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