From 183c549c95ab1266f48fdcede26868f630f37760 Mon Sep 17 00:00:00 2001
From: Niko Huuskonen <niko.huuskonen.00@gmail.com>
Date: Fri, 28 Aug 2026 09:34:11 +0300
Subject: [PATCH] fix: make jellyfin cache read faster and async
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- This addresses the issue where client freezes for a bit until the whole cache gets applied. Also changed the hydration to happen in chunks, reducing time complexity from O(n²) to O(n²/K) where K is chunk size
- Changed global queue restoring to be O(n) instead of O(n²)

Signed-off-by: Niko Huuskonen <niko.huuskonen.00@gmail.com>
---
 .../logic/MediaSource/JellyfinMediaSource.ts  | 12 ++++++++---
 src/renderer/logic/queue.ts                   | 20 +++++++++++--------
 2 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/src/renderer/logic/MediaSource/JellyfinMediaSource.ts b/src/renderer/logic/MediaSource/JellyfinMediaSource.ts
index a7ce025b..e24bb5dc 100644
--- a/src/renderer/logic/MediaSource/JellyfinMediaSource.ts
+++ b/src/renderer/logic/MediaSource/JellyfinMediaSource.ts
@@ -112,7 +112,7 @@ export class JellyfinMediaSource extends MediaSource {
       this.accessToken = cache.accessToken;
       this.userId = cache.userId;
       this.lastSyncedAt = cache.lastSyncedAt;
-      this.hydrateFromCache(cache.items);
+      await this.hydrateFromCache(cache.items);
 
       if (await this.verifySession()) {
         this.isConnected.value = true;
@@ -452,8 +452,14 @@ export class JellyfinMediaSource extends MediaSource {
     this.isSyncing.value = false;
   }
 
-  private hydrateFromCache(items: JellyfinItem[]) {
-    items.forEach((item) => this.amethyst.player.queue.add(this.createTrackFromJellyfinItem(item)));
+  // Batches and yields between chunks so hydrating a large cached library doesn't
+  // freeze the renderer's main thread for the whole loop in one synchronous turn
+  private async hydrateFromCache(items: JellyfinItem[]) {
+    for (let i = 0; i < items.length; i += PAGE_SIZE) {
+      const chunk = items.slice(i, i + PAGE_SIZE).map((item) => this.createTrackFromJellyfinItem(item));
+      await this.amethyst.player.queue.add(chunk);
+      await new Promise((resolve) => setTimeout(resolve, 0));
+    }
   }
 
   private upsertTrack(item: JellyfinItem, existingById: Map<string, Track>) {
diff --git a/src/renderer/logic/queue.ts b/src/renderer/logic/queue.ts
index f427bf62..b5ce7e9e 100644
--- a/src/renderer/logic/queue.ts
+++ b/src/renderer/logic/queue.ts
@@ -59,8 +59,9 @@ export class Queue {
   public constructor(private amethyst: Amethyst, paths?: string[]) {
     if (paths) this.add(paths);
     else {
-      // load saved queue from local storage
-      this.savedQueue.value.forEach((item) => {
+      // load saved queue from local storage, built up front and added in one batch so
+      // restoring a large queue doesn't re-serialize the whole list to storage per track
+      const tracks = this.savedQueue.value.map((item) => {
         const track = new Track(this.amethyst, item.path);
 
         if (item.type == MediaSourceType.Subsonic) {
@@ -71,8 +72,10 @@ export class Queue {
           track.sourceType = MediaSourceType.Jellyfin;
         }
 
-        this.add(track);
+        return track;
       });
+
+      this.add(tracks);
     }
   }
 
@@ -151,16 +154,17 @@ export class Queue {
   }
 
   /**
-   * Adds a track to the queue
-   * @param item A filepath to the track
+   * Adds a track, or a batch of filepaths/tracks under a single localStorage sync, to the queue
+   * @param item A filepath, a track, or an array of either
    */
-  public async add(item: (string | string[]) | Track) {
+  public async add(item: (string | string[]) | Track | Track[]) {
     if (item instanceof Track) {
       this.list.value.set(item.path, item);
     }
     else if (item instanceof Array) {
-      const paths = Array.from(item);
-      paths.forEach((path) => this.list.value.set(path, new Track(this.amethyst, path)));
+      item.forEach((entry) => entry instanceof Track
+        ? this.list.value.set(entry.path, entry)
+        : this.list.value.set(entry, new Track(this.amethyst, entry)));
     }
     else if (typeof item === "string") {
       this.list.value.set(item, new Track(this.amethyst, item));