Look up queued and downloaded chapters once per chapter list

app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadCache.kt

@@ -124,6 +124,27 @@ class DownloadCache(
             .launchIn(scope)
     }
 
+    /**
+     * Returns the ids of the downloaded chapters among the given chapters of one manga.
+     *
+     * @param chapters the chapters to query, all of the same manga.
+     * @param mangaTitle the title of the manga to query.
+     * @param sourceId the id of the source of the chapters.
+     */
+    fun getDownloadedChapterIds(chapters: List<Chapter>, mangaTitle: String, sourceId: Long): Set<Long> {
+        renewCache()
+
+        val mangaDir = rootDownloadsDir.sourceDirs[sourceId]?.mangaDirs?.get(provider.getMangaDirName(mangaTitle))
+        if (mangaDir == null || mangaDir.chapterDirs.isEmpty()) return emptySet()
+
+        return chapters
+            .filter { chapter ->
+                provider.getValidChapterDirNames(chapter.name, chapter.scanlator, chapter.url)
+                    .any { it in mangaDir.chapterDirs }
+            }
+            .mapTo(HashSet()) { it.id }
+    }
+
     /**
      * Returns true if the chapter is downloaded.
      *

app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadManager.kt

@@ -93,6 +93,13 @@ class DownloadManager(
         return queueState.value.find { it.chapter.id == chapterId }
     }
 
+    /**
+     * Returns the queued downloads by chapter id, for looking up many chapters at once.
+     */
+    fun getQueuedDownloadsByChapterId(): Map<Long, Download> {
+        return queueState.value.associateBy { it.chapter.id }
+    }
+
     fun startDownloadNow(chapterId: Long) {
         val existingDownload = getQueuedDownloadOrNull(chapterId)
         // If not in queue try to start a new download
@@ -172,6 +179,16 @@ class DownloadManager(
             }
     }
 
+    /**
+     * Returns the ids of the downloaded chapters among the given chapters of the manga.
+     *
+     * @param chapters the chapters to query, all of [manga].
+     * @param manga the manga of the chapters.
+     */
+    fun getDownloadedChapterIds(chapters: List<Chapter>, manga: Manga): Set<Long> {
+        return cache.getDownloadedChapterIds(chapters, manga.title, manga.source)
+    }
+
     /**
      * Returns true if the chapter is downloaded.
      *

app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaViewModel.kt

@@ -543,23 +543,11 @@ class MangaViewModel(
 
     private fun List<Chapter>.toChapterListItems(manga: Manga): List<ChapterList.Item> {
         val isLocal = manga.isLocal()
+        val queuedDownloads = if (isLocal) emptyMap() else downloadManager.getQueuedDownloadsByChapterId()
+        val downloadedChapterIds = if (isLocal) emptySet() else downloadManager.getDownloadedChapterIds(this, manga)
         return map { chapter ->
-            val activeDownload = if (isLocal) {
-                null
-            } else {
-                downloadManager.getQueuedDownloadOrNull(chapter.id)
-            }
-            val downloaded = if (isLocal) {
-                true
-            } else {
-                downloadManager.isChapterDownloaded(
-                    chapter.name,
-                    chapter.scanlator,
-                    chapter.url,
-                    manga.title,
-                    manga.source,
-                )
-            }
+            val activeDownload = queuedDownloads[chapter.id]
+            val downloaded = isLocal || chapter.id in downloadedChapterIds
             val downloadState = when {
                 activeDownload != null -> activeDownload.status
                 downloaded -> Download.State.DOWNLOADED

app/src/main/java/eu/kanade/tachiyomi/ui/updates/UpdatesViewModel.kt

@@ -211,9 +211,10 @@ class UpdatesViewModel(
     }
 
     private fun List<UpdatesWithRelations>.toUpdateItems(): List<UpdatesItem> {
+        val queuedDownloads = downloadManager.getQueuedDownloadsByChapterId()
         return this
             .map { update ->
-                val activeDownload = downloadManager.getQueuedDownloadOrNull(update.chapterId)
+                val activeDownload = queuedDownloads[update.chapterId]
                 val downloaded = downloadManager.isChapterDownloaded(
                     update.chapterName,
                     update.scanlator,