boost/smart_ptr/detail/sp_counted_base_aix.hpp
#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_AIX_HPP_INCLUDED
#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_AIX_HPP_INCLUDED
//
// detail/sp_counted_base_aix.hpp
// based on: detail/sp_counted_base_w32.hpp
//
// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
// Copyright 2004-2005 Peter Dimov
// Copyright 2006 Michael van der Westhuizen
//
// 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)
//
//
// Lock-free algorithm by Alexander Terekhov
//
// Thanks to Ben Hitchings for the #weak + (#shared != 0)
// formulation
//
#include <boost/detail/sp_typeinfo.hpp>
#include <builtins.h>
#include <sys/atomic_op.h>
namespace boost
{
namespace detail
{
inline void atomic_increment( int32_t* pw )
{
// ++*pw;
fetch_and_add( pw, 1 );
}
inline int32_t atomic_decrement( int32_t * pw )
{
// return --*pw;
int32_t originalValue;
__lwsync();
originalValue = fetch_and_add( pw, -1 );
__isync();
return (originalValue - 1);
}
inline int32_t atomic_conditional_increment( int32_t * pw )
{
// if( *pw != 0 ) ++*pw;
// return *pw;
int32_t tmp = fetch_and_add( pw, 0 );
for( ;; )
{
if( tmp == 0 ) return 0;
if( compare_and_swap( pw, &tmp, tmp + 1 ) ) return (tmp + 1);
}
}
class sp_counted_base
{
private:
sp_counted_base( sp_counted_base const & );
sp_counted_base & operator= ( sp_counted_base const & );
int32_t use_count_; // #shared
int32_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;
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_ ) == 0 )
{
dispose();
weak_release();
}
}
void weak_add_ref() // nothrow
{
atomic_increment( &weak_count_ );
}
void weak_release() // nothrow
{
if( atomic_decrement( &weak_count_ ) == 0 )
{
destroy();
}
}
long use_count() const // nothrow
{
return fetch_and_add( const_cast<int32_t*>(&use_count_), 0 );
}
};
} // namespace detail
} // namespace boost
#endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_AIX_HPP_INCLUDED