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

   1 #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_AIX_HPP_INCLUDED
   2 #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_AIX_HPP_INCLUDED
   3
   4 //
   5 //  detail/sp_counted_base_aix.hpp
   6 //   based on: detail/sp_counted_base_w32.hpp
   7 //
   8 //  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
   9 //  Copyright 2004-2005 Peter Dimov
  10 //  Copyright 2006 Michael van der Westhuizen
  11 //
  12 //  Distributed under the Boost Software License, Version 1.0. (See
  13 //  accompanying file LICENSE_1_0.txt or copy at
  14 //  http://www.boost.org/LICENSE_1_0.txt)
  15 //
  16 //
  17 //  Lock-free algorithm by Alexander Terekhov
  18 //
  19 //  Thanks to Ben Hitchings for the #weak + (#shared != 0)
  20 //  formulation
  21 //
  22
  23 #include <boost/detail/sp_typeinfo.hpp>
  24 #include <builtins.h>
  25 #include <sys/atomic_op.h>
  26
  27 namespace boost
  28 {
  29
  30 namespace detail
  31 {
  32
  33 inline void atomic_increment( int32_t* pw )
  34 {
  35     // ++*pw;
  36
  37     fetch_and_add( pw, 1 );
  38 }
  39
  40 inline int32_t atomic_decrement( int32_t * pw )
  41 {
  42     // return --*pw;
  43
  44     int32_t originalValue;
  45
  46     __lwsync();
  47     originalValue = fetch_and_add( pw, -1 );
  48     __isync();
  49
  50     return (originalValue - 1);
  51 }
  52
  53 inline int32_t atomic_conditional_increment( int32_t * pw )
  54 {
  55     // if( *pw != 0 ) ++*pw;
  56     // return *pw;
  57
  58     int32_t tmp = fetch_and_add( pw, 0 );
  59     for( ;; )
  60     {
  61         if( tmp == 0 ) return 0;
  62         if( compare_and_swap( pw, &tmp, tmp + 1 ) ) return (tmp + 1);
  63     }
  64 }
  65
  66 class sp_counted_base
  67 {
  68 private:
  69
  70     sp_counted_base( sp_counted_base const & );
  71     sp_counted_base & operator= ( sp_counted_base const & );
  72
  73     int32_t use_count_;        // #shared
  74     int32_t weak_count_;       // #weak + (#shared != 0)
  75
  76 public:
  77
  78     sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
  79     {
  80     }
  81
  82     virtual ~sp_counted_base() // nothrow
  83     {
  84     }
  85
  86     // dispose() is called when use_count_ drops to zero, to release
  87     // the resources managed by *this.
  88
  89     virtual void dispose() = 0; // nothrow
  90
  91     // destroy() is called when weak_count_ drops to zero.
  92
  93     virtual void destroy() // nothrow
  94     {
  95         delete this;
  96     }
  97
  98     virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
  99     virtual void * get_untyped_deleter() = 0;
 100
 101     void add_ref_copy()
 102     {
 103         atomic_increment( &use_count_ );
 104     }
 105
 106     bool add_ref_lock() // true on success
 107     {
 108         return atomic_conditional_increment( &use_count_ ) != 0;
 109     }
 110
 111     void release() // nothrow
 112     {
 113         if( atomic_decrement( &use_count_ ) == 0 )
 114         {
 115             dispose();
 116             weak_release();
 117         }
 118     }
 119
 120     void weak_add_ref() // nothrow
 121     {
 122         atomic_increment( &weak_count_ );
 123     }
 124
 125     void weak_release() // nothrow
 126     {
 127         if( atomic_decrement( &weak_count_ ) == 0 )
 128         {
 129             destroy();
 130         }
 131     }
 132
 133     long use_count() const // nothrow
 134     {
 135         return fetch_and_add( const_cast<int32_t*>(&use_count_), 0 );
 136     }
 137 };
 138
 139 } // namespace detail
 140
 141 } // namespace boost
 142
 143 #endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_AIX_HPP_INCLUDED