ThreadableJob.h

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/*
 * ThreadableJob.h - declaration of class ThreadableJob
 *
 * Copyright (c) 2009-2014 Tobias Doerffel <tobydox/at/users.sourceforge.net>
 *
 * This file is part of LMMS - https://lmms.io
 *
 * 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 (see COPYING); if not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301 USA.
 *
 */
 
#ifndef LMMS_THREADABLE_JOB_H
#define LMMS_THREADABLE_JOB_H
 
#include "LmmsTypes.h"
 
#include <atomic>
 
namespace lmms
{
 
class ThreadableJob
{
public:
 
    enum class ProcessingState : int
    {
        Unstarted,
        Queued,
        InProgress,
        Done
    };
 
    ThreadableJob() :
        m_state(ProcessingState::Unstarted)
    {
    }
 
    inline ProcessingState state() const
    {
        return m_state.load();
    }
 
    inline void reset()
    {
        m_state = ProcessingState::Unstarted;
    }
 
    inline void queue()
    {
        m_state = ProcessingState::Queued;
    }
    
    inline void done()
    {
        m_state = ProcessingState::Done;
    }
 
    void process()
    {
        auto expected = ProcessingState::Queued;
        if (m_state.compare_exchange_strong(expected, ProcessingState::InProgress))
        {
            doProcessing();
            m_state = ProcessingState::Done;
        }
    }
 
    virtual bool requiresProcessing() const = 0;
 
 
protected:
    virtual void doProcessing() = 0;
 
    std::atomic<ProcessingState> m_state;
} ;
 
} // namespace lmms
 
#endif // LMMS_THREADABLE_JOB_H