Windows file dialog: Clean up thread manually.

Do not use deleteLater() to delete the thread.

Task-number: QTBUG-36357

Change-Id: Ie7c87b92a7c73d5fbac01d4951d387ee2facd05c
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

src/plugins/platforms/windows/qwindowsdialoghelpers.cpp

@@ -502,10 +502,30 @@ template <class BaseClass>
 QWindowsDialogHelperBase<BaseClass>::QWindowsDialogHelperBase() :
     m_nativeDialog(0),
     m_ownerWindow(0),
-    m_timerId(0)
+    m_timerId(0),
+    m_thread(0)
 {
 }
 
+template <class BaseClass>
+void QWindowsDialogHelperBase<BaseClass>::cleanupThread()
+{
+    if (m_thread) { // Thread may be running if the dialog failed to close.
+        if (m_thread->isRunning())
+            m_thread->wait(500);
+        if (m_thread->isRunning()) {
+            m_thread->terminate();
+            m_thread->wait(300);
+            if (m_thread->isRunning())
+                qCCritical(lcQpaDialogs) <<__FUNCTION__ << "Failed to terminate thread.";
+            else
+                qCWarning(lcQpaDialogs) << __FUNCTION__ << "Thread terminated.";
+        }
+        delete m_thread;
+        m_thread = 0;
+    }
+}
+
 template <class BaseClass>
 QWindowsNativeDialogBase *QWindowsDialogHelperBase<BaseClass>::nativeDialog() const
 {
@@ -559,7 +579,6 @@ void QWindowsDialogThread::run()
 {
     qCDebug(lcQpaDialogs) << '>' << __FUNCTION__;
     m_dialog->exec(m_owner);
-    deleteLater();
     qCDebug(lcQpaDialogs) << '<' << __FUNCTION__;
 }
 
@@ -587,6 +606,7 @@ bool QWindowsDialogHelperBase<BaseClass>::show(Qt::WindowFlags,
     // a subsequent call to exec() may follow. So, start an idle timer
     // which will start the dialog thread. If exec() is then called, the
     // timer is stopped and dialog->exec() is called directly.
+    cleanupThread();
     if (modal) {
         m_timerId = this->startTimer(0);
     } else {
@@ -599,8 +619,9 @@ template <class BaseClass>
 void QWindowsDialogHelperBase<BaseClass>::startDialogThread()
 {
     Q_ASSERT(!m_nativeDialog.isNull());
-    QWindowsDialogThread *thread = new QWindowsDialogThread(m_nativeDialog, m_ownerWindow);
-    thread->start();
+    Q_ASSERT(!m_thread);
+    m_thread = new QWindowsDialogThread(m_nativeDialog, m_ownerWindow);
+    m_thread->start();
     stopTimer();
 }
 

src/plugins/platforms/windows/qwindowsdialoghelpers.h

@@ -52,6 +52,7 @@ QT_BEGIN_NAMESPACE
 
 class QFileDialog;
 class QDialog;
+class QThread;
 class QWindowsNativeDialogBase;
 
 namespace QWindowsDialogs
@@ -68,6 +69,7 @@ class QWindowsDialogHelperBase : public BaseClass
     Q_DISABLE_COPY(QWindowsDialogHelperBase)
 public:
     typedef QSharedPointer<QWindowsNativeDialogBase> QWindowsNativeDialogBasePtr;
+    ~QWindowsDialogHelperBase() { cleanupThread(); }
 
     virtual void exec();
     virtual bool show(Qt::WindowFlags windowFlags,
@@ -88,10 +90,12 @@ private:
     inline QWindowsNativeDialogBase *ensureNativeDialog();
     inline void startDialogThread();
     inline void stopTimer();
+    void cleanupThread();
 
     QWindowsNativeDialogBasePtr m_nativeDialog;
     HWND m_ownerWindow;
     int m_timerId;
+    QThread *m_thread;
 };
 
 QT_END_NAMESPACE