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

   1 // BroadcastBlock.cs
   2 //
   3 // Copyright (c) 2011 Jérémie "garuma" Laval
   4 //
   5 // Permission is hereby granted, free of charge, to any person obtaining a copy
   6 // of this software and associated documentation files (the "Software"), to deal
   7 // in the Software without restriction, including without limitation the rights
   8 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   9 // copies of the Software, and to permit persons to whom the Software is
  10 // furnished to do so, subject to the following conditions:
  11 //
  12 // The above copyright notice and this permission notice shall be included in
  13 // all copies or substantial portions of the Software.
  14 //
  15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  21 // THE SOFTWARE.
  22 //
  23 //
  24
  25 using System.Collections.Generic;
  26 using System.Collections.Concurrent;
  27
  28 namespace System.Threading.Tasks.Dataflow
  29 {
  30         public sealed class BroadcastBlock<T> : IPropagatorBlock<T, T>, ITargetBlock<T>, IDataflowBlock, ISourceBlock<T>, IReceivableSourceBlock<T>
  31         {
  32                 static readonly DataflowBlockOptions defaultOptions = new DataflowBlockOptions ();
  33
  34                 CompletionHelper compHelper;
  35                 BlockingCollection<T> messageQueue = new BlockingCollection<T> ();
  36                 MessageBox<T> messageBox;
  37                 MessageVault<T> vault;
  38                 DataflowBlockOptions dataflowBlockOptions;
  39                 readonly Func<T, T> cloner;
  40                 MessageOutgoingQueue<T> outgoing;
  41                 TargetBuffer<T> targets = new TargetBuffer<T> ();
  42                 DataflowMessageHeader headers = DataflowMessageHeader.NewValid ();
  43
  44                 public BroadcastBlock (Func<T, T> cloner) : this (cloner, defaultOptions)
  45                 {
  46
  47                 }
  48
  49                 public BroadcastBlock (Func<T, T> cloner, DataflowBlockOptions dataflowBlockOptions)
  50                 {
  51                         if (dataflowBlockOptions == null)
  52                                 throw new ArgumentNullException ("dataflowBlockOptions");
  53
  54                         this.cloner = cloner;
  55                         this.dataflowBlockOptions = dataflowBlockOptions;
  56                         this.compHelper = CompletionHelper.GetNew (dataflowBlockOptions);
  57                         this.messageBox = new PassingMessageBox<T> (messageQueue, compHelper, () => outgoing.IsCompleted, BroadcastProcess, dataflowBlockOptions);
  58                         this.outgoing = new MessageOutgoingQueue<T> (compHelper, () => messageQueue.IsCompleted);
  59                         this.vault = new MessageVault<T> ();
  60                 }
  61
  62                 public DataflowMessageStatus OfferMessage (DataflowMessageHeader messageHeader,
  63                                                            T messageValue,
  64                                                            ISourceBlock<T> source,
  65                                                            bool consumeToAccept)
  66                 {
  67                         return messageBox.OfferMessage (this, messageHeader, messageValue, source, consumeToAccept);
  68                 }
  69
  70                 public IDisposable LinkTo (ITargetBlock<T> target, bool unlinkAfterOne)
  71                 {
  72                         return targets.AddTarget (target, unlinkAfterOne);
  73                 }
  74
  75                 public T ConsumeMessage (DataflowMessageHeader messageHeader, ITargetBlock<T> target, out bool messageConsumed)
  76                 {
  77                         return cloner(vault.ConsumeMessage (messageHeader, target, out messageConsumed));
  78                 }
  79
  80                 public void ReleaseReservation (DataflowMessageHeader messageHeader, ITargetBlock<T> target)
  81                 {
  82                         vault.ReleaseReservation (messageHeader, target);
  83                 }
  84
  85                 public bool ReserveMessage (DataflowMessageHeader messageHeader, ITargetBlock<T> target)
  86                 {
  87                         return vault.ReserveMessage (messageHeader, target);
  88                 }
  89
  90                 public bool TryReceive (Predicate<T> filter, out T item)
  91                 {
  92                         return outgoing.TryReceive (filter, out item);
  93                 }
  94
  95                 public bool TryReceiveAll (out IList<T> items)
  96                 {
  97                         return outgoing.TryReceiveAll (out items);
  98                 }
  99
 100                 void BroadcastProcess ()
 101                 {
 102                         T input;
 103
 104                         if (!messageQueue.TryTake (out input) || targets.Current == null)
 105                                 return;
 106
 107                         foreach (var target in targets) {
 108                                 DataflowMessageHeader header = headers.Increment ();
 109                                 if (cloner != null)
 110                                         vault.StoreMessage (header, input);
 111                                 target.OfferMessage (header, input, this, cloner != null);
 112                                 // TODO: verify if it's the correct semantic
 113                                 T save = input;
 114                                 if (!messageQueue.TryTake (out input))
 115                                         input = save;
 116                         }
 117                 }
 118
 119                 public void Complete ()
 120                 {
 121                         messageBox.Complete ();
 122                 }
 123
 124                 public void Fault (Exception ex)
 125                 {
 126                         compHelper.Fault (ex);
 127                 }
 128
 129                 public Task Completion {
 130                         get {
 131                                 return compHelper.Completion;
 132                         }
 133                 }
 134
 135                 public override string ToString ()
 136                 {
 137                         return NameHelper.GetName (this, dataflowBlockOptions);
 138                 }
 139         }
 140 }