mozilla-mobile · lmarceau · Oct 1, 2025 · Sep 24, 2025 · Sep 26, 2025 · Sep 26, 2025
@@ -151,7 +151,8 @@ let package = Package(
             name: "WebEngine",
             dependencies: ["Common",
                            .product(name: "GCDWebServers", package: "GCDWebServer")],
-            swiftSettings: [.unsafeFlags(["-enable-testing"])]),
+            swiftSettings: [.unsafeFlags(["-enable-testing"]),
+                            .enableExperimentalFeature("StrictConcurrency")]),
         .testTarget(
             name: "WebEngineTests",
             dependencies: ["WebEngine"]),

@@ -8,11 +8,11 @@ import Foundation
 public protocol MenuHelperWebViewInterface {
     /// Used to add a find in page menu option on webview textfields
     @objc
-    optional func menuHelperFindInPage()
+    optional nonisolated func menuHelperFindInPage()
 
     /// Used to add a search with "client" menu option on the webview textfields
     @objc
-    optional func menuHelperSearchWith()
+    optional nonisolated func menuHelperSearchWith()
 }
 
 /// Used to pass in the Client strings for the webview textfields menu options

@@ -6,20 +6,18 @@ import Foundation
 
 /// The engine used to create an `EngineView` and `EngineSession`.
 /// There is only when engine view to be created, but multiple sessions can exists.
+@MainActor
 public protocol Engine {
     /// Creates a new view for rendering web content.
     /// - Returns: The created `EngineView`
-    @MainActor
     func createView() -> EngineView
 
     /// Creates a new engine session.
     /// - Parameter dependencies: Pass in the required session dependencies on creation
     /// - Returns: The created `EngineSession`
-    @MainActor
     func createSession(dependencies: EngineSessionDependencies) throws -> EngineSession
 
     /// Warm the `Engine` whenever we move the application to foreground
-    @MainActor
     func warmEngine()
 
     /// Idle the `Engine` whenever we move the application to background

@@ -6,12 +6,13 @@ import Foundation
 import UIKit
 
 /// Protocol representing a single engine session. In browsers usually a session corresponds to a tab.
+@MainActor
 public protocol EngineSession: NSObject {
     /// Engine session delegate
     var delegate: EngineSessionDelegate? { get set }
 
     /// Proxy object for handling telemetry events.
-    var telemetryProxy: EngineTelemetryProxy? { get set }
+    nonisolated var telemetryProxy: EngineTelemetryProxy? { get set }
 
     /// Whether the engine session is currently being rendered
     var isActive: Bool { get set }
@@ -34,7 +35,6 @@ public protocol EngineSession: NSObject {
     func goForward()
 
     /// Scroll the session to the top.
-    @MainActor
     func scrollToTop()
 
     /// Show the web view's built-in find interaction.
@@ -63,7 +63,6 @@ public protocol EngineSession: NSObject {
     func restore(state: Data)
 
     /// Close the session. This may free underlying objects. Call this when you are finished using this session.
-    @MainActor
     func close()
 
     /// Switch to standard tracking protection mode.

@@ -12,6 +12,7 @@ import Foundation
 ///
 /// Due to limited documentation on this behavior, the following methods handle
 /// fullscreen transitions based on trial and error.
+@MainActor
 public protocol FullscreenDelegate: AnyObject {
     /// Called when the web view enters fullscreen mode.
     ///

@@ -6,11 +6,13 @@ import Common
 import Foundation
 
 /// Helper to get the metadata fetched out of a `WKEngineSession`
+@MainActor
 protocol MetadataFetcherHelper {
     var delegate: MetadataFetcherDelegate? { get set }
     func fetch(fromSession session: WKEngineSession, url: URL)
 }
 
+@MainActor
 protocol MetadataFetcherDelegate: AnyObject {
     func didLoad(pageMetadata: EnginePageMetadata)
 }

@@ -11,18 +11,22 @@ public enum ReadabilityOperationResult {
     case timeout
 }
 
+@MainActor
 protocol ReaderModeNavigationDelegate: AnyObject {
     func didFailWithError(error: Error)
     func didFinish()
 }
 
 // TODO: FXIOS-11373 - finish handling reader mode in WebEngine - this class is to be tested
+@MainActor
 final class WKReadabilityOperation: Operation,
                                     @unchecked Sendable,
                                     ReaderModeNavigationDelegate,
                                     WKReaderModeDelegate {
     var url: URL
-    var semaphore: DispatchSemaphore
+//    TODO: FXIOS-11373 - The original code had a semaphore, but it's removed here since with @MainActor we
+//    don't want to suspense the main thread. So this class needs to be retought if this project is picked back again.
+//    var semaphore: DispatchSemaphore
     var result: ReadabilityOperationResult?
     var session: WKEngineSession?
     var readerModeCache: ReaderModeCache
@@ -36,7 +40,6 @@ final class WKReadabilityOperation: Operation,
         logger: Logger = DefaultLogger.shared
     ) {
         self.url = url
-        self.semaphore = DispatchSemaphore(value: 0)
         self.readerModeCache = readerModeCache
         self.mainQueue = mainQueue
         self.logger = logger
@@ -46,34 +49,30 @@ final class WKReadabilityOperation: Operation,
         if self.isCancelled {
             return
         }
+        // TODO: FXIOS-11373 - finish handling reader mode in WebEngine - This isn't concurrency safe
 
         // Setup a new session and kick all this off on the main thread since UIKit
         // and WebKit are not safe from other threads.
-        Task { @MainActor in
-            let configProvider = DefaultWKEngineConfigurationProvider()
-            let parameters = WKWebViewParameters()
-            let dependencies = EngineSessionDependencies(webviewParameters: parameters)
-            let session = WKEngineSession.sessionFactory(userScriptManager: DefaultUserScriptManager(),
-                                                         dependencies: dependencies,
-                                                         configurationProvider: configProvider,
-                                                         readerModeDelegate: self)
-            session?.navigationHandler.readerModeNavigationDelegate = self
-            self.session = session
-
-            // Load the page in the session. This either fails with a navigation error, or we
-            // get a readability callback. Or it takes too long, in which case the semaphore
-            // times out. The script on the page will retry every 500ms for 10 seconds.
-            let context = BrowsingContext(type: .internalNavigation, url: self.url)
-            guard let browserURL = BrowserURL(browsingContext: context) else { return }
-            session?.load(browserURL: browserURL)
-        }
-
-        let timeout = DispatchTime.now() + .seconds(10)
-        if semaphore.wait(timeout: timeout) == .timedOut {
-            result = ReadabilityOperationResult.timeout
-        }
-
-        processResult()
+//        Task { @MainActor in
+//            let configProvider = DefaultWKEngineConfigurationProvider()
+//            let parameters = WKWebViewParameters()
+//            let dependencies = EngineSessionDependencies(webviewParameters: parameters)
+//            let session = WKEngineSession.sessionFactory(userScriptManager: DefaultUserScriptManager(),
+//                                                         dependencies: dependencies,
+//                                                         configurationProvider: configProvider,
+//                                                         readerModeDelegate: self)
+//            session?.navigationHandler.readerModeNavigationDelegate = self
+//            self.session = session
+//
+//            // Load the page in the session. This either fails with a navigation error, or we
+//            // get a readability callback. Or it takes too long, in which case the semaphore
+//            // times out. The script on the page will retry every 500ms for 10 seconds.
+//            let context = BrowsingContext(type: .internalNavigation, url: self.url)
+//            guard let browserURL = BrowserURL(browsingContext: context) else { return }
+//            session?.load(browserURL: browserURL)
+//        }
+//
+//        processResult()
     }
 
     private func processResult() {
@@ -106,7 +105,7 @@ final class WKReadabilityOperation: Operation,
 
     func didFailWithError(error: Error) {
         result = ReadabilityOperationResult.error(error as NSError)
-        semaphore.signal()
+//        semaphore.signal()
     }
 
     func didFinish() {
@@ -140,6 +139,6 @@ final class WKReadabilityOperation: Operation,
         guard session == self.session else { return }
 
         result = ReadabilityOperationResult.success(readabilityResult)
-        semaphore.signal()
+//        semaphore.signal()
     }
 }
@@ -5,6 +5,7 @@
 import Foundation
 
 // TODO: FXIOS-11373 - finish handling reader mode in WebEngine - this class is to be tested
+@MainActor
 final class WKReadabilityService {
     private let ReadabilityServiceDefaultConcurrency = 1
     var queue: OperationQueue

@@ -6,6 +6,7 @@ import Common
 import Foundation
 
 /// Delegate that contains callbacks that we have added on top of the built-in WKWebViewDelegate
+@MainActor
 public protocol WKReaderModeDelegate: AnyObject {
     func readerMode(
         _ readerMode: ReaderModeStyleSetter,

@@ -124,6 +124,7 @@ class WKReaderModeHandlers: WKReaderModeHandlersProtocol, Notifiable {
         }
     }
 
+    @MainActor
     private func handleReaderModeError(url: URL,
                                        readerModeConfiguration: ReaderModeConfiguration) -> GCDWebServerResponse? {
         WKReadabilityService().process(url, cache: readerModeCache)

@@ -6,6 +6,7 @@ import Common
 import Foundation
 import WebKit
 
+@MainActor
 public class WKEngine: Engine {
     private let sourceTimerFactory: DispatchSourceTimerFactory
     private var shutdownWebServerTimer: DispatchSourceInterface?
@@ -15,7 +16,6 @@ public class WKEngine: Engine {
     private let configProvider: WKEngineConfigurationProvider
 
     // TODO: FXIOS-13670 With Swift 6 we can use default params in the init
-    @MainActor
     public static func factory(engineDependencies: EngineDependencies) -> WKEngine {
         let configProvider = DefaultWKEngineConfigurationProvider()
         let userScriptManager = DefaultUserScriptManager()
@@ -29,7 +29,6 @@ public class WKEngine: Engine {
         )
     }
 
-    @MainActor
     init(userScriptManager: WKUserScriptManager,
          webServerUtil: WKWebServerUtil,
          sourceTimerFactory: DispatchSourceTimerFactory,
@@ -48,7 +47,6 @@ public class WKEngine: Engine {
         return WKEngineView.factory(frame: .zero)
     }
 
-    @MainActor
     public func createSession(dependencies: EngineSessionDependencies) throws -> EngineSession {
         guard let session = WKEngineSession.sessionFactory(userScriptManager: userScriptManager,
                                                            dependencies: dependencies,
@@ -59,7 +57,6 @@ public class WKEngine: Engine {
         return session
     }
 
-    @MainActor
     public func warmEngine() {
         shutdownWebServerTimer?.cancel()
         shutdownWebServerTimer = nil

@@ -6,19 +6,22 @@ import Common
 import Foundation
 @preconcurrency import WebKit
 
+@MainActor
 protocol SessionHandler: AnyObject {
     func commitURLChange()
     func fetchMetadata(withURL url: URL)
     func received(error: NSError, forURL url: URL)
 }
 
+@MainActor
 protocol WKJavascriptInterface: AnyObject {
     /// Calls a javascript method.
     /// - Parameter method: The method signature to be called in javascript world.
     /// - Parameter scope: An optional string defining the scope in which the method should be called.
     func callJavascriptMethod(_ method: String, scope: String?)
 }
 
+@MainActor
 class WKEngineSession: NSObject,
                        EngineSession,
                        WKEngineWebViewDelegate,
@@ -30,7 +33,7 @@ class WKEngineSession: NSObject,
             uiHandler.delegate = delegate
         }
     }
-    weak var telemetryProxy: EngineTelemetryProxy?
+    nonisolated(unsafe) weak var telemetryProxy: EngineTelemetryProxy?
     weak var fullscreenDelegate: FullscreenDelegate?
 
     private(set) var webView: WKEngineWebView