ceph/src/boost/libs/smart_ptr/include/boost/smart_ptr/detail/sp_counted_base_w32.hpp

   1 #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
   2 #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
   3
   4 // MS compatible compilers support #pragma once
   5
   6 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
   7 # pragma once
   8 #endif
   9
  10 //
  11 //  detail/sp_counted_base_w32.hpp
  12 //
  13 //  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
  14 //  Copyright 2004-2005 Peter Dimov
  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/smart_ptr/detail/sp_interlocked.hpp>
  28 #include <boost/detail/workaround.hpp>
  29 #include <boost/detail/sp_typeinfo.hpp>
  30
  31 namespace boost
  32 {
  33
  34 namespace detail
  35 {
  36
  37 class sp_counted_base
  38 {
  39 private:
  40
  41     sp_counted_base( sp_counted_base const & );
  42     sp_counted_base & operator= ( sp_counted_base const & );
  43
  44     long use_count_;        // #shared
  45     long weak_count_;       // #weak + (#shared != 0)
  46
  47 public:
  48
  49     sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
  50     {
  51     }
  52
  53     virtual ~sp_counted_base() // nothrow
  54     {
  55     }
  56
  57     // dispose() is called when use_count_ drops to zero, to release
  58     // the resources managed by *this.
  59
  60     virtual void dispose() = 0; // nothrow
  61
  62     // destroy() is called when weak_count_ drops to zero.
  63
  64     virtual void destroy() // nothrow
  65     {
  66         delete this;
  67     }
  68
  69     virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
  70     virtual void * get_untyped_deleter() = 0;
  71
  72     void add_ref_copy()
  73     {
  74         BOOST_SP_INTERLOCKED_INCREMENT( &use_count_ );
  75     }
  76
  77     bool add_ref_lock() // true on success
  78     {
  79         for( ;; )
  80         {
  81             long tmp = static_cast< long const volatile& >( use_count_ );
  82             if( tmp == 0 ) return false;
  83
  84 #if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, == 1200 )
  85
  86             // work around a code generation bug
  87
  88             long tmp2 = tmp + 1;
  89             if( BOOST_SP_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp2, tmp ) == tmp2 - 1 ) return true;
  90
  91 #else
  92
  93             if( BOOST_SP_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp + 1, tmp ) == tmp ) return true;
  94
  95 #endif
  96         }
  97     }
  98
  99     void release() // nothrow
 100     {
 101         if( BOOST_SP_INTERLOCKED_DECREMENT( &use_count_ ) == 0 )
 102         {
 103             dispose();
 104             weak_release();
 105         }
 106     }
 107
 108     void weak_add_ref() // nothrow
 109     {
 110         BOOST_SP_INTERLOCKED_INCREMENT( &weak_count_ );
 111     }
 112
 113     void weak_release() // nothrow
 114     {
 115         if( BOOST_SP_INTERLOCKED_DECREMENT( &weak_count_ ) == 0 )
 116         {
 117             destroy();
 118         }
 119     }
 120
 121     long use_count() const // nothrow
 122     {
 123         return static_cast<long const volatile &>( use_count_ );
 124     }
 125 };
 126
 127 } // namespace detail
 128
 129 } // namespace boost
 130
 131 #endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED