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

   1 // TransformBlock.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 TransformBlock<TInput, TOutput> :
  29                 IPropagatorBlock<TInput, TOutput>, IReceivableSourceBlock<TOutput> {
  30                 readonly ExecutionDataflowBlockOptions dataflowBlockOptions;
  31                 readonly CompletionHelper compHelper;
  32                 readonly BlockingCollection<TInput> messageQueue = new BlockingCollection<TInput> ();
  33                 readonly MessageBox<TInput> messageBox;
  34                 readonly OutgoingQueue<TOutput> outgoing;
  35                 readonly Func<TInput, TOutput> transform;
  36                 readonly Func<TInput, Task<TOutput>> asyncTransform;
  37
  38                 TransformBlock (ExecutionDataflowBlockOptions dataflowBlockOptions)
  39                 {
  40                         if (dataflowBlockOptions == null)
  41                                 throw new ArgumentNullException ("dataflowBlockOptions");
  42
  43                         this.dataflowBlockOptions = dataflowBlockOptions;
  44                         this.compHelper = new CompletionHelper (dataflowBlockOptions);
  45                 }
  46
  47                 public TransformBlock (Func<TInput, TOutput> transform)
  48                         : this (transform, ExecutionDataflowBlockOptions.Default)
  49                 {
  50                 }
  51
  52                 public TransformBlock (Func<TInput, TOutput> transform,
  53                                        ExecutionDataflowBlockOptions dataflowBlockOptions)
  54                         : this (dataflowBlockOptions)
  55                 {
  56                         if (transform == null)
  57                                 throw new ArgumentNullException("transform");
  58
  59                         this.transform = transform;
  60                         this.messageBox = new ExecutingMessageBox<TInput> (
  61                                 this, messageQueue, compHelper,
  62                                 () => outgoing.IsCompleted, TransformProcess, () => outgoing.Complete (),
  63                                 dataflowBlockOptions);
  64                         this.outgoing = new OutgoingQueue<TOutput> (this, compHelper,
  65                                 () => messageQueue.IsCompleted, messageBox.DecreaseCount,
  66                                 dataflowBlockOptions);
  67                 }
  68
  69                 public TransformBlock(Func<TInput, Task<TOutput>> transform)
  70                         : this(transform, ExecutionDataflowBlockOptions.Default)
  71                 {
  72                 }
  73
  74                 public TransformBlock (Func<TInput, Task<TOutput>> transform,
  75                                        ExecutionDataflowBlockOptions dataflowBlockOptions)
  76                         : this (dataflowBlockOptions)
  77                 {
  78                         if (transform == null)
  79                                 throw new ArgumentNullException("transform");
  80
  81                         this.asyncTransform = transform;
  82                         this.messageBox = new AsyncExecutingMessageBox<TInput, Task<TOutput>> (
  83                                 this, messageQueue, compHelper, () => outgoing.IsCompleted,
  84                                 AsyncTransformProcess, AsyncProcessFinishedTask, () => outgoing.Complete (),
  85                                 dataflowBlockOptions);
  86                         this.outgoing = new OutgoingQueue<TOutput> (this, compHelper,
  87                                 () => messageQueue.IsCompleted, messageBox.DecreaseCount,
  88                                 dataflowBlockOptions);
  89                 }
  90
  91                 DataflowMessageStatus ITargetBlock<TInput>.OfferMessage (
  92                         DataflowMessageHeader messageHeader, TInput messageValue,
  93                         ISourceBlock<TInput> source, bool consumeToAccept)
  94                 {
  95                         return messageBox.OfferMessage (messageHeader, messageValue, source, consumeToAccept);
  96                 }
  97
  98                 public IDisposable LinkTo (ITargetBlock<TOutput> target, DataflowLinkOptions linkOptions)
  99                 {
 100                         return outgoing.AddTarget (target, linkOptions);
 101                 }
 102
 103                 TOutput ISourceBlock<TOutput>.ConsumeMessage (
 104                         DataflowMessageHeader messageHeader, ITargetBlock<TOutput> target,
 105                         out bool messageConsumed)
 106                 {
 107                         return outgoing.ConsumeMessage (messageHeader, target, out messageConsumed);
 108                 }
 109
 110                 void ISourceBlock<TOutput>.ReleaseReservation (
 111                         DataflowMessageHeader messageHeader, ITargetBlock<TOutput> target)
 112                 {
 113                         outgoing.ReleaseReservation (messageHeader, target);
 114                 }
 115
 116                 bool ISourceBlock<TOutput>.ReserveMessage (
 117                         DataflowMessageHeader messageHeader, ITargetBlock<TOutput> target)
 118                 {
 119                         return outgoing.ReserveMessage (messageHeader, target);
 120                 }
 121
 122                 public bool TryReceive (Predicate<TOutput> filter, out TOutput item)
 123                 {
 124                         return outgoing.TryReceive (filter, out item);
 125                 }
 126
 127                 public bool TryReceiveAll (out IList<TOutput> items)
 128                 {
 129                         return outgoing.TryReceiveAll (out items);
 130                 }
 131
 132                 /// <summary>
 133                 /// Transforms one item from the queue if the transform delegate is synchronous.
 134                 /// </summary>
 135                 /// <returns>Returns whether an item was processed. Returns <c>false</c> if the queue is empty.</returns>
 136                 bool TransformProcess ()
 137                 {
 138                         TInput input;
 139
 140                         var dequeued = messageQueue.TryTake (out input);
 141                         if (dequeued)
 142                                 outgoing.AddData (transform (input));
 143
 144                         return dequeued;
 145                 }
 146
 147                 /// <summary>
 148                 /// Processes one item from the queue if the transform delegate is asynchronous.
 149                 /// </summary>
 150                 /// <param name="task">The Task that was returned by the synchronous part of the delegate.</param>
 151                 /// <returns>Returns whether an item was processed. Returns <c>false</c> if the queue was empty.</returns>
 152                 bool AsyncTransformProcess (out Task<TOutput> task)
 153                 {
 154                         TInput input;
 155
 156                         var dequeued = messageQueue.TryTake (out input);
 157                         if (dequeued)
 158                                 task = asyncTransform (input);
 159                         else
 160                                 task = null;
 161
 162                         return dequeued;
 163                 }
 164
 165                 /// <summary>
 166                 /// Process result of finished asynchronous transformation.
 167                 /// </summary>
 168                 void AsyncProcessFinishedTask (Task<TOutput> task)
 169                 {
 170                         if (task == null || task.IsCanceled)
 171                                 messageBox.DecreaseCount ();
 172                         else
 173                                 outgoing.AddData (task.Result);
 174                 }
 175
 176                 public void Complete ()
 177                 {
 178                         messageBox.Complete ();
 179                 }
 180
 181                 void IDataflowBlock.Fault (Exception exception)
 182                 {
 183                         compHelper.RequestFault (exception);
 184                 }
 185
 186                 public Task Completion {
 187                         get { return compHelper.Completion; }
 188                 }
 189
 190                 public int OutputCount {
 191                         get { return outgoing.Count; }
 192                 }
 193
 194                 public int InputCount {
 195                         get { return messageQueue.Count; }
 196                 }
 197
 198                 public override string ToString ()
 199                 {
 200                         return NameHelper.GetName (this, dataflowBlockOptions);
 201                 }
 202         }
 203 }