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

   1 // BroadcastBlock.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 using System.Collections.Generic;
  25 using System.Collections.Concurrent;
  26
  27 namespace System.Threading.Tasks.Dataflow {
  28         public sealed class BroadcastBlock<T> : IPropagatorBlock<T, T>, IReceivableSourceBlock<T> {
  29                 readonly CompletionHelper compHelper;
  30                 readonly BlockingCollection<T> messageQueue = new BlockingCollection<T> ();
  31                 readonly MessageBox<T> messageBox;
  32                 readonly DataflowBlockOptions dataflowBlockOptions;
  33                 readonly Func<T, T> cloningFunction;
  34                 readonly BroadcastOutgoingQueue<T> outgoing;
  35
  36                 public BroadcastBlock (Func<T, T> cloningFunction)
  37                         : this (cloningFunction, DataflowBlockOptions.Default)
  38                 {
  39                 }
  40
  41                 public BroadcastBlock (Func<T, T> cloningFunction,
  42                                        DataflowBlockOptions dataflowBlockOptions)
  43                 {
  44                         if (dataflowBlockOptions == null)
  45                                 throw new ArgumentNullException ("dataflowBlockOptions");
  46
  47                         this.cloningFunction = cloningFunction;
  48                         this.dataflowBlockOptions = dataflowBlockOptions;
  49                         this.compHelper = CompletionHelper.GetNew (dataflowBlockOptions);
  50                         this.messageBox = new PassingMessageBox<T> (this, messageQueue, compHelper,
  51                                 () => outgoing.IsCompleted, _ => BroadcastProcess (), dataflowBlockOptions);
  52                         this.outgoing = new BroadcastOutgoingQueue<T> (this, compHelper,
  53                                 () => messageQueue.IsCompleted, messageBox.DecreaseCount,
  54                                 dataflowBlockOptions, cloningFunction != null);
  55                 }
  56
  57                 DataflowMessageStatus ITargetBlock<T>.OfferMessage (
  58                         DataflowMessageHeader messageHeader, T messageValue, ISourceBlock<T> source,
  59                         bool consumeToAccept)
  60                 {
  61                         return messageBox.OfferMessage (messageHeader, messageValue, source,
  62                                 consumeToAccept);
  63                 }
  64
  65                 public IDisposable LinkTo (ITargetBlock<T> target, DataflowLinkOptions linkOptions)
  66                 {
  67                         if (linkOptions == null)
  68                                 throw new ArgumentNullException("linkOptions");
  69
  70                         return outgoing.AddTarget (target, linkOptions);
  71                 }
  72
  73                 T ISourceBlock<T>.ConsumeMessage (DataflowMessageHeader messageHeader,
  74                                                   ITargetBlock<T> target,
  75                                                   out bool messageConsumed)
  76                 {
  77                         T message = outgoing.ConsumeMessage (
  78                                 messageHeader, target, out messageConsumed);
  79                         if (messageConsumed && cloningFunction != null)
  80                                 message = cloningFunction (message);
  81                         return message;
  82                 }
  83
  84                 bool ISourceBlock<T>.ReserveMessage (DataflowMessageHeader messageHeader,
  85                                                      ITargetBlock<T> target)
  86                 {
  87                         return outgoing.ReserveMessage (messageHeader, target);
  88                 }
  89
  90                 void ISourceBlock<T>.ReleaseReservation (DataflowMessageHeader messageHeader,
  91                                                          ITargetBlock<T> target)
  92                 {
  93                         outgoing.ReleaseReservation (messageHeader, target);
  94                 }
  95
  96                 public bool TryReceive (Predicate<T> filter, out T item)
  97                 {
  98                         var received = outgoing.TryReceive (filter, out item);
  99                         if (received && cloningFunction != null)
 100                                 item = cloningFunction (item);
 101                         return received;
 102                 }
 103
 104                 bool IReceivableSourceBlock<T>.TryReceiveAll (out IList<T> items)
 105                 {
 106                         T item;
 107                         if (!TryReceive (null, out item)) {
 108                                 items = null;
 109                                 return false;
 110                         }
 111
 112                         items = new[] { item };
 113                         return true;
 114                 }
 115
 116                 /// <summary>
 117                 /// Moves items from the input queue to the output queue.
 118                 /// </summary>
 119                 void BroadcastProcess ()
 120                 {
 121                         T item;
 122                         while (messageQueue.TryTake (out item))
 123                                 outgoing.AddData (item);
 124                 }
 125
 126                 public void Complete ()
 127                 {
 128                         messageBox.Complete ();
 129                         outgoing.Complete ();
 130                 }
 131
 132                 void IDataflowBlock.Fault (Exception exception)
 133                 {
 134                         compHelper.RequestFault (exception);
 135                 }
 136
 137                 public Task Completion {
 138                         get { return compHelper.Completion; }
 139                 }
 140
 141                 public override string ToString ()
 142                 {
 143                         return NameHelper.GetName (this, dataflowBlockOptions);
 144                 }
 145         }
 146 }