| #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 |