Mercurial > pub > ImplabNet
annotate Implab/Parallels/AsyncQueue.cs @ 127:d86da8d2d4c3 v2
fixed AsyncQueue iterator
| author | cin |
|---|---|
| date | Tue, 27 Jan 2015 18:18:29 +0300 |
| parents | f803565868a4 |
| children | 6241bff0cd64 |
| rev | line source |
|---|---|
| 119 | 1 using System.Threading; |
| 2 using System.Collections.Generic; | |
| 3 using System; | |
| 4 using System.Collections; | |
| 124 | 5 using System.Diagnostics; |
| 119 | 6 |
| 7 namespace Implab.Parallels { | |
| 8 public class AsyncQueue<T> : IEnumerable<T> { | |
| 9 class Chunk { | |
| 10 public Chunk next; | |
| 11 | |
| 12 int m_low; | |
| 13 int m_hi; | |
| 14 int m_alloc; | |
| 15 readonly int m_size; | |
| 16 readonly T[] m_data; | |
| 17 | |
| 18 public Chunk(int size) { | |
| 19 m_size = size; | |
| 20 m_data = new T[size]; | |
| 21 } | |
| 22 | |
| 23 public Chunk(int size, T value) { | |
| 24 m_size = size; | |
| 25 m_hi = 1; | |
| 26 m_alloc = 1; | |
| 27 m_data = new T[size]; | |
| 28 m_data[0] = value; | |
| 29 } | |
| 30 | |
| 121 | 31 public Chunk(int size, T[] data, int offset, int length, int alloc) { |
| 32 m_size = size; | |
| 33 m_hi = length; | |
| 34 m_alloc = alloc; | |
| 35 m_data = new T[size]; | |
| 36 Array.Copy(data, offset, m_data, 0, length); | |
| 37 } | |
| 38 | |
| 119 | 39 public int Low { |
| 40 get { return m_low; } | |
| 41 } | |
| 42 | |
| 43 public int Hi { | |
| 44 get { return m_hi; } | |
| 45 } | |
| 46 | |
| 127 | 47 public int Size { |
| 48 get { return m_size; } | |
| 49 } | |
| 50 | |
| 121 | 51 public bool TryEnqueue(T value, out bool extend) { |
| 120 | 52 var alloc = Interlocked.Increment(ref m_alloc) - 1; |
| 119 | 53 |
| 120 | 54 if (alloc >= m_size) { |
| 55 extend = alloc == m_size; | |
| 119 | 56 return false; |
| 57 } | |
| 120 | 58 |
| 59 extend = false; | |
| 119 | 60 m_data[alloc] = value; |
| 61 | |
| 62 while (alloc != Interlocked.CompareExchange(ref m_hi, alloc + 1, alloc)) { | |
| 63 // spin wait for commit | |
| 64 } | |
| 65 return true; | |
| 66 } | |
| 67 | |
| 124 | 68 /// <summary> |
| 69 /// Prevents from allocating new space in the chunk and waits for all write operations to complete | |
| 70 /// </summary> | |
| 71 public void Commit() { | |
| 72 var actual = Math.Min(Interlocked.Exchange(ref m_alloc, m_size + 1), m_size); | |
| 73 | |
| 74 while (m_hi != actual) | |
| 75 Thread.MemoryBarrier(); | |
| 76 } | |
| 77 | |
| 121 | 78 public bool TryDequeue(out T value, out bool recycle) { |
| 119 | 79 int low; |
| 80 do { | |
| 81 low = m_low; | |
| 82 if (low >= m_hi) { | |
| 83 value = default(T); | |
| 84 recycle = (low == m_size); | |
| 85 return false; | |
| 86 } | |
| 87 } while(low != Interlocked.CompareExchange(ref m_low, low + 1, low)); | |
| 88 | |
| 89 recycle = (low == m_size - 1); | |
| 90 value = m_data[low]; | |
| 91 | |
| 92 return true; | |
| 93 } | |
| 94 | |
| 120 | 95 public bool TryEnqueueBatch(T[] batch, int offset, int length, out int enqueued, out bool extend) { |
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96 //int alloc; |
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97 //int allocSize; |
| 120 | 98 |
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99 var alloc = Interlocked.Add(ref m_alloc, length) - length; |
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100 if (alloc > m_size) { |
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101 // the chunk is full and someone already |
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102 // creating the new one |
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103 enqueued = 0; // nothing was added |
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104 extend = false; // the caller shouldn't try to extend the queue |
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105 return false; // nothing was added |
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106 } |
| 120 | 107 |
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108 enqueued = Math.Min(m_size - alloc, length); |
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109 extend = length > enqueued; |
| 120 | 110 |
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111 if (enqueued == 0) |
| 120 | 112 return false; |
| 113 | |
| 114 | |
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115 Array.Copy(batch, offset, m_data, alloc, enqueued); |
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116 |
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117 while (alloc != Interlocked.CompareExchange(ref m_hi, alloc + enqueued, alloc)) { |
| 120 | 118 // spin wait for commit |
| 119 } | |
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120 |
| 120 | 121 return true; |
| 122 } | |
| 123 | |
| 121 | 124 public bool TryDequeueBatch(T[] buffer, int offset, int length,out int dequeued, out bool recycle) { |
| 125 int low, hi, batchSize; | |
| 126 | |
| 127 do { | |
| 128 low = m_low; | |
| 129 hi = m_hi; | |
| 130 if (low >= hi) { | |
| 131 dequeued = 0; | |
| 132 recycle = (low == m_size); // recycling could be restarted and we need to signal again | |
| 133 return false; | |
| 134 } | |
| 135 batchSize = Math.Min(hi - low, length); | |
| 136 } while(low != Interlocked.CompareExchange(ref m_low, low + batchSize, low)); | |
| 137 | |
| 138 recycle = (low == m_size - batchSize); | |
| 139 dequeued = batchSize; | |
| 140 | |
| 141 Array.Copy(m_data, low, buffer, offset, batchSize); | |
| 142 | |
| 143 return true; | |
| 144 } | |
| 145 | |
| 119 | 146 public T GetAt(int pos) { |
| 147 return m_data[pos]; | |
| 148 } | |
| 149 } | |
| 150 | |
| 151 public const int DEFAULT_CHUNK_SIZE = 32; | |
| 121 | 152 public const int MAX_CHUNK_SIZE = 262144; |
| 119 | 153 |
| 154 Chunk m_first; | |
| 155 Chunk m_last; | |
| 156 | |
| 121 | 157 /// <summary> |
| 158 /// Adds the specified value to the queue. | |
| 159 /// </summary> | |
| 160 /// <param name="value">Tha value which will be added to the queue.</param> | |
| 119 | 161 public void Enqueue(T value) { |
| 162 var last = m_last; | |
| 163 // spin wait to the new chunk | |
| 164 bool extend = true; | |
| 121 | 165 while (last == null || !last.TryEnqueue(value, out extend)) { |
| 119 | 166 // try to extend queue |
| 167 if (extend || last == null) { | |
| 125 | 168 var chunk = new Chunk(DEFAULT_CHUNK_SIZE, value); |
| 119 | 169 if (EnqueueChunk(last, chunk)) |
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170 break; // success! exit! |
| 119 | 171 last = m_last; |
| 172 } else { | |
| 121 | 173 while (last == m_last) { |
| 119 | 174 Thread.MemoryBarrier(); |
| 175 } | |
| 121 | 176 last = m_last; |
| 119 | 177 } |
| 178 } | |
| 179 } | |
| 180 | |
| 121 | 181 /// <summary> |
| 182 /// Adds the specified data to the queue. | |
| 183 /// </summary> | |
| 184 /// <param name="data">The buffer which contains the data to be enqueued.</param> | |
| 185 /// <param name="offset">The offset of the data in the buffer.</param> | |
| 186 /// <param name="length">The size of the data to read from the buffer.</param> | |
| 187 public void EnqueueRange(T[] data, int offset, int length) { | |
| 188 if (data == null) | |
| 189 throw new ArgumentNullException("data"); | |
| 190 if (offset < 0) | |
| 191 throw new ArgumentOutOfRangeException("offset"); | |
| 192 if (length < 1 || offset + length > data.Length) | |
| 193 throw new ArgumentOutOfRangeException("length"); | |
| 194 | |
| 195 var last = m_last; | |
| 196 | |
| 197 bool extend; | |
| 198 int enqueued; | |
| 199 | |
| 200 while (length > 0) { | |
| 201 extend = true; | |
| 202 if (last != null && last.TryEnqueueBatch(data, offset, length, out enqueued, out extend)) { | |
| 203 length -= enqueued; | |
| 204 offset += enqueued; | |
| 205 } | |
| 206 | |
| 207 if (extend) { | |
| 208 // there was no enough space in the chunk | |
| 209 // or there was no chunks in the queue | |
| 210 | |
| 211 while (length > 0) { | |
| 212 | |
| 213 var size = Math.Min(length, MAX_CHUNK_SIZE); | |
| 214 | |
| 215 var chunk = new Chunk( | |
| 125 | 216 Math.Max(size, DEFAULT_CHUNK_SIZE), |
| 121 | 217 data, |
| 218 offset, | |
| 219 size, | |
| 220 length // length >= size | |
| 221 ); | |
| 222 | |
| 223 if (!EnqueueChunk(last, chunk)) { | |
| 224 // looks like the queue has been updated then proceed from the beginning | |
| 225 last = m_last; | |
| 226 break; | |
| 227 } | |
| 228 | |
| 229 // we have successfully added the new chunk | |
| 230 last = chunk; | |
| 231 length -= size; | |
| 232 offset += size; | |
| 233 } | |
| 234 } else { | |
| 235 // we don't need to extend the queue, if we successfully enqueued data | |
| 236 if (length == 0) | |
| 237 break; | |
| 238 | |
| 239 // if we need to wait while someone is extending the queue | |
| 240 // spinwait | |
| 241 while (last == m_last) { | |
| 242 Thread.MemoryBarrier(); | |
| 243 } | |
| 244 | |
| 245 last = m_last; | |
| 246 } | |
| 247 } | |
| 248 } | |
| 249 | |
| 250 /// <summary> | |
| 251 /// Tries to retrieve the first element from the queue. | |
| 252 /// </summary> | |
| 253 /// <returns><c>true</c>, if element is dequeued, <c>false</c> otherwise.</returns> | |
| 254 /// <param name="value">The value of the dequeued element.</param> | |
| 119 | 255 public bool TryDequeue(out T value) { |
| 256 var chunk = m_first; | |
| 257 bool recycle; | |
| 258 while (chunk != null) { | |
| 259 | |
| 260 var result = chunk.TryDequeue(out value, out recycle); | |
| 261 | |
| 262 if (recycle) // this chunk is waste | |
| 263 RecycleFirstChunk(chunk); | |
| 264 else | |
| 265 return result; // this chunk is usable and returned actual result | |
| 266 | |
| 267 if (result) // this chunk is waste but the true result is always actual | |
| 268 return true; | |
| 269 | |
| 270 // try again | |
| 271 chunk = m_first; | |
| 272 } | |
| 273 | |
| 274 // the queue is empty | |
| 275 value = default(T); | |
| 276 return false; | |
| 277 } | |
| 278 | |
| 121 | 279 /// <summary> |
| 280 /// Tries to dequeue the specified amount of data from the queue. | |
| 281 /// </summary> | |
| 282 /// <returns><c>true</c>, if data was deuqueued, <c>false</c> otherwise.</returns> | |
| 283 /// <param name="buffer">The buffer to which the data will be written.</param> | |
| 284 /// <param name="offset">The offset in the buffer at which the data will be written.</param> | |
| 285 /// <param name="length">The maximum amount of data to be retrieved.</param> | |
| 286 /// <param name="dequeued">The actual amout of the retrieved data.</param> | |
| 287 public bool TryDequeueRange(T[] buffer, int offset, int length, out int dequeued) { | |
| 288 if (buffer == null) | |
| 289 throw new ArgumentNullException("buffer"); | |
| 290 if (offset < 0) | |
| 291 throw new ArgumentOutOfRangeException("offset"); | |
| 292 if (length < 1 || offset + length > buffer.Length) | |
| 293 throw new ArgumentOutOfRangeException("length"); | |
| 294 | |
| 295 var chunk = m_first; | |
| 296 bool recycle; | |
| 297 dequeued = 0; | |
| 298 while (chunk != null) { | |
| 299 | |
| 300 int actual; | |
| 301 if (chunk.TryDequeueBatch(buffer, offset, length, out actual, out recycle)) { | |
| 302 offset += actual; | |
| 303 length -= actual; | |
| 304 dequeued += actual; | |
| 305 } | |
| 306 | |
| 307 if (recycle) // this chunk is waste | |
| 308 RecycleFirstChunk(chunk); | |
| 309 else if (actual == 0) | |
| 310 break; // the chunk is usable, but doesn't contain any data (it's the last chunk in the queue) | |
| 311 | |
| 312 if (length == 0) | |
| 313 return true; | |
| 314 | |
| 315 // we still may dequeue something | |
| 316 // try again | |
| 317 chunk = m_first; | |
| 318 } | |
| 319 | |
| 320 return dequeued != 0; | |
| 321 } | |
| 322 | |
| 323 /// <summary> | |
| 324 /// Tries to dequeue all remaining data in the first chunk. | |
| 325 /// </summary> | |
| 326 /// <returns><c>true</c>, if data was dequeued, <c>false</c> otherwise.</returns> | |
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327 /// <param name="buffer">The buffer to which the data will be written.</param> |
| 121 | 328 /// <param name="offset">The offset in the buffer at which the data will be written.</param> |
| 329 /// <param name="length">Tha maximum amount of the data to be dequeued.</param> | |
| 330 /// <param name="dequeued">The actual amount of the dequeued data.</param> | |
| 331 public bool TryDequeueChunk(T[] buffer, int offset, int length, out int dequeued) { | |
| 332 if (buffer == null) | |
| 333 throw new ArgumentNullException("buffer"); | |
| 334 if (offset < 0) | |
| 335 throw new ArgumentOutOfRangeException("offset"); | |
| 336 if (length < 1 || offset + length > buffer.Length) | |
| 337 throw new ArgumentOutOfRangeException("length"); | |
| 338 | |
| 339 var chunk = m_first; | |
| 340 bool recycle; | |
| 341 dequeued = 0; | |
| 342 | |
| 343 while (chunk != null) { | |
| 344 | |
| 345 int actual; | |
| 346 if (chunk.TryDequeueBatch(buffer, offset, length, out actual, out recycle)) { | |
| 347 dequeued = actual; | |
| 348 } | |
| 349 | |
| 350 if (recycle) // this chunk is waste | |
| 351 RecycleFirstChunk(chunk); | |
| 352 | |
| 353 // if we have dequeued any data, then return | |
| 354 if (dequeued != 0) | |
| 355 return true; | |
| 356 | |
| 357 // we still may dequeue something | |
| 358 // try again | |
| 359 chunk = m_first; | |
| 360 } | |
| 361 | |
| 362 return false; | |
| 363 } | |
| 364 | |
| 119 | 365 bool EnqueueChunk(Chunk last, Chunk chunk) { |
| 366 if (Interlocked.CompareExchange(ref m_last, chunk, last) != last) | |
| 367 return false; | |
| 368 | |
| 369 if (last != null) | |
| 370 last.next = chunk; | |
| 124 | 371 else { |
| 119 | 372 m_first = chunk; |
| 124 | 373 } |
| 119 | 374 return true; |
| 375 } | |
| 376 | |
| 377 void RecycleFirstChunk(Chunk first) { | |
| 378 var next = first.next; | |
| 379 | |
| 124 | 380 if (first != Interlocked.CompareExchange(ref m_first, next, first)) |
| 381 return; | |
| 382 | |
| 119 | 383 if (next == null) { |
| 124 | 384 |
| 119 | 385 if (first != Interlocked.CompareExchange(ref m_last, null, first)) { |
| 124 | 386 /*while (first.next == null) |
| 387 Thread.MemoryBarrier();*/ | |
| 388 | |
| 119 | 389 // race |
| 124 | 390 // someone already updated the tail, restore the pointer to the queue head |
| 391 m_first = first; | |
| 119 | 392 } |
| 393 // the tail is updated | |
| 394 } | |
| 395 | |
| 396 // we need to update the head | |
| 124 | 397 //Interlocked.CompareExchange(ref m_first, next, first); |
| 119 | 398 // if the head is already updated then give up |
| 124 | 399 //return; |
| 119 | 400 |
| 401 } | |
| 402 | |
| 123 | 403 public void Clear() { |
| 404 // start the new queue | |
| 125 | 405 var chunk = new Chunk(DEFAULT_CHUNK_SIZE); |
| 124 | 406 |
| 407 do { | |
| 408 Thread.MemoryBarrier(); | |
| 409 var first = m_first; | |
| 410 var last = m_last; | |
| 411 | |
| 412 if (last == null) // nothing to clear | |
| 413 return; | |
| 123 | 414 |
| 124 | 415 if (first == null || (first.next == null && first != last)) // inconcistency |
| 416 continue; | |
| 417 | |
| 418 // here we will create inconsistency which will force others to spin | |
| 419 // and prevent from fetching. chunk.next = null | |
| 420 if (first != Interlocked.CompareExchange(ref m_first, chunk, first)) | |
| 421 continue;// inconsistent | |
| 422 | |
| 423 m_last = chunk; | |
| 424 | |
| 425 return; | |
| 426 | |
| 427 } while(true); | |
| 123 | 428 } |
| 429 | |
| 430 public T[] Drain() { | |
| 431 // start the new queue | |
| 125 | 432 var chunk = new Chunk(DEFAULT_CHUNK_SIZE); |
| 123 | 433 |
| 434 do { | |
| 124 | 435 Thread.MemoryBarrier(); |
| 436 var first = m_first; | |
| 437 var last = m_last; | |
| 438 | |
| 439 if (last == null) | |
| 440 return new T[0]; | |
| 441 | |
| 442 if (first == null || (first.next == null && first != last)) | |
| 443 continue; | |
| 123 | 444 |
| 124 | 445 // here we will create inconsistency which will force others to spin |
| 446 // and prevent from fetching. chunk.next = null | |
| 447 if (first != Interlocked.CompareExchange(ref m_first, chunk, first)) | |
| 448 continue;// inconsistent | |
| 123 | 449 |
| 124 | 450 last = Interlocked.Exchange(ref m_last, chunk); |
| 451 | |
| 452 return ReadChunks(first, last); | |
| 453 | |
| 454 } while(true); | |
| 123 | 455 } |
| 456 | |
| 124 | 457 T[] ReadChunks(Chunk chunk, object last) { |
| 123 | 458 var result = new List<T>(); |
| 125 | 459 var buffer = new T[DEFAULT_CHUNK_SIZE]; |
| 123 | 460 int actual; |
| 461 bool recycle; | |
| 462 while (chunk != null) { | |
| 124 | 463 // ensure all write operations on the chunk are complete |
| 464 chunk.Commit(); | |
| 465 | |
| 123 | 466 // we need to read the chunk using this way |
| 467 // since some client still may completing the dequeue | |
| 468 // operation, such clients most likely won't get results | |
| 469 while (chunk.TryDequeueBatch(buffer, 0, buffer.Length, out actual, out recycle)) | |
| 470 result.AddRange(new ArraySegmentCollection(buffer, 0, actual)); | |
| 471 | |
| 124 | 472 if (chunk == last) { |
| 473 chunk = null; | |
| 474 } else { | |
| 475 while (chunk.next == null) | |
| 476 Thread.MemoryBarrier(); | |
| 477 chunk = chunk.next; | |
| 478 } | |
| 123 | 479 } |
| 480 | |
| 481 return result.ToArray(); | |
| 482 } | |
| 483 | |
| 484 struct ArraySegmentCollection : ICollection<T> { | |
| 485 readonly T[] m_data; | |
| 486 readonly int m_offset; | |
| 487 readonly int m_length; | |
| 488 | |
| 489 public ArraySegmentCollection(T[] data, int offset, int length) { | |
| 490 m_data = data; | |
| 491 m_offset = offset; | |
| 492 m_length = length; | |
| 493 } | |
| 494 | |
| 495 #region ICollection implementation | |
| 496 | |
| 497 public void Add(T item) { | |
| 498 throw new InvalidOperationException(); | |
| 499 } | |
| 500 | |
| 501 public void Clear() { | |
| 502 throw new InvalidOperationException(); | |
| 503 } | |
| 504 | |
| 505 public bool Contains(T item) { | |
| 506 return false; | |
| 507 } | |
| 508 | |
| 509 public void CopyTo(T[] array, int arrayIndex) { | |
| 510 Array.Copy(m_data,m_offset,array,arrayIndex, m_length); | |
| 511 } | |
| 512 | |
| 513 public bool Remove(T item) { | |
| 514 throw new NotImplementedException(); | |
| 515 } | |
| 516 | |
| 517 public int Count { | |
| 518 get { | |
| 519 return m_length; | |
| 520 } | |
| 521 } | |
| 522 | |
| 523 public bool IsReadOnly { | |
| 524 get { | |
| 525 return true; | |
| 526 } | |
| 527 } | |
| 528 | |
| 529 #endregion | |
| 530 | |
| 531 #region IEnumerable implementation | |
| 532 | |
| 533 public IEnumerator<T> GetEnumerator() { | |
| 534 for (int i = m_offset; i < m_length + m_offset; i++) | |
| 535 yield return m_data[i]; | |
| 536 } | |
| 537 | |
| 538 #endregion | |
| 539 | |
| 540 #region IEnumerable implementation | |
| 541 | |
| 542 IEnumerator IEnumerable.GetEnumerator() { | |
| 543 return GetEnumerator(); | |
| 544 } | |
| 545 | |
| 546 #endregion | |
| 547 } | |
| 548 | |
| 119 | 549 #region IEnumerable implementation |
| 550 | |
| 551 class Enumerator : IEnumerator<T> { | |
| 552 Chunk m_current; | |
| 553 int m_pos = -1; | |
| 554 | |
| 555 public Enumerator(Chunk fisrt) { | |
| 556 m_current = fisrt; | |
| 557 } | |
| 558 | |
| 559 #region IEnumerator implementation | |
| 560 | |
| 561 public bool MoveNext() { | |
| 562 if (m_current == null) | |
| 563 return false; | |
| 564 | |
| 565 if (m_pos == -1) | |
| 566 m_pos = m_current.Low; | |
| 567 else | |
| 568 m_pos++; | |
| 127 | 569 |
| 119 | 570 if (m_pos == m_current.Hi) { |
| 127 | 571 |
| 572 m_current = m_pos == m_current.Size ? m_current.next : null; | |
| 573 | |
| 119 | 574 m_pos = 0; |
| 127 | 575 |
| 576 if (m_current == null) | |
| 577 return false; | |
| 119 | 578 } |
| 579 | |
| 580 return true; | |
| 581 } | |
| 582 | |
| 583 public void Reset() { | |
| 584 throw new NotSupportedException(); | |
| 585 } | |
| 586 | |
| 587 object IEnumerator.Current { | |
| 588 get { | |
| 589 return Current; | |
| 590 } | |
| 591 } | |
| 592 | |
| 593 #endregion | |
| 594 | |
| 595 #region IDisposable implementation | |
| 596 | |
| 597 public void Dispose() { | |
| 598 } | |
| 599 | |
| 600 #endregion | |
| 601 | |
| 602 #region IEnumerator implementation | |
| 603 | |
| 604 public T Current { | |
| 605 get { | |
| 606 if (m_pos == -1 || m_current == null) | |
| 607 throw new InvalidOperationException(); | |
| 608 return m_current.GetAt(m_pos); | |
| 609 } | |
| 610 } | |
| 611 | |
| 612 #endregion | |
| 613 } | |
| 614 | |
| 615 public IEnumerator<T> GetEnumerator() { | |
| 616 return new Enumerator(m_first); | |
| 617 } | |
| 618 | |
| 619 #endregion | |
| 620 | |
| 621 #region IEnumerable implementation | |
| 622 | |
| 623 IEnumerator IEnumerable.GetEnumerator() { | |
| 624 return GetEnumerator(); | |
| 625 } | |
| 626 | |
| 627 #endregion | |
| 628 } | |
| 629 } |