Hey. Is it just wrong to use Launched Effect when ...

# compose

[Vlad]

Hey. Is it just wrong to use Launched Effect when you don't need the block to be suspended?
Like common use case:

LaunchedEffect(navigationRequest) {
   navigator.pushNotSuspend(navigiationRequest)
   // perhaps notify vm that request consumed, but that is another topic
}

Because Launched Effect needs additional time to launch a coroutine which we don't actually utilize?
What to use instead?
Just:

remember(navigationRequest) {
    navigator.pushNotSuspend(navigiationRequest)
}

[Stylianos Gakis]

DisposableEffect(Unit) {
doYourThing()
onDispose {}
}

[Stylianos Gakis]

That one does not launch a coroutine

[Vlad]

Yea, I thought about that.
Just was a little bit unsure to use dispose while not using onDispose

[Stylianos Gakis]

Yeah that's fine, people reach for this when they want to avoid launching a coroutine, exactly like you describe your use case here

[Vlad]

Because I just realized that 95% of my LaunchedEffect blocks don't need suspension

[Vlad]

And I noted that the first line inside the block of LaunchedEffect is called 200ms later than DisposableEffect's.
But that is in debug. Dunno what would be the number in release

[Vlad]

And I got the 🤦‍♂️ moment

[jw]

I think you want SideEffect

[Vlad]

I still often need that thing to be called only once and not called on recompositions

[Vlad]

SideEffect called on every succsefful recomposition

[jw]

I would probably do a snapshotFlow of navigationRequest and perform navigation in the collection

[jw]

I'm reading the thread somewhat backwards...

[Vlad]

But the collection is suspended.
So we will need LaunchedEffect which will eat the time when we don't need it?

[jw]

There is no real penalty for not suspending. Suspend functions can either return a result synchronously through the return value or suspend and propagate the result through the continuation.

[jw]

Unless you're observing some kind of problem with it, I wouldn't worry about it.

[jw]

Especially for something that only happens multiple times per minute, rather than like multiple times per millisecond

[Vlad]

2024-11-21 18:00:25.517 ---DisposableEffect()
2024-11-21 18:00:25.713 ----LaunchedEffect()

My current problem is that I see that my every navigate method is delayed by these almost 200ms (debug mode), when I never need that?!

[jw]

Sounds like you have something monopolizing your main dispatcher and/or thread, as that's like 10+ frames later which is not normal.

[Vlad]

2024-11-21 18:59:49.168 ---DisposableEffect()
2024-11-21 18:59:49.179 ----LaunchedEffect()

In the release variant the difference is not that critical (10-50ms) but still if not needed then why.