1 | #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SPIN_HPP_INCLUDED |
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2 | #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SPIN_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 | // |
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11 | // detail/sp_counted_base_spin.hpp - spinlock pool atomic emulation |
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12 | // |
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13 | // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd. |
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14 | // Copyright 2004-2008 Peter Dimov |
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15 | // |
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16 | // Distributed under the Boost Software License, Version 1.0. (See |
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17 | // accompanying file LICENSE_1_0.txt or copy at |
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18 | // http://www.boost.org/LICENSE_1_0.txt) |
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19 | // |
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20 | |
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21 | #include <boost/detail/sp_typeinfo.hpp> |
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22 | #include <boost/smart_ptr/detail/spinlock_pool.hpp> |
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23 | |
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24 | namespace boost |
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25 | { |
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26 | |
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27 | namespace detail |
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28 | { |
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29 | |
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30 | inline int atomic_exchange_and_add( int * pw, int dv ) |
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31 | { |
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32 | spinlock_pool<1>::scoped_lock lock( pw ); |
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33 | |
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34 | int r = *pw; |
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35 | *pw += dv; |
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36 | return r; |
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37 | } |
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38 | |
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39 | inline void atomic_increment( int * pw ) |
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40 | { |
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41 | spinlock_pool<1>::scoped_lock lock( pw ); |
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42 | ++*pw; |
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43 | } |
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44 | |
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45 | inline int atomic_conditional_increment( int * pw ) |
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46 | { |
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47 | spinlock_pool<1>::scoped_lock lock( pw ); |
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48 | |
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49 | int rv = *pw; |
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50 | if( rv != 0 ) ++*pw; |
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51 | return rv; |
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52 | } |
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53 | |
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54 | class sp_counted_base |
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55 | { |
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56 | private: |
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57 | |
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58 | sp_counted_base( sp_counted_base const & ); |
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59 | sp_counted_base & operator= ( sp_counted_base const & ); |
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60 | |
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61 | int use_count_; // #shared |
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62 | int weak_count_; // #weak + (#shared != 0) |
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63 | |
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64 | public: |
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65 | |
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66 | sp_counted_base(): use_count_( 1 ), weak_count_( 1 ) |
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67 | { |
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68 | } |
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69 | |
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70 | virtual ~sp_counted_base() // nothrow |
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71 | { |
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72 | } |
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73 | |
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74 | // dispose() is called when use_count_ drops to zero, to release |
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75 | // the resources managed by *this. |
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76 | |
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77 | virtual void dispose() = 0; // nothrow |
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78 | |
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79 | // destroy() is called when weak_count_ drops to zero. |
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80 | |
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81 | virtual void destroy() // nothrow |
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82 | { |
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83 | delete this; |
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84 | } |
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85 | |
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86 | virtual void * get_deleter( sp_typeinfo const & ti ) = 0; |
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87 | |
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88 | void add_ref_copy() |
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89 | { |
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90 | atomic_increment( &use_count_ ); |
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91 | } |
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92 | |
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93 | bool add_ref_lock() // true on success |
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94 | { |
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95 | return atomic_conditional_increment( &use_count_ ) != 0; |
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96 | } |
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97 | |
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98 | void release() // nothrow |
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99 | { |
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100 | if( atomic_exchange_and_add( &use_count_, -1 ) == 1 ) |
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101 | { |
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102 | dispose(); |
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103 | weak_release(); |
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104 | } |
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105 | } |
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106 | |
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107 | void weak_add_ref() // nothrow |
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108 | { |
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109 | atomic_increment( &weak_count_ ); |
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110 | } |
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111 | |
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112 | void weak_release() // nothrow |
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113 | { |
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114 | if( atomic_exchange_and_add( &weak_count_, -1 ) == 1 ) |
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115 | { |
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116 | destroy(); |
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117 | } |
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118 | } |
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119 | |
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120 | long use_count() const // nothrow |
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121 | { |
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122 | spinlock_pool<1>::scoped_lock lock( &use_count_ ); |
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123 | return use_count_; |
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124 | } |
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125 | }; |
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126 | |
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127 | } // namespace detail |
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128 | |
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129 | } // namespace boost |
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130 | |
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131 | #endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SPIN_HPP_INCLUDED |
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