Mitigate a deadlock when loading room timelines (#6674)

This may be happening because we were not destroying focused event timelines used for the media viewer/gallery when necessary, and having several of those back paginating *may* have caused a deadlock in the event cache.

libraries/mediaviewer/impl/src/main/kotlin/io/element/android/libraries/mediaviewer/impl/datasource/MediaGalleryDataSource.kt

@@ -17,6 +17,7 @@ import io.element.android.libraries.matrix.api.room.BaseRoom
 import io.element.android.libraries.matrix.api.timeline.Timeline
 import io.element.android.libraries.matrix.api.timeline.item.event.toEventOrTransactionId
 import io.element.android.libraries.mediaviewer.impl.model.GroupedMediaItems
+import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
@@ -27,10 +28,11 @@ import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.onCompletion
 import kotlinx.coroutines.flow.onEach
+import timber.log.Timber
 import java.util.concurrent.atomic.AtomicBoolean
 
 interface MediaGalleryDataSource {
-    fun start()
+    fun start(coroutineScope: CoroutineScope)
     fun groupedMediaItemsFlow(): Flow<AsyncData<GroupedMediaItems>>
     fun getLastData(): AsyncData<GroupedMediaItems>
     suspend fun loadMore(direction: Timeline.PaginationDirection)
@@ -58,7 +60,7 @@ class TimelineMediaGalleryDataSource(
     private val isStarted = AtomicBoolean(false)
 
     @OptIn(ExperimentalCoroutinesApi::class)
-    override fun start() {
+    override fun start(coroutineScope: CoroutineScope) {
         if (!isStarted.compareAndSet(false, true)) {
             return
         }
@@ -96,9 +98,12 @@ class TimelineMediaGalleryDataSource(
             groupedMediaItemsFlow.emit(AsyncData.Success(groupedMediaItems))
         }
             .onCompletion {
-                timeline?.close()
+                timeline?.let {
+                    Timber.d("Timeline media gallery data source flow completed for room ${room.roomId}, closing timeline")
+                    it.close()
+                }
             }
-            .launchIn(room.roomCoroutineScope)
+            .launchIn(coroutineScope)
     }
 
     override suspend fun loadMore(direction: Timeline.PaginationDirection) {

libraries/mediaviewer/impl/src/main/kotlin/io/element/android/libraries/mediaviewer/impl/gallery/MediaGalleryPresenter.kt

@@ -78,7 +78,7 @@ class MediaGalleryPresenter(
             .collectAsState(AsyncData.Uninitialized)
 
         LaunchedEffect(Unit) {
-            mediaGalleryDataSource.start()
+            mediaGalleryDataSource.start(this)
         }
 
         val permissions by room.permissionsAsState(MediaPermissions.DEFAULT) { perms ->

libraries/mediaviewer/impl/src/main/kotlin/io/element/android/libraries/mediaviewer/impl/viewer/MediaViewerDataSource.kt

@@ -35,6 +35,7 @@ import kotlinx.collections.immutable.ImmutableList
 import kotlinx.collections.immutable.persistentListOf
 import kotlinx.collections.immutable.toImmutableList
 import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.withContext
@@ -62,11 +63,12 @@ class MediaViewerDataSource(
     private val localMediaStates: MutableMap<String, MutableState<AsyncData<LocalMedia>>> =
         mutableMapOf()
 
-    fun setup() {
+    fun setup(coroutineScope: CoroutineScope) {
-        galleryDataSource.start()
+        galleryDataSource.start(coroutineScope)
     }
 
     fun dispose() {
+        Timber.d("Disposing MediaViewerDataSource, closing ${mediaFiles.size} media files")
         mediaFiles.forEach { it.close() }
         mediaFiles.clear()
         localMediaStates.clear()

libraries/mediaviewer/impl/src/main/kotlin/io/element/android/libraries/mediaviewer/impl/viewer/MediaViewerPresenter.kt

@@ -88,7 +88,7 @@ class MediaViewerPresenter(
         var mediaBottomSheetState by remember { mutableStateOf<MediaBottomSheetState>(MediaBottomSheetState.Hidden) }
 
         DisposableEffect(Unit) {
-            dataSource.setup()
+            dataSource.setup(coroutineScope)
             onDispose {
                 dataSource.dispose()
             }

libraries/mediaviewer/impl/src/main/kotlin/io/element/android/libraries/mediaviewer/impl/viewer/SingleMediaGalleryDataSource.kt

@@ -20,12 +20,13 @@ import io.element.android.libraries.mediaviewer.impl.datasource.MediaGalleryData
 import io.element.android.libraries.mediaviewer.impl.model.GroupedMediaItems
 import io.element.android.libraries.mediaviewer.impl.model.MediaItem
 import kotlinx.collections.immutable.persistentListOf
+import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.flow.flowOf
 
 class SingleMediaGalleryDataSource(
     private val data: GroupedMediaItems,
 ) : MediaGalleryDataSource {
-    override fun start() = Unit
+    override fun start(coroutineScope: CoroutineScope) = Unit
     override fun groupedMediaItemsFlow() = flowOf(AsyncData.Success(data))
     override fun getLastData(): AsyncData<GroupedMediaItems> = AsyncData.Success(data)
 

libraries/mediaviewer/impl/src/test/kotlin/io/element/android/libraries/mediaviewer/impl/datasource/FakeMediaGalleryDataSource.kt

@@ -13,6 +13,7 @@ import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.timeline.Timeline
 import io.element.android.libraries.mediaviewer.impl.model.GroupedMediaItems
 import io.element.android.tests.testutils.lambda.lambdaError
+import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
 
@@ -21,7 +22,7 @@ class FakeMediaGalleryDataSource(
     private val loadMoreLambda: (Timeline.PaginationDirection) -> Unit = { lambdaError() },
     private val deleteItemLambda: (EventId) -> Unit = { lambdaError() },
     ) : MediaGalleryDataSource {
-    override fun start() = startLambda()
+    override fun start(coroutineScope: CoroutineScope) = startLambda()
 
     private val groupedMediaItemsFlow = MutableSharedFlow<AsyncData<GroupedMediaItems>>(
         replay = 1

libraries/mediaviewer/impl/src/test/kotlin/io/element/android/libraries/mediaviewer/impl/datasource/TimelineMediaGalleryDataSourceTest.kt

@@ -80,7 +80,7 @@ class TimelineMediaGalleryDataSourceTest {
                     roomCoroutineScope = backgroundScope,
                 )
             )
-            sut.start()
+            sut.start(backgroundScope)
             assertThat(sut.getLastData()).isEqualTo(AsyncData.Uninitialized)
             sut.groupedMediaItemsFlow().test {
                 assertThat(awaitItem().isLoading()).isTrue()
@@ -95,7 +95,7 @@ class TimelineMediaGalleryDataSourceTest {
                 )
                 assertThat(sut.getLastData().isSuccess()).isTrue()
                 // Also test that starting again should have no effect
-                sut.start()
+                sut.start(backgroundScope)
             }
         }
         // Ensure that the timeline has been closed on flow completion
@@ -117,7 +117,7 @@ class TimelineMediaGalleryDataSourceTest {
                 roomCoroutineScope = backgroundScope,
             )
         )
-        sut.start()
+        sut.start(backgroundScope)
         sut.groupedMediaItemsFlow().test {
             skipItems(2)
             sut.loadMore(Timeline.PaginationDirection.BACKWARDS)
@@ -140,7 +140,7 @@ class TimelineMediaGalleryDataSourceTest {
                 roomCoroutineScope = backgroundScope,
             )
         )
-        sut.start()
+        sut.start(backgroundScope)
         sut.groupedMediaItemsFlow().test {
             skipItems(2)
             sut.deleteItem(AN_EVENT_ID)
@@ -159,7 +159,7 @@ class TimelineMediaGalleryDataSourceTest {
                 roomCoroutineScope = backgroundScope,
             )
         )
-        sut.start()
+        sut.start(backgroundScope)
         sut.groupedMediaItemsFlow().test {
             assertThat(awaitItem().isLoading()).isTrue()
             assertThat(sut.getLastData().isLoading()).isTrue()
@@ -181,7 +181,7 @@ class TimelineMediaGalleryDataSourceTest {
                 roomCoroutineScope = backgroundScope,
             )
         )
-        sut.start()
+        sut.start(backgroundScope)
         sut.groupedMediaItemsFlow().test {
             assertThat(awaitItem().isLoading()).isTrue()
             assertThat(sut.getLastData().isLoading()).isTrue()

libraries/mediaviewer/impl/src/test/kotlin/io/element/android/libraries/mediaviewer/impl/viewer/MediaViewerDataSourceTest.kt

@@ -50,7 +50,7 @@ class MediaViewerDataSourceTest {
         val sut = createMediaViewerDataSource(
             galleryDataSource = galleryDataSource,
         )
-        sut.setup()
+        sut.setup(backgroundScope)
         startLambda.assertions().isCalledOnce()
     }
 

libraries/mediaviewer/impl/src/test/kotlin/io/element/android/libraries/mediaviewer/impl/viewer/SingleMediaGalleryDataSourceTest.kt

@@ -37,9 +37,9 @@ class SingleMediaGalleryDataSourceTest {
     val warmUpRule = WarmUpRule()
 
     @Test
-    fun `function start is no op`() {
+    fun `function start is no op`() = runTest {
         val sut = SingleMediaGalleryDataSource(aGroupedMediaItems())
-        sut.start()
+        sut.start(backgroundScope)
     }
 
     @Test