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

   1 //
   2 // AsyncTaskMethodBuilder.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 AsyncTaskMethodBuilder
  38         {
  39                 readonly Task<object> task;
  40                 IAsyncStateMachine stateMachine;
  41
  42                 private AsyncTaskMethodBuilder (Task<object> task)
  43                 {
  44                         this.task = task;
  45                         this.stateMachine = null;
  46                 }
  47
  48                 public Task Task {
  49                         get {
  50                                 return task;
  51                         }
  52                 }
  53
  54                 public void AwaitOnCompleted<TAwaiter, TStateMachine> (ref TAwaiter awaiter, ref TStateMachine stateMachine)
  55                         where TAwaiter : INotifyCompletion
  56                         where TStateMachine : IAsyncStateMachine
  57                 {
  58                         var action = new Action (stateMachine.MoveNext);
  59                         awaiter.OnCompleted (action);
  60                 }
  61
  62                 public void AwaitUnsafeOnCompleted<TAwaiter, TStateMachine> (ref TAwaiter awaiter, ref TStateMachine stateMachine)
  63                         where TAwaiter : ICriticalNotifyCompletion
  64                         where TStateMachine : IAsyncStateMachine
  65                 {
  66                         var action = new Action (stateMachine.MoveNext);
  67                         awaiter.UnsafeOnCompleted (action);
  68                 }
  69
  70                 public static AsyncTaskMethodBuilder Create ()
  71                 {
  72                         var task = new Task<object> (TaskActionInvoker.Empty, null, CancellationToken.None, TaskCreationOptions.None, null);
  73                         task.SetupScheduler (TaskScheduler.Current);
  74                         return new AsyncTaskMethodBuilder (task);
  75                 }
  76
  77                 public void SetException (Exception exception)
  78                 {
  79                         if (exception is OperationCanceledException) {
  80                                 if (Task.TrySetCanceled ())
  81                                         return;
  82                         } else {
  83                                 if (Task.TrySetException (new AggregateException (exception)))
  84                                         return;
  85                         }
  86
  87                         throw new InvalidOperationException ("The task has already completed");
  88                 }
  89
  90                 public void SetStateMachine (IAsyncStateMachine stateMachine)
  91                 {
  92                         if (stateMachine == null)
  93                                 throw new ArgumentNullException ("stateMachine");
  94
  95                         if (this.stateMachine != null)
  96                                 throw new InvalidOperationException ("The state machine was previously set");
  97
  98                         this.stateMachine = stateMachine;
  99                 }
 100
 101                 public void SetResult ()
 102                 {
 103                         if (!task.TrySetResult (null))
 104                                 throw new InvalidOperationException ("The task has already completed");
 105                 }
 106
 107                 public void Start<TStateMachine> (ref TStateMachine stateMachine) where TStateMachine : IAsyncStateMachine
 108                 {
 109                         if (stateMachine == null)
 110                                 throw new ArgumentNullException ("stateMachine");
 111
 112                         stateMachine.MoveNext ();
 113                 }
 114         }
 115 }
 116
 117 #endif