atomic_count_pthreads.hpp 1.74 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96
#ifndef BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_PTHREADS_HPP_INCLUDED
#define BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_PTHREADS_HPP_INCLUDED

//
//  boost/detail/atomic_count_pthreads.hpp
//
//  Copyright (c) 2001, 2002 Peter Dimov and Multi Media Ltd.
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//

#include <pthread.h>

//
//  The generic pthread_mutex-based implementation sometimes leads to
//    inefficiencies. Example: a class with two atomic_count members
//    can get away with a single mutex.
//
//  Users can detect this situation by checking BOOST_AC_USE_PTHREADS.
//

namespace boost
{

namespace detail
{

class atomic_count
{
private:

    class scoped_lock
    {
    public:

        scoped_lock(pthread_mutex_t & m): m_(m)
        {
            pthread_mutex_lock(&m_);
        }

        ~scoped_lock()
        {
            pthread_mutex_unlock(&m_);
        }

    private:

        pthread_mutex_t & m_;
    };

public:

    explicit atomic_count(long v): value_(v)
    {
        pthread_mutex_init(&mutex_, 0);
    }

    ~atomic_count()
    {
        pthread_mutex_destroy(&mutex_);
    }

    long operator++()
    {
        scoped_lock lock(mutex_);
        return ++value_;
    }

    long operator--()
    {
        scoped_lock lock(mutex_);
        return --value_;
    }

    operator long() const
    {
        scoped_lock lock(mutex_);
        return value_;
    }

private:

    atomic_count(atomic_count const &);
    atomic_count & operator=(atomic_count const &);

    mutable pthread_mutex_t mutex_;
    long value_;
};

} // namespace detail

} // namespace boost

#endif // #ifndef BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_PTHREADS_HPP_INCLUDED