ceph/src/boost/boost/smart_ptr/detail/sp_counted_base_sync.hpp

   1 #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SYNC_HPP_INCLUDED
   2 #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SYNC_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 //  detail/sp_counted_base_sync.hpp - g++ 4.1+ __sync intrinsics
  11 //
  12 //  Copyright (c) 2007 Peter Dimov
  13 //
  14 //  Distributed under the Boost Software License, Version 1.0.
  15 //  See accompanying file LICENSE_1_0.txt or copy at
  16 //  http://www.boost.org/LICENSE_1_0.txt
  17
  18 #include <boost/smart_ptr/detail/sp_typeinfo_.hpp>
  19 #include <boost/config.hpp>
  20 #include <limits.h>
  21
  22 #if defined( __ia64__ ) && defined( __INTEL_COMPILER )
  23 # include <ia64intrin.h>
  24 #endif
  25
  26 #if defined(BOOST_SP_REPORT_IMPLEMENTATION)
  27
  28 #include <boost/config/pragma_message.hpp>
  29 BOOST_PRAGMA_MESSAGE("Using __sync sp_counted_base")
  30
  31 #endif
  32
  33 namespace boost
  34 {
  35
  36 namespace detail
  37 {
  38
  39 #if INT_MAX >= 2147483647
  40
  41 typedef int sp_int32_t;
  42
  43 #else
  44
  45 typedef long sp_int32_t;
  46
  47 #endif
  48
  49 inline void atomic_increment( sp_int32_t * pw )
  50 {
  51     __sync_fetch_and_add( pw, 1 );
  52 }
  53
  54 inline sp_int32_t atomic_decrement( sp_int32_t * pw )
  55 {
  56     return __sync_fetch_and_add( pw, -1 );
  57 }
  58
  59 inline sp_int32_t atomic_conditional_increment( sp_int32_t * pw )
  60 {
  61     // long r = *pw;
  62     // if( r != 0 ) ++*pw;
  63     // return r;
  64
  65     sp_int32_t r = *pw;
  66
  67     for( ;; )
  68     {
  69         if( r == 0 )
  70         {
  71             return r;
  72         }
  73
  74         sp_int32_t r2 = __sync_val_compare_and_swap( pw, r, r + 1 );
  75
  76         if( r2 == r )
  77         {
  78             return r;
  79         }
  80         else
  81         {
  82             r = r2;
  83         }
  84     }
  85 }
  86
  87 class BOOST_SYMBOL_VISIBLE sp_counted_base
  88 {
  89 private:
  90
  91     sp_counted_base( sp_counted_base const & );
  92     sp_counted_base & operator= ( sp_counted_base const & );
  93
  94     sp_int32_t use_count_;        // #shared
  95     sp_int32_t weak_count_;       // #weak + (#shared != 0)
  96
  97 public:
  98
  99     sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
 100     {
 101     }
 102
 103     virtual ~sp_counted_base() // nothrow
 104     {
 105     }
 106
 107     // dispose() is called when use_count_ drops to zero, to release
 108     // the resources managed by *this.
 109
 110     virtual void dispose() = 0; // nothrow
 111
 112     // destroy() is called when weak_count_ drops to zero.
 113
 114     virtual void destroy() // nothrow
 115     {
 116         delete this;
 117     }
 118
 119     virtual void * get_deleter( sp_typeinfo_ const & ti ) = 0;
 120     virtual void * get_local_deleter( sp_typeinfo_ const & ti ) = 0;
 121     virtual void * get_untyped_deleter() = 0;
 122
 123     void add_ref_copy()
 124     {
 125         atomic_increment( &use_count_ );
 126     }
 127
 128     bool add_ref_lock() // true on success
 129     {
 130         return atomic_conditional_increment( &use_count_ ) != 0;
 131     }
 132
 133     void release() // nothrow
 134     {
 135         if( atomic_decrement( &use_count_ ) == 1 )
 136         {
 137             dispose();
 138             weak_release();
 139         }
 140     }
 141
 142     void weak_add_ref() // nothrow
 143     {
 144         atomic_increment( &weak_count_ );
 145     }
 146
 147     void weak_release() // nothrow
 148     {
 149         if( atomic_decrement( &weak_count_ ) == 1 )
 150         {
 151             destroy();
 152         }
 153     }
 154
 155     long use_count() const // nothrow
 156     {
 157         return const_cast< sp_int32_t const volatile & >( use_count_ );
 158     }
 159 };
 160
 161 } // namespace detail
 162
 163 } // namespace boost
 164
 165 #endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SYNC_HPP_INCLUDED