kithara-platform 0.0.1-alpha4

Cross-platform primitives (sync, time, thread) for native and wasm32.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45

use std::pin::pin;

use futures::future::{self as future_util, Either};
use js_sys::{Function, Promise, Reflect, global};
use wasm_bindgen::{JsCast, JsValue};
use wasm_bindgen_futures::JsFuture;

pub use crate::common::time::{Duration, Instant, SystemTime, TimeoutError};

pub async fn sleep(duration: Duration) {
    let ms = i32::try_from(duration.as_millis()).unwrap_or(i32::MAX);
    let promise = Promise::new(&mut |resolve, _| {
        let set_timeout: Function = Reflect::get(&global(), &JsValue::from_str("setTimeout"))
            .expect("BUG: setTimeout is a standard browser global, must always exist")
            .unchecked_into();
        let _ = set_timeout.call2(&JsValue::UNDEFINED, &resolve, &JsValue::from(ms));
    });
    let _ = JsFuture::from(promise).await;
}

/// Coarse `Date.now()` timestamp in milliseconds, safe in every wasm scope.
///
/// Unlike [`Instant`] (which reads `performance.now()` and traps in an
/// `AudioWorkletGlobalScope`, where `performance` is undefined), `Date.now()`
/// is valid on the audio render thread. wasm-only: native code with the same
/// need should use [`Instant`] directly, which is cheap there. Coarse
/// (millisecond, wall-clock) — for second-scale deadlines, not precise
/// interval timing.
#[must_use]
pub fn coarse_now_ms() -> f64 {
    js_sys::Date::now()
}

pub async fn timeout<F>(duration: Duration, future: F) -> Result<F::Output, TimeoutError>
where
    F: Future,
{
    let deadline = pin!(sleep(duration));
    let work = pin!(future);

    match future_util::select(work, deadline).await {
        Either::Left((output, _)) => Ok(output),
        Either::Right(((), _)) => Err(TimeoutError),
    }
}