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

   1 #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SPIN_HPP_INCLUDED
   2 #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SPIN_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_spin.hpp - spinlock pool atomic emulation
  12 //
  13 //  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
  14 //  Copyright 2004-2008 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 #include <boost/detail/sp_typeinfo.hpp>
  22 #include <boost/smart_ptr/detail/spinlock_pool.hpp>
  23
  24 namespace boost
  25 {
  26
  27 namespace detail
  28 {
  29
  30 inline int atomic_exchange_and_add( int * pw, int dv )
  31 {
  32     spinlock_pool<1>::scoped_lock lock( pw );
  33
  34     int r = *pw;
  35     *pw += dv;
  36     return r;
  37 }
  38
  39 inline void atomic_increment( int * pw )
  40 {
  41     spinlock_pool<1>::scoped_lock lock( pw );
  42     ++*pw;
  43 }
  44
  45 inline int atomic_conditional_increment( int * pw )
  46 {
  47     spinlock_pool<1>::scoped_lock lock( pw );
  48
  49     int rv = *pw;
  50     if( rv != 0 ) ++*pw;
  51     return rv;
  52 }
  53
  54 class sp_counted_base
  55 {
  56 private:
  57
  58     sp_counted_base( sp_counted_base const & );
  59     sp_counted_base & operator= ( sp_counted_base const & );
  60
  61     int use_count_;        // #shared
  62     int weak_count_;       // #weak + (#shared != 0)
  63
  64 public:
  65
  66     sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
  67     {
  68     }
  69
  70     virtual ~sp_counted_base() // nothrow
  71     {
  72     }
  73
  74     // dispose() is called when use_count_ drops to zero, to release
  75     // the resources managed by *this.
  76
  77     virtual void dispose() = 0; // nothrow
  78
  79     // destroy() is called when weak_count_ drops to zero.
  80
  81     virtual void destroy() // nothrow
  82     {
  83         delete this;
  84     }
  85
  86     virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
  87     virtual void * get_untyped_deleter() = 0;
  88
  89     void add_ref_copy()
  90     {
  91         atomic_increment( &use_count_ );
  92     }
  93
  94     bool add_ref_lock() // true on success
  95     {
  96         return atomic_conditional_increment( &use_count_ ) != 0;
  97     }
  98
  99     void release() // nothrow
 100     {
 101         if( atomic_exchange_and_add( &use_count_, -1 ) == 1 )
 102         {
 103             dispose();
 104             weak_release();
 105         }
 106     }
 107
 108     void weak_add_ref() // nothrow
 109     {
 110         atomic_increment( &weak_count_ );
 111     }
 112
 113     void weak_release() // nothrow
 114     {
 115         if( atomic_exchange_and_add( &weak_count_, -1 ) == 1 )
 116         {
 117             destroy();
 118         }
 119     }
 120
 121     long use_count() const // nothrow
 122     {
 123         spinlock_pool<1>::scoped_lock lock( &use_count_ );
 124         return use_count_;
 125     }
 126 };
 127
 128 } // namespace detail
 129
 130 } // namespace boost
 131
 132 #endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SPIN_HPP_INCLUDED