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#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_STD_ATOMIC_HPP_INCLUDED
#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_STD_ATOMIC_HPP_INCLUDED
// MS compatible compilers support #pragma once
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif
// detail/sp_counted_base_std_atomic.hpp - C++11 std::atomic
//
// Copyright (c) 2007, 2013 Peter Dimov
//
// 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 <boost/detail/sp_typeinfo.hpp>
#include <atomic>
#include <cstdint>
namespace boost
{
namespace detail
{
inline void atomic_increment( std::atomic_int_least32_t * pw )
{
pw->fetch_add( 1, std::memory_order_relaxed );
}
inline std::int_least32_t atomic_decrement( std::atomic_int_least32_t * pw )
{
return pw->fetch_sub( 1, std::memory_order_acq_rel );
}
inline std::int_least32_t atomic_conditional_increment( std::atomic_int_least32_t * pw )
{
// long r = *pw;
// if( r != 0 ) ++*pw;
// return r;
std::int_least32_t r = pw->load( std::memory_order_relaxed );
for( ;; )
{
if( r == 0 )
{
return r;
}
if( pw->compare_exchange_weak( r, r + 1, std::memory_order_relaxed, std::memory_order_relaxed ) )
{
return r;
}
}
}
class sp_counted_base
{
private:
sp_counted_base( sp_counted_base const & );
sp_counted_base & operator= ( sp_counted_base const & );
std::atomic_int_least32_t use_count_; // #shared
std::atomic_int_least32_t weak_count_; // #weak + (#shared != 0)
public:
sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
{
}
virtual ~sp_counted_base() // nothrow
{
}
// dispose() is called when use_count_ drops to zero, to release
// the resources managed by *this.
virtual void dispose() = 0; // nothrow
// destroy() is called when weak_count_ drops to zero.
virtual void destroy() // nothrow
{
delete this;
}
virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
virtual void * get_untyped_deleter() = 0;
void add_ref_copy()
{
atomic_increment( &use_count_ );
}
bool add_ref_lock() // true on success
{
return atomic_conditional_increment( &use_count_ ) != 0;
}
void release() // nothrow
{
if( atomic_decrement( &use_count_ ) == 1 )
{
dispose();
weak_release();
}
}
void weak_add_ref() // nothrow
{
atomic_increment( &weak_count_ );
}
void weak_release() // nothrow
{
if( atomic_decrement( &weak_count_ ) == 1 )
{
destroy();
}
}
long use_count() const // nothrow
{
return use_count_.load( std::memory_order_acquire );
}
};
} // namespace detail
} // namespace boost
#endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_STD_ATOMIC_HPP_INCLUDED
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