1 | #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SYNC_HPP_INCLUDED |
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2 | #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SYNC_HPP_INCLUDED |
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3 | |
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4 | // MS compatible compilers support #pragma once |
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5 | |
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6 | #if defined(_MSC_VER) && (_MSC_VER >= 1020) |
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7 | # pragma once |
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8 | #endif |
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9 | |
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10 | // detail/sp_counted_base_sync.hpp - g++ 4.1+ __sync intrinsics |
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11 | // |
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12 | // Copyright (c) 2007 Peter Dimov |
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13 | // |
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14 | // Distributed under the Boost Software License, Version 1.0. |
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15 | // See accompanying file LICENSE_1_0.txt or copy at |
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16 | // http://www.boost.org/LICENSE_1_0.txt |
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17 | |
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18 | #include <boost/detail/sp_typeinfo.hpp> |
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19 | #include <limits.h> |
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20 | |
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21 | #if defined( __ia64__ ) && defined( __INTEL_COMPILER ) |
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22 | # include <ia64intrin.h> |
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23 | #endif |
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24 | |
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25 | namespace boost |
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26 | { |
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27 | |
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28 | namespace detail |
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29 | { |
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30 | |
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31 | #if INT_MAX >= 2147483647 |
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32 | |
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33 | typedef int sp_int32_t; |
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34 | |
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35 | #else |
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36 | |
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37 | typedef long sp_int32_t; |
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38 | |
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39 | #endif |
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40 | |
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41 | inline void atomic_increment( sp_int32_t * pw ) |
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42 | { |
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43 | __sync_fetch_and_add( pw, 1 ); |
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44 | } |
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45 | |
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46 | inline sp_int32_t atomic_decrement( sp_int32_t * pw ) |
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47 | { |
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48 | return __sync_fetch_and_add( pw, -1 ); |
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49 | } |
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50 | |
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51 | inline sp_int32_t atomic_conditional_increment( sp_int32_t * pw ) |
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52 | { |
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53 | // long r = *pw; |
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54 | // if( r != 0 ) ++*pw; |
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55 | // return r; |
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56 | |
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57 | sp_int32_t r = *pw; |
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58 | |
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59 | for( ;; ) |
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60 | { |
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61 | if( r == 0 ) |
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62 | { |
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63 | return r; |
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64 | } |
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65 | |
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66 | sp_int32_t r2 = __sync_val_compare_and_swap( pw, r, r + 1 ); |
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67 | |
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68 | if( r2 == r ) |
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69 | { |
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70 | return r; |
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71 | } |
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72 | else |
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73 | { |
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74 | r = r2; |
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75 | } |
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76 | } |
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77 | } |
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78 | |
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79 | class sp_counted_base |
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80 | { |
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81 | private: |
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82 | |
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83 | sp_counted_base( sp_counted_base const & ); |
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84 | sp_counted_base & operator= ( sp_counted_base const & ); |
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85 | |
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86 | sp_int32_t use_count_; // #shared |
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87 | sp_int32_t weak_count_; // #weak + (#shared != 0) |
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88 | |
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89 | public: |
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90 | |
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91 | sp_counted_base(): use_count_( 1 ), weak_count_( 1 ) |
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92 | { |
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93 | } |
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94 | |
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95 | virtual ~sp_counted_base() // nothrow |
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96 | { |
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97 | } |
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98 | |
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99 | // dispose() is called when use_count_ drops to zero, to release |
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100 | // the resources managed by *this. |
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101 | |
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102 | virtual void dispose() = 0; // nothrow |
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103 | |
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104 | // destroy() is called when weak_count_ drops to zero. |
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105 | |
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106 | virtual void destroy() // nothrow |
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107 | { |
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108 | delete this; |
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109 | } |
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110 | |
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111 | virtual void * get_deleter( sp_typeinfo const & ti ) = 0; |
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112 | |
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113 | void add_ref_copy() |
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114 | { |
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115 | atomic_increment( &use_count_ ); |
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116 | } |
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117 | |
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118 | bool add_ref_lock() // true on success |
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119 | { |
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120 | return atomic_conditional_increment( &use_count_ ) != 0; |
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121 | } |
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122 | |
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123 | void release() // nothrow |
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124 | { |
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125 | if( atomic_decrement( &use_count_ ) == 1 ) |
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126 | { |
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127 | dispose(); |
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128 | weak_release(); |
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129 | } |
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130 | } |
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131 | |
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132 | void weak_add_ref() // nothrow |
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133 | { |
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134 | atomic_increment( &weak_count_ ); |
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135 | } |
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136 | |
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137 | void weak_release() // nothrow |
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138 | { |
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139 | if( atomic_decrement( &weak_count_ ) == 1 ) |
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140 | { |
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141 | destroy(); |
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142 | } |
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143 | } |
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144 | |
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145 | long use_count() const // nothrow |
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146 | { |
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147 | return const_cast< sp_int32_t const volatile & >( use_count_ ); |
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148 | } |
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149 | }; |
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150 | |
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151 | } // namespace detail |
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152 | |
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153 | } // namespace boost |
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154 | |
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155 | #endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SYNC_HPP_INCLUDED |
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