Improve concurrency model for iOS

ios/Ascently/Services/SyncService.swift

@@ -10,7 +10,7 @@ class SyncService: ObservableObject {
     @Published var isConnected = false
     @Published var isTesting = false
     @Published var isOfflineMode = false
-    
+
     @Published var providerType: SyncProviderType = .server {
         didSet {
             updateActiveProvider()
@@ -23,8 +23,6 @@ class SyncService: ObservableObject {
     private let userDefaults = UserDefaults.standard
     private let logTag = "SyncService"
     private var syncTask: Task<Void, Never>?
-    private var pendingChanges = false
-    private let syncDebounceDelay: TimeInterval = 2.0
 
     private enum Keys {
         static let serverURL = "sync_server_url"
@@ -39,7 +37,7 @@ class SyncService: ObservableObject {
     // Legacy properties for compatibility with SettingsView
     var serverURL: String {
         get { userDefaults.string(forKey: Keys.serverURL) ?? "" }
-        set { 
+        set {
             userDefaults.set(newValue, forKey: Keys.serverURL)
             // If active provider is server, it will pick up the change from UserDefaults
         }
@@ -66,28 +64,28 @@ class SyncService: ObservableObject {
         isConnected = userDefaults.bool(forKey: Keys.isConnected)
         isAutoSyncEnabled = userDefaults.object(forKey: Keys.autoSyncEnabled) as? Bool ?? true
         isOfflineMode = userDefaults.bool(forKey: Keys.offlineMode)
-        
+
         if let savedType = userDefaults.string(forKey: Keys.providerType),
            let type = SyncProviderType(rawValue: savedType) {
             self.providerType = type
         } else {
             self.providerType = .server // Default
         }
-        
+
         updateActiveProvider()
     }
-    
+
     private func updateActiveProvider() {
         switch providerType {
         case .server:
             activeProvider = ServerSyncProvider()
         case .iCloud:
             // Placeholder for iCloud provider
-            activeProvider = nil 
+            activeProvider = nil
         case .none:
             activeProvider = nil
         }
-        
+
         // Update status based on new provider
         if let provider = activeProvider {
             isConnected = provider.isConnected
@@ -101,7 +99,7 @@ class SyncService: ObservableObject {
             AppLogger.info("Sync skipped: Offline mode is enabled.", tag: logTag)
             return
         }
-        
+
         guard let provider = activeProvider else {
             if providerType == .none {
                 return
@@ -127,7 +125,7 @@ class SyncService: ObservableObject {
 
         do {
             try await provider.sync(dataManager: dataManager)
-            
+
             // Update last sync time
             // Provider might have updated it in UserDefaults, reload it
             if let lastSync = userDefaults.object(forKey: Keys.lastSyncTime) as? Date {
@@ -144,12 +142,12 @@ class SyncService: ObservableObject {
             AppLogger.error("Test connection failed: No active provider", tag: logTag)
             throw SyncError.notConfigured
         }
-        
+
         isTesting = true
         defer { isTesting = false }
-        
+
         try await provider.testConnection()
-        
+
         isConnected = provider.isConnected
         userDefaults.set(isConnected, forKey: Keys.isConnected)
     }
@@ -162,34 +160,19 @@ class SyncService: ObservableObject {
             return
         }
 
-        if isSyncing {
-            pendingChanges = true
-            return
-        }
+        guard !isSyncing else { return }
 
         syncTask?.cancel()
 
         syncTask = Task {
-            try? await Task.sleep(nanoseconds: UInt64(syncDebounceDelay * 1_000_000_000))
-
+            try? await Task.sleep(for: .seconds(2))
             guard !Task.isCancelled else { return }
 
-            repeat {
-                pendingChanges = false
-
-                do {
-                    try await syncWithServer(dataManager: dataManager)
-                } catch {
-                    await MainActor.run {
-                        self.isSyncing = false
-                    }
-                    return
-                }
-
-                if pendingChanges {
-                    try? await Task.sleep(nanoseconds: UInt64(syncDebounceDelay * 1_000_000_000))
-                }
-            } while pendingChanges && !Task.isCancelled
+            do {
+                try await syncWithServer(dataManager: dataManager)
+            } catch {
+                self.isSyncing = false
+            }
         }
     }
 
@@ -198,30 +181,26 @@ class SyncService: ObservableObject {
 
         syncTask?.cancel()
         syncTask = nil
-        pendingChanges = false
 
         Task {
             do {
                 try await syncWithServer(dataManager: dataManager)
             } catch {
-                await MainActor.run {
-                    self.isSyncing = false
-                }
+                self.isSyncing = false
             }
         }
     }
 
     func disconnect() {
         activeProvider?.disconnect()
-        
+
         syncTask?.cancel()
         syncTask = nil
-        pendingChanges = false
         isSyncing = false
         isConnected = false
         lastSyncTime = nil
         syncError = nil
-        
+
         // These are shared keys, so clearing them affects all providers if they use them
         // But disconnect() is usually user initiated action
         userDefaults.set(false, forKey: Keys.isConnected)
@@ -239,8 +218,7 @@ class SyncService: ObservableObject {
         userDefaults.removeObject(forKey: Keys.autoSyncEnabled)
         syncTask?.cancel()
         syncTask = nil
-        pendingChanges = false
-        
+
         activeProvider?.disconnect()
     }