5 files changed, 58 insertions, 7 deletions
diff --git a/src/plugins/platforms/xcb/qglxintegration.cpp b/src/plugins/platforms/xcb/qglxintegration.cpp
index 45ccd9929e..3ce0041aeb 100644
--- a/src/plugins/platforms/xcb/qglxintegration.cpp
+++ b/src/plugins/platforms/xcb/qglxintegration.cpp
@@ -523,11 +523,11 @@ void QGLXContext::swapBuffers(QPlatformSurface *surface)
 
     if (surface->surface()->surfaceClass() == QSurface::Window) {
         QXcbWindow *platformWindow = static_cast<QXcbWindow *>(surface);
-        // OpenGL context might be bound to a non-gui thread
-        // use QueuedConnection to sync the window from the platformWindow's thread
-        // as QXcbWindow is no QObject, a wrapper slot in QXcbConnection is used.
+        // OpenGL context might be bound to a non-gui thread use QueuedConnection to sync
+        // the window from the platformWindow's thread as QXcbWindow is no QObject, an
+        // event is sent to QXcbConnection. (this is faster than a metacall)
         if (platformWindow->needsSync())
-            QMetaObject::invokeMethod(m_screen->connection(), "syncWindow", Qt::QueuedConnection, Q_ARG(QXcbWindow*, platformWindow));
+            platformWindow->postSyncWindowRequest();
     }
 }
 
diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index 7f23c84cb9..a2ce392151 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -1842,9 +1842,26 @@ QXcbSystemTrayTracker *QXcbConnection::systemTrayTracker()
     return m_systemTrayTracker;
 }
 
-void QXcbConnection::syncWindow(QXcbWindow *window)
+bool QXcbConnection::event(QEvent *e)
 {
-    window->updateSyncRequestCounter();
+    if (e->type() == QEvent::User + 1) {
+        QXcbSyncWindowRequest *ev = static_cast<QXcbSyncWindowRequest *>(e);
+        QXcbWindow *w = ev->window();
+        if (w) {
+            w->updateSyncRequestCounter();
+            ev->invalidate();
+        }
+        return true;
+    }
+    return QObject::event(e);
+}
+
+void QXcbSyncWindowRequest::invalidate()
+{
+    if (m_window) {
+        m_window->clearSyncWindowRequest();
+        m_window = 0;
+    }
 }
 
 QXcbConnectionGrabber::QXcbConnectionGrabber(QXcbConnection *connection)
diff --git a/src/plugins/platforms/xcb/qxcbconnection.h b/src/plugins/platforms/xcb/qxcbconnection.h
index 354ba54e70..9e9865a2e9 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.h
+++ b/src/plugins/platforms/xcb/qxcbconnection.h
@@ -355,6 +355,18 @@ public:
 
 typedef QHash<xcb_window_t, QXcbWindowEventListener *> WindowMapper;
 
+class QXcbSyncWindowRequest : public QEvent
+{
+public:
+    QXcbSyncWindowRequest(QXcbWindow *w) : QEvent(QEvent::Type(QEvent::User + 1)), m_window(w) { }
+
+    QXcbWindow *window() const { return m_window; }
+    void invalidate();
+
+private:
+    QXcbWindow *m_window;
+};
+
 class QAbstractEventDispatcher;
 class QXcbConnection : public QObject
 {
@@ -468,8 +480,10 @@ public:
 
     QXcbEventReader *eventReader() const { return m_reader; }
 
+protected:
+    bool event(QEvent *e) Q_DECL_OVERRIDE;
+
 public slots:
-    void syncWindow(QXcbWindow *window);
     void flush() { xcb_flush(m_connection); }
 
 private slots:
diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index 787fdb6641..a127ac0293 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -223,6 +223,7 @@ QXcbWindow::QXcbWindow(QWindow *window)
 #endif
     , m_lastWindowStateEvent(-1)
     , m_syncState(NoSyncNeeded)
+    , m_pendingSyncRequest(0)
 {
     m_screen = static_cast<QXcbScreen *>(window->screen()->handle());
 
@@ -565,6 +566,9 @@ void QXcbWindow::destroy()
     delete m_eglSurface;
     m_eglSurface = 0;
 #endif
+
+    if (m_pendingSyncRequest)
+        m_pendingSyncRequest->invalidate();
 }
 
 void QXcbWindow::setGeometry(const QRect &rect)
@@ -2371,4 +2375,13 @@ bool QXcbWindow::needsSync() const
     return m_syncState == SyncAndConfigureReceived;
 }
 
+void QXcbWindow::postSyncWindowRequest()
+{
+    if (!m_pendingSyncRequest) {
+        QXcbSyncWindowRequest *e = new QXcbSyncWindowRequest(this);
+        m_pendingSyncRequest = e;
+        QCoreApplication::postEvent(m_screen->connection(), e);
+    }
+}
+
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/xcb/qxcbwindow.h b/src/plugins/platforms/xcb/qxcbwindow.h
index 72b5c7bcc9..a8cadd8e6c 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.h
+++ b/src/plugins/platforms/xcb/qxcbwindow.h
@@ -57,7 +57,9 @@ QT_BEGIN_NAMESPACE
 
 class QXcbScreen;
 class QXcbEGLSurface;
+class QXcbSyncWindowRequest;
 class QIcon;
+
 class QXcbWindow : public QXcbObject, public QXcbWindowEventListener, public QPlatformWindow
 {
 public:
@@ -159,6 +161,9 @@ public:
 
     bool needsSync() const;
 
+    void postSyncWindowRequest();
+    void clearSyncWindowRequest() { m_pendingSyncRequest = 0; }
+
 public Q_SLOTS:
     void updateSyncRequestCounter();
 
@@ -235,6 +240,8 @@ private:
         SyncAndConfigureReceived
     };
     SyncState m_syncState;
+
+    QXcbSyncWindowRequest *m_pendingSyncRequest;
 };
 
 QT_END_NAMESPACE