atomic_counter.h

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/*
    Copyright (C) 2010 Tim Mayberry

    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., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#ifndef PBD_ATOMIC_COUNTER_H
#define PBD_ATOMIC_COUNTER_H

#include <glib.h>

namespace PBD {

class atomic_counter
{
        atomic_counter (const atomic_counter&);
        atomic_counter& operator= (const atomic_counter&);

public:

        atomic_counter (gint value = 0)
                :
                        m_value(value)
        { }

        gint get() const
        {
                return g_atomic_int_get (&m_value);
        }

        void set (gint new_value)
        {
                g_atomic_int_set (&m_value, new_value);
        }

        void increment ()
        {
                g_atomic_int_inc (&m_value);
        }

        void operator++ ()
        {
                increment ();
        }

        bool decrement_and_test ()
        {
                return g_atomic_int_dec_and_test (&m_value);
        }
        
        bool operator-- ()
        {
                return decrement_and_test ();
        }

        bool compare_and_exchange (gint old_value, gint new_value)
        {
                return g_atomic_int_compare_and_exchange
                        (
                         &m_value,
                         old_value,
                         new_value
                        );
        }

        bool cas (gint old_value, gint new_value)
        {
                return compare_and_exchange (old_value, new_value);
        }

private:

        // Has to be mutable when using the apple version of gcc.
        mutable volatile gint             m_value;

};

} // namespace PBD

#endif // PBD_ATOMIC_COUNTER_H