Mercurial > pub > ImplabNet
annotate Implab/Parallels/AsyncQueue.cs @ 126:f7b2b8bfbb8c v2
minor changes
| author | cin |
|---|---|
| date | Mon, 26 Jan 2015 02:12:01 +0300 |
| parents | f803565868a4 |
| children | d86da8d2d4c3 |
| 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 | |
| 121 | 47 public bool TryEnqueue(T value, out bool extend) { |
| 120 | 48 var alloc = Interlocked.Increment(ref m_alloc) - 1; |
| 119 | 49 |
| 120 | 50 if (alloc >= m_size) { |
| 51 extend = alloc == m_size; | |
| 119 | 52 return false; |
| 53 } | |
| 120 | 54 |
| 55 extend = false; | |
| 119 | 56 m_data[alloc] = value; |
| 57 | |
| 58 while (alloc != Interlocked.CompareExchange(ref m_hi, alloc + 1, alloc)) { | |
| 59 // spin wait for commit | |
| 60 } | |
| 61 return true; | |
| 62 } | |
| 63 | |
| 124 | 64 /// <summary> |
| 65 /// Prevents from allocating new space in the chunk and waits for all write operations to complete | |
| 66 /// </summary> | |
| 67 public void Commit() { | |
| 68 var actual = Math.Min(Interlocked.Exchange(ref m_alloc, m_size + 1), m_size); | |
| 69 | |
| 70 while (m_hi != actual) | |
| 71 Thread.MemoryBarrier(); | |
| 72 } | |
| 73 | |
| 121 | 74 public bool TryDequeue(out T value, out bool recycle) { |
| 119 | 75 int low; |
| 76 do { | |
| 77 low = m_low; | |
| 78 if (low >= m_hi) { | |
| 79 value = default(T); | |
| 80 recycle = (low == m_size); | |
| 81 return false; | |
| 82 } | |
| 83 } while(low != Interlocked.CompareExchange(ref m_low, low + 1, low)); | |
| 84 | |
| 85 recycle = (low == m_size - 1); | |
| 86 value = m_data[low]; | |
| 87 | |
| 88 return true; | |
| 89 } | |
| 90 | |
| 120 | 91 public bool TryEnqueueBatch(T[] batch, int offset, int length, out int enqueued, out bool extend) { |
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92 //int alloc; |
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93 //int allocSize; |
| 120 | 94 |
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95 var alloc = Interlocked.Add(ref m_alloc, length) - length; |
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96 if (alloc > m_size) { |
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97 // the chunk is full and someone already |
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98 // creating the new one |
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99 enqueued = 0; // nothing was added |
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100 extend = false; // the caller shouldn't try to extend the queue |
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101 return false; // nothing was added |
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102 } |
| 120 | 103 |
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104 enqueued = Math.Min(m_size - alloc, length); |
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105 extend = length > enqueued; |
| 120 | 106 |
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107 if (enqueued == 0) |
| 120 | 108 return false; |
| 109 | |
| 110 | |
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111 Array.Copy(batch, offset, m_data, alloc, enqueued); |
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112 |
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113 while (alloc != Interlocked.CompareExchange(ref m_hi, alloc + enqueued, alloc)) { |
| 120 | 114 // spin wait for commit |
| 115 } | |
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116 |
| 120 | 117 return true; |
| 118 } | |
| 119 | |
| 121 | 120 public bool TryDequeueBatch(T[] buffer, int offset, int length,out int dequeued, out bool recycle) { |
| 121 int low, hi, batchSize; | |
| 122 | |
| 123 do { | |
| 124 low = m_low; | |
| 125 hi = m_hi; | |
| 126 if (low >= hi) { | |
| 127 dequeued = 0; | |
| 128 recycle = (low == m_size); // recycling could be restarted and we need to signal again | |
| 129 return false; | |
| 130 } | |
| 131 batchSize = Math.Min(hi - low, length); | |
| 132 } while(low != Interlocked.CompareExchange(ref m_low, low + batchSize, low)); | |
| 133 | |
| 134 recycle = (low == m_size - batchSize); | |
| 135 dequeued = batchSize; | |
| 136 | |
| 137 Array.Copy(m_data, low, buffer, offset, batchSize); | |
| 138 | |
| 139 return true; | |
| 140 } | |
| 141 | |
| 119 | 142 public T GetAt(int pos) { |
| 143 return m_data[pos]; | |
| 144 } | |
| 145 } | |
| 146 | |
| 147 public const int DEFAULT_CHUNK_SIZE = 32; | |
| 121 | 148 public const int MAX_CHUNK_SIZE = 262144; |
| 119 | 149 |
| 150 Chunk m_first; | |
| 151 Chunk m_last; | |
| 152 | |
| 121 | 153 /// <summary> |
| 154 /// Adds the specified value to the queue. | |
| 155 /// </summary> | |
| 156 /// <param name="value">Tha value which will be added to the queue.</param> | |
| 119 | 157 public void Enqueue(T value) { |
| 158 var last = m_last; | |
| 159 // spin wait to the new chunk | |
| 160 bool extend = true; | |
| 121 | 161 while (last == null || !last.TryEnqueue(value, out extend)) { |
| 119 | 162 // try to extend queue |
| 163 if (extend || last == null) { | |
| 125 | 164 var chunk = new Chunk(DEFAULT_CHUNK_SIZE, value); |
| 119 | 165 if (EnqueueChunk(last, chunk)) |
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166 break; // success! exit! |
| 119 | 167 last = m_last; |
| 168 } else { | |
| 121 | 169 while (last == m_last) { |
| 119 | 170 Thread.MemoryBarrier(); |
| 171 } | |
| 121 | 172 last = m_last; |
| 119 | 173 } |
| 174 } | |
| 175 } | |
| 176 | |
| 121 | 177 /// <summary> |
| 178 /// Adds the specified data to the queue. | |
| 179 /// </summary> | |
| 180 /// <param name="data">The buffer which contains the data to be enqueued.</param> | |
| 181 /// <param name="offset">The offset of the data in the buffer.</param> | |
| 182 /// <param name="length">The size of the data to read from the buffer.</param> | |
| 183 public void EnqueueRange(T[] data, int offset, int length) { | |
| 184 if (data == null) | |
| 185 throw new ArgumentNullException("data"); | |
| 186 if (offset < 0) | |
| 187 throw new ArgumentOutOfRangeException("offset"); | |
| 188 if (length < 1 || offset + length > data.Length) | |
| 189 throw new ArgumentOutOfRangeException("length"); | |
| 190 | |
| 191 var last = m_last; | |
| 192 | |
| 193 bool extend; | |
| 194 int enqueued; | |
| 195 | |
| 196 while (length > 0) { | |
| 197 extend = true; | |
| 198 if (last != null && last.TryEnqueueBatch(data, offset, length, out enqueued, out extend)) { | |
| 199 length -= enqueued; | |
| 200 offset += enqueued; | |
| 201 } | |
| 202 | |
| 203 if (extend) { | |
| 204 // there was no enough space in the chunk | |
| 205 // or there was no chunks in the queue | |
| 206 | |
| 207 while (length > 0) { | |
| 208 | |
| 209 var size = Math.Min(length, MAX_CHUNK_SIZE); | |
| 210 | |
| 211 var chunk = new Chunk( | |
| 125 | 212 Math.Max(size, DEFAULT_CHUNK_SIZE), |
| 121 | 213 data, |
| 214 offset, | |
| 215 size, | |
| 216 length // length >= size | |
| 217 ); | |
| 218 | |
| 219 if (!EnqueueChunk(last, chunk)) { | |
| 220 // looks like the queue has been updated then proceed from the beginning | |
| 221 last = m_last; | |
| 222 break; | |
| 223 } | |
| 224 | |
| 225 // we have successfully added the new chunk | |
| 226 last = chunk; | |
| 227 length -= size; | |
| 228 offset += size; | |
| 229 } | |
| 230 } else { | |
| 231 // we don't need to extend the queue, if we successfully enqueued data | |
| 232 if (length == 0) | |
| 233 break; | |
| 234 | |
| 235 // if we need to wait while someone is extending the queue | |
| 236 // spinwait | |
| 237 while (last == m_last) { | |
| 238 Thread.MemoryBarrier(); | |
| 239 } | |
| 240 | |
| 241 last = m_last; | |
| 242 } | |
| 243 } | |
| 244 } | |
| 245 | |
| 246 /// <summary> | |
| 247 /// Tries to retrieve the first element from the queue. | |
| 248 /// </summary> | |
| 249 /// <returns><c>true</c>, if element is dequeued, <c>false</c> otherwise.</returns> | |
| 250 /// <param name="value">The value of the dequeued element.</param> | |
| 119 | 251 public bool TryDequeue(out T value) { |
| 252 var chunk = m_first; | |
| 253 bool recycle; | |
| 254 while (chunk != null) { | |
| 255 | |
| 256 var result = chunk.TryDequeue(out value, out recycle); | |
| 257 | |
| 258 if (recycle) // this chunk is waste | |
| 259 RecycleFirstChunk(chunk); | |
| 260 else | |
| 261 return result; // this chunk is usable and returned actual result | |
| 262 | |
| 263 if (result) // this chunk is waste but the true result is always actual | |
| 264 return true; | |
| 265 | |
| 266 // try again | |
| 267 chunk = m_first; | |
| 268 } | |
| 269 | |
| 270 // the queue is empty | |
| 271 value = default(T); | |
| 272 return false; | |
| 273 } | |
| 274 | |
| 121 | 275 /// <summary> |
| 276 /// Tries to dequeue the specified amount of data from the queue. | |
| 277 /// </summary> | |
| 278 /// <returns><c>true</c>, if data was deuqueued, <c>false</c> otherwise.</returns> | |
| 279 /// <param name="buffer">The buffer to which the data will be written.</param> | |
| 280 /// <param name="offset">The offset in the buffer at which the data will be written.</param> | |
| 281 /// <param name="length">The maximum amount of data to be retrieved.</param> | |
| 282 /// <param name="dequeued">The actual amout of the retrieved data.</param> | |
| 283 public bool TryDequeueRange(T[] buffer, int offset, int length, out int dequeued) { | |
| 284 if (buffer == null) | |
| 285 throw new ArgumentNullException("buffer"); | |
| 286 if (offset < 0) | |
| 287 throw new ArgumentOutOfRangeException("offset"); | |
| 288 if (length < 1 || offset + length > buffer.Length) | |
| 289 throw new ArgumentOutOfRangeException("length"); | |
| 290 | |
| 291 var chunk = m_first; | |
| 292 bool recycle; | |
| 293 dequeued = 0; | |
| 294 while (chunk != null) { | |
| 295 | |
| 296 int actual; | |
| 297 if (chunk.TryDequeueBatch(buffer, offset, length, out actual, out recycle)) { | |
| 298 offset += actual; | |
| 299 length -= actual; | |
| 300 dequeued += actual; | |
| 301 } | |
| 302 | |
| 303 if (recycle) // this chunk is waste | |
| 304 RecycleFirstChunk(chunk); | |
| 305 else if (actual == 0) | |
| 306 break; // the chunk is usable, but doesn't contain any data (it's the last chunk in the queue) | |
| 307 | |
| 308 if (length == 0) | |
| 309 return true; | |
| 310 | |
| 311 // we still may dequeue something | |
| 312 // try again | |
| 313 chunk = m_first; | |
| 314 } | |
| 315 | |
| 316 return dequeued != 0; | |
| 317 } | |
| 318 | |
| 319 /// <summary> | |
| 320 /// Tries to dequeue all remaining data in the first chunk. | |
| 321 /// </summary> | |
| 322 /// <returns><c>true</c>, if data was dequeued, <c>false</c> otherwise.</returns> | |
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323 /// <param name="buffer">The buffer to which the data will be written.</param> |
| 121 | 324 /// <param name="offset">The offset in the buffer at which the data will be written.</param> |
| 325 /// <param name="length">Tha maximum amount of the data to be dequeued.</param> | |
| 326 /// <param name="dequeued">The actual amount of the dequeued data.</param> | |
| 327 public bool TryDequeueChunk(T[] buffer, int offset, int length, out int dequeued) { | |
| 328 if (buffer == null) | |
| 329 throw new ArgumentNullException("buffer"); | |
| 330 if (offset < 0) | |
| 331 throw new ArgumentOutOfRangeException("offset"); | |
| 332 if (length < 1 || offset + length > buffer.Length) | |
| 333 throw new ArgumentOutOfRangeException("length"); | |
| 334 | |
| 335 var chunk = m_first; | |
| 336 bool recycle; | |
| 337 dequeued = 0; | |
| 338 | |
| 339 while (chunk != null) { | |
| 340 | |
| 341 int actual; | |
| 342 if (chunk.TryDequeueBatch(buffer, offset, length, out actual, out recycle)) { | |
| 343 dequeued = actual; | |
| 344 } | |
| 345 | |
| 346 if (recycle) // this chunk is waste | |
| 347 RecycleFirstChunk(chunk); | |
| 348 | |
| 349 // if we have dequeued any data, then return | |
| 350 if (dequeued != 0) | |
| 351 return true; | |
| 352 | |
| 353 // we still may dequeue something | |
| 354 // try again | |
| 355 chunk = m_first; | |
| 356 } | |
| 357 | |
| 358 return false; | |
| 359 } | |
| 360 | |
| 119 | 361 bool EnqueueChunk(Chunk last, Chunk chunk) { |
| 362 if (Interlocked.CompareExchange(ref m_last, chunk, last) != last) | |
| 363 return false; | |
| 364 | |
| 365 if (last != null) | |
| 366 last.next = chunk; | |
| 124 | 367 else { |
| 119 | 368 m_first = chunk; |
| 124 | 369 } |
| 119 | 370 return true; |
| 371 } | |
| 372 | |
| 373 void RecycleFirstChunk(Chunk first) { | |
| 374 var next = first.next; | |
| 375 | |
| 124 | 376 if (first != Interlocked.CompareExchange(ref m_first, next, first)) |
| 377 return; | |
| 378 | |
| 119 | 379 if (next == null) { |
| 124 | 380 |
| 119 | 381 if (first != Interlocked.CompareExchange(ref m_last, null, first)) { |
| 124 | 382 /*while (first.next == null) |
| 383 Thread.MemoryBarrier();*/ | |
| 384 | |
| 119 | 385 // race |
| 124 | 386 // someone already updated the tail, restore the pointer to the queue head |
| 387 m_first = first; | |
| 119 | 388 } |
| 389 // the tail is updated | |
| 390 } | |
| 391 | |
| 392 // we need to update the head | |
| 124 | 393 //Interlocked.CompareExchange(ref m_first, next, first); |
| 119 | 394 // if the head is already updated then give up |
| 124 | 395 //return; |
| 119 | 396 |
| 397 } | |
| 398 | |
| 123 | 399 public void Clear() { |
| 400 // start the new queue | |
| 125 | 401 var chunk = new Chunk(DEFAULT_CHUNK_SIZE); |
| 124 | 402 |
| 403 do { | |
| 404 Thread.MemoryBarrier(); | |
| 405 var first = m_first; | |
| 406 var last = m_last; | |
| 407 | |
| 408 if (last == null) // nothing to clear | |
| 409 return; | |
| 123 | 410 |
| 124 | 411 if (first == null || (first.next == null && first != last)) // inconcistency |
| 412 continue; | |
| 413 | |
| 414 // here we will create inconsistency which will force others to spin | |
| 415 // and prevent from fetching. chunk.next = null | |
| 416 if (first != Interlocked.CompareExchange(ref m_first, chunk, first)) | |
| 417 continue;// inconsistent | |
| 418 | |
| 419 m_last = chunk; | |
| 420 | |
| 421 return; | |
| 422 | |
| 423 } while(true); | |
| 123 | 424 } |
| 425 | |
| 426 public T[] Drain() { | |
| 427 // start the new queue | |
| 125 | 428 var chunk = new Chunk(DEFAULT_CHUNK_SIZE); |
| 123 | 429 |
| 430 do { | |
| 124 | 431 Thread.MemoryBarrier(); |
| 432 var first = m_first; | |
| 433 var last = m_last; | |
| 434 | |
| 435 if (last == null) | |
| 436 return new T[0]; | |
| 437 | |
| 438 if (first == null || (first.next == null && first != last)) | |
| 439 continue; | |
| 123 | 440 |
| 124 | 441 // here we will create inconsistency which will force others to spin |
| 442 // and prevent from fetching. chunk.next = null | |
| 443 if (first != Interlocked.CompareExchange(ref m_first, chunk, first)) | |
| 444 continue;// inconsistent | |
| 123 | 445 |
| 124 | 446 last = Interlocked.Exchange(ref m_last, chunk); |
| 447 | |
| 448 return ReadChunks(first, last); | |
| 449 | |
| 450 } while(true); | |
| 123 | 451 } |
| 452 | |
| 124 | 453 T[] ReadChunks(Chunk chunk, object last) { |
| 123 | 454 var result = new List<T>(); |
| 125 | 455 var buffer = new T[DEFAULT_CHUNK_SIZE]; |
| 123 | 456 int actual; |
| 457 bool recycle; | |
| 458 while (chunk != null) { | |
| 124 | 459 // ensure all write operations on the chunk are complete |
| 460 chunk.Commit(); | |
| 461 | |
| 123 | 462 // we need to read the chunk using this way |
| 463 // since some client still may completing the dequeue | |
| 464 // operation, such clients most likely won't get results | |
| 465 while (chunk.TryDequeueBatch(buffer, 0, buffer.Length, out actual, out recycle)) | |
| 466 result.AddRange(new ArraySegmentCollection(buffer, 0, actual)); | |
| 467 | |
| 124 | 468 if (chunk == last) { |
| 469 chunk = null; | |
| 470 } else { | |
| 471 while (chunk.next == null) | |
| 472 Thread.MemoryBarrier(); | |
| 473 chunk = chunk.next; | |
| 474 } | |
| 123 | 475 } |
| 476 | |
| 477 return result.ToArray(); | |
| 478 } | |
| 479 | |
| 480 struct ArraySegmentCollection : ICollection<T> { | |
| 481 readonly T[] m_data; | |
| 482 readonly int m_offset; | |
| 483 readonly int m_length; | |
| 484 | |
| 485 public ArraySegmentCollection(T[] data, int offset, int length) { | |
| 486 m_data = data; | |
| 487 m_offset = offset; | |
| 488 m_length = length; | |
| 489 } | |
| 490 | |
| 491 #region ICollection implementation | |
| 492 | |
| 493 public void Add(T item) { | |
| 494 throw new InvalidOperationException(); | |
| 495 } | |
| 496 | |
| 497 public void Clear() { | |
| 498 throw new InvalidOperationException(); | |
| 499 } | |
| 500 | |
| 501 public bool Contains(T item) { | |
| 502 return false; | |
| 503 } | |
| 504 | |
| 505 public void CopyTo(T[] array, int arrayIndex) { | |
| 506 Array.Copy(m_data,m_offset,array,arrayIndex, m_length); | |
| 507 } | |
| 508 | |
| 509 public bool Remove(T item) { | |
| 510 throw new NotImplementedException(); | |
| 511 } | |
| 512 | |
| 513 public int Count { | |
| 514 get { | |
| 515 return m_length; | |
| 516 } | |
| 517 } | |
| 518 | |
| 519 public bool IsReadOnly { | |
| 520 get { | |
| 521 return true; | |
| 522 } | |
| 523 } | |
| 524 | |
| 525 #endregion | |
| 526 | |
| 527 #region IEnumerable implementation | |
| 528 | |
| 529 public IEnumerator<T> GetEnumerator() { | |
| 530 for (int i = m_offset; i < m_length + m_offset; i++) | |
| 531 yield return m_data[i]; | |
| 532 } | |
| 533 | |
| 534 #endregion | |
| 535 | |
| 536 #region IEnumerable implementation | |
| 537 | |
| 538 IEnumerator IEnumerable.GetEnumerator() { | |
| 539 return GetEnumerator(); | |
| 540 } | |
| 541 | |
| 542 #endregion | |
| 543 } | |
| 544 | |
| 119 | 545 #region IEnumerable implementation |
| 546 | |
| 547 class Enumerator : IEnumerator<T> { | |
| 548 Chunk m_current; | |
| 549 int m_pos = -1; | |
| 550 | |
| 551 public Enumerator(Chunk fisrt) { | |
| 552 m_current = fisrt; | |
| 553 } | |
| 554 | |
| 555 #region IEnumerator implementation | |
| 556 | |
| 557 public bool MoveNext() { | |
| 558 if (m_current == null) | |
| 559 return false; | |
| 560 | |
| 561 if (m_pos == -1) | |
| 562 m_pos = m_current.Low; | |
| 563 else | |
| 564 m_pos++; | |
| 565 if (m_pos == m_current.Hi) { | |
| 566 m_pos = 0; | |
| 567 m_current = m_current.next; | |
| 568 } | |
| 569 | |
| 570 return true; | |
| 571 } | |
| 572 | |
| 573 public void Reset() { | |
| 574 throw new NotSupportedException(); | |
| 575 } | |
| 576 | |
| 577 object IEnumerator.Current { | |
| 578 get { | |
| 579 return Current; | |
| 580 } | |
| 581 } | |
| 582 | |
| 583 #endregion | |
| 584 | |
| 585 #region IDisposable implementation | |
| 586 | |
| 587 public void Dispose() { | |
| 588 } | |
| 589 | |
| 590 #endregion | |
| 591 | |
| 592 #region IEnumerator implementation | |
| 593 | |
| 594 public T Current { | |
| 595 get { | |
| 596 if (m_pos == -1 || m_current == null) | |
| 597 throw new InvalidOperationException(); | |
| 598 return m_current.GetAt(m_pos); | |
| 599 } | |
| 600 } | |
| 601 | |
| 602 #endregion | |
| 603 } | |
| 604 | |
| 605 public IEnumerator<T> GetEnumerator() { | |
| 606 return new Enumerator(m_first); | |
| 607 } | |
| 608 | |
| 609 #endregion | |
| 610 | |
| 611 #region IEnumerable implementation | |
| 612 | |
| 613 IEnumerator IEnumerable.GetEnumerator() { | |
| 614 return GetEnumerator(); | |
| 615 } | |
| 616 | |
| 617 #endregion | |
| 618 } | |
| 619 } |