Stop executing locator's threads when about to shutdown occurred

Mark that about to shutdown has occurred and don't start
any new thread after that.

Fixes: QTCREATORBUG-25318
Change-Id: I14d47c93dd8e8a82f6f68264a03d5831ec95da75
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/coreplugin/coreplugin.cpp

@@ -443,6 +443,7 @@ QString CorePlugin::msgCrashpadInformation()
 ExtensionSystem::IPlugin::ShutdownFlag CorePlugin::aboutToShutdown()
 {
     Find::aboutToShutdown();
+    m_locator->aboutToShutdown();
     m_mainWindow->aboutToShutdown();
     return SynchronousShutdown;
 }

src/plugins/coreplugin/locator/locator.cpp

@@ -169,6 +169,16 @@ bool Locator::delayedInitialize()
     return true;
 }
 
+void Locator::aboutToShutdown()
+{
+    m_refreshTimer.stop();
+    if (m_refreshTask.isRunning()) {
+        m_refreshTask.cancel();
+        m_refreshTask.waitForFinished();
+    }
+    emit aboutToShutdownOccurred();
+}
+
 void Locator::loadSettings()
 {
     SettingsDatabase *settings = ICore::settingsDatabase();

src/plugins/coreplugin/locator/locator.h

@@ -48,6 +48,7 @@ public:
     ~Locator() override;
 
     static Locator *instance();
+    void aboutToShutdown();
 
     void initialize();
     void extensionsInitialized();
@@ -62,6 +63,7 @@ public:
 
 signals:
     void filtersChanged();
+    void aboutToShutdownOccurred();
 
 public slots:
     void refresh(QList<ILocatorFilter *> filters);

src/plugins/coreplugin/locator/locatorwidget.cpp

@@ -616,6 +616,13 @@ LocatorWidget::LocatorWidget(Locator *locator) :
     connect(qApp, &QApplication::focusChanged, this, &LocatorWidget::updatePreviousFocusWidget);
 
     connect(locator, &Locator::filtersChanged, this, &LocatorWidget::updateFilterList);
+    connect(locator, &Locator::aboutToShutdownOccurred, this, [this]() {
+        m_shuttingDown = true;
+        if (m_entriesWatcher->isRunning()) {
+            m_entriesWatcher->cancel();
+            m_entriesWatcher->waitForFinished();
+        }
+    });
     updateFilterList();
 }
 
@@ -828,6 +835,9 @@ void LocatorWidget::setProgressIndicatorVisible(bool visible)
 
 void LocatorWidget::updateCompletionList(const QString &text)
 {
+    if (m_shuttingDown)
+        return;
+
     m_updateRequested = true;
     if (m_entriesWatcher->future().isRunning()) {
         // Cancel the old future. We may not just block the UI thread to wait for the search to

src/plugins/coreplugin/locator/locatorwidget.h

@@ -98,6 +98,7 @@ private:
     QTimer m_showPopupTimer;
     QFutureWatcher<LocatorFilterEntry> *m_entriesWatcher = nullptr;
     QString m_requestedCompletionText;
+    bool m_shuttingDown = false;
     bool m_needsClearResult = true;
     bool m_updateRequested = false;
     bool m_possibleToolTipRequest = false;