Don't use shared background context for fetching item counts

A significant fraction of the time was spent waiting for the background
context to be available, before the count could even be started. Since
the counts don't need to use the shared background context, let them
each use their own context to avoid contention.

Persistence/Sources/Persistence/PersistentContainer.swift

@@ -19,8 +19,9 @@ public class PersistentContainer: NSPersistentContainer, @unchecked Sendable {
     
     public private(set) lazy var backgroundContext: NSManagedObjectContext = {
         let context = NSManagedObjectContext(concurrencyType: .privateQueueConcurrencyType)
-        // todo: should the background context really be parented to the view context, or should they both be direct children of the PSC?
-        context.parent = self.viewContext
+        // the background context needs to be parented directly to the PSC
+        // if it's parented to the viewContext, it blocks the viewContext (and potentially the main thread) when it needs to look things up
+        context.persistentStoreCoordinator = self.persistentStoreCoordinator
         return context
     }()
     

Persistence/Sources/Persistence/Reader.xcdatamodeld/.xccurrentversion

@@ -3,6 +3,6 @@
 <plist version="1.0">
 <dict>
 	<key>_XCCurrentVersionName</key>
-	<string>Reader.xcdatamodel</string>
+	<string>Reader 2.xcdatamodel</string>
 </dict>
 </plist>

Persistence/Sources/Persistence/Reader.xcdatamodeld/Reader 2.xcdatamodel/contents

@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<model type="com.apple.IDECoreDataModeler.DataModel" documentVersion="1.0" lastSavedToolsVersion="21279" systemVersion="22A5331f" minimumToolsVersion="Automatic" sourceLanguage="Swift" userDefinedModelVersionIdentifier="">
+    <entity name="Feed" representedClassName="Feed" syncable="YES">
+        <attribute name="id" attributeType="String"/>
+        <attribute name="lastUpdated" optional="YES" attributeType="Date" usesScalarValueType="NO"/>
+        <attribute name="title" attributeType="String"/>
+        <attribute name="url" optional="YES" attributeType="URI"/>
+        <relationship name="groups" toMany="YES" deletionRule="Nullify" destinationEntity="Group" inverseName="feeds" inverseEntity="Group"/>
+        <relationship name="items" toMany="YES" deletionRule="Cascade" destinationEntity="Item" inverseName="feed" inverseEntity="Item"/>
+    </entity>
+    <entity name="Group" representedClassName="Group" syncable="YES">
+        <attribute name="id" attributeType="String"/>
+        <attribute name="title" attributeType="String"/>
+        <relationship name="feeds" toMany="YES" deletionRule="Nullify" destinationEntity="Feed" inverseName="groups" inverseEntity="Feed"/>
+    </entity>
+    <entity name="Item" representedClassName="Item" versionHashModifier="5" syncable="YES">
+        <attribute name="author" optional="YES" attributeType="String"/>
+        <attribute name="content" optional="YES" attributeType="String"/>
+        <attribute name="excerpt" optional="YES" attributeType="String"/>
+        <attribute name="generatedExcerpt" attributeType="Boolean" defaultValueString="NO" usesScalarValueType="YES"/>
+        <attribute name="id" attributeType="String"/>
+        <attribute name="needsReadStateSync" attributeType="Boolean" defaultValueString="NO" usesScalarValueType="YES"/>
+        <attribute name="published" optional="YES" attributeType="Date" usesScalarValueType="NO"/>
+        <attribute name="read" attributeType="Boolean" usesScalarValueType="YES"/>
+        <attribute name="title" optional="YES" attributeType="String"/>
+        <attribute name="url" optional="YES" attributeType="URI"/>
+        <relationship name="feed" maxCount="1" deletionRule="Nullify" destinationEntity="Feed" inverseName="items" inverseEntity="Feed"/>
+        <fetchIndex name="byID">
+            <fetchIndexElement property="id" type="Binary" order="ascending"/>
+        </fetchIndex>
+        <fetchIndex name="byRead">
+            <fetchIndexElement property="read" type="Binary" order="ascending"/>
+        </fetchIndex>
+    </entity>
+    <entity name="SyncState" representedClassName="SyncState" syncable="YES" codeGenerationType="class">
+        <attribute name="lastSync" attributeType="Date" usesScalarValueType="NO"/>
+    </entity>
+    <fetchRequest name="FetchRequest" entity="Item" predicateString="TRUEPREDICATE"/>
+</model>

Persistence/Sources/Persistence/Reader.xcdatamodeld/Reader.xcdatamodel/contents

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
-<model type="com.apple.IDECoreDataModeler.DataModel" documentVersion="1.0" lastSavedToolsVersion="21223.11" systemVersion="22A5266r" minimumToolsVersion="Automatic" sourceLanguage="Swift" userDefinedModelVersionIdentifier="">
+<model type="com.apple.IDECoreDataModeler.DataModel" documentVersion="1.0" lastSavedToolsVersion="21279" systemVersion="22A5331f" minimumToolsVersion="Automatic" sourceLanguage="Swift" userDefinedModelVersionIdentifier="">
     <entity name="Feed" representedClassName="Feed" syncable="YES">
         <attribute name="id" attributeType="String"/>
         <attribute name="lastUpdated" optional="YES" attributeType="Date" usesScalarValueType="NO"/>
@@ -30,10 +30,4 @@
         <attribute name="lastSync" attributeType="Date" usesScalarValueType="NO"/>
     </entity>
     <fetchRequest name="FetchRequest" entity="Item" predicateString="TRUEPREDICATE"/>
-    <elements>
-        <element name="Feed" positionX="-54" positionY="9" width="128" height="119"/>
-        <element name="Group" positionX="-63" positionY="-18" width="128" height="74"/>
-        <element name="Item" positionX="-45" positionY="63" width="128" height="194"/>
-        <element name="SyncState" positionX="-63" positionY="90" width="128" height="44"/>
-    </elements>
 </model>

Reader.xcodeproj/xcshareddata/xcschemes/Reader.xcscheme

@@ -75,7 +75,18 @@
             argument = "-com.apple.CoreData.ConcurrencyDebug 1"
             isEnabled = "YES">
          </CommandLineArgument>
+         <CommandLineArgument
+            argument = "-com.apple.CoreData.SQLDebug 1"
+            isEnabled = "NO">
+         </CommandLineArgument>
       </CommandLineArguments>
+      <EnvironmentVariables>
+         <EnvironmentVariable
+            key = "SQLITE_AUTO_TRACE"
+            value = "1"
+            isEnabled = "NO">
+         </EnvironmentVariable>
+      </EnvironmentVariables>
    </LaunchAction>
    <ProfileAction
       buildConfiguration = "Release"

Reader/BackgroundManager.swift

@@ -104,6 +104,7 @@ class BackgroundManager: NSObject {
             do {
                 try await fervorController.persistentContainer.upsertItems(items)
                 logger.info("Upserted \(items.count) items during background refresh")
+                logger.info("Most recent unread item: \(items.first(where: { $0.read == false })!.title!, privacy: .public)")
                 
                 await WidgetHelper.updateWidgetData(fervorController: fervorController)
                 

Reader/ItemListType.swift

@@ -9,7 +9,7 @@ import Foundation
 import CoreData
 import Persistence
 
-enum ItemListType: Hashable {
+enum ItemListType: Hashable, Equatable {
     case unread
     case all
     case group(Group)
@@ -52,7 +52,9 @@ enum ItemListType: Hashable {
         case .all:
             return nil
         case .group(let group):
-            req.predicate = NSPredicate(format: "read = NO AND feed in %@", group.feeds!)
+            // use the feed ids, because passing the NSSet of feeds into the predicate results in a multithreading violation if the request is used on a different context
+            let feedIDs = group.feeds!.map { ($0 as! Feed).objectID }
+            req.predicate = NSPredicate(format: "read = NO AND feed in %@", feedIDs)
         case .feed(let feed):
             req.predicate = NSPredicate(format: "read = NO AND feed = %@", feed)
         }

Reader/Screens/AppSplitViewController.swift

@@ -45,7 +45,11 @@ class AppSplitViewController: UISplitViewController {
         setViewController(sidebarNav, for: .primary)
         
         secondaryNav = UINavigationController()
-        secondaryNav.isNavigationBarHidden = true
+        // the toggle sidebar button only appears if there's a navigation bar
+        // so we just make always transparent, rather than disabling it
+        let secondaryNavBarAppearance = UINavigationBarAppearance()
+        secondaryNavBarAppearance.configureWithTransparentBackground()
+        secondaryNav.navigationBar.standardAppearance = secondaryNavBarAppearance
         secondaryNav.view.backgroundColor = .appBackground
         setViewController(secondaryNav, for: .secondary)
         

Reader/Screens/Home/HomeCollectionViewCell.swift

@@ -7,9 +7,16 @@
 
 import UIKit
 import Fervor
+import Persistence
+import OSLog
+
+private let signposter = OSSignposter(subsystem: "net.shadowfacts.Reader", category: "HomeCollectionViewCell")
 
 class HomeCollectionViewCell: UICollectionViewListCell {
     
+    private var currentItemCountTask: Task<Void, Never>?
+    private var itemCount: Int?
+    
     #if !targetEnvironment(macCatalyst)
     override func updateConfiguration(using state: UICellConfigurationState) {
         var backgroundConfig = UIBackgroundConfiguration.listGroupedCell().updated(for: state)
@@ -22,4 +29,47 @@ class HomeCollectionViewCell: UICollectionViewListCell {
     }
     #endif
     
+    override func prepareForReuse() {
+        super.prepareForReuse()
+        currentItemCountTask?.cancel()
+        itemCount = nil
+    }
+    
+    func updateUI(item: ItemListType, persistentContainer: PersistentContainer) {
+        var config = UIListContentConfiguration.valueCell()
+        config.text = item.title
+        if let itemCount {
+            config.secondaryText = itemCount.formatted(.number)
+        }
+        config.secondaryTextProperties.color = .tintColor
+        self.contentConfiguration = config
+        
+        currentItemCountTask = Task(priority: .userInitiated) {
+            let state = signposter.beginInterval("fetch count", id: signposter.makeSignpostID(), "\(String(item.hashValue, radix: 16), privacy: .public)")
+            if let count = await fetchCount(item: item, in: persistentContainer),
+               !Task.isCancelled {
+                self.itemCount = count
+                config.secondaryText = count.formatted(.number)
+                self.contentConfiguration = config
+            }
+            signposter.endInterval("fetch count", state)
+        }
+    }
+    
+    private func fetchCount(item: ItemListType, in persistentContainer: PersistentContainer) async -> Int? {
+        guard let request = item.countFetchRequest else {
+            return nil
+        }
+        return await withCheckedContinuation({ continuation in
+            let state = signposter.beginInterval("waiting to perform", id: signposter.makeSignpostID(), "\(String(item.hashValue, radix: 16), privacy: .public)")
+            persistentContainer.performBackgroundTask { context in
+                signposter.endInterval("waiting to perform", state)
+                let state = signposter.beginInterval("count", id: signposter.makeSignpostID(), "\(String(item.hashValue, radix: 16), privacy: .public)")
+                let count = try? context.count(for: request)
+                signposter.endInterval("count", state)
+                continuation.resume(returning: count)
+            }
+        })
+    }
+    
 }

Reader/Screens/Home/HomeViewController.swift

@@ -126,15 +126,8 @@ class HomeViewController: UIViewController {
             config.text = section.title
             supplementaryView.contentConfiguration = config
         }
-        let listCell = UICollectionView.CellRegistration<HomeCollectionViewCell, ItemListType> { cell, indexPath, item in
-            var config = UIListContentConfiguration.valueCell()
-            config.text = item.title
-            if let req = item.countFetchRequest,
-               let count = try? self.fervorController.persistentContainer.viewContext.count(for: req) {
-                config.secondaryText = "\(count)"
-                config.secondaryTextProperties.color = .tintColor
-            }
-            cell.contentConfiguration = config
+        let listCell = UICollectionView.CellRegistration<HomeCollectionViewCell, ItemListType> { [unowned self] cell, indexPath, item in
+            cell.updateUI(item: item, persistentContainer: self.fervorController.persistentContainer)
             
             cell.accessories = [.disclosureIndicator()]
         }

Reader/Screens/Items/ItemsViewController.swift

@@ -60,6 +60,22 @@ class ItemsViewController: UIViewController {
             
         var configuration = UICollectionLayoutListConfiguration(appearance: .plain)
         configuration.backgroundColor = .clear
+        configuration.trailingSwipeActionsConfigurationProvider = { [unowned self] indexPath in
+            guard let itemID = self.dataSource.itemIdentifier(for: indexPath) else {
+                return nil
+            }
+            let item = fervorController.persistentContainer.viewContext.object(with: itemID) as! Item
+            let action = UIContextualAction(style: .normal, title: item.read ? "Mark as Unread" : "Mark as Read") { _, _, completion in
+                Task {
+                    await self.fervorController.markItem(item, read: !item.read)
+                    completion(true)
+                }
+            }
+            action.image = UIImage(systemName: item.read ? "checkmark.circle" : "checkmark.circle.fill")
+            return UISwipeActionsConfiguration(actions: [
+                action
+            ])
+        }
         let layout = UICollectionViewCompositionalLayout.list(using: configuration)
         collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: layout)
         collectionView.delegate = self

Reader/Screens/Read/ReadViewController.swift

@@ -72,7 +72,10 @@ class ReadViewController: UIViewController {
         webView.isOpaque = false
         webView.backgroundColor = .clear
         if #available(iOS 16.0, *) {
+            // TODO: Xcode 14 RC doesn't have the macOS 13 SDK, so we can't use this
+            #if !targetEnvironment(macCatalyst)
             webView.isFindInteractionEnabled = true
+            #endif
         }
         if let content = itemContentHTML() {
             webView.loadHTMLString(content, baseURL: item.url)

Reader/Widgets/WidgetHelper.swift

@@ -11,6 +11,7 @@ import Persistence
 import OSLog
 
 private let logger = Logger(subsystem: "net.shadowfacts.Reader", category: "WidgetHelper")
+private let signposter = OSSignposter(logger: logger)
 
 struct WidgetHelper {
     private init() {}
@@ -26,7 +27,9 @@ struct WidgetHelper {
             req.sortDescriptors = [NSSortDescriptor(key: "published", ascending: false)]
             req.fetchLimit = 32
             req.predicate = NSPredicate(format: "read = NO")
+            let state = signposter.beginInterval("fetch")
             var items = (try? context.fetch(req)) ?? []
+            signposter.endInterval("fetch", state)
             
             var prioritizedItems: [Item] = []
             
@@ -51,6 +54,8 @@ struct WidgetHelper {
             }
         }
         
+        logger.info("Saving widget data with first item: '\(prioritizedItems.first!.title ?? "<untitled>", privacy: .public)'")
+        
         WidgetData(recentItems: prioritizedItems).save(account: fervorController.account!)
         
         WidgetCenter.shared.reloadAllTimelines()