ||
| /// | ||
| /// self registers a timeout in the global reactor, which in turn sets a timeout in the poll call. | ||
| #[derive(Debug)] | ||
| pub(super) struct Timer { | ||
| /// The waker to wake when the timer fires. | ||
| waker: Arc<State>, | ||
|
|
||
| /// The ongoing timeout or interval. | ||
| ongoing_timeout: TimerId, | ||
|
|
||
| /// Keep the closure alive so we don't drop it. | ||
| closure: Option<Closure<dyn FnMut()>>, | ||
| } | ||
|
|
||
| #[derive(Debug)] | ||
| struct State { | ||
| /// The number of times this timer has been woken. | ||
| woken: AtomicUsize, | ||
|
|
||
| /// The waker to wake when the timer fires. | ||
| waker: AtomicWaker, | ||
| } | ||
|
|
||
| #[derive(Debug)] | ||
| enum TimerId { | ||
| NoTimer, | ||
| Timeout(i32), | ||
| Interval(i32), | ||
| } | ||
|
|
||
| impl Timer { | ||
| /// Create a timer that will never fire. | ||
| #[inline] | ||
| pub(super) fn never() -> Self { | ||
| Self { | ||
| waker: Arc::new(State { | ||
| woken: AtomicUsize::new(0), | ||
| waker: AtomicWaker::new(), | ||
| }), | ||
| ongoing_timeout: TimerId::NoTimer, | ||
| closure: None, | ||
| } | ||
| } | ||
|
|
||
| /// Create a timer that will fire at the given instant. | ||
| #[inline] | ||
| pub(super) fn after(duration: Duration) -> Timer { | ||
| let mut this = Self::never(); | ||
| this.set_after(duration); | ||
| this | ||
| } | ||
|
|
||
| /// Create a timer that will fire at the given instant. | ||
| #[inline] | ||
| pub(super) fn interval(period: Duration) -> Timer { | ||
| let mut this = Self::never(); | ||
| this.set_interval(period); | ||
| this | ||
| } | ||
|
|
||
| /// Returns `true` if self timer will fire at some point. | ||
| #[inline] | ||
| pub(super) fn will_fire(&self) -> bool { | ||
| matches!( | ||
| self.ongoing_timeout, | ||
| TimerId::Timeout(_) | TimerId::Interval(_) | ||
| ) | ||
| } | ||
|
|
||
| /// Set the timer to fire after the given duration. | ||
| #[inline] | ||
| pub(super) fn set_after(&mut self, duration: Duration) { | ||
| // Set the timeout. | ||
| let id = { | ||
| let waker = self.waker.clone(); | ||
| let closure: Closure<dyn FnMut()> = Closure::wrap(Box::new(move || { | ||
| waker.wake(); | ||
| })); | ||
|
|
||
| let result = web_sys::window() | ||
| .unwrap() | ||
| .set_timeout_with_callback_and_timeout_and_arguments_0( | ||
| closure.as_ref().unchecked_ref(), | ||
| duration.as_millis().try_into().expect("timeout too long"), | ||
| ); | ||
|
|
||
| // Make sure we don't drop the closure before it's called. | ||
| self.closure = Some(closure); | ||
|
|
||
| match result { | ||
| Ok(id) => id, | ||
| Err(_) => { | ||
| panic!("failed to set timeout") | ||
| } | ||
| } | ||
| }; | ||
|
|
||
| // Set our ID. | ||
| self.ongoing_timeout = TimerId::Timeout(id); | ||
| } | ||
|
|
||
| /// Set the timer to emit events periodically. | ||
| #[inline] | ||
| pub(super) fn set_interval(&mut self, period: Duration) { | ||
| // Set the timeout. | ||
| let id = { | ||
| let waker = self.waker.clone(); | ||
| let closure: Closure<dyn FnMut()> = Closure::wrap(Box::new(move || { | ||
| waker.wake(); | ||
| })); | ||
|
|
||
| let result = web_sys::window() | ||
| .unwrap() | ||
| .set_interval_with_callback_and_timeout_and_arguments_0( | ||
| closure.as_ref().unchecked_ref(), | ||
| period.as_millis().try_into().expect("timeout too long"), | ||
| ); | ||
|
|
||
| // Make sure we don't drop the closure before it's called. | ||
| self.closure = Some(closure); | ||
|
|
||
| match result { | ||
| Ok(id) => id, | ||
| Err(_) => { | ||
| panic!("failed to set interval") | ||
| } | ||
| } | ||
| }; | ||
|
|
||
| // Set our ID. | ||
| self.ongoing_timeout = TimerId::Interval(id); | ||
| } | ||
|
|
||
| /// Poll for the next timer event. | ||
| #[inline] | ||
| pub(super) fn poll_next(&mut self, cx: &mut Context<'_>) -> Poll<Option<()>> { | ||
| let mut registered = false; | ||
| let mut woken = self.waker.woken.load(Ordering::Acquire); | ||
|
|
||
| loop { | ||
| if woken > 0 { | ||
| // Try to decrement the number of woken events. | ||
| if let Err(new_woken) = self.waker.woken.compare_exchange( | ||
| woken, | ||
| woken - 1, | ||
| Ordering::SeqCst, | ||
| Ordering::Acquire, | ||
| ) { | ||
| woken = new_woken; | ||
| continue; | ||
| } | ||
|
|
||
| // If we are using a one-shot timer, clear it. | ||
| if let TimerId::Timeout(_) = self.ongoing_timeout { | ||
| self.clear(); | ||
| } | ||
|
|
||
| return Poll::Ready(Some(())); | ||
| } | ||
|
|
||
| if !registered { | ||
| // Register the waker. | ||
| self.waker.waker.register(cx.waker()); | ||
| registered = true; | ||
| } else { | ||
| // We've already registered, so we can just return pending. | ||
| return Poll::Pending; | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /// Clear the current timeout. | ||
| fn clear(&mut self) { | ||
| match self.ongoing_timeout { | ||
| TimerId::NoTimer => {} | ||
| TimerId::Timeout(id) => { | ||
| web_sys::window().unwrap().clear_timeout_with_handle(id); | ||
| } | ||
| TimerId::Interval(id) => { | ||
| web_sys::window().unwrap().clear_interval_with_handle(id); | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| impl State { | ||
| fn wake(&self) { | ||
| self.woken.fetch_add(1, Ordering::SeqCst); | ||
| self.waker.wake(); | ||
| } | ||
| } | ||
|
|
||
| impl Drop for Timer { | ||
| fn drop(&mut self) { | ||
| self.clear(); | ||
| } | ||
| } |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,3 +1,5 @@ | ||
| #![cfg(not(target_family = "wasm"))] | ||
|
|
||
| use async_io::block_on; | ||
| use std::{ | ||
| future::Future, | ||
|
|
||
Oops, something went wrong.