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Attempt to fix room list item duplicates at midnight (#6793)

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* Attempt to fix room list item duplicates at midnight

This seems to happen because of a race condition between `RoomListDataSource.observeDateTimeChanges` and `RoomListDataSource.replaceWith` being called at almost the same time and the first one using the newly received items from observing the timeline items but not updating the cache which will be later reused by `replaceWith`, containing incorrect indices
This commit is contained in:
Jorge Martin Espinosa 2026-05-18 22:18:52 +02:00 • committed by GitHub
parent 1774d1d39a
commit 4e3853a718
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2 changed files with 66 additions and 2 deletions
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5
features/home/impl/src/main/kotlin/io/element/android/features/home/impl/datasource/RoomListDataSource.kt
View file

@ -83,8 +83,8 @@ class RoomListDataSource(
val loadingState = roomList.loadingState
fun launchIn(coroutineScope: CoroutineScope) {
roomList
fun launchIn(coroutineScope: CoroutineScope): Job {
return roomList
.summaries
.onEach { roomSummaries ->
replaceWith(roomSummaries)
@ -212,6 +212,7 @@ class RoomListDataSource(
private suspend fun rebuildAllRoomSummaries() {
lock.withLock {
roomList.summaries.replayCache.firstOrNull()?.let { roomSummaries ->
diffCacheUpdater.updateWith(roomSummaries)
buildAndEmitAllRooms(roomSummaries, useCache = false)
}
}

63
features/home/impl/src/test/kotlin/io/element/android/features/home/impl/datasource/RoomListDataSourceTest.kt
View file

@ -16,6 +16,7 @@ import io.element.android.libraries.dateformatter.test.FakeDateFormatter
import io.element.android.libraries.matrix.api.roomlist.RoomListService
import io.element.android.libraries.matrix.test.A_ROOM_ID
import io.element.android.libraries.matrix.test.A_ROOM_ID_2
import io.element.android.libraries.matrix.test.A_ROOM_ID_3
import io.element.android.libraries.matrix.test.notificationsettings.FakeNotificationSettingsService
import io.element.android.libraries.matrix.test.room.aRoomSummary
import io.element.android.libraries.matrix.test.roomlist.FakeDynamicRoomList
@ -197,6 +198,68 @@ class RoomListDataSourceTest {
}
}
@Test
fun `regression test for race with DateTimeObserver and new items`() = runTest {
val roomList = FakeDynamicRoomList(summaries = MutableStateFlow(listOf(aRoomSummary(), aRoomSummary(A_ROOM_ID_2))))
val roomListService = FakeRoomListService(
createRoomListLambda = { roomList }
).apply {
postState(RoomListService.State.Running)
}
val dateTimeObserver = FakeDateTimeObserver()
var dateFormatterResult = "Today"
val dateFormatter = FakeDateFormatter({ _, _, _ -> dateFormatterResult })
val roomListDataSource = createRoomListDataSource(
roomListService = roomListService,
roomListRoomSummaryFactory = aRoomListRoomSummaryFactory(
dateFormatter = dateFormatter,
),
dateTimeObserver = dateTimeObserver,
)
roomListDataSource.roomSummariesFlow.test {
// Observe room list items changes
val job = roomListDataSource.launchIn(backgroundScope)
// Get the initial room list
val initialRoomList = awaitItem()
assertThat(initialRoomList).hasSize(2)
assertThat(initialRoomList[0].roomId).isEqualTo(A_ROOM_ID)
assertThat(initialRoomList[0].timestamp).isEqualTo(dateFormatterResult)
assertThat(initialRoomList[1].roomId).isEqualTo(A_ROOM_ID_2)
assertThat(initialRoomList[1].timestamp).isEqualTo(dateFormatterResult)
// Stop processing room list updates so we can force a race condition with the date time observer updates
job.cancel()
// Trigger a date change and a new item at the same time
dateFormatterResult = "Yesterday"
roomList.summaries.tryEmit(listOf(aRoomSummary(roomId = A_ROOM_ID), aRoomSummary(roomId = A_ROOM_ID_3), aRoomSummary(roomId = A_ROOM_ID_2)))
dateTimeObserver.given(DateTimeObserver.Event.DateChanged(Instant.MIN, Instant.now()))
// The race condition would have caused the cache indices to be corrupted and only 2 items would be emitted
val rebuiltRoomList = awaitItem()
assertThat(rebuiltRoomList).hasSize(3)
assertThat(rebuiltRoomList[0].roomId).isEqualTo(A_ROOM_ID)
assertThat(rebuiltRoomList[0].timestamp).isEqualTo(dateFormatterResult)
assertThat(rebuiltRoomList[1].roomId).isEqualTo(A_ROOM_ID_3)
assertThat(rebuiltRoomList[1].timestamp).isEqualTo(dateFormatterResult)
assertThat(rebuiltRoomList[2].roomId).isEqualTo(A_ROOM_ID_2)
assertThat(rebuiltRoomList[2].timestamp).isEqualTo(dateFormatterResult)
// Restart processing room list updates
roomListDataSource.launchIn(backgroundScope)
// Check there is a new list and it's not the same as the previous one
val newRoomList = awaitItem()
assertThat(newRoomList).hasSize(3)
assertThat(newRoomList[0].roomId).isEqualTo(A_ROOM_ID)
assertThat(newRoomList[0].timestamp).isEqualTo(dateFormatterResult)
assertThat(newRoomList[1].roomId).isEqualTo(A_ROOM_ID_3)
assertThat(newRoomList[1].timestamp).isEqualTo(dateFormatterResult)
assertThat(newRoomList[2].roomId).isEqualTo(A_ROOM_ID_2)
assertThat(newRoomList[2].timestamp).isEqualTo(dateFormatterResult)
}
}
private fun TestScope.createRoomListDataSource(
roomListService: FakeRoomListService = FakeRoomListService(),
roomListRoomSummaryFactory: RoomListRoomSummaryFactory = aRoomListRoomSummaryFactory(),