138 lines
3.1 KiB
Plaintext
138 lines
3.1 KiB
Plaintext
#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_STD_ATOMIC_HPP_INCLUDED
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#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_STD_ATOMIC_HPP_INCLUDED
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// MS compatible compilers support #pragma once
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#if defined(_MSC_VER) && (_MSC_VER >= 1020)
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# pragma once
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#endif
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// detail/sp_counted_base_std_atomic.hpp - C++11 std::atomic
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//
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// Copyright (c) 2007, 2013 Peter Dimov
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//
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// Distributed under the Boost Software License, Version 1.0.
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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#include <boost/detail/sp_typeinfo.hpp>
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#include <atomic>
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#include <cstdint>
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namespace boost
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{
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namespace detail
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{
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inline void atomic_increment( std::atomic_int_least32_t * pw )
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{
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pw->fetch_add( 1, std::memory_order_relaxed );
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}
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inline std::int_least32_t atomic_decrement( std::atomic_int_least32_t * pw )
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{
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return pw->fetch_sub( 1, std::memory_order_acq_rel );
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}
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inline std::int_least32_t atomic_conditional_increment( std::atomic_int_least32_t * pw )
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{
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// long r = *pw;
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// if( r != 0 ) ++*pw;
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// return r;
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std::int_least32_t r = pw->load( std::memory_order_relaxed );
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for( ;; )
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{
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if( r == 0 )
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{
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return r;
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}
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if( pw->compare_exchange_weak( r, r + 1, std::memory_order_relaxed, std::memory_order_relaxed ) )
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{
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return r;
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}
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}
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}
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class sp_counted_base
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{
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private:
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sp_counted_base( sp_counted_base const & );
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sp_counted_base & operator= ( sp_counted_base const & );
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std::atomic_int_least32_t use_count_; // #shared
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std::atomic_int_least32_t weak_count_; // #weak + (#shared != 0)
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public:
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sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
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{
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}
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virtual ~sp_counted_base() // nothrow
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{
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}
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// dispose() is called when use_count_ drops to zero, to release
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// the resources managed by *this.
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virtual void dispose() = 0; // nothrow
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// destroy() is called when weak_count_ drops to zero.
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virtual void destroy() // nothrow
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{
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delete this;
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}
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virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
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virtual void * get_untyped_deleter() = 0;
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void add_ref_copy()
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{
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atomic_increment( &use_count_ );
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}
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bool add_ref_lock() // true on success
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{
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return atomic_conditional_increment( &use_count_ ) != 0;
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}
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void release() // nothrow
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{
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if( atomic_decrement( &use_count_ ) == 1 )
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{
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dispose();
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weak_release();
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}
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}
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void weak_add_ref() // nothrow
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{
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atomic_increment( &weak_count_ );
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}
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void weak_release() // nothrow
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{
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if( atomic_decrement( &weak_count_ ) == 1 )
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{
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destroy();
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}
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}
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long use_count() const // nothrow
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{
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return use_count_.load( std::memory_order_acquire );
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}
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};
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} // namespace detail
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} // namespace boost
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#endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_STD_ATOMIC_HPP_INCLUDED
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