annotate Implab/AbstractEvent.cs @ 167:96681e9d0cea ref20160224

sync
author cin
date Wed, 02 Mar 2016 00:20:48 +0300
parents 5802131432e4
children 822aab37b107
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1 using System;
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2 using Implab.Parallels;
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3 using System.Threading;
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4 using System.Reflection;
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5
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6 namespace Implab {
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7 public abstract class AbstractEvent<THandler> : ICancellationToken, ICancellable {
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8
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9 const int UNRESOLVED_SATE = 0;
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10 const int TRANSITIONAL_STATE = 1;
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11 protected const int SUCCEEDED_STATE = 2;
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12 protected const int REJECTED_STATE = 3;
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13 protected const int CANCELLED_STATE = 4;
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14
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15 const int CANCEL_NOT_REQUESTED = 0;
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16 const int CANCEL_REQUESTING = 1;
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17 const int CANCEL_REQUESTED = 2;
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18
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19 const int RESERVED_HANDLERS_COUNT = 4;
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20
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21 int m_state;
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22 Exception m_error;
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23 int m_handlersCount;
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24
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25 //readonly THandler[] m_handlers = new THandler[RESERVED_HANDLERS_COUNT];
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26 THandler[] m_handlers;
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27 MTQueue<THandler> m_extraHandlers;
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28 int m_handlerPointer = -1;
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29 int m_handlersCommited;
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30
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31 int m_cancelRequest;
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32 Exception m_cancelationReason;
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33 MTQueue<Action<Exception>> m_cancelationHandlers;
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34
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35
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36 #region state managment
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37 bool BeginTransit() {
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38 return UNRESOLVED_SATE == Interlocked.CompareExchange(ref m_state, TRANSITIONAL_STATE, UNRESOLVED_SATE);
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39 }
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40
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41 void CompleteTransit(int state) {
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42 if (TRANSITIONAL_STATE != Interlocked.CompareExchange(ref m_state, state, TRANSITIONAL_STATE))
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43 throw new InvalidOperationException("Can't complete transition when the object isn't in the transitional state");
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44 }
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45
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46 void WaitTransition() {
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47 while (m_state == TRANSITIONAL_STATE) {
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48 Thread.MemoryBarrier();
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49 }
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50 }
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51
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52 protected bool BeginSetResult() {
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53 if (!BeginTransit()) {
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54 WaitTransition();
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55 if (m_state != CANCELLED_STATE)
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56 throw new InvalidOperationException("The promise is already resolved");
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57 return false;
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58 }
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59 return true;
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60 }
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61
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62 protected void EndSetResult() {
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63 CompleteTransit(SUCCEEDED_STATE);
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64 Signal();
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65 }
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66
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67
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68
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69 /// <summary>
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70 /// Выполняет обещание, сообщая об ошибке
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71 /// </summary>
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72 /// <remarks>
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73 /// Поскольку обещание должно работать в многопточной среде, при его выполнении сразу несколько потоков
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74 /// могу вернуть ошибку, при этом только первая будет использована в качестве результата, остальные
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75 /// будут проигнорированы.
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76 /// </remarks>
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77 /// <param name="error">Исключение возникшее при выполнении операции</param>
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78 /// <exception cref="InvalidOperationException">Данное обещание уже выполнено</exception>
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79 protected void SetError(Exception error) {
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80 if (BeginTransit()) {
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81 if (error is OperationCanceledException) {
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82 m_error = error.InnerException;
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83 CompleteTransit(CANCELLED_STATE);
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84 } else {
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85 m_error = error is PromiseTransientException ? error.InnerException : error;
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86 CompleteTransit(REJECTED_STATE);
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87 }
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88 Signal();
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89 } else {
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90 WaitTransition();
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91 if (m_state == SUCCEEDED_STATE)
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92 throw new InvalidOperationException("The promise is already resolved");
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93 }
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94 }
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95
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96 /// <summary>
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97 /// Отменяет операцию, если это возможно.
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98 /// </summary>
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99 /// <remarks>Для определения была ли операция отменена следует использовать свойство <see cref="IsCancelled"/>.</remarks>
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100 protected void SetCancelled(Exception reason) {
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101 if (BeginTransit()) {
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102 m_error = reason;
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103 CompleteTransit(CANCELLED_STATE);
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104 Signal();
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105 }
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106 }
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107
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108 protected abstract void SignalHandler(THandler handler, int signal);
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109
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110 void Signal() {
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111 var hp = m_handlerPointer;
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112 var slot = hp +1 ;
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113 while (slot < m_handlersCommited) {
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114 if (Interlocked.CompareExchange(ref m_handlerPointer, slot, hp) == hp) {
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115 SignalHandler(m_handlers[slot], m_state);
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116 }
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117 hp = m_handlerPointer;
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118 slot = hp +1 ;
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119 }
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120
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121
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122 if (m_extraHandlers != null) {
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123 THandler handler;
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124 while (m_extraHandlers.TryDequeue(out handler))
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125 SignalHandler(handler, m_state);
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126 }
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127 }
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128
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129 #endregion
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130
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131 protected abstract Signal GetResolveSignal();
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132
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133 #region synchronization traits
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134 protected void WaitResult(int timeout) {
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135 if (!(IsResolved || GetResolveSignal().Wait(timeout)))
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136 throw new TimeoutException();
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137
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138 switch (m_state) {
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139 case SUCCEEDED_STATE:
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140 return;
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141 case CANCELLED_STATE:
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142 throw new OperationCanceledException();
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143 case REJECTED_STATE:
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144 throw new TargetInvocationException(m_error);
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145 default:
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146 throw new ApplicationException(String.Format("Invalid promise state {0}", m_state));
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147 }
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148 }
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149 #endregion
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150
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151 #region handlers managment
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152
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153 protected void AddHandler(THandler handler) {
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154
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155 if (m_state > 1) {
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156 // the promise is in the resolved state, just invoke the handler
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157 SignalHandler(handler, m_state);
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158 } else {
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159 var slot = Interlocked.Increment(ref m_handlersCount) - 1;
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160
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161 if (slot < RESERVED_HANDLERS_COUNT) {
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162
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163 if (slot == 0) {
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164 m_handlers = new THandler[RESERVED_HANDLERS_COUNT];
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165 } else {
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166 while (m_handlers == null)
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167 Thread.MemoryBarrier();
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168 }
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169
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170 m_handlers[slot] = handler;
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171
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172 while (slot != Interlocked.CompareExchange(ref m_handlersCommited, slot + 1, slot)) {
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173 }
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174
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175 if (m_state > 1) {
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176 do {
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177 var hp = m_handlerPointer;
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178 slot = hp + 1;
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179 if (slot < m_handlersCommited) {
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180 if (Interlocked.CompareExchange(ref m_handlerPointer, slot, hp) != hp)
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181 continue;
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182 SignalHandler(m_handlers[slot], m_state);
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183 }
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184 break;
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185 } while(true);
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186 }
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187 } else {
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188 if (slot == RESERVED_HANDLERS_COUNT) {
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189 m_extraHandlers = new MTQueue<THandler>();
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190 } else {
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191 while (m_extraHandlers == null)
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192 Thread.MemoryBarrier();
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193 }
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194
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195 m_extraHandlers.Enqueue(handler);
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196
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197 if (m_state > 1 && m_extraHandlers.TryDequeue(out handler))
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198 // if the promise have been resolved while we was adding the handler to the queue
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199 // we can't guarantee that someone is still processing it
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200 // therefore we need to fetch a handler from the queue and execute it
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201 // note that fetched handler may be not the one that we have added
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202 // even we can fetch no handlers at all :)
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203 SignalHandler(handler, m_state);
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204 }
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205 }
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206 }
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207
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208 #endregion
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209
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210 #region IPromise implementation
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211
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212 public bool IsResolved {
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213 get {
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214 Thread.MemoryBarrier();
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215 return m_state > 1;
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216 }
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217 }
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218
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219 public bool IsCancelled {
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220 get {
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221 Thread.MemoryBarrier();
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222 return m_state == CANCELLED_STATE;
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223 }
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224 }
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225
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226 #endregion
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227
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228 public Exception Error {
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229 get {
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230 return m_error;
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231 }
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232 }
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233
145
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234 public bool CancelOperationIfRequested() {
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235 if (IsCancellationRequested) {
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236 CancelOperation(CancellationReason);
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237 return true;
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238 }
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239 return false;
144
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240 }
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241
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242 public virtual void CancelOperation(Exception reason) {
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243 SetCancelled(reason);
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244 }
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245
145
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246 public void CancellationRequested(Action<Exception> handler) {
144
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247 Safe.ArgumentNotNull(handler, "handler");
145
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diff changeset
248 if (IsCancellationRequested)
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diff changeset
249 handler(CancellationReason);
144
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250
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251 if (m_cancelationHandlers == null)
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252 Interlocked.CompareExchange(ref m_cancelationHandlers, new MTQueue<Action<Exception>>(), null);
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253
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254 m_cancelationHandlers.Enqueue(handler);
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255
145
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diff changeset
256 if (IsCancellationRequested && m_cancelationHandlers.TryDequeue(out handler))
144
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257 // TryDeque implies MemoryBarrier()
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258 handler(m_cancelationReason);
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parents:
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259 }
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260
145
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diff changeset
261 public bool IsCancellationRequested {
144
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262 get {
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263 do {
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264 if (m_cancelRequest == CANCEL_NOT_REQUESTED)
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parents:
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265 return false;
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266 if (m_cancelRequest == CANCEL_REQUESTED)
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267 return true;
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parents:
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268 Thread.MemoryBarrier();
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parents:
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269 } while(true);
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parents:
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270 }
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parents:
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271 }
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272
145
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diff changeset
273 public Exception CancellationReason {
144
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parents:
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274 get {
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parents:
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275 do {
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parents:
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276 Thread.MemoryBarrier();
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parents:
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277 } while(m_cancelRequest == CANCEL_REQUESTING);
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parents:
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278
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279 return m_cancelationReason;
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parents:
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280 }
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parents:
diff changeset
281 }
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parents:
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282
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283 #region ICancellable implementation
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284
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285 public void Cancel() {
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parents:
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286 Cancel(null);
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parents:
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287 }
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parents:
diff changeset
288
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parents:
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289 public void Cancel(Exception reason) {
145
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parents: 144
diff changeset
290 if (CANCEL_NOT_REQUESTED == Interlocked.CompareExchange(ref m_cancelRequest, CANCEL_REQUESTING, CANCEL_NOT_REQUESTED)) {
144
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parents:
diff changeset
291 m_cancelationReason = reason;
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parents:
diff changeset
292 m_cancelRequest = CANCEL_REQUESTED;
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parents:
diff changeset
293 if (m_cancelationHandlers != null) {
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parents:
diff changeset
294 Action<Exception> handler;
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cin
parents:
diff changeset
295 while (m_cancelationHandlers.TryDequeue(out handler))
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cin
parents:
diff changeset
296 handler(m_cancelationReason);
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parents:
diff changeset
297 }
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cin
parents:
diff changeset
298 }
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cin
parents:
diff changeset
299 }
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cin
parents:
diff changeset
300
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cin
parents:
diff changeset
301 #endregion
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cin
parents:
diff changeset
302 }
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cin
parents:
diff changeset
303 }
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cin
parents:
diff changeset
304