mcs/class/System.Threading.Tasks.Dataflow/System.Threading.Tasks.Dataflow/ObservableDataflowBlock.cs

   1 // ObservableDataflowBlock.cs
   2 //
   3 // Copyright (c) 2011 Jérémie "garuma" Laval
   4 // Copyright (c) 2012 Petr Onderka
   5 //
   6 // Permission is hereby granted, free of charge, to any person obtaining a copy
   7 // of this software and associated documentation files (the "Software"), to deal
   8 // in the Software without restriction, including without limitation the rights
   9 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10 // copies of the Software, and to permit persons to whom the Software is
  11 // furnished to do so, subject to the following conditions:
  12 //
  13 // The above copyright notice and this permission notice shall be included in
  14 // all copies or substantial portions of the Software.
  15 //
  16 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22 // THE SOFTWARE.
  23
  24 namespace System.Threading.Tasks.Dataflow {
  25         /// <summary>
  26         /// Rx Observable that represents a source block.
  27         /// </summary>
  28         class ObservableDataflowBlock<TSource> : IObservable<TSource> {
  29                 class ObserverWrapper : ITargetBlock<TSource> {
  30                         readonly IObserver<TSource> observer;
  31
  32                         public ObserverWrapper (IObserver<TSource> observer)
  33                         {
  34                                 this.observer = observer;
  35                         }
  36
  37                         public void Complete ()
  38                         {
  39                                 observer.OnCompleted ();
  40                         }
  41
  42                         public void Fault (Exception exception)
  43                         {
  44                                 observer.OnError (exception);
  45                         }
  46
  47                         public Task Completion {
  48                                 get { return null; }
  49                         }
  50
  51                         public DataflowMessageStatus OfferMessage (
  52                                 DataflowMessageHeader messageHeader, TSource messageValue,
  53                                 ISourceBlock<TSource> source, bool consumeToAccept)
  54                         {
  55                                 if (consumeToAccept) {
  56                                         if (!source.ReserveMessage (messageHeader, this))
  57                                                 return DataflowMessageStatus.NotAvailable;
  58                                         bool consumed;
  59                                         messageValue = source.ConsumeMessage (messageHeader, this, out consumed);
  60                                         if (!consumed)
  61                                                 return DataflowMessageStatus.NotAvailable;
  62                                 }
  63
  64                                 observer.OnNext (messageValue);
  65
  66                                 return DataflowMessageStatus.Accepted;
  67                         }
  68                 }
  69
  70                 readonly ISourceBlock<TSource> source;
  71
  72                 public ObservableDataflowBlock (ISourceBlock<TSource> source)
  73                 {
  74                         this.source = source;
  75                 }
  76
  77                 public IDisposable Subscribe (IObserver<TSource> observer)
  78                 {
  79                         var wrapper = new ObserverWrapper (observer);
  80                         return source.LinkTo (wrapper);
  81                 }
  82         }
  83 }