1 | // |
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2 | // AtomicCounter.h |
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3 | // |
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4 | // $Id: //poco/1.3/Foundation/include/Poco/AtomicCounter.h#6 $ |
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5 | // |
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6 | // Library: Foundation |
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7 | // Package: Core |
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8 | // Module: AtomicCounter |
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9 | // |
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10 | // Definition of the AtomicCounter class. |
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11 | // |
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12 | // Copyright (c) 2009, Applied Informatics Software Engineering GmbH. |
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13 | // and Contributors. |
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14 | // |
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15 | // Permission is hereby granted, free of charge, to any person or organization |
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16 | // obtaining a copy of the software and accompanying documentation covered by |
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17 | // this license (the "Software") to use, reproduce, display, distribute, |
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18 | // execute, and transmit the Software, and to prepare derivative works of the |
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19 | // Software, and to permit third-parties to whom the Software is furnished to |
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20 | // do so, all subject to the following: |
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21 | // |
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22 | // The copyright notices in the Software and this entire statement, including |
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23 | // the above license grant, this restriction and the following disclaimer, |
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24 | // must be included in all copies of the Software, in whole or in part, and |
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25 | // all derivative works of the Software, unless such copies or derivative |
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26 | // works are solely in the form of machine-executable object code generated by |
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27 | // a source language processor. |
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28 | // |
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29 | // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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30 | // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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31 | // FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT |
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32 | // SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE |
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33 | // FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, |
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34 | // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
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35 | // DEALINGS IN THE SOFTWARE. |
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36 | // |
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37 | |
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38 | |
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39 | #ifndef Foundation_AtomicCounter_INCLUDED |
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40 | #define Foundation_AtomicCounter_INCLUDED |
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41 | |
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42 | |
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43 | #include "Poco/Foundation.h" |
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44 | #if POCO_OS == POCO_OS_WINDOWS_NT |
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45 | #include "Poco/UnWindows.h" |
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46 | #elif POCO_OS == POCO_OS_MAC_OS_X |
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47 | #include <libkern/OSAtomic.h> |
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48 | #else |
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49 | #include "Poco/Mutex.h" |
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50 | #endif // POCO_OS |
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51 | |
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52 | |
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53 | namespace Poco { |
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54 | |
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55 | |
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56 | class Foundation_API AtomicCounter |
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57 | /// This class implements a simple counter, which |
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58 | /// provides atomic operations that are safe to |
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59 | /// use in a multithreaded environment. |
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60 | /// |
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61 | /// Typical usage of AtomicCounter is for implementing |
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62 | /// reference counting and similar things. |
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63 | /// |
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64 | /// On some platforms, the implementation of AtomicCounter |
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65 | /// is based on atomic primitives specific to the platform |
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66 | /// (such as InterlockedIncrement, etc. on Windows), and |
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67 | /// thus very efficient. On platforms that do not support |
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68 | /// atomic primitives, operations are guarded by a FastMutex. |
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69 | /// |
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70 | /// The following platforms currently have atomic |
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71 | /// primitives: |
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72 | /// - Windows |
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73 | /// - Mac OS X |
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74 | { |
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75 | public: |
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76 | typedef int ValueType; /// The underlying integer type. |
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77 | |
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78 | AtomicCounter(); |
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79 | /// Creates a new AtomicCounter and initializes it to zero. |
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80 | |
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81 | explicit AtomicCounter(ValueType initialValue); |
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82 | /// Creates a new AtomicCounter and initializes it with |
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83 | /// the given value. |
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84 | |
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85 | AtomicCounter(const AtomicCounter& counter); |
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86 | /// Creates the counter by copying another one. |
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87 | |
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88 | ~AtomicCounter(); |
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89 | /// Destroys the AtomicCounter. |
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90 | |
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91 | AtomicCounter& operator = (const AtomicCounter& counter); |
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92 | /// Assigns the value of another AtomicCounter. |
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93 | |
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94 | AtomicCounter& operator = (ValueType value); |
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95 | /// Assigns a value to the counter. |
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96 | |
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97 | operator ValueType () const; |
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98 | /// Returns the value of the counter. |
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99 | |
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100 | ValueType value() const; |
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101 | /// Returns the value of the counter. |
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102 | |
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103 | ValueType operator ++ (); // prefix |
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104 | /// Increments the counter and returns the result. |
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105 | |
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106 | ValueType operator ++ (int); // postfix |
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107 | /// Increments the counter and returns the previous value. |
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108 | |
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109 | ValueType operator -- (); // prefix |
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110 | /// Decrements the counter and returns the result. |
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111 | |
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112 | ValueType operator -- (int); // postfix |
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113 | /// Decrements the counter and returns the previous value. |
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114 | |
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115 | bool operator ! () const; |
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116 | /// Returns true if the counter is zero, false otherwise. |
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117 | |
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118 | private: |
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119 | #if POCO_OS == POCO_OS_WINDOWS_NT |
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120 | typedef volatile LONG ImplType; |
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121 | #elif POCO_OS == POCO_OS_MAC_OS_X |
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122 | typedef int32_t ImplType; |
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123 | #else // generic implementation based on FastMutex |
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124 | struct ImplType |
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125 | { |
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126 | mutable FastMutex mutex; |
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127 | volatile int value; |
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128 | }; |
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129 | #endif // POCO_OS |
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130 | |
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131 | ImplType _counter; |
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132 | }; |
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133 | |
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134 | |
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135 | // |
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136 | // inlines |
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137 | // |
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138 | |
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139 | |
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140 | #if POCO_OS == POCO_OS_WINDOWS_NT |
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141 | // |
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142 | // Windows |
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143 | // |
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144 | inline AtomicCounter::operator AtomicCounter::ValueType () const |
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145 | { |
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146 | return _counter; |
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147 | } |
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148 | |
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149 | |
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150 | inline AtomicCounter::ValueType AtomicCounter::value() const |
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151 | { |
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152 | return _counter; |
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153 | } |
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154 | |
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155 | |
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156 | inline AtomicCounter::ValueType AtomicCounter::operator ++ () // prefix |
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157 | { |
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158 | return InterlockedIncrement(&_counter); |
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159 | } |
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160 | |
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161 | |
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162 | inline AtomicCounter::ValueType AtomicCounter::operator ++ (int) // postfix |
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163 | { |
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164 | ValueType result(_counter); |
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165 | InterlockedIncrement(&_counter); |
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166 | return result; |
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167 | } |
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168 | |
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169 | |
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170 | inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix |
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171 | { |
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172 | return InterlockedDecrement(&_counter); |
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173 | } |
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174 | |
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175 | |
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176 | inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix |
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177 | { |
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178 | ValueType result(_counter); |
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179 | InterlockedDecrement(&_counter); |
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180 | return result; |
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181 | } |
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182 | |
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183 | |
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184 | inline bool AtomicCounter::operator ! () const |
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185 | { |
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186 | return _counter == 0; |
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187 | } |
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188 | |
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189 | |
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190 | #elif POCO_OS == POCO_OS_MAC_OS_X |
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191 | // |
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192 | // Mac OS X |
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193 | // |
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194 | inline AtomicCounter::operator AtomicCounter::ValueType () const |
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195 | { |
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196 | return _counter; |
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197 | } |
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198 | |
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199 | |
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200 | inline AtomicCounter::ValueType AtomicCounter::value() const |
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201 | { |
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202 | return _counter; |
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203 | } |
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204 | |
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205 | |
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206 | inline AtomicCounter::ValueType AtomicCounter::operator ++ () // prefix |
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207 | { |
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208 | return OSAtomicIncrement32(&_counter); |
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209 | } |
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210 | |
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211 | |
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212 | inline AtomicCounter::ValueType AtomicCounter::operator ++ (int) // postfix |
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213 | { |
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214 | ValueType result(_counter); |
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215 | OSAtomicIncrement32(&_counter); |
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216 | return result; |
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217 | } |
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218 | |
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219 | |
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220 | inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix |
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221 | { |
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222 | return OSAtomicDecrement32(&_counter); |
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223 | } |
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224 | |
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225 | |
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226 | inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix |
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227 | { |
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228 | ValueType result(_counter); |
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229 | OSAtomicDecrement32(&_counter); |
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230 | return result; |
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231 | } |
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232 | |
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233 | |
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234 | inline bool AtomicCounter::operator ! () const |
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235 | { |
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236 | return _counter == 0; |
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237 | } |
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238 | |
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239 | |
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240 | #else |
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241 | // |
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242 | // Generic implementation based on FastMutex |
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243 | // |
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244 | inline AtomicCounter::operator AtomicCounter::ValueType () const |
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245 | { |
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246 | ValueType result; |
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247 | { |
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248 | FastMutex::ScopedLock lock(_counter.mutex); |
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249 | result = _counter.value; |
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250 | } |
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251 | return result; |
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252 | } |
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253 | |
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254 | |
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255 | inline AtomicCounter::ValueType AtomicCounter::value() const |
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256 | { |
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257 | ValueType result; |
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258 | { |
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259 | FastMutex::ScopedLock lock(_counter.mutex); |
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260 | result = _counter.value; |
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261 | } |
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262 | return result; |
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263 | } |
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264 | |
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265 | |
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266 | inline AtomicCounter::ValueType AtomicCounter::operator ++ () // prefix |
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267 | { |
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268 | ValueType result; |
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269 | { |
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270 | FastMutex::ScopedLock lock(_counter.mutex); |
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271 | result = ++_counter.value; |
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272 | } |
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273 | return result; |
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274 | } |
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275 | |
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276 | |
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277 | inline AtomicCounter::ValueType AtomicCounter::operator ++ (int) // postfix |
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278 | { |
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279 | ValueType result; |
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280 | { |
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281 | FastMutex::ScopedLock lock(_counter.mutex); |
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282 | result = _counter.value++; |
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283 | } |
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284 | return result; |
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285 | } |
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286 | |
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287 | |
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288 | inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix |
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289 | { |
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290 | ValueType result; |
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291 | { |
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292 | FastMutex::ScopedLock lock(_counter.mutex); |
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293 | result = --_counter.value; |
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294 | } |
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295 | return result; |
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296 | } |
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297 | |
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298 | |
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299 | inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix |
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300 | { |
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301 | ValueType result; |
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302 | { |
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303 | FastMutex::ScopedLock lock(_counter.mutex); |
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304 | result = _counter.value--; |
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305 | } |
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306 | return result; |
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307 | } |
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308 | |
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309 | |
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310 | inline bool AtomicCounter::operator ! () const |
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311 | { |
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312 | bool result; |
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313 | { |
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314 | FastMutex::ScopedLock lock(_counter.mutex); |
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315 | result = _counter.value == 0; |
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316 | } |
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317 | return result; |
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318 | } |
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319 | |
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320 | |
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321 | #endif // POCO_OS |
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322 | |
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323 | |
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324 | } // namespace Poco |
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325 | |
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326 | |
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327 | #endif // Foundation_AtomicCounter_INCLUDED |
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