fix(apple): Use Task.detached when starting from MainActor (#7766)

When starting a Task, by default it's launched with the same priority as
the calling code.

In the UI these are run on the `MainActor` with highest priority by
default. If the worker thread running the Task closure gets blocked, it
will cause the UI to hang.

To fix this, we use `Task.detached` which runs the closure without a
specific priority, which is lower than the UI thread.

Furthermore, `weak self` is used to prevent retain cycles if the parent
thread `deinit`s.

This was causing an issue primarily when making IPC calls because those
will sometimes hang until the XPC service is launched for the first
time.

---------

Signed-off-by: Jamil <jamilbk@users.noreply.github.com>

swift/apple/FirezoneKit/Sources/FirezoneKit/Managers/VPNConfigurationManager.swift

@@ -174,7 +174,7 @@ public class VPNConfigurationManager {
     }
   }
 
-  func loadFromPreferences(vpnStateUpdateHandler: @escaping (NEVPNStatus, Settings?, String?) -> Void) async throws {
+  func loadFromPreferences(vpnStateUpdateHandler: @escaping @MainActor (NEVPNStatus, Settings?, String?) -> Void) async throws {
     // loadAllFromPreferences() returns list of VPN configurations created by our main app's bundle ID.
     // Since our bundle ID can change (by us), find the one that's current and ignore the others.
     let managers = try await NETunnelProviderManager.loadAllFromPreferences()
@@ -206,7 +206,7 @@ public class VPNConfigurationManager {
         Telemetry.accountSlug = providerConfiguration[VPNConfigurationManagerKeys.accountSlug]
 
         // Share what we found with our caller
-        vpnStateUpdateHandler(status, settings, actorName)
+        await vpnStateUpdateHandler(status, settings, actorName)
 
         // Stop looking for our tunnel
         break
@@ -216,7 +216,7 @@ public class VPNConfigurationManager {
     // If no tunnel configuration was found, update state to
     // prompt user to create one.
     if manager == nil {
-      vpnStateUpdateHandler(.invalid, nil, nil)
+      await vpnStateUpdateHandler(.invalid, nil, nil)
     }
 
     // Hook up status updates
@@ -475,7 +475,7 @@ public class VPNConfigurationManager {
 
   // Subscribe to system notifications about our VPN status changing
   // and let our handler know about them.
-  private func subscribeToVPNStatusUpdates(handler: @escaping (NEVPNStatus, Settings?, String?) -> Void) {
+  private func subscribeToVPNStatusUpdates(handler: @escaping @MainActor (NEVPNStatus, Settings?, String?) -> Void) {
     Log.log("\(#function)")
 
     for task in tunnelObservingTasks {
@@ -500,7 +500,7 @@ public class VPNConfigurationManager {
             resourcesListCache = ResourceList.loading
           }
 
-          handler(session.status, nil, nil)
+          await handler(session.status, nil, nil)
         }
       }
     )

swift/apple/FirezoneKit/Sources/FirezoneKit/Stores/Store.swift

@@ -70,19 +70,17 @@ public final class Store: ObservableObject {
   func bindToVPNConfigurationUpdates() async throws {
     // Load our existing VPN configuration and set an update handler
     try await self.vpnConfigurationManager.loadFromPreferences(
-      vpnStateUpdateHandler: { [weak self] status, settings, actorName in
+      vpnStateUpdateHandler: { @MainActor [weak self] status, settings, actorName in
         guard let self else { return }
 
-        DispatchQueue.main.async {
-          self.status = status
+        self.status = status
 
-          if let settings {
-            self.settings = settings
-          }
+        if let settings {
+          self.settings = settings
+        }
 
-          if let actorName {
-            self.actorName = actorName
-          }
+        if let actorName {
+          self.actorName = actorName
         }
 
         if status == .disconnected {
@@ -98,7 +96,9 @@ public final class Store: ObservableObject {
   /// reason and alert the user if it was due to receiving a 401 from the
   /// portal.
   private func maybeShowSignedOutAlert() {
-    Task {
+    Task.detached { [weak self] in
+      guard let self else { return }
+
       do {
         if let savedValue = try await self.vpnConfigurationManager.consumeStopReason(),
            let rawValue = Int(savedValue),
@@ -106,7 +106,7 @@ public final class Store: ObservableObject {
            case .authenticationCanceled = reason
         {
 #if os(macOS)
-          self.sessionNotification.showSignedOutAlertmacOS()
+          await self.sessionNotification.showSignedOutAlertmacOS()
 #endif
         }
       } catch {
@@ -190,7 +190,7 @@ public final class Store: ObservableObject {
 
   func signIn(authResponse: AuthResponse) async throws {
     // Save actorName
-    DispatchQueue.main.async { self.actorName = authResponse.actorName }
+    await MainActor.run { self.actorName = authResponse.actorName }
 
     try await self.vpnConfigurationManager.saveSettings(settings)
     try await self.vpnConfigurationManager.saveAuthResponse(authResponse)
@@ -212,9 +212,8 @@ public final class Store: ObservableObject {
     self.vpnConfigurationManager.fetchResources(callback: callback)
     let intervalInSeconds: TimeInterval = 1
     let timer = Timer(timeInterval: intervalInSeconds, repeats: true) { [weak self] _ in
-      Task { @MainActor in
-        guard let self else { return }
-        self.vpnConfigurationManager.fetchResources(callback: callback)
+      Task.detached {
+        await self?.vpnConfigurationManager.fetchResources(callback: callback)
       }
     }
     RunLoop.main.add(timer, forMode: .common)
@@ -226,11 +225,13 @@ public final class Store: ObservableObject {
     resourcesTimer = nil
   }
 
-  func save(_ newSettings: Settings) async throws {
-    Task {
+  func save(_ newSettings: Settings) {
+    Task.detached { [weak self] in
+      guard let self else { return }
+
       do {
         try await self.vpnConfigurationManager.saveSettings(newSettings)
-        DispatchQueue.main.async { self.settings = newSettings }
+        await DispatchQueue.main.async { self.settings = newSettings }
       } catch {
         Log.error(error)
       }
@@ -241,8 +242,6 @@ public final class Store: ObservableObject {
     self.vpnConfigurationManager.toggleInternetResource(enabled: enabled)
     var newSettings = settings
     newSettings.internetResourceEnabled = self.vpnConfigurationManager.internetResourceEnabled
-    Task {
-      try await save(newSettings)
-    }
+    save(newSettings)
   }
 }

swift/apple/FirezoneKit/Sources/FirezoneKit/Views/FirstTimeView.swift

@@ -36,9 +36,7 @@ struct FirstTimeView: View {
           .buttonStyle(.borderedProminent)
           .controlSize(.large)
           Button("Open menu") {
-            DispatchQueue.main.async {
-              menuBar.showMenu()
-            }
+            menuBar.showMenu()
             AppViewModel.WindowDefinition.main.window()?.close()
           }
           .buttonStyle(.borderedProminent)

swift/apple/FirezoneKit/Sources/FirezoneKit/Views/MenuBar.swift

@@ -265,13 +265,15 @@ public final class MenuBar: NSObject, ObservableObject {
   }
 
   @objc private func signOutButtonTapped() {
-    Task {
-      try await model.store.signOut()
+    Task.detached { [weak self] in
+      try await self?.model.store.signOut()
     }
   }
 
   @objc private func grantPermissionMenuItemTapped() {
-    Task {
+    Task.detached { [weak self] in
+      guard let self else { return }
+
       do {
         // If we get here, it means either system extension got disabled or
         // our VPN configuration got removed. Since we don't know which, reinstall
@@ -314,9 +316,11 @@ public final class MenuBar: NSObject, ObservableObject {
   }
 
   @objc private func quitButtonTapped() {
-    Task {
-      model.store.stop()
-      NSApp.terminate(self)
+    Task.detached { [weak self] in
+      guard let self else { return }
+
+      await self.model.store.stop()
+      await NSApp.terminate(self)
     }
   }
 
@@ -357,8 +361,8 @@ public final class MenuBar: NSObject, ObservableObject {
     guard connectingAnimationTimer == nil else { return }
     let timer = Timer(timeInterval: 0.25, repeats: true) { [weak self] _ in
       guard let self = self else { return }
-      Task {
-        await self.connectingAnimationShowNextFrame()
+      Task.detached { [weak self] in
+        await self?.connectingAnimationShowNextFrame()
       }
     }
     RunLoop.main.add(timer, forMode: .common)

swift/apple/FirezoneKit/Sources/FirezoneKit/Views/SettingsView.swift

@@ -47,16 +47,13 @@ public final class SettingsViewModel: ObservableObject {
   }
 
   func saveSettings() {
-    Task {
       if [.connected, .connecting, .reasserting].contains(store.status) {
-        _ = try await store.signOut()
+        Task.detached { [weak self] in
+          do { try await self?.store.signOut() } catch { Log.error(error) }
+        }
       }
-      do {
-        try await store.save(settings)
-      } catch {
-        Log.error(error)
-      }
-    }
+
+      store.save(settings)
   }
 
   // Calculates the total size of our logs by summing the size of the
@@ -493,11 +490,13 @@ public struct SettingsView: View {
                 isProcessing: $isExportingLogs,
                 action: {
                   self.isExportingLogs = true
-                  Task {
+                  Task.detached {
                     let archiveURL = LogExporter.tempFile()
                     try await LogExporter.export(to: archiveURL)
-                    self.logTempZipFileURL = archiveURL
-                    self.isPresentingExportLogShareSheet = true
+                    await MainActor.run {
+                      self.logTempZipFileURL = archiveURL
+                      self.isPresentingExportLogShareSheet = true
+                    }
                   }
                 }
               )
@@ -606,7 +605,7 @@ public struct SettingsView: View {
           return
         }
 
-        Task {
+        Task.detached {
           do {
             try await LogExporter.export(
               to: destinationURL,
@@ -619,15 +618,15 @@ public struct SettingsView: View {
           } catch {
             Log.error(error)
 
-            let alert = NSAlert()
-            alert.messageText = "Error exporting logs: \(error.localizedDescription)"
-            alert.alertStyle = .critical
+            let alert = await NSAlert()
             await MainActor.run {
+              alert.messageText = "Error exporting logs: \(error.localizedDescription)"
+              alert.alertStyle = .critical
               let _ = alert.runModal()
             }
           }
 
-          self.isExportingLogs = false
+          await MainActor.run { self.isExportingLogs = false }
         }
       }
     }