Mercurial > pub > ImplabNet
annotate Implab/AbstractPromise.cs @ 138:f75cfa58e3d4 v2
added ICancellable.Cancel(Exception) to allow specify the reason of cancellation
| author | cin |
|---|---|
| date | Tue, 17 Feb 2015 18:16:26 +0300 |
| parents | 671f60cd0250 |
| children | 16f926ee499d |
| rev | line source |
|---|---|
| 119 | 1 using System; |
| 2 using Implab.Parallels; | |
| 3 using System.Threading; | |
| 4 using System.Reflection; | |
| 5 | |
| 6 namespace Implab { | |
| 7 public abstract class AbstractPromise<THandler> { | |
| 8 | |
| 9 const int UNRESOLVED_SATE = 0; | |
| 10 const int TRANSITIONAL_STATE = 1; | |
| 11 const int SUCCEEDED_STATE = 2; | |
| 12 const int REJECTED_STATE = 3; | |
| 13 const int CANCELLED_STATE = 4; | |
| 14 | |
| 125 | 15 const int RESERVED_HANDLERS_COUNT = 4; |
| 16 | |
| 119 | 17 int m_state; |
| 18 Exception m_error; | |
| 125 | 19 int m_handlersCount; |
| 119 | 20 |
| 125 | 21 readonly THandler[] m_handlers = new THandler[RESERVED_HANDLERS_COUNT]; |
| 22 MTQueue<THandler> m_extraHandlers; | |
| 23 int m_handlerPointer = -1; | |
| 24 int m_handlersCommited; | |
| 119 | 25 |
| 26 #region state managment | |
| 27 bool BeginTransit() { | |
| 28 return UNRESOLVED_SATE == Interlocked.CompareExchange(ref m_state, TRANSITIONAL_STATE, UNRESOLVED_SATE); | |
| 29 } | |
| 30 | |
| 31 void CompleteTransit(int state) { | |
| 32 if (TRANSITIONAL_STATE != Interlocked.CompareExchange(ref m_state, state, TRANSITIONAL_STATE)) | |
| 33 throw new InvalidOperationException("Can't complete transition when the object isn't in the transitional state"); | |
| 34 } | |
| 35 | |
| 36 void WaitTransition() { | |
| 37 while (m_state == TRANSITIONAL_STATE) { | |
| 38 Thread.MemoryBarrier(); | |
| 39 } | |
| 40 } | |
| 41 | |
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42 protected bool BeginSetResult() { |
| 119 | 43 if (!BeginTransit()) { |
| 44 WaitTransition(); | |
| 45 if (m_state != CANCELLED_STATE) | |
| 46 throw new InvalidOperationException("The promise is already resolved"); | |
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47 return false; |
| 119 | 48 } |
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49 return true; |
| 119 | 50 } |
| 51 | |
| 52 protected void EndSetResult() { | |
| 53 CompleteTransit(SUCCEEDED_STATE); | |
| 54 OnSuccess(); | |
| 55 } | |
| 56 | |
| 57 | |
| 58 | |
| 59 /// <summary> | |
| 60 /// Выполняет обещание, сообщая об ошибке | |
| 61 /// </summary> | |
| 62 /// <remarks> | |
| 63 /// Поскольку обещание должно работать в многопточной среде, при его выполнении сразу несколько потоков | |
| 64 /// могу вернуть ошибку, при этом только первая будет использована в качестве результата, остальные | |
| 65 /// будут проигнорированы. | |
| 66 /// </remarks> | |
| 67 /// <param name="error">Исключение возникшее при выполнении операции</param> | |
| 68 /// <exception cref="InvalidOperationException">Данное обещание уже выполнено</exception> | |
| 69 protected void SetError(Exception error) { | |
| 70 if (BeginTransit()) { | |
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71 if (error is OperationCanceledException) { |
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72 CompleteTransit(CANCELLED_STATE); |
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73 m_error = error.InnerException; |
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74 OnCancelled(); |
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75 } else { |
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76 m_error = error is PromiseTransientException ? error.InnerException : error; |
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77 CompleteTransit(REJECTED_STATE); |
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78 OnError(); |
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79 } |
| 119 | 80 } else { |
| 81 WaitTransition(); | |
| 82 if (m_state == SUCCEEDED_STATE) | |
| 83 throw new InvalidOperationException("The promise is already resolved"); | |
| 84 } | |
| 85 } | |
| 86 | |
| 87 /// <summary> | |
| 88 /// Отменяет операцию, если это возможно. | |
| 89 /// </summary> | |
| 90 /// <remarks>Для определения была ли операция отменена следует использовать свойство <see cref="IsCancelled"/>.</remarks> | |
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91 protected void SetCancelled(Exception reason) { |
| 119 | 92 if (BeginTransit()) { |
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93 m_error = reason; |
| 119 | 94 CompleteTransit(CANCELLED_STATE); |
| 95 OnCancelled(); | |
| 96 } | |
| 97 } | |
| 98 | |
| 99 protected abstract void SignalSuccess(THandler handler); | |
| 100 | |
| 101 protected abstract void SignalError(THandler handler, Exception error); | |
| 102 | |
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103 protected abstract void SignalCancelled(THandler handler, Exception reason); |
| 119 | 104 |
| 105 void OnSuccess() { | |
| 125 | 106 var hp = m_handlerPointer; |
| 107 var slot = hp +1 ; | |
| 108 while (slot < m_handlersCommited) { | |
| 109 if (Interlocked.CompareExchange(ref m_handlerPointer, slot, hp) == hp) { | |
| 110 SignalSuccess(m_handlers[slot]); | |
| 111 } | |
| 112 hp = m_handlerPointer; | |
| 113 slot = hp +1 ; | |
| 114 } | |
| 115 | |
| 116 | |
| 117 if (m_extraHandlers != null) { | |
| 118 THandler handler; | |
| 119 while (m_extraHandlers.TryDequeue(out handler)) | |
| 120 SignalSuccess(handler); | |
| 121 } | |
| 119 | 122 } |
| 123 | |
| 124 void OnError() { | |
| 125 | 125 var hp = m_handlerPointer; |
| 126 var slot = hp +1 ; | |
| 127 while (slot < m_handlersCommited) { | |
| 128 if (Interlocked.CompareExchange(ref m_handlerPointer, slot, hp) == hp) { | |
| 129 SignalError(m_handlers[slot],m_error); | |
| 130 } | |
| 131 hp = m_handlerPointer; | |
| 132 slot = hp +1 ; | |
| 133 } | |
| 134 | |
| 135 if (m_extraHandlers != null) { | |
| 136 THandler handler; | |
| 137 while (m_extraHandlers.TryDequeue(out handler)) | |
| 138 SignalError(handler, m_error); | |
| 139 } | |
| 119 | 140 } |
| 141 | |
| 142 void OnCancelled() { | |
| 125 | 143 var hp = m_handlerPointer; |
| 144 var slot = hp +1 ; | |
| 145 while (slot < m_handlersCommited) { | |
| 146 if (Interlocked.CompareExchange(ref m_handlerPointer, slot, hp) == hp) { | |
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147 SignalCancelled(m_handlers[slot], m_error); |
| 125 | 148 } |
| 149 hp = m_handlerPointer; | |
| 150 slot = hp +1 ; | |
| 151 } | |
| 152 | |
| 153 if (m_extraHandlers != null) { | |
| 154 THandler handler; | |
| 155 while (m_extraHandlers.TryDequeue(out handler)) | |
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156 SignalCancelled(handler, m_error); |
| 125 | 157 } |
| 119 | 158 } |
| 159 | |
| 160 #endregion | |
| 161 | |
| 162 protected abstract void Listen(PromiseEventType events, Action handler); | |
| 163 | |
| 164 #region synchronization traits | |
| 165 protected void WaitResult(int timeout) { | |
| 166 if (!IsResolved) { | |
| 167 var lk = new object(); | |
| 168 | |
| 169 Listen(PromiseEventType.All, () => { | |
| 170 lock(lk) { | |
| 171 Monitor.Pulse(lk); | |
| 172 } | |
| 173 }); | |
| 174 | |
| 175 lock (lk) { | |
| 176 while(!IsResolved) { | |
| 177 if(!Monitor.Wait(lk,timeout)) | |
| 178 throw new TimeoutException(); | |
| 179 } | |
| 180 } | |
| 181 | |
| 182 } | |
| 183 switch (m_state) { | |
| 184 case SUCCEEDED_STATE: | |
| 185 return; | |
| 186 case CANCELLED_STATE: | |
| 187 throw new OperationCanceledException(); | |
| 188 case REJECTED_STATE: | |
| 189 throw new TargetInvocationException(m_error); | |
| 190 default: | |
| 191 throw new ApplicationException(String.Format("Invalid promise state {0}", m_state)); | |
| 192 } | |
| 193 } | |
| 194 #endregion | |
| 195 | |
| 196 #region handlers managment | |
| 197 | |
| 198 protected void AddHandler(THandler handler) { | |
| 199 | |
| 125 | 200 if (m_state > 1) { |
| 119 | 201 // the promise is in the resolved state, just invoke the handler |
| 125 | 202 InvokeHandler(handler); |
| 203 } else { | |
| 204 var slot = Interlocked.Increment(ref m_handlersCount) - 1; | |
| 205 | |
| 206 if (slot < RESERVED_HANDLERS_COUNT) { | |
| 207 m_handlers[slot] = handler; | |
| 208 | |
| 209 while (slot != Interlocked.CompareExchange(ref m_handlersCommited, slot + 1, slot)) { | |
| 210 } | |
| 119 | 211 |
| 125 | 212 if (m_state > 1) { |
| 213 do { | |
| 214 var hp = m_handlerPointer; | |
| 215 slot = hp + 1; | |
| 216 if (slot < m_handlersCommited) { | |
| 217 if (Interlocked.CompareExchange(ref m_handlerPointer, slot, hp) != hp) | |
| 218 continue; | |
| 219 InvokeHandler(m_handlers[slot]); | |
| 220 } | |
| 221 break; | |
| 222 } while(true); | |
| 223 } | |
| 224 } else { | |
| 225 if (slot == RESERVED_HANDLERS_COUNT) { | |
| 226 m_extraHandlers = new MTQueue<THandler>(); | |
| 227 } else { | |
| 228 while (m_extraHandlers == null) | |
| 229 Thread.MemoryBarrier(); | |
| 230 } | |
| 119 | 231 |
| 125 | 232 m_extraHandlers.Enqueue(handler); |
| 233 | |
| 234 if (m_state > 1 && m_extraHandlers.TryDequeue(out handler)) | |
| 119 | 235 // if the promise have been resolved while we was adding the handler to the queue |
| 236 // we can't guarantee that someone is still processing it | |
| 237 // therefore we need to fetch a handler from the queue and execute it | |
| 238 // note that fetched handler may be not the one that we have added | |
| 239 // even we can fetch no handlers at all :) | |
| 240 InvokeHandler(handler); | |
| 125 | 241 } |
| 119 | 242 } |
| 243 } | |
| 244 | |
| 245 protected void InvokeHandler(THandler handler) { | |
| 246 switch (m_state) { | |
| 247 case SUCCEEDED_STATE: | |
| 248 SignalSuccess(handler); | |
| 249 break; | |
| 250 case CANCELLED_STATE: | |
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251 SignalCancelled(handler, m_error); |
| 119 | 252 break; |
| 253 case REJECTED_STATE: | |
| 254 SignalError(handler, m_error); | |
| 255 break; | |
| 256 default: | |
| 257 throw new Exception(String.Format("Invalid promise state {0}", m_state)); | |
| 258 } | |
| 259 } | |
| 260 | |
| 261 #endregion | |
| 262 | |
| 263 #region IPromise implementation | |
| 264 | |
| 265 public void Join(int timeout) { | |
| 266 WaitResult(timeout); | |
| 267 } | |
| 268 | |
| 269 public void Join() { | |
| 270 WaitResult(-1); | |
| 271 } | |
| 272 | |
| 273 public bool IsResolved { | |
| 274 get { | |
| 275 Thread.MemoryBarrier(); | |
| 276 return m_state > 1; | |
| 277 } | |
| 278 } | |
| 279 | |
| 280 public bool IsCancelled { | |
| 281 get { | |
| 282 Thread.MemoryBarrier(); | |
| 283 return m_state == CANCELLED_STATE; | |
| 284 } | |
| 285 } | |
| 286 | |
| 287 #endregion | |
| 288 | |
| 289 #region ICancellable implementation | |
| 290 | |
| 291 public void Cancel() { | |
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292 SetCancelled(null); |
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293 } |
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294 |
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295 public void Cancel(Exception reason) { |
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296 SetCancelled(reason); |
| 119 | 297 } |
| 298 | |
| 299 #endregion | |
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300 |
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301 public Exception Error { |
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302 get { |
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303 return m_error; |
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304 } |
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305 } |
| 119 | 306 } |
| 307 } | |
| 308 |