Add async support in WS

[sansyrox]

Description

This PR fixes #116

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[ShadowJonathan]

I would not recommend doing ctx.spawn, websocket messages may be handled out of order due to scheduling.

[sansyrox]

I would not recommend doing ctx.spawn, websocket messages may be handled out of order due to scheduling.

@ShadowJonathan , ctx.spawn is being used for async functions. So, ig out of order execution may work.
Do you have any other suggestions otherwise?

[ShadowJonathan]

It's mostly so that message B doesn't get processed after message A, I suggest doing the .await on the asyncio coroutine inside the ws object handler function.

[sansyrox]

@ShadowJonathan , I tried converting this function(https://github.com/sansyrox/robyn/pull/134/files#diff-0d0da7574dadb5452e2f359138c914a901f38425138f1c2facc37f403b98ab7fR38) to an async function but it is not supported by Actix at the moment :(

Correct me if I am missing something.

[ShadowJonathan]

Ooooh wait, that explains it some more, yes, then this approach should be fine enough.

Maybe warn users that websocket message handling can be concurrent, and doesn't wait for each handler to complete before spawning the next one.

Or, you could maybe use wait instead.

[sansyrox]

Ooooh wait, that explains it some more, yes, then this approach should be fine enough.

Perfect!

Maybe warn users that websocket message handling can be concurrent, and doesn't wait for each handler to complete before spawning the next one.

This makes sense. If someone wants to have synchronous execution, they can use regular sync functions whereas the async functions can be used when the order does not matter. This would give a more concurrent feel imo.

[ShadowJonathan]

(I recommend trying out that wait function though, it seems plenty more perfect for your usecase)

[sansyrox]

(I recommend trying out that wait function though, it seems plenty more perfect for your usecase)

But won't it block the execution of other calls while the current call is completed?

[ShadowJonathan]

As far as i see it, it blocks the current task until the asyncio future is completed, so it'll wait until the python async function has handled this message first before it moves on to the next.

Documentation says the actor wont receive any new messages during this time.

[sansyrox]

Documentation says the actor wont receive any new messages during this time.

Hmm.. This is something I didn't want to happen for async functions in WebSockets. Otherwise, I would've used pyo3-asyncio::tokio::run_until_complete method.

I am taking inspiration from expressjs or fastifyjs where async functions may execute out of order to provide a more non-blocking experience.

Sync functions are always executed in order.

[ShadowJonathan]

Just looked up a bunch more documentation from actix, i think it's fine to wait, the actor will receive messages inbetween these handle calls, i think, but it is up to you.

If you're doing spawn, then i really recommend noting this down in documentation.

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Edit: Looking some more, "actor cannot receive messages at this time" is probably exactly what you want in this situation, because then the websocket stream will be halted until the python async function has been handled.

[sansyrox]

Edit: Looking some more, "actor cannot receive messages at this time" is probably exactly what you want in this situation, because then the websocket stream will be halted until the python async function has been handled.

I feel maybe I am unable to articulate my point or I am unable to understand why order would be beneficial here. 😅

I'll try again:

I feel that "halting" would block the socket. Which, IMO, should be restricted to synchronous functions. Async functions "should" work out of order without blocking.

[sansyrox]

Now, that I think if the order is really important in async functions. I can just add a param called non_blocking=False