Splitting a WebSocketStream

[alx3715]

Hello and thanks for your work on this project!

I want to send and receive WebSocket messages concurrently from two dedicated tasks.
Is there a simple way to split WebSocketStream into read and write halves?
If not, is there a workaround? As this is a somewhat common usecase.
I checked examples but they demonstrate only request-response pattern instead of full duplex communication.

[Berrysoft]

Currently there's no simple way. However, BiLock is exactly what you want. Just wrap the WebSocketStream into a BiLock. There're two kinds of BiLock, sync and unsync, and you're free to choose the desired one.

[alx3715]

If the write task frequently sends some data while read task receives data rarely. Won't that mean that write task will have to wait on lock().await call before being able to send something?

[Berrysoft]

Could you show us an MWE?

[alx3715]

Here it is: https://github.com/alx3715/ws_split/

When I run compiows example and spawn both recv+send tasks, client doesn't receive anything.
When I run (hopefully!) identical tokiotungstenite example, client seems to properly receive periodic messages.
(Forgive me in advance if I did something silly, in the process of learning Rust).

[George-Miao]

This seems to be a bug with our split implementation. Will look into it.

[alx3715]

Want to double-check one thing.
I used BiLock as suggested and at least for me it seems to behave as expected. Is it actually a bug or is it just missing support for splitting the Ws stream in a way it won't require to hold a lock during the whole receive?

[Berrysoft]

Well, the main cause is that you're holding a lock during the whole receive. However, it's not you're writing something wrong. It's the design problem of our BiLock & split implementation.

[Berrysoft]

#713

This PR adds futures-compat implementations, and it's possible to split a CompatWebSocketStream.

The bug of BiLock is tracking in #685 .