prevent close event while non-cancelable async tasks are running

src/mainwindow/mainwindow-async.cpp

@@ -263,10 +263,13 @@ struct NODISCARD MainWindow::AsyncBase
 {
 public:
     const std::shared_ptr<ProgressCounter> progressCounter;
+    const CancelDispositionEnum cancelDisposition = CancelDispositionEnum::Allow;
 
 public:
-    explicit AsyncBase(std::shared_ptr<ProgressCounter> pc)
+    explicit AsyncBase(std::shared_ptr<ProgressCounter> pc,
+                       const CancelDispositionEnum cancelDisposition_)
         : progressCounter{std::move(pc)}
+        , cancelDisposition{cancelDisposition_}
     {
         if (!progressCounter) {
             throw std::invalid_argument("pc");
@@ -285,12 +288,16 @@ struct NODISCARD MainWindow::AsyncBase
     NODISCARD PollResultEnum poll() { return poll(std::chrono::milliseconds{0}); }
     void request_cancel();
     NODISCARD bool requested_cancel() const;
+    NODISCARD bool is_allowed_to_cancel() const;
 };
 
 MainWindow::AsyncBase::~AsyncBase() = default;
 
 void MainWindow::AsyncBase::request_cancel()
 {
+    if (!is_allowed_to_cancel()) {
+        return;
+    }
     progressCounter->requestCancel();
     virt_request_cancel();
 }
@@ -300,6 +307,11 @@ bool MainWindow::AsyncBase::requested_cancel() const
     return progressCounter->requestedCancel();
 }
 
+bool MainWindow::AsyncBase::is_allowed_to_cancel() const
+{
+    return cancelDisposition == CancelDispositionEnum::Allow;
+}
+
 MainWindow::AsyncTask::AsyncTask(QObject *parent)
     : QObject(parent)
 {}
@@ -337,7 +349,7 @@ void MainWindow::AsyncTask::tick()
         return;
     }
 
-    if (m_task->poll() != PollResultEnum::Finished) {
+    if (deref(m_task).poll() != PollResultEnum::Finished) {
         return;
     }
 
@@ -347,7 +359,12 @@ void MainWindow::AsyncTask::tick()
 
 void MainWindow::AsyncTask::request_cancel()
 {
-    m_task->request_cancel();
+    deref(m_task).request_cancel();
+}
+
+bool MainWindow::AsyncTask::is_allowed_to_cancel() const
+{
+    return deref(m_task).is_allowed_to_cancel();
 }
 
 void MainWindow::AsyncTask::reset()
@@ -403,7 +420,7 @@ struct NODISCARD MainWindow::AsyncHelper : public AsyncBase
                          UniqueStorage ps,
                          const QString &dialogText,
                          const CancelDispositionEnum allow_cancel)
-        : AsyncBase{std::move(pc)}
+        : AsyncBase{std::move(pc), allow_cancel}
         , mainWindow{mw}
         , fileName{name}
         , pDevice(std::move(pd))

src/mainwindow/mainwindow.cpp

@@ -1556,18 +1556,41 @@ bool MainWindow::eventFilter(QObject *const obj, QEvent *const event)
 
 void MainWindow::closeEvent(QCloseEvent *const event)
 {
-    // REVISIT: wait and see if we're actually exiting first?
-    writeSettings();
+    qInfo() << MM_SOURCE_LOCATION().function_name();
+
+    if (m_asyncTask) {
+        // first check avoids prompting to save while saving.
+        if (!m_asyncTask.is_allowed_to_cancel()) {
+            qInfo() << "Note: Ignoring close request because the current async task cannot be canceled.";
+            event->ignore();
+            return;
+        }
+    }
 
     if (!maybeSave()) {
         event->ignore();
         return;
     }
 
     if (m_asyncTask) {
-        qInfo() << "Attempting to async task for faster shutdown";
-        m_progressDlg->reject();
+        // second check is in case we just scheduled a save.
+        if (!m_asyncTask.is_allowed_to_cancel()) {
+            qInfo() << "Note: Ignoring close request because the scheduled async task cannot be canceled.";
+            event->ignore();
+            return;
+        }
+        if (m_asyncTask.isWorking()) {
+            qInfo() << "Attempting to cancel async task for faster shutdown";
+            m_asyncTask.request_cancel();
+        }
+        if (auto dlg = m_progressDlg.get()) {
+            qInfo() << "Attempting to reject the progress dialog for faster shutdown";
+            dlg->reject();
+        }
     }
+
+    writeSettings();
+
     event->accept();
 }
 

src/mainwindow/mainwindow.h

@@ -271,6 +271,7 @@ class NODISCARD_QOBJECT MainWindow final : public QMainWindow
         void begin(std::unique_ptr<AsyncBase> task);
         void tick();
         void request_cancel();
+        NODISCARD bool is_allowed_to_cancel() const;
 
     private:
         void reset();