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154 lines
3.4 KiB
C++
154 lines
3.4 KiB
C++
#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED
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#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED
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//
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// detail/sp_counted_base_vacpp_ppc.hpp - xlC(vacpp) on POWER
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// based on: detail/sp_counted_base_w32.hpp
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//
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// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
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// Copyright 2004-2005 Peter Dimov
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// Copyright 2006 Michael van der Westhuizen
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// Copyright 2012 IBM Corp.
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// 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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//
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//
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// Lock-free algorithm by Alexander Terekhov
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//
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// Thanks to Ben Hitchings for the #weak + (#shared != 0)
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// formulation
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//
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#include <boost/smart_ptr/detail/sp_typeinfo_.hpp>
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#include <boost/config.hpp>
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extern "builtin" void __lwsync(void);
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extern "builtin" void __isync(void);
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extern "builtin" int __fetch_and_add(volatile int* addr, int val);
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extern "builtin" int __compare_and_swap(volatile int*, int*, int);
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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( int *pw )
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{
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// ++*pw;
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__lwsync();
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__fetch_and_add(pw, 1);
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__isync();
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}
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inline int atomic_decrement( int *pw )
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{
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// return --*pw;
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__lwsync();
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int originalValue = __fetch_and_add(pw, -1);
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__isync();
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return (originalValue - 1);
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}
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inline int atomic_conditional_increment( int *pw )
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{
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// if( *pw != 0 ) ++*pw;
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// return *pw;
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__lwsync();
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int v = *const_cast<volatile int*>(pw);
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for (;;)
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// loop until state is known
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{
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if (v == 0) return 0;
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if (__compare_and_swap(pw, &v, v + 1))
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{
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__isync(); return (v + 1);
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}
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}
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}
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class BOOST_SYMBOL_VISIBLE 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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int use_count_; // #shared
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int weak_count_; // #weak + (#shared != 0)
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char pad[64] __attribute__((__aligned__(64)));
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// pad to prevent false sharing
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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_local_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_ ) == 0 )
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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_ ) == 0 )
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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 *const_cast<volatile int*>(&use_count_);
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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_VACPP_PPC_HPP_INCLUDED
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