runguard.h

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/*****************************************************************************
 * Copyright 2015 Haye Hinrichsen, Christoph Wick
 *
 * This file is part of Entropy Piano Tuner.
 *
 * Entropy Piano Tuner 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.
 *
 * Entropy Piano Tuner 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
 * Entropy Piano Tuner. If not, see http://www.gnu.org/licenses/.
 *****************************************************************************/

//============================================================================
//        RunGuard, preventing multiple instances of the application
//============================================================================

#ifndef RUNGUARD_H
#define RUNGUARD_H

#include <QObject>
#include <QSharedMemory>
#include <QSystemSemaphore>


class RunGuard
{
public:
    RunGuard (const QString& key);
    ~RunGuard() {release();};

    bool isAnotherRunning();
    bool tryToRun();
    void release();

private:
    QString generateKeyHash (const QString& key, const QString& salt);

    const QString key;          
    const QString memLockKey;   
    const QString sharedmemKey; 

    QSharedMemory sharedMem;    
    QSystemSemaphore memLock;   
};

#endif  // RUN_GUARD