refs #325 update worker base class for asynchronous updates

src/blackgui/updateworker.h

@@ -0,0 +1,102 @@
+/* Copyright (C) 2013
+ * swift project Community / Contributors
+ *
+ * This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
+ * directory of this distribution and at http://www.swift-project.org/license.html. No part of swift project,
+ * including this file, may be copied, modified, propagated, or distributed except according to the terms
+ * contained in the LICENSE file.
+ */
+
+//! \file
+
+#ifndef BLACKGUI_UPDATEWORKER_H
+#define BLACKGUI_UPDATEWORKER_H
+
+#include <QObject>
+#include <QThread>
+#include <QDebug>
+
+namespace BlackGui
+{
+    //! Base class for workers
+    class IUpdateWorker : public QObject
+    {
+        Q_OBJECT
+
+    public:
+        //! Constructor
+        //! \remarks no parent, as objects with parents can not be moved to thread
+        IUpdateWorker(bool sort) : QObject(), m_sort(sort) {}
+
+        //! Destructor
+        virtual ~IUpdateWorker() { terminateThread();}
+
+    signals:
+        void updateFinished();
+
+    public slots:
+
+        //! Terminate myself when thread is done
+        void terminate()
+        {
+            terminateThread();
+            deleteLater();
+        }
+
+        //! Start thread, return nullptr if cannot be started
+        //! \remarks If start fails, object needs to be terminated manually
+        bool start()
+        {
+            if (!m_thread) { initializeThread(); }
+            m_thread->start();
+            bool ok = QMetaObject::invokeMethod(this, "ps_runUpdate", Qt::QueuedConnection);
+            if (ok) { return true; }
+
+            // startup failed
+            this->terminateThread();
+            return false;
+        }
+
+    protected:
+        //! Do the update (perform work here in another thread)
+        virtual void update() = 0;
+
+        bool    m_sort   = true;      //!< perform sort?
+        int     m_sortColumn = -1;    //!< which column to sort
+        QThread *m_thread = nullptr;  //!< corresponding thread
+        Qt::SortOrder m_sortOrder = Qt::AscendingOrder; //!< sort order
+
+    private slots:
+        //! Update, call virtual method so inheriting class needs no slots
+        void ps_runUpdate()
+        {
+            this->update();
+            emit this->updateFinished();
+            this->terminate(); // clean up thread, delete worker (myself)
+        }
+
+    private:
+        //! Terminate and clean up thread
+        void terminateThread()
+        {
+            if (!m_thread)
+            {
+                QThread *t = m_thread;
+                m_thread = nullptr;
+                t->quit();
+                t->deleteLater();
+            }
+        }
+
+        //! Initialize thread
+        void initializeThread()
+        {
+            if (m_thread) { return; }
+            m_thread = new QThread();
+            this->moveToThread(m_thread);
+        }
+
+    };
+} // namespace
+
+#endif // guard