Wasm support

I'm assuming a browser (javascript) environment. Quick thoughts:

• Async will be unusable because AsRawFd/AsRawSocket types don't exist on wasm.
• Timer can be perhaps be implemented by calling setTimeout() in javascript.
• Instead of running a thread-local or work-stealing executor, just spawn tasks through javascript.
• Blocking executor should either be normal spawn or panic.

[FuriouZz]

Hello there 👋🏾 I will be glad to help you with this issue!

@FuriouZz Thank you, help would be very welcome! :)

[Stupremee]

Imo blocking executor should just redirect to a normal spawn because it’s easier to convert current code to Wasm. But it should be mentioned in the documentation somewhere.

For reference, see wasm support in async-std: async-rs/async-std#757

@Stupremee Is the blocking executor even used on wasm? I would assume no since there are no files and no stdin/stdout/stderr on wasm, but I could be wrong?

[huangjj27]

I would assume no since there are no files and no stdin/stdout/stderr on wasm, but I could be wrong?

Maybe it's about WASI ? It would be glad to see WASI is also supported

@huangjj27 I believe WASI still in development and does not have what we need yet... hopefully soon :)

[jjl]

I've got a WIP PR #99 where i've started to implement this. At the minute, most things are basically commented out with cfg, but I've started some of the basic plumbing to get everything building.

There's plenty left to do, like actually call some javascript apis to spawn the task and work on e.g. Timer, but people seem interested in contributing from this thread, so I thought I'd start making things public early.

[fogti]

support for emscripten might be useful, too ((maybe) related: https://users.rust-lang.org/t/how-to-get-tcpstream-to-work-in-wasm/13103/6)... althrough I'm not sure how common emscripten usage is, as of today.

[kwek20]

This is still an issue for me @stjepang ; i'm running on windows with rust 1.47:
cargo run --example windows-uds --target wasm32-unknown-unknown
It will fail on nb-connect-1.0.2 which is missing socket imports from async-io-> winapi-rs

Ive given it a look but im lost in dependencies :) , any idea?