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79 lines
1.6 KiB
C++
79 lines
1.6 KiB
C++
#ifndef BOOST_DETAIL_LWM_GCC_HPP_INCLUDED
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#define BOOST_DETAIL_LWM_GCC_HPP_INCLUDED
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//
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// boost/detail/lwm_gcc.hpp
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//
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// lightweight_mutex for GNU libstdc++ v3
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//
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// http://gcc.gnu.org/onlinedocs/porting/Thread-safety.html
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//
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// Copyright (c) 2002 Peter Dimov and Multi Media Ltd.
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// Copyright (c) 2002 Lars Gullik Bjønnes <larsbj@lyx.org>
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//
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// Permission to copy, use, modify, sell and distribute this software
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// is granted provided this copyright notice appears in all copies.
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// This software is provided "as is" without express or implied
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// warranty, and with no claim as to its suitability for any purpose.
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//
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#include <bits/atomicity.h>
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#include <sched.h>
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namespace boost
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{
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namespace detail
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{
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class lightweight_mutex
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{
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private:
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_Atomic_word a_;
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lightweight_mutex(lightweight_mutex const &);
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lightweight_mutex & operator=(lightweight_mutex const &);
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public:
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lightweight_mutex(): a_(0)
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{
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}
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class scoped_lock;
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friend class scoped_lock;
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class scoped_lock
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{
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private:
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lightweight_mutex & m_;
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scoped_lock(scoped_lock const &);
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scoped_lock & operator=(scoped_lock const &);
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public:
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explicit scoped_lock(lightweight_mutex & m): m_(m)
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{
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while( __exchange_and_add(&m_.a_, 1) )
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{
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__atomic_add(&m_.a_, -1);
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sched_yield();
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}
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}
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~scoped_lock()
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{
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__atomic_add(&m_.a_, -1);
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}
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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_DETAIL_LWM_GCC_HPP_INCLUDED
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