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
  26 using System;
  27 using System.Threading.Tasks;
  28 using System.Collections.Generic;
  29 using System.Collections.Concurrent;
  30
  31 namespace System.Threading.Tasks.Dataflow
  32 {
  33         public sealed class BroadcastBlock<T> : IPropagatorBlock<T, T>, ITargetBlock<T>, IDataflowBlock, ISourceBlock<T>, IReceivableSourceBlock<T>
  34         {
  35                 static readonly DataflowBlockOptions defaultOptions = new DataflowBlockOptions ();
  36
  37                 CompletionHelper compHelper = CompletionHelper.GetNew ();
  38                 BlockingCollection<T> messageQueue = new BlockingCollection<T> ();
  39                 MessageBox<T> messageBox;
  40                 MessageVault<T> vault;
  41                 DataflowBlockOptions dataflowBlockOptions;
  42                 readonly Func<T, T> cloner;
  43                 MessageOutgoingQueue<T> outgoing;
  44                 TargetBuffer<T> targets = new TargetBuffer<T> ();
  45                 DataflowMessageHeader headers = DataflowMessageHeader.NewValid ();
  46
  47                 public BroadcastBlock (Func<T, T> cloner) : this (cloner, defaultOptions)
  48                 {
  49
  50                 }
  51
  52                 public BroadcastBlock (Func<T, T> cloner, DataflowBlockOptions dataflowBlockOptions)
  53                 {
  54                         if (dataflowBlockOptions == null)
  55                                 throw new ArgumentNullException ("dataflowBlockOptions");
  56
  57                         this.cloner = cloner;
  58                         this.dataflowBlockOptions = dataflowBlockOptions;
  59                         this.messageBox = new PassingMessageBox<T> (messageQueue, compHelper, () => outgoing.IsCompleted, BroadcastProcess, dataflowBlockOptions);
  60                         this.outgoing = new MessageOutgoingQueue<T> (compHelper, () => messageQueue.IsCompleted);
  61                         this.vault = new MessageVault<T> ();
  62                 }
  63
  64                 public DataflowMessageStatus OfferMessage (DataflowMessageHeader messageHeader,
  65                                                            T messageValue,
  66                                                            ISourceBlock<T> source,
  67                                                            bool consumeToAccept)
  68                 {
  69                         return messageBox.OfferMessage (this, messageHeader, messageValue, source, consumeToAccept);
  70                 }
  71
  72                 public IDisposable LinkTo (ITargetBlock<T> target, bool unlinkAfterOne)
  73                 {
  74                         return targets.AddTarget (target, unlinkAfterOne);
  75                 }
  76
  77                 public T ConsumeMessage (DataflowMessageHeader messageHeader, ITargetBlock<T> target, out bool messageConsumed)
  78                 {
  79                         return cloner(vault.ConsumeMessage (messageHeader, target, out messageConsumed));
  80                 }
  81
  82                 public void ReleaseReservation (DataflowMessageHeader messageHeader, ITargetBlock<T> target)
  83                 {
  84                         vault.ReleaseReservation (messageHeader, target);
  85                 }
  86
  87                 public bool ReserveMessage (DataflowMessageHeader messageHeader, ITargetBlock<T> target)
  88                 {
  89                         return vault.ReserveMessage (messageHeader, target);
  90                 }
  91
  92                 public bool TryReceive (Predicate<T> filter, out T item)
  93                 {
  94                         return outgoing.TryReceive (filter, out item);
  95                 }
  96
  97                 public bool TryReceiveAll (out IList<T> items)
  98                 {
  99                         return outgoing.TryReceiveAll (out items);
 100                 }
 101
 102                 void BroadcastProcess ()
 103                 {
 104                         T input;
 105
 106                         if (!messageQueue.TryTake (out input) || targets.Current == null)
 107                                 return;
 108
 109                         foreach (var target in targets) {
 110                                 DataflowMessageHeader header = headers.Increment ();
 111                                 if (cloner != null)
 112                                         vault.StoreMessage (header, input);
 113                                 target.OfferMessage (header, input, this, cloner != null);
 114                                 // TODO: verify if it's the correct semantic
 115                                 T save = input;
 116                                 if (!messageQueue.TryTake (out input))
 117                                         input = save;
 118                         }
 119                 }
 120
 121                 public void Complete ()
 122                 {
 123                         messageBox.Complete ();
 124                 }
 125
 126                 public void Fault (Exception ex)
 127                 {
 128                         compHelper.Fault (ex);
 129                 }
 130
 131                 public Task Completion {
 132                         get {
 133                                 return compHelper.Completion;
 134                         }
 135                 }
 136         }
 137 }
 138