async-std@1.6-beta.1: wasm-timer `Delay` pauses

[azriel91]

Heya, e4df140 uses wasm_timer::Delay in src/utils.rs for WASM target's Timer implementation. When running a countdown async task in a loop with a 50 ms delay, it pauses for 4 seconds every 19 iterations (observed in both Chrome and Firefox):

Switching it to futures_timer::Delay allows it to loop smoothly:

#776 has the change, though futures-timer depends on async-std in [dev-dependencies], so not sure if you'd like the somewhat cyclic reference.

futures-timer backs onto gloo_timers, which calls the browser's setTimeout API. I couldn't figure out how wasm-timer does it.

[dignifiedquire]

Interesting, futures-timer was a dependency before in here, so this should be fine

[Fishrock123]

Perhaps there is some misunderstanding, but wasm-timer still uses javascript setTimeout.

The bug is probably due to this unwrap failing and defaulting to 5 seconds: https://github.com/tomaka/wasm-timer/blob/master/src/timer/global/wasm.rs#L60

I'm considering trying to work on optimizing futures-timer, given the information above is there any reason to use wasm-timer?

[azriel91]

Perhaps there is some misunderstanding, but wasm-timer still uses javascript setTimeout.

ah, I didn't grep the wasm-timer repository; did human-eye file traversal, and gave up because I went too far down the (wrong) rabbit hole.

I like futures-timer's simplicity. If deciding whether or not to use wasm-timer, one would have to:

• understand the value the additional complexity provides
• figure out why that unwrap is failing

[tomaka]

Author of wasm-timer here:
To create wasm-timer I took what was futures-timer at the time and changed "the backend".

The reason why I didn't do it the way futures-timer 0.3 does is because the public-facing API at the time was exposing the Instant and Interval types. I had to expose a custom version of Instant, and Interval is quite complicated to implement.

Nowadays there's no good reason to use wasm_timer anymore.

[tomaka]

Additionally, wasm_timer was a quickly written "hack" to make existing code compile. Like many hacks, it stays there longer than it should.

[dignifiedquire]

thank you @tomaka both for your hacks and the info 👍