webview: isolate WKWebsiteDataStore and add async script message handler on macOS

include/wx/osx/webview_webkit.h

@@ -32,13 +32,14 @@ class WXDLLIMPEXP_WEBVIEW wxWebViewWebKit : public wxWebView
 public:
     wxDECLARE_DYNAMIC_CLASS(wxWebViewWebKit);
 
-    wxWebViewWebKit() {}
+    wxWebViewWebKit() : m_nonPersistentWebsiteDataStore(false) {}
     wxWebViewWebKit(wxWindow *parent,
                     wxWindowID winID = wxID_ANY,
                     const wxString& strURL = wxASCII_STR(wxWebViewDefaultURLStr),
                     const wxPoint& pos = wxDefaultPosition,
                     const wxSize& size = wxDefaultSize, long style = 0,
                     const wxString& name = wxASCII_STR(wxWebViewNameStr))
+        : m_nonPersistentWebsiteDataStore(false)
     {
         Create(parent, winID, strURL, pos, size, style, name);
     }
@@ -75,6 +76,18 @@ class WXDLLIMPEXP_WEBVIEW wxWebViewWebKit : public wxWebView
     virtual void EnableAccessToDevTools(bool enable = true) wxOVERRIDE;
     virtual bool SetUserAgent(const wxString& userAgent) wxOVERRIDE;
 
+    // Per-instance website data isolation for dual Studio processes.
+    // On macOS this maps to WKWebsiteDataStore (identifier on 14+,
+    // non-persistent fallback for secondary instances on older OS), not a
+    // custom filesystem path like WebView2's UserDataFolder.
+    virtual void SetUserDataPathOption(const wxString& path) wxOVERRIDE;
+
+    // Force WKWebsiteDataStore.nonPersistentDataStore (in-memory, not shared
+    // with the default store). Takes precedence over SetUserDataPathOption.
+    // Must be called before Create().
+    virtual void SetNonPersistentWebsiteDataStore(bool enable = true) wxOVERRIDE;
+    virtual bool IsNonPersistentWebsiteDataStore() const wxOVERRIDE;
+
     //History functions
     virtual void ClearHistory() wxOVERRIDE;
     virtual void EnableHistory(bool enable = true) wxOVERRIDE;
@@ -96,6 +109,7 @@ class WXDLLIMPEXP_WEBVIEW wxWebViewWebKit : public wxWebView
 
     bool RunScript(const wxString& javascript, wxString* output = NULL) const wxOVERRIDE;
     virtual bool AddScriptMessageHandler(const wxString& name) wxOVERRIDE;
+    virtual bool AddScriptMessageHandler(const wxString& name, bool runScriptSync) wxOVERRIDE;
     virtual bool RemoveScriptMessageHandler(const wxString& name) wxOVERRIDE;
     virtual bool AddUserScript(const wxString& javascript,
         wxWebViewUserScriptInjectionTime injectionTime = wxWEBVIEW_INJECT_AT_DOCUMENT_START) wxOVERRIDE;
@@ -115,6 +129,8 @@ class WXDLLIMPEXP_WEBVIEW wxWebViewWebKit : public wxWebView
     OSXWebViewPtr m_webView;
     wxStringToWebHandlerMap m_handlers;
     wxString m_customUserAgent;
+    wxString m_customUserDataPath;
+    bool m_nonPersistentWebsiteDataStore;
 
     WX_NSObject m_navigationDelegate;
     WX_NSObject m_UIDelegate;

include/wx/webview.h

@@ -171,6 +171,12 @@ class WXDLLIMPEXP_WEBVIEW wxWebView : public wxControl
     // User data path for storing cookies and other data for wxWebViewEdge
     virtual void SetUserDataPathOption(const wxString&) {};
 
+    // Request a non-persistent website data store (macOS WKWebView:
+    // WKWebsiteDataStore.nonPersistentDataStore). No-op on backends that
+    // do not support it. Must be called before Create().
+    virtual void SetNonPersistentWebsiteDataStore(bool WXUNUSED(enable) = true) {}
+    virtual bool IsNonPersistentWebsiteDataStore() const { return false; }
+
     // General methods
     virtual void EnableContextMenu(bool enable = true)
     {
@@ -197,6 +203,18 @@ class WXDLLIMPEXP_WEBVIEW wxWebView : public wxControl
     virtual bool RunScript(const wxString& javascript, wxString* output = NULL) const = 0;
     virtual bool AddScriptMessageHandler(const wxString& name)
     { wxUnusedVar(name); return false; }
+    // Optional second argument: when false, backends that support it inject the
+    // handler's bootstrap script asynchronously. Currently only the macOS/WebKit
+    // backend overrides this; the default implementation ignores the flag and
+    // falls back to the single-argument overload (GTK/Edge unchanged).
+    // Use async mode on macOS to avoid a hang when RunScriptSync() spins
+    // wxYield() waiting for evaluateJavaScript while the WKWebView is
+    // off-screen / in a throttled WebContent process.
+    virtual bool AddScriptMessageHandler(const wxString& name, bool runScriptSync)
+    {
+        wxUnusedVar(runScriptSync);
+        return AddScriptMessageHandler(name);
+    }
     virtual bool RemoveScriptMessageHandler(const wxString& name)
     { wxUnusedVar(name); return false; }
     virtual bool AddUserScript(const wxString& javascript,

interface/wx/webview.h

@@ -774,6 +774,28 @@ class wxWebView : public wxControl
     */
     virtual bool AddScriptMessageHandler(const wxString& name);
 
+    /**
+        Same as AddScriptMessageHandler(const wxString& name) with an extra flag
+        controlling how the handler bootstrap script is injected into the currently
+        loaded document.
+
+        @param name Name of the message handler that can be used from javascript
+        @param runScriptSync If @true the alias is injected with a synchronous
+            RunScript(). If @false it is injected asynchronously. Currently only
+            the macOS/WebKit backend honours @false; other backends ignore the flag
+            and behave like the single-argument overload. Use @false on macOS to
+            avoid a main-thread hang when the view is off-screen and its WebContent
+            process is throttled, which makes the synchronous RunScriptSync()
+            busy-wait never complete.
+
+        @return @true if the handler could be added, @false if it could not be added.
+
+        @see AddScriptMessageHandler(const wxString& name)
+
+        @since 3.1.5
+    */
+    virtual bool AddScriptMessageHandler(const wxString& name, bool runScriptSync);
+
     /**
         Remove a script message handler with the given name that was previously added via
         AddScriptMessageHandler().

src/osx/webview_webkit.mm

@@ -29,9 +29,11 @@
 
 #include "wx/hashmap.h"
 #include "wx/filesys.h"
+#include "wx/filename.h"
 #include "wx/msgdlg.h"
 #include "wx/textdlg.h"
 #include "wx/filedlg.h"
+#include "wx/log.h"
 
 #include <WebKit/WebKit.h>
 #include <Foundation/NSURLError.h>
@@ -49,6 +51,83 @@
 wxBEGIN_EVENT_TABLE(wxWebViewWebKit, wxControl)
 wxEND_EVENT_TABLE()
 
+namespace
+{
+
+// Last path component is the instance slot created by Studio
+// (…/WebViewCache/0, …/WebViewCache/1, …).
+long wxWebViewWebKitSlotFromPath(const wxString& path)
+{
+    if (path.empty())
+        return 0;
+
+    wxFileName fn(path);
+    long slot = 0;
+    if (!fn.GetFullName().ToLong(&slot))
+        slot = 0;
+    return slot;
+}
+
+WKWebsiteDataStore* wxWebViewWebKitDataStoreForPath(const wxString& path,
+                                                    bool forceNonPersistent)
+{
+    if (forceNonPersistent)
+    {
+        wxLogMessage("wxWebViewWebKit: using nonPersistentDataStore (explicit request)");
+        return [WKWebsiteDataStore nonPersistentDataStore];
+    }
+
+    if (path.empty())
+        return [WKWebsiteDataStore defaultDataStore];
+
+    const long slot = wxWebViewWebKitSlotFromPath(path);
+
+#if defined(__MAC_OS_X_VERSION_MAX_ALLOWED) && __MAC_OS_X_VERSION_MAX_ALLOWED >= 140000
+    if (WX_IS_MACOS_AVAILABLE(14, 0))
+    {
+        NSString* dir = wxCFStringRef(path).AsNSString();
+        NSString* uuidPath = [dir stringByAppendingPathComponent:@"webview_store.uuid"];
+        NSString* uuidStr = [NSString stringWithContentsOfFile:uuidPath
+                                                     encoding:NSUTF8StringEncoding
+                                                        error:nil];
+        NSUUID* uuid = nil;
+        if (uuidStr.length > 0)
+            uuid = [[NSUUID alloc] initWithUUIDString:uuidStr];
+        if (!uuid)
+        {
+            uuid = [NSUUID UUID];
+            [[NSFileManager defaultManager] createDirectoryAtPath:dir
+                                     withIntermediateDirectories:YES
+                                                      attributes:nil
+                                                           error:nil];
+            [[uuid UUIDString] writeToFile:uuidPath
+                                atomically:YES
+                                  encoding:NSUTF8StringEncoding
+                                     error:nil];
+        }
+        wxLogMessage("wxWebViewWebKit: using persistent data store slot=%ld uuid=%s",
+                     slot,
+                     (const char*)wxCFStringRef([uuid UUIDString]).AsString().utf8_str());
+        return [WKWebsiteDataStore dataStoreForIdentifier:uuid];
+    }
+#endif // macOS 14 SDK
+
+    // macOS < 14: only one persistent store exists. Keep slot 0 on the default
+    // store for single-instance cookie continuity; secondary instances use a
+    // non-persistent store so they do not fight over defaultDataStore.
+    if (slot == 0)
+    {
+        wxLogMessage("wxWebViewWebKit: macOS < 14 slot 0 using defaultDataStore");
+        return [WKWebsiteDataStore defaultDataStore];
+    }
+
+    wxLogMessage("wxWebViewWebKit: macOS < 14 slot=%ld using nonPersistentDataStore",
+                 slot);
+    return [WKWebsiteDataStore nonPersistentDataStore];
+}
+
+} // namespace
+
 @interface WXWKWebView: WKWebView
 {
     wxWebViewWebKit* m_webView;
@@ -124,6 +203,10 @@ - (id)initWithWxWindow: (wxWebViewWebKit*)inWindow;
     NSRect r = wxOSXGetFrameForControl( this, pos , size ) ;
     WKWebViewConfiguration* webViewConfig = [[WKWebViewConfiguration alloc] init];
 
+    webViewConfig.websiteDataStore =
+        wxWebViewWebKitDataStoreForPath(m_customUserDataPath,
+                                        m_nonPersistentWebsiteDataStore);
+
     // WebKit API available since macOS 10.11 and iOS 9.0
     SEL fullScreenSelector = @selector(_setFullScreenEnabled:);
     if ([webViewConfig.preferences respondsToSelector:fullScreenSelector])
@@ -346,6 +429,24 @@ - (id)initWithWxWindow: (wxWebViewWebKit*)inWindow;
         return false;
 }
 
+void wxWebViewWebKit::SetUserDataPathOption(const wxString& path)
+{
+    // Must be called before Create(); Create() consumes m_customUserDataPath
+    // when building WKWebViewConfiguration.websiteDataStore.
+    m_customUserDataPath = path;
+}
+
+void wxWebViewWebKit::SetNonPersistentWebsiteDataStore(bool enable)
+{
+    // Must be called before Create(); takes precedence over SetUserDataPathOption.
+    m_nonPersistentWebsiteDataStore = enable;
+}
+
+bool wxWebViewWebKit::IsNonPersistentWebsiteDataStore() const
+{
+    return m_nonPersistentWebsiteDataStore;
+}
+
 void wxWebViewWebKit::SetZoomType(wxWebViewZoomType zoomType)
 {
     // there is only one supported zoom type at the moment so this setter
@@ -444,14 +545,35 @@ - (id)initWithWxWindow: (wxWebViewWebKit*)inWindow;
 }
 
 bool wxWebViewWebKit::AddScriptMessageHandler(const wxString& name)
+{
+    return AddScriptMessageHandler(name, true);
+}
+
+bool wxWebViewWebKit::AddScriptMessageHandler(const wxString& name, bool runScriptSync)
 {
     [m_webView.configuration.userContentController addScriptMessageHandler:
         [[WebViewScriptMessageHandler alloc] initWithWxWindow:this] name:wxCFStringRef(name).AsNSString()];
     // Make webkit message handler available under common name
     wxString js = wxString::Format("window.%s = window.webkit.messageHandlers.%s;",
-            name, name);
+                                   name, name);
+    // AddUserScript() injects the alias into every *future* document load. The
+    // call below is only needed to expose it in the document that is already
+    // loaded (if any).
     AddUserScript(js);
-    RunScript(js);
+    if (runScriptSync)
+    {
+        RunScript(js);
+    }
+    else
+    {
+        // Asynchronous injection: RunScript() -> RunScriptSync() busy-waits with
+        // while(!done) wxYield() for evaluateJavaScript's completion handler. When
+        // this view is off-screen / in a background tab, macOS can throttle or
+        // suspend its WebContent process so that handler never fires, hanging the
+        // main thread. Inject without blocking instead.
+        [m_webView evaluateJavaScript:wxCFStringRef(js).AsNSString()
+                    completionHandler:nil];
+    }
     return true;
 }