opensim-development – Blame information for rev 1
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1 | eva | 1 | // |
2 | // Lazy.cs |
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3 | // |
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4 | // Authors: |
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5 | // Zoltan Varga (vargaz@gmail.com) |
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6 | // Marek Safar (marek.safar@gmail.com) |
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7 | // |
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8 | // Copyright (C) 2009 Novell |
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9 | // |
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10 | // Permission is hereby granted, free of charge, to any person obtaining |
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11 | // a copy of this software and associated documentation files (the |
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12 | // "Software"), to deal in the Software without restriction, including |
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13 | // without limitation the rights to use, copy, modify, merge, publish, |
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14 | // distribute, sublicense, and/or sell copies of the Software, and to |
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15 | // permit persons to whom the Software is furnished to do so, subject to |
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16 | // the following conditions: |
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17 | // |
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18 | // The above copyright notice and this permission notice shall be |
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19 | // included in all copies or substantial portions of the Software. |
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20 | // |
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21 | // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
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22 | // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
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23 | // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
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24 | // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE |
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25 | // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION |
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26 | // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION |
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27 | // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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28 | // |
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29 | |||
30 | using System; |
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31 | using System.Runtime.Serialization; |
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32 | using System.Runtime.InteropServices; |
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33 | using System.Security.Permissions; |
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34 | using System.Threading; |
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35 | using System.Diagnostics; |
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36 | |||
37 | namespace OpenSim.Framework |
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38 | { |
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39 | public enum LazyThreadSafetyMode |
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40 | { |
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41 | None, |
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42 | PublicationOnly, |
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43 | ExecutionAndPublication |
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44 | } |
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45 | |||
46 | [SerializableAttribute] |
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47 | [ComVisibleAttribute(false)] |
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48 | [HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization = true, ExternalThreading = true)] |
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49 | public class Lazy<T> |
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50 | { |
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51 | T value; |
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52 | bool inited; |
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53 | LazyThreadSafetyMode mode; |
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54 | Func<T> factory; |
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55 | object monitor; |
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56 | Exception exception; |
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57 | |||
58 | public Lazy() |
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59 | : this(LazyThreadSafetyMode.ExecutionAndPublication) |
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60 | { |
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61 | } |
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62 | |||
63 | public Lazy(Func<T> valueFactory) |
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64 | : this(valueFactory, LazyThreadSafetyMode.ExecutionAndPublication) |
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65 | { |
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66 | } |
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67 | |||
68 | public Lazy(bool isThreadSafe) |
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69 | : this(() => Activator.CreateInstance<T>(), isThreadSafe ? LazyThreadSafetyMode.ExecutionAndPublication : LazyThreadSafetyMode.None) |
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70 | { |
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71 | } |
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72 | |||
73 | public Lazy(Func<T> valueFactory, bool isThreadSafe) |
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74 | : this(valueFactory, isThreadSafe ? LazyThreadSafetyMode.ExecutionAndPublication : LazyThreadSafetyMode.None) |
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75 | { |
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76 | } |
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77 | |||
78 | public Lazy(LazyThreadSafetyMode mode) |
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79 | : this(() => Activator.CreateInstance<T>(), mode) |
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80 | { |
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81 | } |
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82 | |||
83 | public Lazy(Func<T> valueFactory, LazyThreadSafetyMode mode) |
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84 | { |
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85 | if (valueFactory == null) |
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86 | throw new ArgumentNullException("valueFactory"); |
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87 | this.factory = valueFactory; |
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88 | if (mode != LazyThreadSafetyMode.None) |
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89 | monitor = new object(); |
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90 | this.mode = mode; |
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91 | } |
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92 | |||
93 | // Don't trigger expensive initialization |
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94 | [DebuggerBrowsable(DebuggerBrowsableState.Never)] |
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95 | public T Value |
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96 | { |
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97 | get |
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98 | { |
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99 | if (inited) |
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100 | return value; |
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101 | if (exception != null) |
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102 | throw exception; |
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103 | |||
104 | return InitValue(); |
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105 | } |
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106 | } |
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107 | |||
108 | T InitValue() |
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109 | { |
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110 | switch (mode) |
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111 | { |
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112 | case LazyThreadSafetyMode.None: |
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113 | { |
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114 | var init_factory = factory; |
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115 | if (init_factory == null) |
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116 | throw exception = new InvalidOperationException("The initialization function tries to access Value on this instance"); |
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117 | try |
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118 | { |
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119 | factory = null; |
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120 | T v = init_factory(); |
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121 | value = v; |
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122 | Thread.MemoryBarrier(); |
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123 | inited = true; |
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124 | } |
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125 | catch (Exception ex) |
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126 | { |
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127 | exception = ex; |
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128 | throw; |
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129 | } |
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130 | break; |
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131 | } |
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132 | case LazyThreadSafetyMode.PublicationOnly: |
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133 | { |
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134 | var init_factory = factory; |
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135 | T v; |
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136 | |||
137 | //exceptions are ignored |
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138 | if (init_factory != null) |
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139 | v = init_factory(); |
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140 | else |
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141 | v = default(T); |
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142 | |||
143 | lock (monitor) |
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144 | { |
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145 | if (inited) |
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146 | return value; |
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147 | value = v; |
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148 | Thread.MemoryBarrier(); |
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149 | inited = true; |
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150 | factory = null; |
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151 | } |
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152 | break; |
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153 | } |
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154 | case LazyThreadSafetyMode.ExecutionAndPublication: |
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155 | { |
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156 | lock (monitor) |
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157 | { |
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158 | if (inited) |
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159 | return value; |
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160 | |||
161 | if (factory == null) |
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162 | throw exception = new InvalidOperationException("The initialization function tries to access Value on this instance"); |
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163 | |||
164 | var init_factory = factory; |
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165 | try |
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166 | { |
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167 | factory = null; |
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168 | T v = init_factory(); |
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169 | value = v; |
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170 | Thread.MemoryBarrier(); |
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171 | inited = true; |
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172 | } |
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173 | catch (Exception ex) |
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174 | { |
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175 | exception = ex; |
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176 | throw; |
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177 | } |
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178 | } |
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179 | break; |
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180 | } |
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181 | default: |
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182 | throw new InvalidOperationException("Invalid LazyThreadSafetyMode " + mode); |
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183 | } |
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184 | |||
185 | if (monitor == null) |
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186 | { |
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187 | value = factory(); |
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188 | inited = true; |
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189 | } |
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190 | else |
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191 | { |
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192 | lock (monitor) |
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193 | { |
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194 | if (inited) |
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195 | return value; |
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196 | |||
197 | if (factory == null) |
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198 | throw new InvalidOperationException("The initialization function tries to access Value on this instance"); |
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199 | |||
200 | var init_factory = factory; |
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201 | try |
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202 | { |
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203 | factory = null; |
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204 | T v = init_factory(); |
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205 | value = v; |
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206 | Thread.MemoryBarrier(); |
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207 | inited = true; |
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208 | } |
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209 | catch |
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210 | { |
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211 | factory = init_factory; |
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212 | throw; |
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213 | } |
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214 | } |
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215 | } |
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216 | |||
217 | return value; |
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218 | } |
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219 | |||
220 | public bool IsValueCreated |
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221 | { |
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222 | get |
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223 | { |
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224 | return inited; |
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225 | } |
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226 | } |
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227 | |||
228 | public override string ToString() |
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229 | { |
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230 | if (inited) |
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231 | return value.ToString(); |
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232 | else |
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233 | return "Value is not created"; |
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234 | } |
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235 | } |
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236 | } |