How come I get this error ```java.lang.IllegalStat...

# compose

[Mario Andhika]

How come I get this error

java.lang.IllegalStateException: Reading a state that was created after the snapshot was taken or in a snapshot that has not yet been applied                                                                                                    	at androidx.compose.runtime.snapshots.SnapshotKt.readError(Snapshot.kt:1865)                                                                                                  	at androidx.compose.runtime.snapshots.SnapshotKt.readable(Snapshot.kt:1849)                                                                                                    	at androidx.compose.runtime.SnapshotMutableStateImpl.getValue(SnapshotState.kt:130)                                                                                                    	at asia.zeals.mobile.android.viewmodels.AppStateViewModel.getScreenState(AppStateViewModel.kt:51)                                                                                                    	at asia.zeals.mobile.android.MainActivity$onCreate$1$1$1$1.invoke(MainActivity.kt:73)                                                                                                    	at asia.zeals.mobile.android.MainActivity$onCreate$1$1$1$1.invoke(MainActivity.kt:72)                                                                                                    	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:107)                                                                                                    	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:34)

when using encrypted datastore library: <https://github.com/osipxd/encrypted-datastore> ,
but not when I use regular, unencrypted datastore?

[Mario Andhika]

The commented out code doesn’t crash, but the uncommented one does

//        PreferenceDataStoreFactory.create(
//            corruptionHandler = ReplaceFileCorruptionHandler(
//                produceNewData = { emptyPreferences() }
//            ),
//            migrations = listOf(SharedPreferencesMigration(androidContext(), "settings")),
//            scope = CoroutineScope(<http://Dispatchers.IO|Dispatchers.IO> + SupervisorJob()),
//            produceFile = { androidContext().preferencesDataStoreFile("settings") }
//        )

        val context = androidContext()
        PreferenceDataStoreFactory.createEncrypted(
            corruptionHandler = ReplaceFileCorruptionHandler(
                produceNewData = { emptyPreferences() }
            ),
            migrations = listOf(SharedPreferencesMigration(context, "settings")),
            scope = CoroutineScope(<http://Dispatchers.IO|Dispatchers.IO> + SupervisorJob()),
            produceFile = {
                EncryptedFile(
                context = context,
                file = context.preferencesDataStoreFile("settings.preferences_pb"),
                masterKey = MasterKey(context)
            )
            }
        )

[shikasd]

This error usually means that you have created a mutableStateOf in composition, but tried to use it in background thread before composition was completed

[Mario Andhika]

class AppStateViewModel(
    private val repository: Repository
):ViewModel() {

    var screenState by mutableStateOf(ScreenState.LOADING)
}

From the stack trace, the screenState variable above is what’s causing it. I created it in a ViewModel though. And it’s initialized

[Jan Skrasek]

Hi Andrei, we experienced this exception when mutating state in VM from a bg thread. Is that disallowed?

class MyVM {
     val state = mutableStateOf(1)

     init { 
          viewModelScope.launch(Dispatchers.Default) {
              // heavy suspeding work
              state.value = 2
          }
     }
}

switching the dsipatcher to Main helps.
Alternatively, was there a development, i.e. we use a version year old, maybe they were some fixes.
Thx

[Jan Skrasek]

(VM is created in composition, so it could match your "description")

[shikasd]

Writing to state should be fine, I don't think this is the same crash

[shikasd]

I think there was a fix that allowed this at some point in 1.7 lifecycle

[Jan Skrasek]

I found this, but not that I would be smarter after reading it 🙂
https://kotlinlang.slack.com/archives/CJLTWPH7S/p1713463395908709?thread_ts=1713458442.583329&cid=CJLTWPH7S

[shikasd]

Yeah, that's the change I am referring to. Global snapshot usually means anything outside of composition, so thats what is happening here.

[Jan Skrasek]

Thx a lot.