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

   1 #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CLANG_HPP_INCLUDED
   2 #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CLANG_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_clang.hpp - __c11 clang intrinsics
  11 //
  12 //  Copyright (c) 2007, 2013, 2015 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/detail/sp_typeinfo.hpp>
  19 #include <boost/cstdint.hpp>
  20
  21 namespace boost
  22 {
  23
  24 namespace detail
  25 {
  26
  27 typedef _Atomic( boost::int_least32_t ) atomic_int_least32_t;
  28
  29 inline void atomic_increment( atomic_int_least32_t * pw )
  30 {
  31     __c11_atomic_fetch_add( pw, 1, __ATOMIC_RELAXED );
  32 }
  33
  34 inline boost::int_least32_t atomic_decrement( atomic_int_least32_t * pw )
  35 {
  36     return __c11_atomic_fetch_sub( pw, 1, __ATOMIC_ACQ_REL );
  37 }
  38
  39 inline boost::int_least32_t atomic_conditional_increment( atomic_int_least32_t * pw )
  40 {
  41     // long r = *pw;
  42     // if( r != 0 ) ++*pw;
  43     // return r;
  44
  45     boost::int_least32_t r = __c11_atomic_load( pw, __ATOMIC_RELAXED );
  46
  47     for( ;; )
  48     {
  49         if( r == 0 )
  50         {
  51             return r;
  52         }
  53
  54         if( __c11_atomic_compare_exchange_weak( pw, &r, r + 1, __ATOMIC_RELAXED, __ATOMIC_RELAXED ) )
  55         {
  56             return r;
  57         }
  58     }
  59 }
  60
  61 #if defined(__clang__)
  62 # pragma clang diagnostic push
  63 # pragma clang diagnostic ignored "-Wweak-vtables"
  64 #endif
  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     atomic_int_least32_t use_count_;    // #shared
  74     atomic_int_least32_t weak_count_;   // #weak + (#shared != 0)
  75
  76 public:
  77
  78     sp_counted_base()
  79     {
  80         __c11_atomic_init( &use_count_, 1 );
  81         __c11_atomic_init( &weak_count_, 1 );
  82     }
  83
  84     virtual ~sp_counted_base() // nothrow
  85     {
  86     }
  87
  88     // dispose() is called when use_count_ drops to zero, to release
  89     // the resources managed by *this.
  90
  91     virtual void dispose() = 0; // nothrow
  92
  93     // destroy() is called when weak_count_ drops to zero.
  94
  95     virtual void destroy() // nothrow
  96     {
  97         delete this;
  98     }
  99
 100     virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
 101     virtual void * get_untyped_deleter() = 0;
 102
 103     void add_ref_copy()
 104     {
 105         atomic_increment( &use_count_ );
 106     }
 107
 108     bool add_ref_lock() // true on success
 109     {
 110         return atomic_conditional_increment( &use_count_ ) != 0;
 111     }
 112
 113     void release() // nothrow
 114     {
 115         if( atomic_decrement( &use_count_ ) == 1 )
 116         {
 117             dispose();
 118             weak_release();
 119         }
 120     }
 121
 122     void weak_add_ref() // nothrow
 123     {
 124         atomic_increment( &weak_count_ );
 125     }
 126
 127     void weak_release() // nothrow
 128     {
 129         if( atomic_decrement( &weak_count_ ) == 1 )
 130         {
 131             destroy();
 132         }
 133     }
 134
 135     long use_count() const // nothrow
 136     {
 137         return __c11_atomic_load( const_cast< atomic_int_least32_t* >( &use_count_ ), __ATOMIC_ACQUIRE );
 138     }
 139 };
 140
 141 #if defined(__clang__)
 142 # pragma clang diagnostic pop
 143 #endif
 144
 145 } // namespace detail
 146
 147 } // namespace boost
 148
 149 #endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CLANG_HPP_INCLUDED