cashapp / cashapp/molecule

Debouncing state emissions

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enhancement PR welcome
Dominant language
Kotlin
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Description

I'm trying to migrate

val data = snapshotFlow { buildFromState() }.debounce(1.seconds)
...
data.collectAsState(null)

to remove the view side default null value.

But there's no easy way to debounce in Molecule. I think the closest you can get would be

val debouncedFlow = snapshotFlow { buildFromState() }.debounce(1.seconds)
val state = scope.launchMolecule { 
    debouncedFlow.collectAsState(buildFromState()).value
}

but this moves from Compose (the actual state) -> Flow (snapshotFlow) -> Molecule -> Compose (collectAsState) -> Compose UI, which is very inefficient compared to reading the state directly inside Molecule. It also requires calling buildFromState() redundantly.

If there was a way to control/throttle the recomposition timing in Molecule, then I could try and make it only recompose every second or when the debounce concluded.

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by tracing the Molecule recomposition behavior around launchMolecule and compare it with the snapshotFlow/debounce and collectAsState examples in the issue. Determine whether controlled or throttled recomposition is feasible without redundant buildFromState() calls; done requires an agreed design and corresponding behavior tests.

Written by the indexing model from the issue text.

Assessment

Tech stack
kotlin
Domain
mobile-dev
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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