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132
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1 /**
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2 * The mutex module provides a primitive for maintaining mutually exclusive
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3 * access.
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4 *
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5 * Copyright: Copyright (C) 2005-2006 Sean Kelly. All rights reserved.
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6 * License: BSD style: $(LICENSE)
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7 * Authors: Sean Kelly
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8 */
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9 module tango.core.sync.Mutex;
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10
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11
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12 public import tango.core.Exception : SyncException;
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13
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14 version( Win32 )
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15 {
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16 private import tango.sys.win32.UserGdi;
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17 }
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18 else version( Posix )
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19 {
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20 private import tango.stdc.posix.pthread;
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21 }
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22
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23
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24 ////////////////////////////////////////////////////////////////////////////////
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25 // Mutex
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26 //
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27 // void lock();
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28 // void unlock();
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29 // bool tryLock();
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30 ////////////////////////////////////////////////////////////////////////////////
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31
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32
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33 /**
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34 * This class represents a general purpose, recursive mutex.
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35 */
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36 class Mutex :
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37 Object.Monitor
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38 {
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39 ////////////////////////////////////////////////////////////////////////////
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40 // Initialization
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41 ////////////////////////////////////////////////////////////////////////////
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42
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43
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44 /**
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45 * Initializes a mutex object.
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46 *
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47 * Throws:
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48 * SyncException on error.
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49 */
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50 this()
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51 {
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52 version( Win32 )
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53 {
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54 InitializeCriticalSection( &m_hndl );
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55 }
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56 else version( Posix )
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57 {
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58 int rc = pthread_mutex_init( &m_hndl, &sm_attr );
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59 if( rc )
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60 throw new SyncException( "Unable to initialize mutex" );
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61 }
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62 m_proxy.link = this;
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63 (cast(void**) this)[1] = &m_proxy;
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64 }
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65
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66
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67 ~this()
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68 {
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69 version( Win32 )
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70 {
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71 DeleteCriticalSection( &m_hndl );
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72 }
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73 else version( Posix )
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74 {
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75 int rc = pthread_mutex_destroy( &m_hndl );
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76 assert( !rc, "Unable to destroy mutex" );
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77 }
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78 (cast(void**) this)[1] = null;
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79 }
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80
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81
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82 ////////////////////////////////////////////////////////////////////////////
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83 // General Actions
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84 ////////////////////////////////////////////////////////////////////////////
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85
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86
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87 /**
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88 * If this lock is not already held by the caller, the lock is acquired,
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89 * then the internal counter is incremented by one.
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90 *
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91 * Throws:
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92 * SyncException on error.
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93 */
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94 void lock()
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95 {
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96 version( Win32 )
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97 {
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98 EnterCriticalSection( &m_hndl );
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99 }
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100 else version( Posix )
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101 {
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102 int rc = pthread_mutex_lock( &m_hndl );
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103 if( rc )
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104 throw new SyncException( "Unable to lock mutex" );
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105 }
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106 }
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107
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108
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109 /**
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110 * Decrements the internal lock count by one. If this brings the count to
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111 * zero, the lock is released.
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112 *
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113 * Throws:
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114 * SyncException on error.
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115 */
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116 void unlock()
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117 {
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118 version( Win32 )
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119 {
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120 LeaveCriticalSection( &m_hndl );
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121 }
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122 else version( Posix )
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123 {
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124 int rc = pthread_mutex_unlock( &m_hndl );
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125 if( rc )
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126 throw new SyncException( "Unable to unlock mutex" );
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127 }
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128 }
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129
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130
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131 /**
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132 * If the lock is held by another caller, the method returns. Otherwise,
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133 * the lock is acquired if it is not already held, and then the internal
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134 * counter is incremented by one.
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135 *
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136 * Returns:
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137 * true if the lock was acquired and false if not.
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138 *
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139 * Throws:
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140 * SyncException on error.
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141 */
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142 bool tryLock()
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143 {
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144 version( Win32 )
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145 {
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146 return TryEnterCriticalSection( &m_hndl ) != 0;
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147 }
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148 else version( Posix )
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149 {
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150 return pthread_mutex_trylock( &m_hndl ) == 0;
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151 }
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152 }
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153
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154
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155 version( Posix )
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156 {
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157 static this()
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158 {
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159 int rc = pthread_mutexattr_init( &sm_attr );
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160 assert( !rc );
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161
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162 rc = pthread_mutexattr_settype( &sm_attr, PTHREAD_MUTEX_RECURSIVE );
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163 assert( !rc );
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164 }
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165
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166
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167 static ~this()
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168 {
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169 int rc = pthread_mutexattr_destroy( &sm_attr );
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170 assert( !rc );
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171 }
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172 }
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173
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174
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175 private:
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176 version( Win32 )
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177 {
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178 CRITICAL_SECTION m_hndl;
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179 }
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180 else version( Posix )
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181 {
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182 static pthread_mutexattr_t sm_attr;
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183
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184 pthread_mutex_t m_hndl;
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185 }
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186
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187 struct MonitorProxy
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188 {
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189 Object.Monitor link;
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190 }
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191
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192 MonitorProxy m_proxy;
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193
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194
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195 package:
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196 version( Posix )
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197 {
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198 pthread_mutex_t* handleAddr()
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199 {
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200 return &m_hndl;
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201 }
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202 }
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203 }
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204
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205
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206 ////////////////////////////////////////////////////////////////////////////////
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207 // Unit Tests
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208 ////////////////////////////////////////////////////////////////////////////////
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209
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210
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211 debug( UnitTest )
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212 {
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213 private import tango.core.Thread;
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214
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215
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216 unittest
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217 {
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218 auto mutex = new Mutex;
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219 int numThreads = 10;
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220 int numTries = 1000;
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221 int lockCount = 0;
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222
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223 void testFn()
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224 {
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225 for( int i = 0; i < numTries; ++i )
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226 {
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227 synchronized( mutex )
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228 {
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229 ++lockCount;
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230 }
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231 }
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232 }
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233
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234 auto group = new ThreadGroup;
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235
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236 for( int i = 0; i < numThreads; ++i )
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237 group.create( &testFn );
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238
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239 group.joinAll();
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240 assert( lockCount == numThreads * numTries );
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241 }
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242 }
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