Improve performance across screens (#4071)

* Keep screens loaded while they're hidden and rebuild the library faster

* Count chapters in SQL for the migration list

* Show the extension list sooner and check trust against loaded stores

* Cancel the previous tracker search when searching again

* Write reader progress less often and keep its work off the main thread

* Stop rebuilding the settings search index on every key

* Watch updates for widgets only while one is placed

The query re-ran on every chapter or manga write even with no widget on
the home screen.

* Observe download pages and limit how often their progress updates

* Throttle the library update notification and write fetch data together

presentation-widget/src/main/java/tachiyomi/presentation/widget/UpdatesGridCoverScreenGlanceReceiver.kt

@@ -1,9 +1,20 @@
 package tachiyomi.presentation.widget
 
+import android.content.Context
 import androidx.glance.appwidget.GlanceAppWidget
 import androidx.glance.appwidget.GlanceAppWidgetReceiver
 
 class UpdatesGridCoverScreenGlanceReceiver : GlanceAppWidgetReceiver() {
     override val glanceAppWidget: GlanceAppWidget
         get() = UpdatesGridCoverScreenGlanceWidget()
+
+    override fun onEnabled(context: Context) {
+        super.onEnabled(context)
+        WidgetManager.onWidgetEnabled(glanceAppWidget)
+    }
+
+    override fun onDisabled(context: Context) {
+        super.onDisabled(context)
+        WidgetManager.onWidgetDisabled(glanceAppWidget)
+    }
 }

presentation-widget/src/main/java/tachiyomi/presentation/widget/UpdatesGridGlanceReceiver.kt

@@ -1,5 +1,6 @@
 package tachiyomi.presentation.widget
 
+import android.content.Context
 import androidx.glance.appwidget.GlanceAppWidget
 import androidx.glance.appwidget.GlanceAppWidgetReceiver
 
@@ -7,4 +8,14 @@ class UpdatesGridGlanceReceiver : GlanceAppWidgetReceiver() {
 
     override val glanceAppWidget: GlanceAppWidget
         get() = UpdatesGridGlanceWidget()
+
+    override fun onEnabled(context: Context) {
+        super.onEnabled(context)
+        WidgetManager.onWidgetEnabled(glanceAppWidget)
+    }
+
+    override fun onDisabled(context: Context) {
+        super.onDisabled(context)
+        WidgetManager.onWidgetDisabled(glanceAppWidget)
+    }
 }

presentation-widget/src/main/java/tachiyomi/presentation/widget/WidgetManager.kt

@@ -1,16 +1,25 @@
 package tachiyomi.presentation.widget
 
 import android.content.Context
+import androidx.glance.appwidget.GlanceAppWidget
+import androidx.glance.appwidget.GlanceAppWidgetManager
 import androidx.glance.appwidget.updateAll
 import dev.zacsweers.metro.Inject
 import eu.kanade.tachiyomi.core.security.SecurityPreferences
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.emptyFlow
+import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.flow.update
+import kotlinx.coroutines.launch
 import logcat.LogPriority
 import tachiyomi.core.common.util.system.logcat
 import tachiyomi.domain.updates.interactor.GetUpdates
@@ -21,21 +30,40 @@ class WidgetManager(
     private val securityPreferences: SecurityPreferences,
 ) {
 
+    @OptIn(ExperimentalCoroutinesApi::class)
     context(context: Context)
     fun init(scope: CoroutineScope) {
-        combine(
-            getUpdates.subscribe(read = false, after = BaseUpdatesGridGlanceWidget.DateLimit),
-            securityPreferences.useAuthenticator.changes(),
-            transform = { a, b -> a to b },
-        )
+        scope.launch(Dispatchers.Default) {
+            val manager = GlanceAppWidgetManager(context)
+            val placed = widgets.filter { manager.getGlanceIds(it.javaClass).isNotEmpty() }
+            placedWidgets.update { it + placed.map { widget -> widget.javaClass } }
+        }
+
+        // Only watch updates while a widget is on the home screen
+        placedWidgets
+            .map { it.isNotEmpty() }
+            .distinctUntilChanged()
+            .flatMapLatest { hasWidgets ->
+                if (hasWidgets) {
+                    combine(
+                        getUpdates.subscribe(
+                            read = false,
+                            after = BaseUpdatesGridGlanceWidget.DateLimit,
+                        ),
+                        securityPreferences.useAuthenticator.changes(),
+                        transform = { a, b -> a to b },
+                    )
+                } else {
+                    emptyFlow()
+                }
+            }
             .distinctUntilChanged { old, new ->
                 old.second == new.second &&
                     old.first.map { it.chapterId }.toSet() == new.first.map { it.chapterId }.toSet()
             }
             .onEach {
                 try {
-                    UpdatesGridGlanceWidget().updateAll(context)
-                    UpdatesGridCoverScreenGlanceWidget().updateAll(context)
+                    widgets.forEach { it.updateAll(context) }
                 } catch (e: Exception) {
                     this.logcat(LogPriority.ERROR, e) { "Failed to update widget" }
                 }
@@ -43,4 +71,19 @@ class WidgetManager(
             .flowOn(Dispatchers.Default)
             .launchIn(scope)
     }
+
+    companion object {
+        private val widgets: List<GlanceAppWidget>
+            get() = listOf(UpdatesGridGlanceWidget(), UpdatesGridCoverScreenGlanceWidget())
+
+        private val placedWidgets = MutableStateFlow(emptySet<Class<out GlanceAppWidget>>())
+
+        internal fun onWidgetEnabled(widget: GlanceAppWidget) {
+            placedWidgets.update { it + widget.javaClass }
+        }
+
+        internal fun onWidgetDisabled(widget: GlanceAppWidget) {
+            placedWidgets.update { it - widget.javaClass }
+        }
+    }
 }