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

   1 //
   2 // AsyncVoidMethodBuilder.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
  34 namespace System.Runtime.CompilerServices
  35 {
  36         public struct AsyncVoidMethodBuilder
  37         {
  38                 static readonly SynchronizationContext null_context = new SynchronizationContext ();
  39
  40                 readonly SynchronizationContext context;
  41                 IAsyncStateMachine stateMachine;
  42
  43                 private AsyncVoidMethodBuilder (SynchronizationContext context)
  44                 {
  45                         this.context = context;
  46                         this.stateMachine = null;
  47                 }
  48
  49                 public void AwaitOnCompleted<TAwaiter, TStateMachine> (ref TAwaiter awaiter, ref TStateMachine stateMachine)
  50                         where TAwaiter : INotifyCompletion
  51                         where TStateMachine : IAsyncStateMachine
  52                 {
  53                         var action = new Action (stateMachine.MoveNext);
  54                         awaiter.OnCompleted (action);
  55                 }
  56
  57                 public void AwaitUnsafeOnCompleted<TAwaiter, TStateMachine> (ref TAwaiter awaiter, ref TStateMachine stateMachine)
  58                         where TAwaiter : ICriticalNotifyCompletion
  59                         where TStateMachine : IAsyncStateMachine
  60                 {
  61                         var action = new Action (stateMachine.MoveNext);
  62                         awaiter.UnsafeOnCompleted (action);
  63                 }
  64
  65                 public static AsyncVoidMethodBuilder Create ()
  66                 {
  67                         var ctx = SynchronizationContext.Current ?? null_context;
  68                         ctx.OperationStarted ();
  69
  70                         return new AsyncVoidMethodBuilder (ctx);
  71                 }
  72
  73                 public void SetException (Exception exception)
  74                 {
  75                         if (exception == null)
  76                                 throw new ArgumentNullException ("exception");
  77
  78                         try {
  79                                 context.Post (l => { throw (Exception) l; }, exception);
  80                         } finally {
  81                                 SetResult ();
  82                         }
  83                 }
  84
  85                 public void SetStateMachine (IAsyncStateMachine stateMachine)
  86                 {
  87                         if (stateMachine == null)
  88                                 throw new ArgumentNullException ("stateMachine");
  89
  90                         if (this.stateMachine != null)
  91                                 throw new InvalidOperationException ("The state machine was previously set");
  92
  93                         this.stateMachine = stateMachine;
  94                 }
  95
  96                 public void SetResult ()
  97                 {
  98                         context.OperationCompleted ();
  99                 }
 100
 101                 public void Start<TStateMachine> (ref TStateMachine stateMachine) where TStateMachine : IAsyncStateMachine
 102                 {
 103                         if (stateMachine == null)
 104                                 throw new ArgumentNullException ("stateMachine");
 105
 106                         stateMachine.MoveNext ();
 107                 }
 108         }
 109 }
 110
 111 #endif