mcs/class/corlib/System.Runtime.CompilerServices/TaskAwaiter.cs

   1 //
   2 // TaskAwaiter.cs
   3 //
   4 // Authors:
   5 //      Marek Safar  <marek.safar@gmail.com>
   6 //
   7 // Copyright (C) 2011 Novell, Inc (http://www.novell.com)
   8 // Copyright (C) 2011 Xamarin, Inc (http://www.xamarin.com)
   9 //
  10 // Permission is hereby granted, free of charge, to any person obtaining
  11 // a copy of this software and associated documentation files (the
  12 // "Software"), to deal in the Software without restriction, including
  13 // without limitation the rights to use, copy, modify, merge, publish,
  14 // distribute, sublicense, and/or sell copies of the Software, and to
  15 // permit persons to whom the Software is furnished to do so, subject to
  16 // the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be
  19 // included in all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28 //
  29
  30 #if NET_4_5
  31
  32 using System.Threading;
  33 using System.Threading.Tasks;
  34
  35 namespace System.Runtime.CompilerServices
  36 {
  37         public struct TaskAwaiter
  38         {
  39                 readonly Task task;
  40
  41                 internal TaskAwaiter (Task task)
  42                 {
  43                         this.task = task;
  44                 }
  45
  46                 public bool IsCompleted {
  47                         get {
  48                                 return task.IsCompleted;
  49                         }
  50                 }
  51
  52                 public void GetResult ()
  53                 {
  54                         if (task.Status != TaskStatus.RanToCompletion)
  55                                 throw HandleUnexpectedTaskResult (task);
  56                 }
  57
  58                 internal static Exception HandleUnexpectedTaskResult (Task task)
  59                 {
  60                         switch (task.Status) {
  61                         case TaskStatus.Canceled:
  62                                 return new TaskCanceledException (task);
  63                         case TaskStatus.Faulted:
  64                                 return task.Exception.InnerException;
  65                         default:
  66                                 return new InvalidOperationException ("The task has not finished yet");
  67                         }
  68                 }
  69
  70                 internal static void HandleOnCompleted (Task task, Action continuation, bool continueOnSourceContext)
  71                 {
  72                         if (continueOnSourceContext && SynchronizationContext.Current != null) {
  73                                 task.ContinueWith (new SynchronizationContextContinuation (continuation, SynchronizationContext.Current));
  74                         } else {
  75                                 task.ContinueWith (new ActionContinuation (continuation));
  76                         }
  77                 }
  78
  79                 public void OnCompleted (Action continuation)
  80                 {
  81                         if (continuation == null)
  82                                 throw new ArgumentNullException ("continuation");
  83
  84                         HandleOnCompleted (task, continuation, true);
  85                 }
  86         }
  87 }
  88
  89 #endif