mcs/class/corlib/System.Threading.Tasks/Task.cs

   1 //
   2 // Task.cs
   3 //
   4 // Authors:
   5 //    Marek Safar  <marek.safar@gmail.com>
   6 //    Jérémie Laval <jeremie dot laval at xamarin dot com>
   7 //
   8 // Copyright (c) 2008 Jérémie "Garuma" Laval
   9 // Copyright 2011-2013 Xamarin Inc (http://www.xamarin.com).
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining a copy
  12 // of this software and associated documentation files (the "Software"), to deal
  13 // in the Software without restriction, including without limitation the rights
  14 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  15 // copies of the Software, and to permit persons to whom the Software is
  16 // furnished to do so, subject to the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be included in
  19 // all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  24 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  25 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  26 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  27 // THE SOFTWARE.
  28 //
  29 //
  30
  31 #if NET_4_0
  32
  33 using System;
  34 using System.Threading;
  35 using System.Collections.Concurrent;
  36 using System.Collections.Generic;
  37 using System.Runtime.CompilerServices;
  38
  39 namespace System.Threading.Tasks
  40 {
  41         [System.Diagnostics.DebuggerDisplay ("Id = {Id}, Status = {Status}")]
  42         [System.Diagnostics.DebuggerTypeProxy (typeof (TaskDebuggerView))]
  43         public class Task : IDisposable, IAsyncResult
  44         {
  45                 // With this attribute each thread has its own value so that it's correct for our Schedule code
  46                 // and for Parent property.
  47                 [System.ThreadStatic]
  48                 static Task current;
  49
  50                 // parent is the outer task in which this task is created
  51                 readonly Task parent;
  52                 // A reference to a Task on which this continuation is attached to
  53                 Task contAncestor;
  54
  55                 static int          id = -1;
  56                 static readonly TaskFactory defaultFactory = new TaskFactory ();
  57
  58                 CountdownEvent childTasks;
  59
  60                 int                 taskId;
  61                 TaskCreationOptions creationOptions;
  62
  63                 internal TaskScheduler       scheduler;
  64
  65                 TaskExceptionSlot exSlot;
  66                 ManualResetEvent wait_handle;
  67
  68                 TaskStatus          status;
  69
  70                 TaskActionInvoker invoker;
  71                 object         state;
  72                 internal AtomicBooleanValue executing;
  73
  74                 TaskCompletionQueue<IContinuation> continuations;
  75
  76                 CancellationToken token;
  77                 CancellationTokenRegistration? cancellationRegistration;
  78
  79                 internal const TaskCreationOptions WorkerTaskNotSupportedOptions = TaskCreationOptions.LongRunning | TaskCreationOptions.PreferFairness;
  80
  81                 const TaskCreationOptions MaxTaskCreationOptions =
  82 #if NET_4_5
  83                         TaskCreationOptions.DenyChildAttach | TaskCreationOptions.HideScheduler |
  84 #endif
  85                         TaskCreationOptions.PreferFairness | TaskCreationOptions.LongRunning | TaskCreationOptions.AttachedToParent;
  86
  87                 public Task (Action action)
  88                         : this (action, TaskCreationOptions.None)
  89                 {
  90
  91                 }
  92
  93                 public Task (Action action, TaskCreationOptions creationOptions)
  94                         : this (action, CancellationToken.None, creationOptions)
  95                 {
  96
  97                 }
  98
  99                 public Task (Action action, CancellationToken cancellationToken)
 100                         : this (action, cancellationToken, TaskCreationOptions.None)
 101                 {
 102
 103                 }
 104
 105                 public Task (Action action, CancellationToken cancellationToken, TaskCreationOptions creationOptions)
 106                         : this (TaskActionInvoker.Create (action), null, cancellationToken, creationOptions, current)
 107                 {
 108                         if (action == null)
 109                                 throw new ArgumentNullException ("action");
 110                         if (creationOptions > MaxTaskCreationOptions || creationOptions < TaskCreationOptions.None)
 111                                 throw new ArgumentOutOfRangeException ("creationOptions");
 112                 }
 113
 114                 public Task (Action<object> action, object state)
 115                         : this (action, state, TaskCreationOptions.None)
 116                 {
 117                 }
 118
 119                 public Task (Action<object> action, object state, TaskCreationOptions creationOptions)
 120                         : this (action, state, CancellationToken.None, creationOptions)
 121                 {
 122                 }
 123
 124                 public Task (Action<object> action, object state, CancellationToken cancellationToken)
 125                         : this (action, state, cancellationToken, TaskCreationOptions.None)
 126                 {
 127                 }
 128
 129                 public Task (Action<object> action, object state, CancellationToken cancellationToken, TaskCreationOptions creationOptions)
 130                         : this (TaskActionInvoker.Create (action), state, cancellationToken, creationOptions, current)
 131                 {
 132                         if (action == null)
 133                                 throw new ArgumentNullException ("action");
 134                         if (creationOptions > MaxTaskCreationOptions || creationOptions < TaskCreationOptions.None)
 135                                 throw new ArgumentOutOfRangeException ("creationOptions");
 136                 }
 137
 138                 internal Task (TaskActionInvoker invoker, object state, CancellationToken cancellationToken,
 139                                TaskCreationOptions creationOptions, Task parent = null, Task contAncestor = null, bool ignoreCancellation = false)
 140                 {
 141                         this.invoker         = invoker;
 142                         this.creationOptions = creationOptions;
 143                         this.state           = state;
 144                         this.taskId          = Interlocked.Increment (ref id);
 145                         this.token           = cancellationToken;
 146                         this.parent          = parent = parent == null ? current : parent;
 147                         this.contAncestor    = contAncestor;
 148                         this.status          = cancellationToken.IsCancellationRequested && !ignoreCancellation ? TaskStatus.Canceled : TaskStatus.Created;
 149
 150                         // Process creationOptions
 151 #if NET_4_5
 152                         if (parent != null && HasFlag (creationOptions, TaskCreationOptions.AttachedToParent)
 153                             && !HasFlag (parent.CreationOptions, TaskCreationOptions.DenyChildAttach))
 154 #else
 155                         if (parent != null && HasFlag (creationOptions, TaskCreationOptions.AttachedToParent))
 156 #endif
 157                                 parent.AddChild ();
 158
 159                         if (token.CanBeCanceled && !ignoreCancellation)
 160                                 cancellationRegistration = token.Register (l => ((Task) l).CancelReal (), this);
 161                 }
 162
 163                 static bool HasFlag (TaskCreationOptions opt, TaskCreationOptions member)
 164                 {
 165                         return (opt & member) == member;
 166                 }
 167
 168                 #region Start
 169                 public void Start ()
 170                 {
 171                         Start (TaskScheduler.Current);
 172                 }
 173
 174                 public void Start (TaskScheduler scheduler)
 175                 {
 176                         if (scheduler == null)
 177                                 throw new ArgumentNullException ("scheduler");
 178
 179                         if (status >= TaskStatus.WaitingToRun)
 180                                 throw new InvalidOperationException ("The Task is not in a valid state to be started.");
 181
 182                         if (IsContinuation)
 183                                 throw new InvalidOperationException ("Start may not be called on a continuation task");
 184
 185                         if (IsPromise)
 186                                 throw new InvalidOperationException ("Start may not be called on a promise-style task");
 187
 188                         SetupScheduler (scheduler);
 189                         Schedule (true);
 190                 }
 191
 192                 internal void SetupScheduler (TaskScheduler scheduler)
 193                 {
 194                         this.scheduler = scheduler;
 195                         Status = TaskStatus.WaitingForActivation;
 196                 }
 197
 198                 public void RunSynchronously ()
 199                 {
 200                         RunSynchronously (TaskScheduler.Current);
 201                 }
 202
 203                 public void RunSynchronously (TaskScheduler scheduler)
 204                 {
 205                         if (scheduler == null)
 206                                 throw new ArgumentNullException ("scheduler");
 207
 208                         if (Status > TaskStatus.WaitingForActivation)
 209                                 throw new InvalidOperationException ("The task is not in a valid state to be started");
 210
 211                         if (IsContinuation)
 212                                 throw new InvalidOperationException ("RunSynchronously may not be called on a continuation task");
 213
 214                         if (IsPromise)
 215                                 throw new InvalidOperationException ("RunSynchronously may not be called on a promise-style task");
 216
 217                         RunSynchronouslyCore (scheduler, true);
 218                 }
 219
 220                 internal void RunSynchronouslyCore (TaskScheduler scheduler, bool throwException)
 221                 {
 222                         SetupScheduler (scheduler);
 223                         Status = TaskStatus.WaitingToRun;
 224
 225                         try {
 226                                 if (scheduler.RunInline (this, false))
 227                                         return;
 228                         } catch (Exception inner) {
 229                                 var ex = new TaskSchedulerException (inner);
 230                                 TrySetException (new AggregateException (ex), false, true);
 231                                 if (throwException)
 232                                         throw ex;
 233
 234                                 return;
 235                         }
 236
 237                         Schedule (throwException);
 238                         WaitCore (Timeout.Infinite, CancellationToken.None, false);
 239                 }
 240                 #endregion
 241
 242                 #region ContinueWith
 243                 public Task ContinueWith (Action<Task> continuationAction)
 244                 {
 245                         return ContinueWith (continuationAction, TaskContinuationOptions.None);
 246                 }
 247
 248                 public Task ContinueWith (Action<Task> continuationAction, TaskContinuationOptions continuationOptions)
 249                 {
 250                         return ContinueWith (continuationAction, CancellationToken.None, continuationOptions, TaskScheduler.Current);
 251                 }
 252
 253                 public Task ContinueWith (Action<Task> continuationAction, CancellationToken cancellationToken)
 254                 {
 255                         return ContinueWith (continuationAction, cancellationToken, TaskContinuationOptions.None, TaskScheduler.Current);
 256                 }
 257
 258                 public Task ContinueWith (Action<Task> continuationAction, TaskScheduler scheduler)
 259                 {
 260                         return ContinueWith (continuationAction, CancellationToken.None, TaskContinuationOptions.None, scheduler);
 261                 }
 262
 263                 public Task ContinueWith (Action<Task> continuationAction, CancellationToken cancellationToken, TaskContinuationOptions continuationOptions, TaskScheduler scheduler)
 264                 {
 265                         if (continuationAction == null)
 266                                 throw new ArgumentNullException ("continuationAction");
 267                         if (scheduler == null)
 268                                 throw new ArgumentNullException ("scheduler");
 269
 270                         return ContinueWith (TaskActionInvoker.Create (continuationAction), cancellationToken, continuationOptions, scheduler);
 271                 }
 272
 273                 internal Task ContinueWith (TaskActionInvoker invoker, CancellationToken cancellationToken, TaskContinuationOptions continuationOptions, TaskScheduler scheduler)
 274                 {
 275                         var lazyCancellation = false;
 276 #if NET_4_5
 277                         lazyCancellation = (continuationOptions & TaskContinuationOptions.LazyCancellation) > 0;
 278 #endif
 279                         var continuation = new Task (invoker, null, cancellationToken, GetCreationOptions (continuationOptions), null, this, lazyCancellation);
 280                         ContinueWithCore (continuation, continuationOptions, scheduler);
 281
 282                         return continuation;
 283                 }
 284
 285                 public Task<TResult> ContinueWith<TResult> (Func<Task, TResult> continuationFunction)
 286                 {
 287                         return ContinueWith<TResult> (continuationFunction, TaskContinuationOptions.None);
 288                 }
 289
 290                 public Task<TResult> ContinueWith<TResult> (Func<Task, TResult> continuationFunction, TaskContinuationOptions continuationOptions)
 291                 {
 292                         return ContinueWith<TResult> (continuationFunction, CancellationToken.None, continuationOptions, TaskScheduler.Current);
 293                 }
 294
 295                 public Task<TResult> ContinueWith<TResult> (Func<Task, TResult> continuationFunction, CancellationToken cancellationToken)
 296                 {
 297                         return ContinueWith<TResult> (continuationFunction, cancellationToken, TaskContinuationOptions.None, TaskScheduler.Current);
 298                 }
 299
 300                 public Task<TResult> ContinueWith<TResult> (Func<Task, TResult> continuationFunction, TaskScheduler scheduler)
 301                 {
 302                         return ContinueWith<TResult> (continuationFunction, CancellationToken.None, TaskContinuationOptions.None, scheduler);
 303                 }
 304
 305                 public Task<TResult> ContinueWith<TResult> (Func<Task, TResult> continuationFunction, CancellationToken cancellationToken,
 306                                                             TaskContinuationOptions continuationOptions, TaskScheduler scheduler)
 307                 {
 308                         if (continuationFunction == null)
 309                                 throw new ArgumentNullException ("continuationFunction");
 310                         if (scheduler == null)
 311                                 throw new ArgumentNullException ("scheduler");
 312
 313                         return ContinueWith<TResult> (TaskActionInvoker.Create (continuationFunction), cancellationToken, continuationOptions, scheduler);
 314                 }
 315
 316                 internal Task<TResult> ContinueWith<TResult> (TaskActionInvoker invoker, CancellationToken cancellationToken, TaskContinuationOptions continuationOptions, TaskScheduler scheduler)
 317                 {
 318                         var lazyCancellation = false;
 319 #if NET_4_5
 320                         lazyCancellation = (continuationOptions & TaskContinuationOptions.LazyCancellation) > 0;
 321 #endif
 322                         var continuation = new Task<TResult> (invoker, null, cancellationToken, GetCreationOptions (continuationOptions), parent, this, lazyCancellation);
 323                         ContinueWithCore (continuation, continuationOptions, scheduler);
 324
 325                         return continuation;
 326                 }
 327
 328                 internal void ContinueWithCore (Task continuation, TaskContinuationOptions options, TaskScheduler scheduler)
 329                 {
 330                         const TaskContinuationOptions wrongRan = TaskContinuationOptions.NotOnRanToCompletion | TaskContinuationOptions.OnlyOnRanToCompletion;
 331                         const TaskContinuationOptions wrongCanceled = TaskContinuationOptions.NotOnCanceled | TaskContinuationOptions.OnlyOnCanceled;
 332                         const TaskContinuationOptions wrongFaulted = TaskContinuationOptions.NotOnFaulted | TaskContinuationOptions.OnlyOnFaulted;
 333
 334                         if (((options & wrongRan) == wrongRan) || ((options & wrongCanceled) == wrongCanceled) || ((options & wrongFaulted) == wrongFaulted))
 335                                 throw new ArgumentException ("continuationOptions", "Some options are mutually exclusive");
 336
 337                         // Already set the scheduler so that user can call Wait and that sort of stuff
 338                         continuation.scheduler = scheduler;
 339                         continuation.Status = TaskStatus.WaitingForActivation;
 340
 341                         ContinueWith (new TaskContinuation (continuation, options));
 342                 }
 343
 344                 internal bool ContinueWith (IContinuation continuation, bool canExecuteInline = true)
 345                 {
 346                         if (IsCompleted) {
 347                                 if (!canExecuteInline)
 348                                         return false;
 349
 350                                 continuation.Execute ();
 351                                 return true;
 352                         }
 353
 354                         continuations.Add (continuation);
 355
 356                         // Retry in case completion was achieved but event adding was too late
 357                         if (IsCompleted && continuations.Remove (continuation)) {
 358                                 if (!canExecuteInline)
 359                                         return false;
 360
 361                                 continuation.Execute ();
 362                         }
 363
 364                         return true;
 365                 }
 366
 367                 internal void RemoveContinuation (IContinuation continuation)
 368                 {
 369                         continuations.Remove (continuation);
 370                 }
 371
 372                 static internal TaskCreationOptions GetCreationOptions (TaskContinuationOptions kind)
 373                 {
 374                         TaskCreationOptions options = TaskCreationOptions.None;
 375                         if ((kind & TaskContinuationOptions.AttachedToParent) > 0)
 376                                 options |= TaskCreationOptions.AttachedToParent;
 377                         if ((kind & TaskContinuationOptions.PreferFairness) > 0)
 378                                 options |= TaskCreationOptions.PreferFairness;
 379                         if ((kind & TaskContinuationOptions.LongRunning) > 0)
 380                                 options |= TaskCreationOptions.LongRunning;
 381
 382                         return options;
 383                 }
 384                 #endregion
 385
 386                 #region Internal and protected thingies
 387                 internal void Schedule (bool throwException)
 388                 {
 389                         Status = TaskStatus.WaitingToRun;
 390                         try {
 391                                 scheduler.QueueTask (this);
 392                         } catch (Exception inner) {
 393                                 var ex = new TaskSchedulerException (inner);
 394                                 TrySetException (new AggregateException (ex), false, true);
 395                                 if (throwException)
 396                                         throw ex;
 397                         }
 398                 }
 399
 400                 void ThreadStart ()
 401                 {
 402                         /* Allow scheduler to break fairness of deque ordering without
 403                          * breaking its semantic (the task can be executed twice but the
 404                          * second time it will return immediately
 405                          */
 406                         if (!executing.TryRelaxedSet ())
 407                                 return;
 408
 409                         // Disable CancellationToken direct cancellation
 410                         if (cancellationRegistration != null) {
 411                                 cancellationRegistration.Value.Dispose ();
 412                                 cancellationRegistration = null;
 413                         }
 414
 415                         // If Task are ran inline on the same thread we might trash these values
 416                         var saveCurrent = current;
 417                         var saveScheduler = TaskScheduler.Current;
 418
 419                         current = this;
 420 #if NET_4_5
 421                         TaskScheduler.Current = HasFlag (creationOptions, TaskCreationOptions.HideScheduler) ? TaskScheduler.Default : scheduler;
 422 #else
 423                         TaskScheduler.Current = scheduler;
 424 #endif
 425
 426                         if (!token.IsCancellationRequested) {
 427
 428                                 status = TaskStatus.Running;
 429
 430                                 try {
 431                                         InnerInvoke ();
 432                                 } catch (OperationCanceledException oce) {
 433                                         if (token != CancellationToken.None && oce.CancellationToken == token)
 434                                                 CancelReal ();
 435                                         else
 436                                                 HandleGenericException (oce);
 437                                 } catch (Exception e) {
 438                                         HandleGenericException (e);
 439                                 }
 440                         } else {
 441                                 CancelReal ();
 442                         }
 443
 444                         if (saveCurrent != null)
 445                                 current = saveCurrent;
 446                         if (saveScheduler != null)
 447                                 TaskScheduler.Current = saveScheduler;
 448                         Finish ();
 449                 }
 450
 451                 internal bool TrySetCanceled ()
 452                 {
 453                         if (IsCompleted)
 454                                 return false;
 455
 456                         if (!executing.TryRelaxedSet ()) {
 457                                 var sw = new SpinWait ();
 458                                 while (!IsCompleted)
 459                                         sw.SpinOnce ();
 460
 461                                 return false;
 462                         }
 463
 464                         CancelReal ();
 465                         return true;
 466                 }
 467
 468                 internal bool TrySetException (AggregateException aggregate, bool cancellation, bool observed)
 469                 {
 470                         if (IsCompleted)
 471                                 return false;
 472
 473                         if (!executing.TryRelaxedSet ()) {
 474                                 var sw = new SpinWait ();
 475                                 while (!IsCompleted)
 476                                         sw.SpinOnce ();
 477
 478                                 return false;
 479                         }
 480
 481                         if (cancellation) {
 482                                 ExceptionSlot.Exception = aggregate;
 483                                 Thread.MemoryBarrier ();
 484
 485                                 CancelReal ();
 486                         } else {
 487                                 HandleGenericException (aggregate);
 488                         }
 489
 490                         if (observed)
 491                                 exSlot.Observed = true;
 492
 493                         return true;
 494                 }
 495
 496                 internal bool TrySetExceptionObserved ()
 497                 {
 498                         if (exSlot != null) {
 499                                 exSlot.Observed = true;
 500                                 return true;
 501                         }
 502                         return false;
 503                 }
 504
 505                 internal void Execute ()
 506                 {
 507                         ThreadStart ();
 508                 }
 509
 510                 internal void AddChild ()
 511                 {
 512                         if (childTasks == null)
 513                                 Interlocked.CompareExchange (ref childTasks, new CountdownEvent (1), null);
 514                         childTasks.AddCount ();
 515                 }
 516
 517                 internal void ChildCompleted (AggregateException childEx)
 518                 {
 519                         if (childEx != null) {
 520                                 if (ExceptionSlot.ChildExceptions == null)
 521                                         Interlocked.CompareExchange (ref ExceptionSlot.ChildExceptions, new ConcurrentQueue<AggregateException> (), null);
 522                                 ExceptionSlot.ChildExceptions.Enqueue (childEx);
 523                         }
 524
 525                         if (childTasks.Signal () && status == TaskStatus.WaitingForChildrenToComplete) {
 526                                 ProcessChildExceptions ();
 527                                 Status = exSlot == null ? TaskStatus.RanToCompletion : TaskStatus.Faulted;
 528                                 ProcessCompleteDelegates ();
 529                                 if (parent != null &&
 530 #if NET_4_5
 531                                     !HasFlag (parent.CreationOptions, TaskCreationOptions.DenyChildAttach) &&
 532 #endif
 533                                         HasFlag (creationOptions, TaskCreationOptions.AttachedToParent))
 534                                         parent.ChildCompleted (this.Exception);
 535                         }
 536                 }
 537
 538                 void InnerInvoke ()
 539                 {
 540                         if (IsContinuation) {
 541                                 var ancestor = contAncestor;
 542                                 contAncestor = null;
 543                                 invoker.Invoke (ancestor, state, this);
 544                         } else {
 545                                 invoker.Invoke (this, state, this);
 546                         }
 547                 }
 548
 549                 internal void Finish ()
 550                 {
 551                         // If there was children created and they all finished, we set the countdown
 552                         if (childTasks != null) {
 553                                 if (childTasks.Signal ())
 554                                         ProcessChildExceptions (true);
 555                         }
 556
 557                         // Don't override Canceled or Faulted
 558                         if (status == TaskStatus.Running) {
 559                                 if (childTasks == null || childTasks.IsSet)
 560                                         Status = TaskStatus.RanToCompletion;
 561                                 else
 562                                         Status = TaskStatus.WaitingForChildrenToComplete;
 563                         }
 564
 565                         if (wait_handle != null)
 566                                 wait_handle.Set ();
 567
 568                         // Tell parent that we are finished
 569                         if (parent != null && HasFlag (creationOptions, TaskCreationOptions.AttachedToParent) &&
 570 #if NET_4_5
 571                             !HasFlag (parent.CreationOptions, TaskCreationOptions.DenyChildAttach) &&
 572 #endif
 573                                 status != TaskStatus.WaitingForChildrenToComplete) {
 574                                 parent.ChildCompleted (this.Exception);
 575                         }
 576
 577                         // Completions are already processed when task is canceled or faulted
 578                         if (status == TaskStatus.RanToCompletion)
 579                                 ProcessCompleteDelegates ();
 580
 581                         // Reset the current thingies
 582                         if (current == this)
 583                                 current = null;
 584                         if (TaskScheduler.Current == scheduler)
 585                                 TaskScheduler.Current = null;
 586
 587                         if (cancellationRegistration.HasValue)
 588                                 cancellationRegistration.Value.Dispose ();
 589                 }
 590
 591                 void ProcessCompleteDelegates ()
 592                 {
 593                         if (continuations.HasElements) {
 594                                 IContinuation continuation;
 595                                 while (continuations.TryGetNextCompletion (out continuation))
 596                                         continuation.Execute ();
 597                         }
 598                 }
 599
 600                 void ProcessChildExceptions (bool isParent = false)
 601                 {
 602                         if (exSlot == null || exSlot.ChildExceptions == null)
 603                                 return;
 604
 605                         if (ExceptionSlot.Exception == null)
 606                                 exSlot.Exception = new AggregateException ();
 607
 608                         AggregateException childEx;
 609                         while (exSlot.ChildExceptions.TryDequeue (out childEx))
 610                                 exSlot.Exception.AddChildException (childEx);
 611
 612                         if (isParent) {
 613                                 Status = TaskStatus.Faulted;
 614                                 ProcessCompleteDelegates ();
 615                         }
 616                 }
 617                 #endregion
 618
 619                 #region Cancel and Wait related method
 620
 621                 internal void CancelReal ()
 622                 {
 623                         Status = TaskStatus.Canceled;
 624
 625                         if (wait_handle != null)
 626                                 wait_handle.Set ();
 627
 628                         ProcessCompleteDelegates ();
 629                 }
 630
 631                 void HandleGenericException (Exception e)
 632                 {
 633                         HandleGenericException (new AggregateException (e));
 634                 }
 635
 636                 void HandleGenericException (AggregateException e)
 637                 {
 638                         ExceptionSlot.Exception = e;
 639                         Thread.MemoryBarrier ();
 640                         Status = TaskStatus.Faulted;
 641
 642                         if (wait_handle != null)
 643                                 wait_handle.Set ();
 644
 645                         ProcessCompleteDelegates ();
 646                 }
 647
 648                 internal bool WaitOnChildren ()
 649                 {
 650                         if (Status == TaskStatus.WaitingForChildrenToComplete && childTasks != null) {
 651                                 childTasks.Wait ();
 652                                 return true;
 653                         }
 654                         return false;
 655                 }
 656
 657                 public void Wait ()
 658                 {
 659                         Wait (Timeout.Infinite, CancellationToken.None);
 660                 }
 661
 662                 public void Wait (CancellationToken cancellationToken)
 663                 {
 664                         Wait (Timeout.Infinite, cancellationToken);
 665                 }
 666
 667                 public bool Wait (TimeSpan timeout)
 668                 {
 669                         return Wait (CheckTimeout (timeout), CancellationToken.None);
 670                 }
 671
 672                 public bool Wait (int millisecondsTimeout)
 673                 {
 674                         return Wait (millisecondsTimeout, CancellationToken.None);
 675                 }
 676
 677                 public bool Wait (int millisecondsTimeout, CancellationToken cancellationToken)
 678                 {
 679                         if (millisecondsTimeout < -1)
 680                                 throw new ArgumentOutOfRangeException ("millisecondsTimeout");
 681
 682                         bool result = WaitCore (millisecondsTimeout, cancellationToken, true);
 683
 684                         if (IsCanceled)
 685                                 throw new AggregateException (new TaskCanceledException (this));
 686
 687                         var exception = Exception;
 688                         if (exception != null)
 689                                 throw exception;
 690
 691                         return result;
 692                 }
 693
 694                 internal bool WaitCore (int millisecondsTimeout, CancellationToken cancellationToken, bool runInline)
 695                 {
 696                         if (IsCompleted)
 697                                 return true;
 698
 699                         // If the task is ready to be run and we were supposed to wait on it indefinitely without cancellation, just run it
 700                         if (runInline && Status == TaskStatus.WaitingToRun && millisecondsTimeout == Timeout.Infinite && scheduler != null && !cancellationToken.CanBeCanceled) {
 701                                 try {
 702                                         scheduler.RunInline (this, true);
 703                                 } catch (Exception e) {
 704                                         throw new TaskSchedulerException (e);
 705                                 }
 706                         }
 707
 708                         bool result = true;
 709
 710                         if (!IsCompleted) {
 711                                 var continuation = new ManualResetContinuation ();
 712                                 try {
 713                                         ContinueWith (continuation);
 714                                         result = continuation.Event.Wait (millisecondsTimeout, cancellationToken);
 715                                 } finally {
 716                                         if (!result)
 717                                                 RemoveContinuation (continuation);
 718                                         continuation.Dispose ();
 719                                 }
 720                         }
 721
 722                         return result;
 723                 }
 724
 725                 public static void WaitAll (params Task[] tasks)
 726                 {
 727                         WaitAll (tasks, Timeout.Infinite, CancellationToken.None);
 728                 }
 729
 730                 public static void WaitAll (Task[] tasks, CancellationToken cancellationToken)
 731                 {
 732                         WaitAll (tasks, Timeout.Infinite, cancellationToken);
 733                 }
 734
 735                 public static bool WaitAll (Task[] tasks, TimeSpan timeout)
 736                 {
 737                         return WaitAll (tasks, CheckTimeout (timeout), CancellationToken.None);
 738                 }
 739
 740                 public static bool WaitAll (Task[] tasks, int millisecondsTimeout)
 741                 {
 742                         return WaitAll (tasks, millisecondsTimeout, CancellationToken.None);
 743                 }
 744
 745                 public static bool WaitAll (Task[] tasks, int millisecondsTimeout, CancellationToken cancellationToken)
 746                 {
 747                         if (tasks == null)
 748                                 throw new ArgumentNullException ("tasks");
 749
 750                         bool result = true;
 751                         foreach (var t in tasks) {
 752                                 if (t == null)
 753                                         throw new ArgumentException ("tasks", "the tasks argument contains a null element");
 754
 755                                 result &= t.Status == TaskStatus.RanToCompletion;
 756                         }
 757
 758                         if (!result) {
 759                                 var continuation = new CountdownContinuation (tasks.Length);
 760                                 try {
 761                                         foreach (var t in tasks)
 762                                                 t.ContinueWith (continuation);
 763
 764                                         result = continuation.Event.Wait (millisecondsTimeout, cancellationToken);
 765                                 } finally {
 766                                         List<Exception> exceptions = null;
 767
 768                                         foreach (var t in tasks) {
 769                                                 if (result) {
 770                                                         if (t.Status == TaskStatus.RanToCompletion)
 771                                                                 continue;
 772                                                         if (exceptions == null)
 773                                                                 exceptions = new List<Exception> ();
 774                                                         if (t.Exception != null)
 775                                                                 exceptions.AddRange (t.Exception.InnerExceptions);
 776                                                         else
 777                                                                 exceptions.Add (new TaskCanceledException (t));
 778                                                 } else {
 779                                                         t.RemoveContinuation (continuation);
 780                                                 }
 781                                         }
 782
 783                                         continuation.Dispose ();
 784
 785                                         if (exceptions != null)
 786                                                 throw new AggregateException (exceptions);
 787                                 }
 788                         }
 789
 790                         return result;
 791                 }
 792
 793                 public static int WaitAny (params Task[] tasks)
 794                 {
 795                         return WaitAny (tasks, Timeout.Infinite, CancellationToken.None);
 796                 }
 797
 798                 public static int WaitAny (Task[] tasks, TimeSpan timeout)
 799                 {
 800                         return WaitAny (tasks, CheckTimeout (timeout));
 801                 }
 802
 803                 public static int WaitAny (Task[] tasks, int millisecondsTimeout)
 804                 {
 805                         return WaitAny (tasks, millisecondsTimeout, CancellationToken.None);
 806                 }
 807
 808                 public static int WaitAny (Task[] tasks, CancellationToken cancellationToken)
 809                 {
 810                         return WaitAny (tasks, Timeout.Infinite, cancellationToken);
 811                 }
 812
 813                 public static int WaitAny (Task[] tasks, int millisecondsTimeout, CancellationToken cancellationToken)
 814                 {
 815                         if (tasks == null)
 816                                 throw new ArgumentNullException ("tasks");
 817                         if (millisecondsTimeout < -1)
 818                                 throw new ArgumentOutOfRangeException ("millisecondsTimeout");
 819                         CheckForNullTasks (tasks);
 820
 821                         if (tasks.Length > 0) {
 822                                 var continuation = new ManualResetContinuation ();
 823                                 bool result = false;
 824                                 try {
 825                                         for (int i = 0; i < tasks.Length; i++) {
 826                                                 var t = tasks[i];
 827                                                 if (t.IsCompleted)
 828                                                         return i;
 829                                                 t.ContinueWith (continuation);
 830                                         }
 831
 832                                         if (!(result = continuation.Event.Wait (millisecondsTimeout, cancellationToken)))
 833                                                 return -1;
 834                                 } finally {
 835                                         if (!result)
 836                                                 foreach (var t in tasks)
 837                                                         t.RemoveContinuation (continuation);
 838                                         continuation.Dispose ();
 839                                 }
 840                         }
 841
 842                         int firstFinished = -1;
 843                         for (int i = 0; i < tasks.Length; i++) {
 844                                 var t = tasks[i];
 845                                 if (t.IsCompleted) {
 846                                         firstFinished = i;
 847                                         break;
 848                                 }
 849                         }
 850
 851                         return firstFinished;
 852                 }
 853
 854                 static int CheckTimeout (TimeSpan timeout)
 855                 {
 856                         try {
 857                                 return checked ((int)timeout.TotalMilliseconds);
 858                         } catch (System.OverflowException) {
 859                                 throw new ArgumentOutOfRangeException ("timeout");
 860                         }
 861                 }
 862
 863                 static void CheckForNullTasks (Task[] tasks)
 864                 {
 865                         foreach (var t in tasks)
 866                                 if (t == null)
 867                                         throw new ArgumentException ("tasks", "the tasks argument contains a null element");
 868                 }
 869                 #endregion
 870
 871                 #region Dispose
 872                 public void Dispose ()
 873                 {
 874                         Dispose (true);
 875                 }
 876
 877                 protected virtual void Dispose (bool disposing)
 878                 {
 879                         if (!IsCompleted)
 880                                 throw new InvalidOperationException ("A task may only be disposed if it is in a completion state");
 881
 882                         // Set action to null so that the GC can collect the delegate and thus
 883                         // any big object references that the user might have captured in a anonymous method
 884                         if (disposing) {
 885                                 invoker = null;
 886                                 state = null;
 887                                 if (cancellationRegistration != null)
 888                                         cancellationRegistration.Value.Dispose ();
 889                                 if (wait_handle != null)
 890                                         wait_handle.Dispose ();
 891                         }
 892                 }
 893                 #endregion
 894
 895 #if NET_4_5
 896                 public
 897 #else
 898                 internal
 899 #endif
 900                 Task ContinueWith (Action<Task, object> continuationAction, object state, CancellationToken cancellationToken,
 901                                                                   TaskContinuationOptions continuationOptions, TaskScheduler scheduler)
 902                 {
 903                         if (continuationAction == null)
 904                                 throw new ArgumentNullException ("continuationAction");
 905                         if (scheduler == null)
 906                                 throw new ArgumentNullException ("scheduler");
 907
 908                         Task continuation = new Task (TaskActionInvoker.Create (continuationAction),
 909                                                                                   state, cancellationToken,
 910                                                                                   GetCreationOptions (continuationOptions),
 911                                                       parent,
 912                                                       this);
 913                         ContinueWithCore (continuation, continuationOptions, scheduler);
 914
 915                         return continuation;
 916                 }
 917
 918 #if NET_4_5
 919
 920                 public ConfiguredTaskAwaitable ConfigureAwait (bool continueOnCapturedContext)
 921                 {
 922                         return new ConfiguredTaskAwaitable (this, continueOnCapturedContext);
 923                 }
 924
 925                 public Task ContinueWith (Action<Task, object> continuationAction, object state)
 926                 {
 927                         return ContinueWith (continuationAction, state, CancellationToken.None, TaskContinuationOptions.None, TaskScheduler.Current);
 928                 }
 929
 930                 public Task ContinueWith (Action<Task, object> continuationAction, object state, CancellationToken cancellationToken)
 931                 {
 932                         return ContinueWith (continuationAction, state, cancellationToken, TaskContinuationOptions.None, TaskScheduler.Current);
 933                 }
 934
 935                 public Task ContinueWith (Action<Task, object> continuationAction, object state, TaskContinuationOptions continuationOptions)
 936                 {
 937                         return ContinueWith (continuationAction, state, CancellationToken.None, continuationOptions, TaskScheduler.Current);
 938                 }
 939
 940                 public Task ContinueWith (Action<Task, object> continuationAction, object state, TaskScheduler scheduler)
 941                 {
 942                         return ContinueWith (continuationAction, state, CancellationToken.None, TaskContinuationOptions.None, scheduler);
 943                 }
 944
 945                 public Task<TResult> ContinueWith<TResult> (Func<Task, object, TResult> continuationFunction, object state)
 946                 {
 947                         return ContinueWith<TResult> (continuationFunction, state, CancellationToken.None, TaskContinuationOptions.None, TaskScheduler.Current);
 948                 }
 949
 950                 public Task<TResult> ContinueWith<TResult> (Func<Task, object, TResult> continuationFunction, object state, TaskContinuationOptions continuationOptions)
 951                 {
 952                         return ContinueWith<TResult> (continuationFunction, state, CancellationToken.None, continuationOptions, TaskScheduler.Current);
 953                 }
 954
 955                 public Task<TResult> ContinueWith<TResult> (Func<Task, object, TResult> continuationFunction, object state, CancellationToken cancellationToken)
 956                 {
 957                         return ContinueWith<TResult> (continuationFunction, state, cancellationToken, TaskContinuationOptions.None, TaskScheduler.Current);
 958                 }
 959
 960                 public Task<TResult> ContinueWith<TResult> (Func<Task, object, TResult> continuationFunction, object state, TaskScheduler scheduler)
 961                 {
 962                         return ContinueWith<TResult> (continuationFunction, state, CancellationToken.None, TaskContinuationOptions.None, scheduler);
 963                 }
 964
 965                 public Task<TResult> ContinueWith<TResult> (Func<Task, object, TResult> continuationFunction, object state, CancellationToken cancellationToken,
 966                                                                                                         TaskContinuationOptions continuationOptions, TaskScheduler scheduler)
 967                 {
 968                         if (continuationFunction == null)
 969                                 throw new ArgumentNullException ("continuationFunction");
 970                         if (scheduler == null)
 971                                 throw new ArgumentNullException ("scheduler");
 972
 973                         var t = new Task<TResult> (TaskActionInvoker.Create (continuationFunction),
 974                                                    state,
 975                                                    cancellationToken,
 976                                                    GetCreationOptions (continuationOptions),
 977                                                    parent,
 978                                                    this);
 979
 980                         ContinueWithCore (t, continuationOptions, scheduler);
 981
 982                         return t;
 983                 }
 984
 985                 public static Task Delay (int millisecondsDelay)
 986                 {
 987                         return Delay (millisecondsDelay, CancellationToken.None);
 988                 }
 989
 990                 public static Task Delay (TimeSpan delay)
 991                 {
 992                         return Delay (CheckTimeout (delay), CancellationToken.None);
 993                 }
 994
 995                 public static Task Delay (TimeSpan delay, CancellationToken cancellationToken)
 996                 {
 997                         return Delay (CheckTimeout (delay), cancellationToken);
 998                 }
 999
1000                 public static Task Delay (int millisecondsDelay, CancellationToken cancellationToken)
1001                 {
1002                         if (millisecondsDelay < -1)
1003                                 throw new ArgumentOutOfRangeException ("millisecondsDelay");
1004
1005                         if (cancellationToken.IsCancellationRequested)
1006                                 return TaskConstants.Canceled;
1007
1008                         var task = new Task (TaskActionInvoker.Empty, null, cancellationToken, TaskCreationOptions.None, null, null);
1009                         task.SetupScheduler (TaskScheduler.Default);
1010
1011                         if (millisecondsDelay != Timeout.Infinite) {
1012                                 var timer = new Timer (delegate (object state) {
1013                                         var t = (Task) state;
1014                                         if (t.Status == TaskStatus.WaitingForActivation) {
1015                                                 t.Status = TaskStatus.Running;
1016                                                 t.Finish ();
1017                                         }
1018                                 }, task, millisecondsDelay, -1);
1019
1020                                 task.ContinueWith (new DisposeContinuation (timer));
1021                         }
1022
1023                         return task;
1024                 }
1025
1026                 public static Task<TResult> FromResult<TResult> (TResult result)
1027                 {
1028                         var tcs = new TaskCompletionSource<TResult> ();
1029                         tcs.SetResult (result);
1030                         return tcs.Task;
1031                 }
1032
1033                 public TaskAwaiter GetAwaiter ()
1034                 {
1035                         return new TaskAwaiter (this);
1036                 }
1037
1038                 public static Task Run (Action action)
1039                 {
1040                         return Run (action, CancellationToken.None);
1041                 }
1042
1043                 public static Task Run (Action action, CancellationToken cancellationToken)
1044                 {
1045                         if (cancellationToken.IsCancellationRequested)
1046                                 return TaskConstants.Canceled;
1047
1048                         return Task.Factory.StartNew (action, cancellationToken, TaskCreationOptions.DenyChildAttach, TaskScheduler.Default);
1049                 }
1050
1051                 public static Task Run (Func<Task> function)
1052                 {
1053                         return Run (function, CancellationToken.None);
1054                 }
1055
1056                 public static Task Run (Func<Task> function, CancellationToken cancellationToken)
1057                 {
1058                         if (cancellationToken.IsCancellationRequested)
1059                                 return TaskConstants.Canceled;
1060
1061                         return TaskExtensionsImpl.Unwrap (Task.Factory.StartNew (function, cancellationToken, TaskCreationOptions.DenyChildAttach, TaskScheduler.Default));
1062                 }
1063
1064                 public static Task<TResult> Run<TResult> (Func<TResult> function)
1065                 {
1066                         return Run (function, CancellationToken.None);
1067                 }
1068
1069                 public static Task<TResult> Run<TResult> (Func<TResult> function, CancellationToken cancellationToken)
1070                 {
1071                         if (cancellationToken.IsCancellationRequested)
1072                                 return TaskConstants<TResult>.Canceled;
1073
1074                         return Task.Factory.StartNew (function, cancellationToken, TaskCreationOptions.DenyChildAttach, TaskScheduler.Default);
1075                 }
1076
1077                 public static Task<TResult> Run<TResult> (Func<Task<TResult>> function)
1078                 {
1079                         return Run (function, CancellationToken.None);
1080                 }
1081
1082                 public static Task<TResult> Run<TResult> (Func<Task<TResult>> function, CancellationToken cancellationToken)
1083                 {
1084                         if (cancellationToken.IsCancellationRequested)
1085                                 return TaskConstants<TResult>.Canceled;
1086
1087                         return TaskExtensionsImpl.Unwrap (Task.Factory.StartNew (function, cancellationToken, TaskCreationOptions.DenyChildAttach, TaskScheduler.Default));
1088                 }
1089
1090                 public static Task WhenAll (params Task[] tasks)
1091                 {
1092                         if (tasks == null)
1093                                 throw new ArgumentNullException ("tasks");
1094
1095                         return WhenAllCore (tasks);
1096                 }
1097
1098                 public static Task WhenAll (IEnumerable<Task> tasks)
1099                 {
1100                         if (tasks == null)
1101                                 throw new ArgumentNullException ("tasks");
1102
1103                         // Call ToList on input enumeration or we end up
1104                         // enumerating it more than once
1105                         return WhenAllCore (new List<Task> (tasks));
1106                 }
1107
1108                 public static Task<TResult[]> WhenAll<TResult> (params Task<TResult>[] tasks)
1109                 {
1110                         if (tasks == null)
1111                                 throw new ArgumentNullException ("tasks");
1112
1113                         return WhenAllCore<TResult> (tasks);
1114                 }
1115
1116                 public static Task<TResult[]> WhenAll<TResult> (IEnumerable<Task<TResult>> tasks)
1117                 {
1118                         if (tasks == null)
1119                                 throw new ArgumentNullException ("tasks");
1120
1121                         // Call ToList on input enumeration or we end up
1122                         // enumerating it more than once
1123                         return WhenAllCore<TResult> (new List<Task<TResult>> (tasks));
1124                 }
1125
1126                 internal static Task<TResult[]> WhenAllCore<TResult> (IList<Task<TResult>> tasks)
1127                 {
1128                         if (tasks.Count == 0)
1129                                 return FromResult(new TResult[0]);
1130
1131                         foreach (var t in tasks) {
1132                                 if (t == null)
1133                                         throw new ArgumentException ("tasks", "the tasks argument contains a null element");
1134                         }
1135
1136                         var task = new Task<TResult[]> (TaskActionInvoker.Empty, null, CancellationToken.None, TaskCreationOptions.None, null, TaskConstants.Finished);
1137                         task.SetupScheduler (TaskScheduler.Current);
1138
1139                         var continuation = new WhenAllContinuation<TResult> (task, tasks);
1140                         foreach (var t in tasks)
1141                                 t.ContinueWith (continuation);
1142
1143                         return task;
1144                 }
1145
1146                 public static Task<Task> WhenAny (params Task[] tasks)
1147                 {
1148                         if (tasks == null)
1149                                 throw new ArgumentNullException ("tasks");
1150
1151                         return WhenAnyCore (tasks);
1152                 }
1153
1154                 public static Task<Task> WhenAny (IEnumerable<Task> tasks)
1155                 {
1156                         if (tasks == null)
1157                                 throw new ArgumentNullException ("tasks");
1158
1159                         return WhenAnyCore (new List<Task> (tasks));
1160                 }
1161
1162                 public static Task<Task<TResult>> WhenAny<TResult> (params Task<TResult>[] tasks)
1163                 {
1164                         if (tasks == null)
1165                                 throw new ArgumentNullException ("tasks");
1166
1167                         return WhenAnyCore<TResult> (tasks);
1168                 }
1169
1170                 public static Task<Task<TResult>> WhenAny<TResult> (IEnumerable<Task<TResult>> tasks)
1171                 {
1172                         if (tasks == null)
1173                                 throw new ArgumentNullException ("tasks");
1174
1175                         return WhenAnyCore<TResult> (new List<Task<TResult>> (tasks));
1176                 }
1177
1178                 static Task<Task<TResult>> WhenAnyCore<TResult> (IList<Task<TResult>> tasks)
1179                 {
1180                         if (tasks.Count == 0)
1181                                 throw new ArgumentException ("The tasks argument contains no tasks", "tasks");
1182
1183                         int completed_index = -1;
1184                         for (int i = 0; i < tasks.Count; ++i) {
1185                                 var t = tasks[i];
1186                                 if (t == null)
1187                                         throw new ArgumentException ("tasks", "the tasks argument contains a null element");
1188
1189                                 if (t.IsCompleted && completed_index < 0)
1190                                         completed_index = i;
1191                         }
1192
1193                         var task = new Task<Task<TResult>> (TaskActionInvoker.Empty, null, CancellationToken.None, TaskCreationOptions.None, null, TaskConstants.Finished);
1194
1195                         if (completed_index > 0) {
1196                                 task.TrySetResult (tasks[completed_index]);
1197                                 return task;
1198                         }
1199
1200                         task.SetupScheduler (TaskScheduler.Current);
1201
1202                         var continuation = new WhenAnyContinuation<Task<TResult>> (task, tasks);
1203                         foreach (var t in tasks)
1204                                 t.ContinueWith (continuation);
1205
1206                         return task;
1207                 }
1208
1209                 public static YieldAwaitable Yield ()
1210                 {
1211                         return new YieldAwaitable ();
1212                 }
1213 #endif
1214
1215                 internal static Task WhenAllCore (IList<Task> tasks)
1216                 {
1217                         bool all_completed = true;
1218                         foreach (var t in tasks) {
1219                                 if (t == null)
1220                                         throw new ArgumentException ("tasks", "the tasks argument contains a null element");
1221
1222                                 all_completed &= t.Status == TaskStatus.RanToCompletion;
1223                         }
1224
1225                         if (all_completed)
1226                                 return TaskConstants.Finished;
1227
1228                         var task = new Task (TaskActionInvoker.Empty, null, CancellationToken.None, TaskCreationOptions.None, null, TaskConstants.Finished);
1229                         task.SetupScheduler (TaskScheduler.Current);
1230
1231                         var continuation = new WhenAllContinuation (task, tasks);
1232                         foreach (var t in tasks)
1233                                 t.ContinueWith (continuation);
1234
1235                         return task;
1236                 }
1237
1238                 internal static Task<Task> WhenAnyCore (IList<Task> tasks)
1239                 {
1240                         if (tasks.Count == 0)
1241                                 throw new ArgumentException ("The tasks argument contains no tasks", "tasks");
1242
1243                         int completed_index = -1;
1244                         for (int i = 0; i < tasks.Count; ++i) {
1245                                 var t = tasks [i];
1246                                 if (t == null)
1247                                         throw new ArgumentException ("tasks", "the tasks argument contains a null element");
1248
1249                                 if (t.IsCompleted && completed_index < 0)
1250                                         completed_index = i;
1251                         }
1252
1253                         var task = new Task<Task> (TaskActionInvoker.Empty, null, CancellationToken.None, TaskCreationOptions.None, null, TaskConstants.Finished);
1254
1255                         if (completed_index > 0) {
1256                                 task.TrySetResult (tasks[completed_index]);
1257                                 return task;
1258                         }
1259
1260                         task.SetupScheduler (TaskScheduler.Current);
1261
1262                         var continuation = new WhenAnyContinuation<Task> (task, tasks);
1263                         foreach (var t in tasks)
1264                                 t.ContinueWith (continuation);
1265
1266                         return task;
1267                 }
1268                 #region Properties
1269
1270                 internal CancellationToken CancellationToken {
1271                         get {
1272                                 return token;
1273                         }
1274                 }
1275
1276                 public static TaskFactory Factory {
1277                         get {
1278                                 return defaultFactory;
1279                         }
1280                 }
1281
1282                 public static int? CurrentId {
1283                         get {
1284                                 Task t = current;
1285                                 return t == null ? (int?)null : t.Id;
1286                         }
1287                 }
1288
1289                 public AggregateException Exception {
1290                         get {
1291                                 if (exSlot == null || !IsFaulted)
1292                                         return null;
1293                                 exSlot.Observed = true;
1294                                 return exSlot.Exception;
1295                         }
1296                 }
1297
1298                 public bool IsCanceled {
1299                         get {
1300                                 return status == TaskStatus.Canceled;
1301                         }
1302                 }
1303
1304                 public bool IsCompleted {
1305                         get {
1306                                 return status >= TaskStatus.RanToCompletion;
1307                         }
1308                 }
1309
1310                 public bool IsFaulted {
1311                         get {
1312                                 return status == TaskStatus.Faulted;
1313                         }
1314                 }
1315
1316                 public TaskCreationOptions CreationOptions {
1317                         get {
1318                                 return creationOptions & MaxTaskCreationOptions;
1319                         }
1320                 }
1321
1322                 public TaskStatus Status {
1323                         get {
1324                                 return status;
1325                         }
1326                         internal set {
1327                                 status = value;
1328                                 Thread.MemoryBarrier ();
1329                         }
1330                 }
1331
1332                 internal TaskExceptionSlot ExceptionSlot {
1333                         get {
1334                                 if (exSlot != null)
1335                                         return exSlot;
1336                                 Interlocked.CompareExchange (ref exSlot, new TaskExceptionSlot (this), null);
1337                                 return exSlot;
1338                         }
1339                 }
1340
1341                 public object AsyncState {
1342                         get {
1343                                 return state;
1344                         }
1345                 }
1346
1347                 bool IAsyncResult.CompletedSynchronously {
1348                         get {
1349                                 return true;
1350                         }
1351                 }
1352
1353                 WaitHandle IAsyncResult.AsyncWaitHandle {
1354                         get {
1355                                 if (invoker == null)
1356                                         throw new ObjectDisposedException (GetType ().ToString ());
1357
1358                                 if (wait_handle == null)
1359                                         Interlocked.CompareExchange (ref wait_handle, new ManualResetEvent (IsCompleted), null);
1360
1361                                 return wait_handle;
1362                         }
1363                 }
1364
1365                 public int Id {
1366                         get {
1367                                 return taskId;
1368                         }
1369                 }
1370
1371                 bool IsContinuation {
1372                         get {
1373                                 return contAncestor != null;
1374                         }
1375                 }
1376
1377                 bool IsPromise {
1378                         get {
1379                                 return invoker == TaskActionInvoker.Promise;
1380                         }
1381                 }
1382
1383                 internal Task ContinuationAncestor {
1384                         get {
1385                                 return contAncestor;
1386                         }
1387                 }
1388
1389                 internal string DisplayActionMethod {
1390                         get {
1391                                 Delegate d = invoker.Action;
1392                                 return d == null ? "<none>" : d.Method.ToString ();
1393                         }
1394                 }
1395
1396                 #endregion
1397         }
1398 }
1399 #endif