Don't start a second sync while syncing is already in progress

Fervor/FervorClient.swift

@@ -131,6 +131,20 @@ public class FervorClient {
         return try await performRequest(request)
     }
     
+    public func read(ids: [FervorID]) async throws -> [FervorID] {
+        var request = URLRequest(url: buildURL(path: "/api/v1/items/read"))
+        request.httpMethod = "POST"
+        request.setURLEncodedBody(params: ["ids": ids.joined(separator: ",")])
+        return try await performRequest(request)
+    }
+    
+    public func unread(ids: [FervorID]) async throws -> [FervorID] {
+        var request = URLRequest(url: buildURL(path: "/api/v1/items/unread"))
+        request.httpMethod = "POST"
+        request.setURLEncodedBody(params: ["ids": ids.joined(separator: ",")])
+        return try await performRequest(request)
+    }
+    
     public struct Auth {
         public let accessToken: String
         public let refreshToken: String?

Reader/CoreData/PersistentContainer.swift

@@ -102,7 +102,7 @@ class PersistentContainer: NSPersistentContainer {
         try await self.saveViewContext()
     }
     
-    func syncItems(_ syncUpdate: ItemsSyncUpdate) async throws {
+    func syncItems(_ syncUpdate: ItemsSyncUpdate, setSyncState: @escaping (FervorController.SyncState) -> Void) async throws {
         try await backgroundContext.perform {
             self.logger.debug("syncItems: deleting \(syncUpdate.delete.count, privacy: .public) items")
             let deleteReq = Item.fetchRequest()
@@ -122,7 +122,8 @@ class PersistentContainer: NSPersistentContainer {
             let existing = try self.backgroundContext.fetch(req)
             self.logger.debug("syncItems: updating \(existing.count, privacy: .public) items, inserting \(syncUpdate.upsert.count - existing.count, privacy: .public)")
             // todo: this feels like it'll be slow when there are many items
-            for item in syncUpdate.upsert {
+            for (index, item) in syncUpdate.upsert.enumerated() {
+                setSyncState(.updateItems(current: index, total: syncUpdate.upsert.count))
                 if let existing = existing.first(where: { $0.id == item.id }) {
                     existing.updateFromServer(item)
                 } else {

Reader/ExcerptGenerator.swift

@@ -15,12 +15,13 @@ public struct ExcerptGenerator {
     
     private static let logger = Logger(subsystem: Bundle.main.bundleIdentifier!, category: "ExcerptGenerator")
     
-    static func generateAll(_ fervorController: FervorController) {
+    static func generateAll(_ fervorController: FervorController) async {
         let req = Item.fetchRequest()
         req.predicate = NSPredicate(format: "generatedExcerpt = NO")
         req.sortDescriptors = [NSSortDescriptor(key: "published", ascending: false)]
         req.fetchBatchSize = 50
-        fervorController.persistentContainer.performBackgroundTask { ctx in
+        let ctx = fervorController.persistentContainer.newBackgroundContext()
+        await ctx.perform {
             guard let items = try? ctx.fetch(req) else { return }
             var count = 0
             for item in items {
@@ -45,7 +46,7 @@ public struct ExcerptGenerator {
                         NSUpdatedObjectsKey: Array(updated)
                     ], into: [fervorController.persistentContainer.viewContext])
                 } catch {
-                    logger.error("Unable to save context: \(error.localizedDescription, privacy: .public)")
+                    logger.error("Unable to save context: \(String(describing: error), privacy: .public)")
                 }
             }
         }

Reader/FervorController.swift

@@ -8,6 +8,7 @@
 import Foundation
 import Fervor
 import OSLog
+import Combine
 
 class FervorController {
     
@@ -25,6 +26,8 @@ class FervorController {
     
     private(set) var persistentContainer: PersistentContainer!
     
+    @Published private(set) var syncState = SyncState.done
+    
     init(instanceURL: URL) {
         self.instanceURL = instanceURL
         self.client = FervorClient(instanceURL: instanceURL, accessToken: nil)
@@ -42,6 +45,12 @@ class FervorController {
         self.persistentContainer = PersistentContainer(account: account, fervorController: self)
     }
     
+    private func setSyncState(_ state: SyncState) {
+        DispatchQueue.main.async {
+            self.syncState = state
+        }
+    }
+    
     func register() async throws -> ClientRegistration {
         let registration = try await client.register(clientName: "Frenzy iOS", website: nil, redirectURI: FervorController.oauthRedirectURI)
         clientID = registration.clientID
@@ -56,49 +65,64 @@ class FervorController {
     }
     
     func syncAll() async throws {
+        guard syncState == .done else {
+            return
+        }
+        // always return to .done, even if we throw and stop syncing early
+        defer { setSyncState(.done) }
+        
+        setSyncState(.groupsAndFeeds)
+        
         logger.info("Syncing groups and feeds")
         async let groups = try client.groups()
         async let feeds = try client.feeds()
         try await persistentContainer.sync(serverGroups: groups, serverFeeds: feeds)
         
+        setSyncState(.items)
+        
         let lastSync = try await persistentContainer.lastSyncDate()
         logger.info("Syncing items with last sync date: \(String(describing: lastSync), privacy: .public)")
         let update = try await client.syncItems(lastSync: lastSync)
-        try await persistentContainer.syncItems(update)
+        try await persistentContainer.syncItems(update, setSyncState: setSyncState(_:))
         try await persistentContainer.updateLastSyncDate(update.syncTimestamp)
+        
+        setSyncState(.excerpts)
+        await ExcerptGenerator.generateAll(self)
     }
     
     @MainActor
-    func syncReadToServer() async throws {
+    func syncReadToServer() async {
         var count = 0
-        // todo: there should be a batch update api endpoint
-        for case let item as Item in persistentContainer.viewContext.updatedObjects {
-            let f = item.read ? client.read(item:) : client.unread(item:)
-            do {
-                let _ = try await f(item.id!)
-                count += 1
-            } catch {
-                logger.error("Failed to sync read state: \(error.localizedDescription, privacy: .public)")
-                item.needsReadStateSync = true
-            }
-        }
         
         // try to sync items which failed last time
         let req = Item.fetchRequest()
         req.predicate = NSPredicate(format: "needsReadStateSync = YES")
-        if let needsSync = try? persistentContainer.viewContext.fetch(req) {
-            for item in needsSync {
-                let f = item.read ? client.read(item:) : client.unread(item:)
+        if var needsSync = try? persistentContainer.viewContext.fetch(req) {
+            let firstReadIndex = needsSync.partition(by: \.read)
+            let unreadIDs = needsSync[..<firstReadIndex].map(\.id.unsafelyUnwrapped)
+            let readIDs = needsSync[firstReadIndex...].map(\.id.unsafelyUnwrapped)
+            var updatedIDs = Set<FervorID>()
+            if !unreadIDs.isEmpty {
                 do {
-                    let _ = try await f(item.id!)
-                    count += 1
-                    item.needsReadStateSync = false
+                    let ids = try await client.unread(ids: unreadIDs)
+                    updatedIDs.formUnion(ids)
                 } catch {
-                    logger.error("Failed to sync read state again: \(error.localizedDescription, privacy: .public)")
-                    item.needsReadStateSync = true
-                    // todo: this should probably fail after a certain number of attempts
+                    logger.error("Failed to sync unread state: \(String(describing: error), privacy: .public)")
                 }
             }
+            if !readIDs.isEmpty {
+                do {
+                    let ids = try await client.read(ids: readIDs)
+                    updatedIDs.formUnion(ids)
+                } catch {
+                    logger.error("Failed to sync read state: \(String(describing: error), privacy: .public)")
+                }
+            }
+            
+            count += updatedIDs.count
+            for item in needsSync where updatedIDs.contains(item.id!) {
+                item.needsReadStateSync = false
+            }
         }
         
         logger.info("Synced \(count, privacy: .public) read/unread to server")
@@ -106,7 +130,7 @@ class FervorController {
         do {
             try persistentContainer.viewContext.save()
         } catch {
-            logger.error("Failed to save view context: \(error.localizedDescription, privacy: .public)")
+            logger.error("Failed to save view context: \(String(describing: error), privacy: .public)")
         }
     }
     
@@ -118,7 +142,7 @@ class FervorController {
             _ = try await f(item.id!)
             item.needsReadStateSync = false
         } catch {
-            logger.error("Failed to mark item (un)read: \(error.localizedDescription, privacy: .public)")
+            logger.error("Failed to mark item (un)read: \(String(describing: error), privacy: .public)")
             item.needsReadStateSync = true
         }
         
@@ -126,9 +150,19 @@ class FervorController {
             do {
                 try persistentContainer.viewContext.save()
             } catch {
-                logger.error("Failed to save view context: \(error.localizedDescription, privacy: .public)")
+                logger.error("Failed to save view context: \(String(describing: error), privacy: .public)")
             }
         }
     }
     
 }
+
+extension FervorController {
+    enum SyncState: Equatable {
+        case groupsAndFeeds
+        case items
+        case updateItems(current: Int, total: Int)
+        case excerpts
+        case done
+    }
+}

Reader/SceneDelegate.swift

@@ -81,11 +81,7 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
         
         if let fervorController = fervorController {
             Task(priority: .userInitiated) {
-                do {
-                    try await fervorController.syncReadToServer()
-                } catch {
-                    logger.error("Unable to sync read state to server: \(error.localizedDescription, privacy: .public)")
-                }
+                await fervorController.syncReadToServer()
             }
         }
     }
@@ -111,12 +107,10 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
         }
         Task(priority: .userInitiated) {
             do {
-                try await self.fervorController.syncAll()
+                try await fervorController.syncAll()
             } catch {
-                logger.error("Unable to sync from server: \(error.localizedDescription, privacy: .public)")
+                logger.error("Unable to sync from server: \(String(describing: error), privacy: .public)")
             }
-            
-            ExcerptGenerator.generateAll(fervorController)
         }
     }
     
@@ -130,6 +124,13 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
             window!.overrideUserInterfaceStyle = .dark
         }
     }
+    
+    func switchToAccount(_ account: LocalData.Account) {
+        LocalData.mostRecentAccountID = account.id
+        fervorController = FervorController(account: account)
+        createAppUI()
+        syncFromServer()
+    }
 
 }
 
@@ -147,15 +148,6 @@ extension SceneDelegate: LoginViewControllerDelegate {
     }
 }
 
-extension SceneDelegate: HomeViewControllerDelegate {
-    func switchToAccount(_ account: LocalData.Account) {
-        LocalData.mostRecentAccountID = account.id
-        fervorController = FervorController(account: account)
-        createAppUI()
-        syncFromServer()
-    }
-}
-
 #if targetEnvironment(macCatalyst)
 extension NSToolbarItem.Identifier {
     static let toggleItemRead = NSToolbarItem.Identifier("ToggleItemRead")

Reader/Screens/AppSplitViewController.swift

@@ -49,6 +49,7 @@ class AppSplitViewController: UISplitViewController {
         setViewController(secondaryNav, for: .secondary)
         
         let home = HomeViewController(fervorController: fervorController)
+        home.delegate = self
         let nav = AppNavigationController(rootViewController: home)
         setViewController(nav, for: .compact)
     }
@@ -61,3 +62,10 @@ extension AppSplitViewController: ItemsViewControllerDelegate {
     }
 }
 
+extension AppSplitViewController: HomeViewControllerDelegate {
+    func switchToAccount(_ account: LocalData.Account) {
+        if let delegate = view.window?.windowScene?.delegate as? SceneDelegate {
+            delegate.switchToAccount(account)
+        }
+    }
+}

Reader/Screens/Home/HomeViewController.swift

@@ -7,6 +7,7 @@
 
 import UIKit
 import CoreData
+import Combine
 
 protocol HomeViewControllerDelegate: AnyObject {
     func switchToAccount(_ account: LocalData.Account)
@@ -26,6 +27,10 @@ class HomeViewController: UIViewController {
     private var groupResultsController: NSFetchedResultsController<Group>!
     private var feedResultsController: NSFetchedResultsController<Feed>!
     
+    private var lastSyncState = FervorController.SyncState.done
+    private var syncStateView: SyncStateView?
+    private var cancellables = Set<AnyCancellable>()
+    
     init(fervorController: FervorController) {
         self.fervorController = fervorController
         
@@ -87,6 +92,13 @@ class HomeViewController: UIViewController {
         feedResultsController = NSFetchedResultsController(fetchRequest: feedReq, managedObjectContext: fervorController.persistentContainer.viewContext, sectionNameKeyPath: nil, cacheName: nil)
         feedResultsController.delegate = self
         try! feedResultsController.performFetch()
+        
+        fervorController.$syncState
+            .debounce(for: .milliseconds(250), scheduler: RunLoop.main, options: nil)
+            .sink { [unowned self] in
+                self.syncStateChanged($0)
+            }
+            .store(in: &cancellables)
     }
     
     override func viewWillAppear(_ animated: Bool) {
@@ -136,6 +148,56 @@ class HomeViewController: UIViewController {
         return dataSource
     }
     
+    private func syncStateChanged(_ newState: FervorController.SyncState) {
+        if newState == .done && syncStateView == nil {
+            return
+        }
+        
+        func updateView(_ syncStateView: SyncStateView) {
+            switch newState {
+            case .groupsAndFeeds:
+                syncStateView.label.text = "Syncing groups and feeds"
+            case .items:
+                syncStateView.label.text = "Syncing items"
+            case .updateItems(current: let current, total: let total):
+                syncStateView.label.text = "Updating \(current + 1) of \(total) item\(total == 1 ? "" : "s")"
+            case .excerpts:
+                syncStateView.label.text = "Generating excerpts"
+            case .done:
+                syncStateView.label.text = "Done syncing"
+
+                UIView.animate(withDuration: 0.25, delay: 1, options: .curveEaseIn) {
+                    syncStateView.transform = CGAffineTransform(translationX: 0, y: syncStateView.bounds.height)
+                } completion: { _ in
+                    syncStateView.removeFromSuperview()
+                }
+            }
+        }
+        
+        if let syncStateView = self.syncStateView {
+            updateView(syncStateView)
+        } else {
+            let syncStateView = SyncStateView()
+            self.syncStateView = syncStateView
+            syncStateView.translatesAutoresizingMaskIntoConstraints = false
+            view.addSubview(syncStateView)
+            NSLayoutConstraint.activate([
+                syncStateView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+                syncStateView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+                syncStateView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
+            ])
+            
+            view.layoutIfNeeded()
+            syncStateView.transform = CGAffineTransform(translationX: 0, y: syncStateView.bounds.height)
+           
+            UIView.animate(withDuration: 0.25, delay: 0, options: .curveEaseOut) {
+                syncStateView.transform = .identity
+            } completion: { _ in
+                updateView(syncStateView)
+            }
+        }
+    }
+    
 }
 
 extension HomeViewController {
@@ -307,3 +369,39 @@ extension HomeViewController: LoginViewControllerDelegate {
         (view.window!.windowScene!.delegate as! SceneDelegate).didLogin(with: controller)
     }
 }
+
+private class SyncStateView: UIView {
+    let label = UILabel()
+    
+    init() {
+        super.init(frame: .zero)
+        
+        let blur = UIBlurEffect(style: .regular)
+        let blurView = UIVisualEffectView(effect: blur)
+        blurView.translatesAutoresizingMaskIntoConstraints = false
+        addSubview(blurView)
+        
+        label.translatesAutoresizingMaskIntoConstraints = false
+        addSubview(label)
+        
+        NSLayoutConstraint.activate([
+            blurView.leadingAnchor.constraint(equalTo: leadingAnchor),
+            blurView.trailingAnchor.constraint(equalTo: trailingAnchor),
+            blurView.topAnchor.constraint(equalTo: topAnchor),
+            blurView.bottomAnchor.constraint(equalTo: bottomAnchor),
+            
+            label.centerXAnchor.constraint(equalTo: safeAreaLayoutGuide.centerXAnchor),
+            label.centerYAnchor.constraint(equalTo: safeAreaLayoutGuide.centerYAnchor),
+            
+            safeAreaLayoutGuide.heightAnchor.constraint(equalToConstant: 50),
+        ])
+        
+        layer.shadowColor = UIColor.black.cgColor
+        layer.shadowOpacity = 0.1
+        layer.shadowRadius = 10
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+}