Fixed
Status Update
No update yet.
Comments
ap...@google.com
Yigit, do you have time to fix it?
reemission of the same liveData is racy
reemission of the same liveData is racy
ap...@google.com
yea i'll take it.
ap...@google.com
Thanks for the detailed analysis. This may not be an issue anymore since we've started using Main.immediate there but I' not sure; I'll try to create a test case.
jb...@google.com
just emitting same live data reproduces the issue.
@Test
fun raceTest() {
val subLiveData = MutableLiveData(1)
val subject = liveData(testScope.coroutineContext) {
emitSource(subLiveData)
emitSource(subLiveData) //crashes
}
subject.addObserver().apply {
testScope.advanceUntilIdle()
}
}
@Test
fun raceTest() {
val subLiveData = MutableLiveData(1)
val subject = liveData(testScope.coroutineContext) {
emitSource(subLiveData)
emitSource(subLiveData) //crashes
}
subject.addObserver().apply {
testScope.advanceUntilIdle()
}
}
Description
Version used: 1.2.0-rc01
The setRetainInstance() method of Fragments was originally the only way to retain state outside of overriding methods in the Activity. However, it ends up tightly coupling the retained state (which should not have any reference to the Context, Views, etc) with the full Fragment API, introducing such exciting combinations such as retained Fragments that also have a View or mixing retained and not retained Fragments together when using setTargetFragment(). This leads to lifecycle combinations that are much more complicated.
With the introduction of ViewModels, developers have a specific API for retaining state that can be associated with Activities, Fragments, and Navigation graphs. This allows developers to use a normal, not retained Fragment and keep the specific state they want retained separate.
This ensures that developers have a much more understandable lifecycle for those Fragments (one that matches all of the rest of their Fragments) while maintaining the useful properties of a single creation and single destruction (in this case, the constructor of the ViewModel and the onCleared() callback from the ViewModel).
We should deprecate the setRetainInstance() method and point developers to use ViewModel for storing their retained state.