Fix widget race conditions

app/src/main/java/org/tasks/widget/AppWidgetManager.kt

@@ -6,34 +6,41 @@ import android.content.Context
 import android.content.Intent
 import dagger.hilt.android.qualifiers.ApplicationContext
 import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.flow.consumeAsFlow
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
 import org.tasks.R
 import org.tasks.compose.throttleLatest
 import org.tasks.injection.ApplicationScope
 import timber.log.Timber
+import java.util.concurrent.atomic.AtomicLong
 import javax.inject.Inject
+import javax.inject.Singleton
 
+@Singleton
 class AppWidgetManager @Inject constructor(
     @param:ApplicationContext private val context: Context,
     @ApplicationScope private val scope: CoroutineScope,
 ) {
     private val appWidgetManager: AppWidgetManager? = AppWidgetManager.getInstance(context)
-    private val updateChannel = Channel<Unit>(Channel.CONFLATED)
+    private val _generation = AtomicLong(0)
+    val generation: Long get() = _generation.get()
+
+    private val updateChannel = Channel<Long>(Channel.CONFLATED)
 
     init {
         updateChannel
             .consumeAsFlow()
             .throttleLatest(1000)
-            .onEach {
-                val appWidgetIds = widgetIds
-                Timber.d("updateWidgets: ${appWidgetIds.joinToString { it.toString() }}")
-                notifyAppWidgetViewDataChanged(appWidgetIds)
+            .onEach { gen ->
+                if (gen == _generation.get()) {
+                    val appWidgetIds = widgetIds
+                    Timber.d("updateWidgets: ${appWidgetIds.joinToString { it.toString() }}")
+                    appWidgetManager?.notifyAppWidgetViewDataChanged(appWidgetIds, R.id.list_view)
+                } else {
+                    Timber.d("Skipping stale widget update")
+                }
             }
             .launchIn(scope)
     }
@@ -43,25 +50,19 @@ class AppWidgetManager @Inject constructor(
                 ?.getAppWidgetIds(ComponentName(context, TasksWidget::class.java))
                 ?: intArrayOf()
 
-    fun reconfigureWidgets(vararg appWidgetIds: Int) = scope.launch {
-        Timber.d("reconfigureWidgets(${appWidgetIds.joinToString()})")
-
+    fun reconfigureWidgets(vararg appWidgetIds: Int) {
+        val newGeneration = _generation.incrementAndGet()
         val ids = appWidgetIds.takeIf { it.isNotEmpty() } ?: widgetIds
-
+        Timber.d("reconfigureWidgets(${ids.joinToString()}) generation=$newGeneration")
         val intent = Intent(context, TasksWidget::class.java)
             .putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, ids)
             .apply { action = AppWidgetManager.ACTION_APPWIDGET_UPDATE }
-
         context.sendBroadcast(intent)
     }
 
     fun updateWidgets() {
-        updateChannel.trySend(Unit)
+        updateChannel.trySend(_generation.get())
     }
 
     fun exists(id: Int) = appWidgetManager?.getAppWidgetInfo(id) != null
-
-    private suspend fun notifyAppWidgetViewDataChanged(appWidgetIds: IntArray) = withContext(Dispatchers.Main) {
-        appWidgetManager?.notifyAppWidgetViewDataChanged(appWidgetIds, R.id.list_view)
-    }
 }

app/src/main/java/org/tasks/widget/TasksWidget.kt

@@ -24,7 +24,6 @@ import org.tasks.intents.TaskIntents
 import org.tasks.preferences.DefaultFilterProvider
 import org.tasks.preferences.Preferences
 import org.tasks.themes.ThemeColor
-import org.tasks.time.DateTimeUtils2.currentTimeMillis
 import timber.log.Timber
 import javax.inject.Inject
 
@@ -37,10 +36,11 @@ class TasksWidget : AppWidgetProvider() {
 
     override fun onUpdate(context: Context, appWidgetManager: AppWidgetManager, appWidgetIds: IntArray) {
         Timber.d("onUpdate appWidgetIds=${appWidgetIds.joinToString { it.toString() }}")
+        val generation = widgetManager.generation
         appWidgetIds.forEach { id ->
             try {
                 val options = appWidgetManager.getAppWidgetOptions(id)
-                appWidgetManager.updateAppWidget(id, createWidget(context, id, options))
+                appWidgetManager.updateAppWidget(id, createWidget(context, id, options, generation))
             } catch (e: Exception) {
                 Timber.e(e)
             }
@@ -56,12 +56,11 @@ class TasksWidget : AppWidgetProvider() {
         Timber.d("onAppWidgetOptionsChanged appWidgetId=$appWidgetId")
         appWidgetManager.updateAppWidget(
             appWidgetId,
-            createWidget(context, appWidgetId, newOptions)
+            createWidget(context, appWidgetId, newOptions, widgetManager.generation)
         )
-        appWidgetManager.notifyAppWidgetViewDataChanged(appWidgetId, R.id.list_view)
     }
 
-    private fun createWidget(context: Context, id: Int, options: Bundle): RemoteViews {
+    private fun createWidget(context: Context, id: Int, options: Bundle, generation: Long): RemoteViews {
         val widgetPreferences = WidgetPreferences(context, preferences, id)
         val settings = widgetPreferences.getWidgetHeaderSettings()
         widgetPreferences.setCompact(
@@ -70,7 +69,7 @@ class TasksWidget : AppWidgetProvider() {
         val filter = runBlocking {
             defaultFilterProvider.getFilterFromPreference(widgetPreferences.filterId)
         }
-        Timber.d("createWidget id=$id filter=$filter")
+        Timber.d("createWidget id=$id generation=$generation filter=$filter")
 
         return RemoteViews(context.packageName, R.layout.scrollable_widget).apply {
             if (settings.showHeader) {
@@ -90,7 +89,7 @@ class TasksWidget : AppWidgetProvider() {
                 opacity = widgetPreferences.footerOpacity,
             )
             setOnClickPendingIntent(R.id.empty_view, getOpenListIntent(context, filter, id))
-            val cacheBuster = "tasks://widget/${currentTimeMillis()}".toUri()
+            val cacheBuster = "tasks://widget/$id/$generation".toUri()
             setRemoteAdapter(
                 R.id.list_view,
                 Intent(context, TasksWidgetAdapter::class.java)

app/src/main/java/org/tasks/widget/TasksWidgetAdapter.kt

@@ -30,14 +30,16 @@ class TasksWidgetAdapter : RemoteViewsService() {
     override fun onGetViewFactory(intent: Intent): RemoteViewsFactory? {
         val widgetId = intent.extras?.getInt(AppWidgetManager.EXTRA_APPWIDGET_ID) ?: return null
         val widgetPreferences = WidgetPreferences(context, preferences, widgetId)
+        val filterId = widgetPreferences.filterId
         val filter = runBlocking {
-            defaultFilterProvider.getFilterFromPreference(widgetPreferences.filterId)
+            defaultFilterProvider.getFilterFromPreference(filterId)
         }
         Timber.d("onGetViewFactory $filter")
         return TasksWidgetViewFactory(
             subtasksHelper,
             widgetPreferences,
             filter,
+            filterId,
             applicationContext,
             widgetId,
             taskDao,

app/src/main/java/org/tasks/widget/TasksWidgetViewFactory.kt

@@ -44,6 +44,7 @@ internal class TasksWidgetViewFactory(
     private val subtasksHelper: SubtasksHelper,
     private val widgetPreferences: WidgetPreferences,
     private val filter: Filter,
+    private val filterId: String?,
     private val context: Context,
     private val widgetId: Int,
     private val taskDao: TaskDao,
@@ -72,6 +73,10 @@ internal class TasksWidgetViewFactory(
 
     override fun onDataSetChanged() {
         Timber.v("onDataSetChanged $filter")
+        if (widgetPreferences.filterId != filterId) {
+            Timber.d("Skipping stale factory: expected $filterId, current ${widgetPreferences.filterId}")
+            return
+        }
         runBlocking {
             val collapsed = widgetPreferences.collapsed
             tasks = SectionedDataSource(