1 | // |
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2 | // Semaphore.h |
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3 | // |
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4 | // $Id: //poco/1.3/Foundation/include/Poco/Semaphore.h#2 $ |
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5 | // |
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6 | // Library: Foundation |
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7 | // Package: Threading |
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8 | // Module: Semaphore |
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9 | // |
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10 | // Definition of the Semaphore class. |
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11 | // |
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12 | // Copyright (c) 2004-2006, 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_Semaphore_INCLUDED |
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40 | #define Foundation_Semaphore_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 | #include "Poco/Exception.h" |
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45 | |
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46 | |
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47 | #if defined(POCO_OS_FAMILY_WINDOWS) |
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48 | #include "Poco/Semaphore_WIN32.h" |
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49 | #else |
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50 | #include "Poco/Semaphore_POSIX.h" |
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51 | #endif |
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52 | |
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53 | |
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54 | namespace Poco { |
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55 | |
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56 | |
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57 | class Foundation_API Semaphore: private SemaphoreImpl |
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58 | /// A Semaphore is a synchronization object with the following |
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59 | /// characteristics: |
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60 | /// A semaphore has a value that is constrained to be a non-negative |
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61 | /// integer and two atomic operations. The allowable operations are V |
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62 | /// (here called set()) and P (here called wait()). A V (set()) operation |
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63 | /// increases the value of the semaphore by one. |
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64 | /// A P (wait()) operation decreases the value of the semaphore by one, |
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65 | /// provided that can be done without violating the constraint that the |
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66 | /// value be non-negative. A P (wait()) operation that is initiated when |
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67 | /// the value of the semaphore is 0 suspends the calling thread. |
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68 | /// The calling thread may continue when the value becomes positive again. |
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69 | { |
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70 | public: |
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71 | Semaphore(int n); |
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72 | Semaphore(int n, int max); |
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73 | /// Creates the semaphore. The current value |
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74 | /// of the semaphore is given in n. The |
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75 | /// maximum value of the semaphore is given |
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76 | /// in max. |
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77 | /// If only n is given, it must be greater than |
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78 | /// zero. |
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79 | /// If both n and max are given, max must be |
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80 | /// greater than zero, n must be greater than |
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81 | /// or equal to zero and less than or equal |
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82 | /// to max. |
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83 | |
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84 | ~Semaphore(); |
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85 | /// Destroys the semaphore. |
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86 | |
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87 | void set(); |
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88 | /// Increments the semaphore's value by one and |
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89 | /// thus signals the semaphore. Another thread |
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90 | /// waiting for the semaphore will be able |
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91 | /// to continue. |
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92 | |
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93 | void wait(); |
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94 | /// Waits for the semaphore to become signalled. |
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95 | /// To become signalled, a semaphore's value must |
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96 | /// be greater than zero. |
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97 | /// Decrements the semaphore's value by one. |
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98 | |
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99 | void wait(long milliseconds); |
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100 | /// Waits for the semaphore to become signalled. |
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101 | /// To become signalled, a semaphore's value must |
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102 | /// be greater than zero. |
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103 | /// Throws a TimeoutException if the semaphore |
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104 | /// does not become signalled within the specified |
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105 | /// time interval. |
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106 | /// Decrements the semaphore's value by one |
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107 | /// if successful. |
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108 | |
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109 | bool tryWait(long milliseconds); |
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110 | /// Waits for the semaphore to become signalled. |
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111 | /// To become signalled, a semaphore's value must |
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112 | /// be greater than zero. |
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113 | /// Returns true if the semaphore |
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114 | /// became signalled within the specified |
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115 | /// time interval, false otherwise. |
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116 | /// Decrements the semaphore's value by one |
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117 | /// if successful. |
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118 | |
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119 | private: |
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120 | Semaphore(); |
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121 | Semaphore(const Semaphore&); |
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122 | Semaphore& operator = (const Semaphore&); |
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123 | }; |
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124 | |
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125 | |
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126 | // |
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127 | // inlines |
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128 | // |
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129 | inline void Semaphore::set() |
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130 | { |
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131 | setImpl(); |
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132 | } |
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133 | |
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134 | |
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135 | inline void Semaphore::wait() |
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136 | { |
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137 | waitImpl(); |
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138 | } |
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139 | |
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140 | |
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141 | inline void Semaphore::wait(long milliseconds) |
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142 | { |
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143 | if (!waitImpl(milliseconds)) |
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144 | throw TimeoutException(); |
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145 | } |
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146 | |
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147 | |
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148 | inline bool Semaphore::tryWait(long milliseconds) |
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149 | { |
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150 | return waitImpl(milliseconds); |
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151 | } |
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152 | |
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153 | |
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154 | } // namespace Poco |
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155 | |
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156 | |
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157 | #endif // Foundation_Semaphore_INCLUDED |
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