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

   1 #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED
   2 #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED
   3
   4 //
   5 //  detail/sp_counted_base_vacpp_ppc.hpp - xlC(vacpp) on POWER
   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 //  Copyright 2012 IBM Corp.
  12 //
  13 //  Distributed under the Boost Software License, Version 1.0. (See
  14 //  accompanying file LICENSE_1_0.txt or copy at
  15 //  http://www.boost.org/LICENSE_1_0.txt)
  16 //
  17 //
  18 //  Lock-free algorithm by Alexander Terekhov
  19 //
  20 //  Thanks to Ben Hitchings for the #weak + (#shared != 0)
  21 //  formulation
  22 //
  23
  24 #include <boost/smart_ptr/detail/sp_typeinfo_.hpp>
  25 #include <boost/smart_ptr/detail/sp_obsolete.hpp>
  26 #include <boost/config.hpp>
  27
  28 #if defined(BOOST_SP_REPORT_IMPLEMENTATION)
  29
  30 #include <boost/config/pragma_message.hpp>
  31 BOOST_PRAGMA_MESSAGE("Using xlC/PowerPC sp_counted_base")
  32
  33 #endif
  34
  35 BOOST_SP_OBSOLETE()
  36
  37 extern "builtin" void __lwsync(void);
  38 extern "builtin" void __isync(void);
  39 extern "builtin" int __fetch_and_add(volatile int* addr, int val);
  40 extern "builtin" int __compare_and_swap(volatile int*, int*, int);
  41
  42 namespace boost
  43 {
  44
  45 namespace detail
  46 {
  47
  48 inline void atomic_increment( int *pw )
  49 {
  50    // ++*pw;
  51    __lwsync();
  52    __fetch_and_add(pw, 1);
  53    __isync();
  54 }
  55
  56 inline int atomic_decrement( int *pw )
  57 {
  58    // return --*pw;
  59    __lwsync();
  60    int originalValue = __fetch_and_add(pw, -1);
  61    __isync();
  62
  63    return (originalValue - 1);
  64 }
  65
  66 inline int atomic_conditional_increment( int *pw )
  67 {
  68    // if( *pw != 0 ) ++*pw;
  69    // return *pw;
  70
  71    __lwsync();
  72    int v = *const_cast<volatile int*>(pw);
  73    for (;;)
  74    // loop until state is known
  75    {
  76       if (v == 0) return 0;
  77       if (__compare_and_swap(pw, &v, v + 1))
  78       {
  79          __isync(); return (v + 1);
  80       }
  81    }
  82 }
  83
  84 class BOOST_SYMBOL_VISIBLE sp_counted_base
  85 {
  86 private:
  87
  88     sp_counted_base( sp_counted_base const & );
  89     sp_counted_base & operator= ( sp_counted_base const & );
  90
  91     int use_count_;        // #shared
  92     int weak_count_;       // #weak + (#shared != 0)
  93     char pad[64] __attribute__((__aligned__(64)));
  94             // pad to prevent false sharing
  95 public:
  96
  97     sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
  98     {
  99     }
 100
 101     virtual ~sp_counted_base() // nothrow
 102     {
 103     }
 104
 105     // dispose() is called when use_count_ drops to zero, to release
 106     // the resources managed by *this.
 107
 108     virtual void dispose() = 0; // nothrow
 109
 110     // destroy() is called when weak_count_ drops to zero.
 111
 112     virtual void destroy() // nothrow
 113     {
 114         delete this;
 115     }
 116
 117     virtual void * get_deleter( sp_typeinfo_ const & ti ) = 0;
 118     virtual void * get_local_deleter( sp_typeinfo_ const & ti ) = 0;
 119     virtual void * get_untyped_deleter() = 0;
 120
 121     void add_ref_copy()
 122     {
 123         atomic_increment( &use_count_ );
 124     }
 125
 126     bool add_ref_lock() // true on success
 127     {
 128         return atomic_conditional_increment( &use_count_ ) != 0;
 129     }
 130
 131     void release() // nothrow
 132     {
 133         if( atomic_decrement( &use_count_ ) == 0 )
 134         {
 135             dispose();
 136             weak_release();
 137         }
 138     }
 139
 140     void weak_add_ref() // nothrow
 141     {
 142         atomic_increment( &weak_count_ );
 143     }
 144
 145     void weak_release() // nothrow
 146     {
 147         if( atomic_decrement( &weak_count_ ) == 0 )
 148         {
 149             destroy();
 150         }
 151     }
 152
 153     long use_count() const // nothrow
 154     {
 155         return *const_cast<volatile int*>(&use_count_);
 156     }
 157 };
 158
 159 } // namespace detail
 160
 161 } // namespace boost
 162
 163 #endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED