Draft: New WASM implementation

[jgraef]

This implementation spawns a local task, which drives the websocket connection. The WebSocket struct that the user gets only contains channels to communicate with the task. This way the WebSocket is Send.

[jgraef]

The new wasm-implementation seems to work. I added an assertion that WebSocket: Send + Sync, but this fails for native, as hyper::Upgraded is not Sync. Works for wasm now though :)

[imlk0]

I got the same Send problem, hope to see this got merged.

[jgraef]

@imlk0

It might eventually get merged, but it's not on my todo list right now. The problem is that WebSocket will not be Sync on native due to limitations by hyper. It might be nice to have only the Send bound for both targets though.

The point is that the current implementation works, and I'm hesitant to switch it out with something that might break things.

What is the specific problem you have? I might be able to help with a workaround.

[imlk0]

@imlk0

It might eventually get merged, but it's not on my todo list right now. The problem is that WebSocket will not be Sync on native due to limitations by hyper. It might be nice to have only the Send bound for both targets though.它最终可能会被合并，但这会儿不在我的待办事项列表中。问题在于由于 hyper 的限制，WebSocket 在原生环境下无法实现 Sync。不过，对于两个目标平台来说，也许最好都只保留 Send 约束。

The point is that the current implementation works, and I'm hesitant to switch it out with something that might break things.关键是当前的实现是有效的，我担心将其替换为可能会导致问题的新实现。

What is the specific problem you have? I might be able to help with a workaround.你遇到的具体问题是什么？我或许能帮忙提供一个变通方案。

Hi, @jgraef, thanks for your quick reply!

I'm try to turn a WebSocket struct into a AsyncRead + AsyncWrite, and I have write some code with StreamReader and SinkWriter and got problem, since I realized that I actually need AsyncRead + AsyncWrite + Send.

I will try the code of this branch and see if it solve my problem.

[jgraef]

This branch is a little bit out of date, but should work fine.

As far as I can tell StreamReader/StreamWriter doesn't have a Send bound. The requirement for a Send bound usually comes when you move a type across thread boundaries. But there are no threads in WASM. For example wasm_bindgen_futures::spawn_local spawns a task, but doesn't require that bound. Sometimes libraries require it though.

Feel free to reach out if you run into any problems with this branch. I might even bring it up-to-date with the master branch, if you need that. After all it's good to know that this feature is needed :)