From ebbfc7a13204e2907eb071b029f20e9fd171689d Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Wed, 6 May 2020 19:32:32 -0400
Subject: [PATCH] Fix race condition on loading notifications

---
 .../MastodonCachePersistentStore.swift        | 15 ++++++
 .../NotificationsTableViewController.swift    | 49 +++++++++----------
 2 files changed, 38 insertions(+), 26 deletions(-)

diff --git a/Tusker/CoreData/MastodonCachePersistentStore.swift b/Tusker/CoreData/MastodonCachePersistentStore.swift
index d404fcd8..450eb74f 100644
--- a/Tusker/CoreData/MastodonCachePersistentStore.swift
+++ b/Tusker/CoreData/MastodonCachePersistentStore.swift
@@ -118,5 +118,20 @@ class MastodonCachePersistentStore: NSPersistentContainer {
             accounts.forEach { self.accountSubject.send($0.id) }
         }
     }
+
+    func addAll(notifications: [Pachyderm.Notification], completion: (() -> Void)? = nil) {
+        backgroundContext.perform {
+            let statuses = notifications.compactMap { $0.status }
+            let accounts = notifications.map { $0.account }
+            statuses.forEach { self.upsert(status: $0, incrementReferenceCount: true) }
+            accounts.forEach { self.upsert(account: $0) }
+            if self.backgroundContext.hasChanges {
+                try! self.backgroundContext.save()
+            }
+            completion?()
+            statuses.forEach { self.statusSubject.send($0.id) }
+            accounts.forEach { self.accountSubject.send($0.id) }
+        }
+    }
     
 }
diff --git a/Tusker/Screens/Notifications/NotificationsTableViewController.swift b/Tusker/Screens/Notifications/NotificationsTableViewController.swift
index f93743a6..e5f1061a 100644
--- a/Tusker/Screens/Notifications/NotificationsTableViewController.swift
+++ b/Tusker/Screens/Notifications/NotificationsTableViewController.swift
@@ -63,14 +63,13 @@ class NotificationsTableViewController: EnhancedTableViewController {
             
             self.groups.append(contentsOf: groups)
             
-            self.mastodonController.persistentContainer.addAll(statuses: notifications.compactMap { $0.status })
-            self.mastodonController.persistentContainer.addAll(accounts: notifications.map { $0.account })
-            
             self.newer = pagination?.newer
             self.older = pagination?.older
             
-            DispatchQueue.main.async {
-                self.tableView.reloadData()
+            self.mastodonController.persistentContainer.addAll(notifications: notifications) {
+                DispatchQueue.main.async {
+                    self.tableView.reloadData()
+                }
             }
         }
     }
@@ -141,15 +140,14 @@ class NotificationsTableViewController: EnhancedTableViewController {
                     IndexPath(row: $0, section: 0)
                 }
                 self.groups.append(contentsOf: groups)
-                
-                self.mastodonController.persistentContainer.addAll(statuses: newNotifications.compactMap { $0.status })
-                self.mastodonController.persistentContainer.addAll(accounts: newNotifications.map { $0.account })
 
                 self.older = pagination?.older
                 
-                DispatchQueue.main.async {
-                    UIView.performWithoutAnimation {
-                        self.tableView.insertRows(at: newIndexPaths, with: .automatic)
+                self.mastodonController.persistentContainer.addAll(notifications: newNotifications) {
+                    DispatchQueue.main.async {
+                        UIView.performWithoutAnimation {
+                            self.tableView.insertRows(at: newIndexPaths, with: .automatic)
+                        }
                     }
                 }
             }
@@ -219,25 +217,24 @@ class NotificationsTableViewController: EnhancedTableViewController {
             
             self.groups.insert(contentsOf: groups, at: 0)
             
-            self.mastodonController.persistentContainer.addAll(statuses: newNotifications.compactMap { $0.status })
-            self.mastodonController.persistentContainer.addAll(accounts: newNotifications.map { $0.account })
-
             if let newer = pagination?.newer {
                 self.newer = newer
             }
-
-            DispatchQueue.main.async {
-                let newIndexPaths = (0..<groups.count).map {
-                    IndexPath(row: $0, section: 0)
+            
+            self.mastodonController.persistentContainer.addAll(notifications: newNotifications) {
+                DispatchQueue.main.async {
+                    let newIndexPaths = (0..<groups.count).map {
+                        IndexPath(row: $0, section: 0)
+                    }
+                    UIView.performWithoutAnimation {
+                        self.tableView.insertRows(at: newIndexPaths, with: .automatic)
+                    }
+                    
+                    self.refreshControl?.endRefreshing()
+                    
+                    // maintain the current position in the list (don't scroll to top)
+                    self.tableView.scrollToRow(at: IndexPath(row: newNotifications.count, section: 0), at: .top, animated: false)
                 }
-                UIView.performWithoutAnimation {
-                    self.tableView.insertRows(at: newIndexPaths, with: .automatic)
-                }
-
-                self.refreshControl?.endRefreshing()
-                
-                // maintain the current position in the list (don't scroll to top)
-                self.tableView.scrollToRow(at: IndexPath(row: newNotifications.count, section: 0), at: .top, animated: false)
             }
         }
     }