+/***************************************************************************
+ * Copyright (C) 2010 by Peter Penz <peter.penz@gmx.at> *
+ * *
+ * This program is free software; you can redistribute it and/or modify *
+ * it under the terms of the GNU General Public License as published by *
+ * the Free Software Foundation; either version 2 of the License, or *
+ * (at your option) any later version. *
+ * *
+ * This program is distributed in the hope that it will be useful, *
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of *
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
+ * GNU General Public License for more details. *
+ * *
+ * You should have received a copy of the GNU General Public License *
+ * along with this program; if not, write to the *
+ * Free Software Foundation, Inc., *
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA *
+ ***************************************************************************/
+
+#ifndef PENDINGTHREADSMAINTAINER_H
+#define PENDINGTHREADSMAINTAINER_H
+
+#include <libdolphin_export.h>
+
+#include <QObject>
+
+class QTimer;
+
+/**
+ * If the creator of a thread gets deleted, although the thread is still
+ * working, usually QThread::wait() is invoked. The drawback of this
+ * approach is that the user interface gets blocked for an undefined amount
+ * of time. If the thread does not contain references to the creator, the
+ * deleting can be forwarded to the PendingThreadsMaintainer. In the following
+ * example it is assumed, that m_thread will be 0, if it has been deleted by the
+ * creator after receiving the signal QThread::finished():
+ *
+ * \code
+ * ThreadCreator::~ThreadCreator()
+ * {
+ * if (m_thread != 0) {
+ * PendingThreadsMaintainer::instance().append(m_thread);
+ * m_thread = 0;
+ * }
+ * }
+ * \endcode
+ *
+ * The thread will get automatically deleted after it (or has already) been finished.
+ *
+ * Implementation note: Connecting to the signal QThread::finished() is
+ * not sufficient, as it is possible that the thread has already emitted
+ * the signal, but the signal has not been received yet by the thread creator.
+ * Because of this a polling is done each 5 seconds to check, whether the
+ * thread has been finished.
+ */
+class LIBDOLPHINPRIVATE_EXPORT PendingThreadsMaintainer : public QObject
+{
+ Q_OBJECT
+
+public:
+ static PendingThreadsMaintainer& instance();
+ virtual ~PendingThreadsMaintainer();
+
+ /**
+ * Appends the thread \p thread to the maintainer. The thread
+ * will be deleted by the maintainer after it has been finished.
+ */
+ void append(QThread* thread);
+
+protected:
+ PendingThreadsMaintainer();
+
+private slots:
+ void cleanup();
+
+private:
+ QList<QThread*> m_threads;
+ QTimer* m_timer;
+
+ friend class PendingThreadsMaintainerSingleton;
+};
+
+#endif