ceph/src/boost/libs/interprocess/include/boost/interprocess/smart_ptr/detail/sp_counted_base_atomic.hpp

   1 #ifndef BOOST_INTERPROCESS_DETAIL_SP_COUNTED_BASE_ATOMIC_HPP_INCLUDED
   2 #define BOOST_INTERPROCESS_DETAIL_SP_COUNTED_BASE_ATOMIC_HPP_INCLUDED
   3
   4 #ifndef BOOST_CONFIG_HPP
   5 #  include <boost/config.hpp>
   6 #endif
   7 #
   8 #if defined(BOOST_HAS_PRAGMA_ONCE)
   9 # pragma once
  10 #endif
  11
  12 //  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
  13 //  Copyright 2004-2005 Peter Dimov
  14 //  Copyright 2007-2012 Ion Gaztanaga
  15 //
  16 // Distributed under the Boost Software License, Version 1.0. (See
  17 // accompanying file LICENSE_1_0.txt or copy at
  18 // http://www.boost.org/LICENSE_1_0.txt)
  19 //
  20 //
  21 //  Lock-free algorithm by Alexander Terekhov
  22 //
  23 //  Thanks to Ben Hitchings for the #weak + (#shared != 0)
  24 //  formulation
  25 //
  26
  27 #include <boost/interprocess/detail/config_begin.hpp>
  28 #include <boost/interprocess/detail/workaround.hpp>
  29
  30 #include <boost/interprocess/detail/atomic.hpp>
  31 #include <typeinfo>
  32
  33 namespace boost {
  34
  35 namespace interprocess {
  36
  37 namespace ipcdetail {
  38
  39 class sp_counted_base
  40 {
  41 private:
  42
  43     sp_counted_base( sp_counted_base const & );
  44     sp_counted_base & operator= ( sp_counted_base const & );
  45
  46     boost::uint32_t use_count_;        // #shared
  47     boost::uint32_t weak_count_;       // #weak + (#shared != 0)
  48
  49 public:
  50
  51     sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
  52     {}
  53
  54     ~sp_counted_base() // nothrow
  55     {}
  56
  57     void add_ref_copy()
  58     {
  59         ipcdetail::atomic_inc32( &use_count_ );
  60     }
  61
  62     bool add_ref_lock() // true on success
  63     {
  64         for( ;; )
  65         {
  66             boost::uint32_t tmp = static_cast< boost::uint32_t const volatile& >( use_count_ );
  67             if( tmp == 0 ) return false;
  68             if( ipcdetail::atomic_cas32( &use_count_, tmp + 1, tmp ) == tmp )
  69                return true;
  70         }
  71     }
  72
  73    bool ref_release() // nothrow
  74    { return 1 == ipcdetail::atomic_dec32( &use_count_ );  }
  75
  76    void weak_add_ref() // nothrow
  77    { ipcdetail::atomic_inc32( &weak_count_ ); }
  78
  79    bool weak_release() // nothrow
  80    { return 1 == ipcdetail::atomic_dec32( &weak_count_ ); }
  81
  82    long use_count() const // nothrow
  83    { return (long)static_cast<boost::uint32_t const volatile &>( use_count_ ); }
  84 };
  85
  86 } // namespace ipcdetail
  87
  88 } // namespace interprocess
  89
  90 } // namespace boost
  91
  92 #include <boost/interprocess/detail/config_end.hpp>
  93
  94 #endif  // #ifndef BOOST_INTERPROCESS_DETAIL_SP_COUNTED_BASE_ATOMIC_HPP_INCLUDED