From 5027660b52a2fe749f1c44ca6a2d2c4cb63e0390 Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Sat, 31 Dec 2022 16:57:13 -0500
Subject: [PATCH] Maybe fix crash when restoring unloaded statuses due to race
 condition

---
 Tusker/CoreData/MastodonCachePersistentStore.swift  | 13 +++++++------
 .../Screens/Timeline/TimelineViewController.swift   | 10 ++++++----
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/Tusker/CoreData/MastodonCachePersistentStore.swift b/Tusker/CoreData/MastodonCachePersistentStore.swift
index 93c8deb1d5..18c8d9fef3 100644
--- a/Tusker/CoreData/MastodonCachePersistentStore.swift
+++ b/Tusker/CoreData/MastodonCachePersistentStore.swift
@@ -256,18 +256,19 @@ class MastodonCachePersistentStore: NSPersistentCloudKitContainer {
         return statusMO
     }
 
-    func addAll(statuses: [Status], completion: (() -> Void)? = nil) {
-        backgroundContext.perform {
-            statuses.forEach { self.upsert(status: $0, context: self.backgroundContext) }
-            self.save(context: self.backgroundContext)
+    func addAll(statuses: [Status], in context: NSManagedObjectContext? = nil, completion: (() -> Void)? = nil) {
+        let context = context ?? backgroundContext
+        context.perform {
+            statuses.forEach { self.upsert(status: $0, context: context) }
+            self.save(context: context)
             statuses.forEach { self.statusSubject.send($0.id) }
             completion?()
         }
     }
     
-    func addAll(statuses: [Status]) async {
+    func addAll(statuses: [Status], in context: NSManagedObjectContext? = nil) async {
         return await withCheckedContinuation { continuation in
-            addAll(statuses: statuses) {
+            addAll(statuses: statuses, in: context) {
                 continuation.resume()
             }
         }
diff --git a/Tusker/Screens/Timeline/TimelineViewController.swift b/Tusker/Screens/Timeline/TimelineViewController.swift
index eda5f7cbee..adc71df8c5 100644
--- a/Tusker/Screens/Timeline/TimelineViewController.swift
+++ b/Tusker/Screens/Timeline/TimelineViewController.swift
@@ -367,17 +367,19 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
                 }
             }
         }
-        await mastodonController.persistentContainer.addAll(statuses: statuses)
+        await mastodonController.persistentContainer.addAll(statuses: statuses, in: mastodonController.persistentContainer.viewContext)
     }
     
     private func applyItemsToRestore(position: TimelinePosition) {
         var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
         snapshot.appendSections([.statuses])
+        let statusIDs = position.statusIDs
+        let centerStatusID = position.centerStatusID
         let items = position.statusIDs.map { Item.status(id: $0, collapseState: .unknown, filterState: .unknown) }
         snapshot.appendItems(items, toSection: .statuses)
         dataSource.apply(snapshot, animatingDifferences: false) {
-            if let centerID = position.centerStatusID,
-               let index = position.statusIDs.firstIndex(of: centerID),
+            if let centerStatusID,
+               let index = statusIDs.firstIndex(of: centerStatusID),
                let indexPath = self.dataSource.indexPath(for: items[index]) {
                 // it sometimes takes multiple attempts to convert on the right scroll position
                 // since we're dealing with a bunch of unmeasured cells, so just try a few times in a loop
@@ -392,7 +394,7 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
                         break
                     }
                 }
-                stateRestorationLogger.fault("TimelineViewController: restored statuses with center ID \(centerID)")
+                stateRestorationLogger.fault("TimelineViewController: restored statuses with center ID \(centerStatusID)")
             } else {
                 stateRestorationLogger.fault("TimelineViewController: restored statuses, but couldn't find center ID")
             }