/*
    Scan Tailor - Interactive post-processing tool for scanned pages.
    Copyright (C)  Joseph Artsimovich <joseph.artsimovich@gmail.com>

    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 3 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, see <http://www.gnu.org/licenses/>.
*/

#ifndef OUT_OF_MEMORY_HANDLER_H_
#define OUT_OF_MEMORY_HANDLER_H_

#include "NonCopyable.h"
#include <QObject>
#include <QMutex>
#ifndef Q_MOC_RUN
#include <boost/scoped_array.hpp>
#endif
#include <stddef.h>

class OutOfMemoryHandler : public QObject
{
    Q_OBJECT
    DECLARE_NON_COPYABLE(OutOfMemoryHandler)
public:
    static OutOfMemoryHandler& instance();

    /**
     * To be called once, before any OOM situations can occur.
     */
    void allocateEmergencyMemory(size_t bytes);

    /** May be called from any thread. */
    void handleOutOfMemorySituation();

    bool hadOutOfMemorySituation() const;
signals:
    /** Will be dispatched from the main thread. */
    void outOfMemory();
private:
    OutOfMemoryHandler();

    mutable QMutex m_mutex;
    boost::scoped_array<char> m_emergencyBuffer;
    bool m_hadOOM;
};

#endif
