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

   1 // TransformManyBlock.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 TransformManyBlock<TInput, TOutput> :
  29                 IPropagatorBlock<TInput, TOutput>, IReceivableSourceBlock<TOutput> {
  30                 readonly CompletionHelper compHelper;
  31                 readonly BlockingCollection<TInput> messageQueue = new BlockingCollection<TInput> ();
  32                 readonly MessageBox<TInput> messageBox;
  33                 readonly ExecutionDataflowBlockOptions dataflowBlockOptions;
  34                 readonly Func<TInput, IEnumerable<TOutput>> transform;
  35                 readonly Func<TInput, Task<IEnumerable<TOutput>>> asyncTransform;
  36                 readonly OutgoingQueue<TOutput> outgoing;
  37
  38                 TransformManyBlock (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 TransformManyBlock (Func<TInput, IEnumerable<TOutput>> transform)
  48                         : this (transform, ExecutionDataflowBlockOptions.Default)
  49                 {
  50                 }
  51
  52                 public TransformManyBlock (Func<TInput, IEnumerable<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> (this, messageQueue, compHelper,
  61                                 () => outgoing.IsCompleted, TransformProcess, () => outgoing.Complete (),
  62                                 dataflowBlockOptions);
  63                         this.outgoing = new OutgoingQueue<TOutput> (this, compHelper,
  64                                 () => messageQueue.IsCompleted, messageBox.DecreaseCount,
  65                                 dataflowBlockOptions);
  66                 }
  67
  68                 public TransformManyBlock (Func<TInput, Task<IEnumerable<TOutput>>> transform)
  69                         : this (transform, ExecutionDataflowBlockOptions.Default)
  70                 {
  71                 }
  72
  73                 public TransformManyBlock (Func<TInput, Task<IEnumerable<TOutput>>> transform,
  74                                            ExecutionDataflowBlockOptions dataflowBlockOptions)
  75                         : this (dataflowBlockOptions)
  76                 {
  77                         if (transform == null)
  78                                 throw new ArgumentNullException ("transform");
  79
  80                         this.asyncTransform = transform;
  81                         this.messageBox = new AsyncExecutingMessageBox<TInput, Task<IEnumerable<TOutput>>> (this, messageQueue, compHelper,
  82                                 () => outgoing.IsCompleted, AsyncTransformProcess, ProcessFinishedTask, () => outgoing.Complete (),
  83                                 dataflowBlockOptions);
  84                         this.outgoing = new OutgoingQueue<TOutput> (this, compHelper,
  85                                 () => messageQueue.IsCompleted, messageBox.DecreaseCount,
  86                                 dataflowBlockOptions);
  87                 }
  88
  89                 DataflowMessageStatus ITargetBlock<TInput>.OfferMessage (
  90                         DataflowMessageHeader messageHeader, TInput messageValue,
  91                         ISourceBlock<TInput> source, bool consumeToAccept)
  92                 {
  93                         return messageBox.OfferMessage (messageHeader, messageValue, source, consumeToAccept);
  94                 }
  95
  96                 public IDisposable LinkTo (ITargetBlock<TOutput> target, DataflowLinkOptions linkOptions)
  97                 {
  98                         return outgoing.AddTarget (target, linkOptions);
  99                 }
 100
 101                 TOutput ISourceBlock<TOutput>.ConsumeMessage (
 102                         DataflowMessageHeader messageHeader, ITargetBlock<TOutput> target,
 103                         out bool messageConsumed)
 104                 {
 105                         return outgoing.ConsumeMessage (messageHeader, target, out messageConsumed);
 106                 }
 107
 108                 void ISourceBlock<TOutput>.ReleaseReservation (
 109                         DataflowMessageHeader messageHeader, ITargetBlock<TOutput> target)
 110                 {
 111                         outgoing.ReleaseReservation (messageHeader, target);
 112                 }
 113
 114                 bool ISourceBlock<TOutput>.ReserveMessage (
 115                         DataflowMessageHeader messageHeader, ITargetBlock<TOutput> target)
 116                 {
 117                         return outgoing.ReserveMessage (messageHeader, target);
 118                 }
 119
 120                 public bool TryReceive (Predicate<TOutput> filter, out TOutput item)
 121                 {
 122                         return outgoing.TryReceive (filter, out item);
 123                 }
 124
 125                 public bool TryReceiveAll (out IList<TOutput> items)
 126                 {
 127                         return outgoing.TryReceiveAll (out items);
 128                 }
 129
 130                 /// <summary>
 131                 /// Transforms one item from the queue if the transform delegate is synchronous.
 132                 /// </summary>
 133                 /// <returns>Returns whether an item was processed. Returns <c>false</c> if the queue is empty.</returns>
 134                 bool TransformProcess ()
 135                 {
 136                         TInput input;
 137
 138                         var dequeued = messageQueue.TryTake (out input);
 139                         if (dequeued) {
 140                                 var result = transform (input);
 141
 142                                 EnqueueTransformed (result);
 143                         }
 144
 145                         return dequeued;
 146                 }
 147
 148                 /// <summary>
 149                 /// Adds the transformed collection to the output queue.
 150                 /// </summary>
 151                 void EnqueueTransformed (IEnumerable<TOutput> transformed)
 152                 {
 153                         bool first = true;
 154                         if (transformed != null) {
 155                                 foreach (var item in transformed) {
 156                                         if (first)
 157                                                 first = false;
 158                                         else
 159                                                 messageBox.IncreaseCount ();
 160                                         outgoing.AddData (item);
 161                                 }
 162                         }
 163                         if (first)
 164                                 messageBox.DecreaseCount ();
 165                 }
 166
 167                 /// <summary>
 168                 /// Processes one item from the queue if the transform delegate is asynchronous.
 169                 /// </summary>
 170                 /// <param name="task">The Task that was returned by the synchronous part of the delegate.</param>
 171                 /// <returns>Returns whether an item was processed. Returns <c>false</c> if the queue was empty.</returns>
 172                 bool AsyncTransformProcess (out Task<IEnumerable<TOutput>> task)
 173                 {
 174                         TInput input;
 175
 176                         var dequeued = messageQueue.TryTake (out input);
 177                         if (dequeued)
 178                                 task = asyncTransform (input);
 179                         else
 180                                 task = null;
 181
 182                         return dequeued;
 183                 }
 184
 185                 /// <summary>
 186                 /// Process result of finished asynchronous transformation.
 187                 /// </summary>
 188                 void ProcessFinishedTask (Task<IEnumerable<TOutput>> task)
 189                 {
 190                         if (task == null || task.IsCanceled)
 191                                 messageBox.DecreaseCount ();
 192                         else
 193                                 EnqueueTransformed (task.Result);
 194                 }
 195
 196                 public void Complete ()
 197                 {
 198                         messageBox.Complete ();
 199                 }
 200
 201                 void IDataflowBlock.Fault (Exception exception)
 202                 {
 203                         compHelper.RequestFault (exception);
 204                 }
 205
 206                 public Task Completion {
 207                         get { return compHelper.Completion; }
 208                 }
 209
 210                 public int OutputCount {
 211                         get { return outgoing.Count; }
 212                 }
 213
 214                 public int InputCount {
 215                         get { return messageQueue.Count; }
 216                 }
 217
 218                 public override string ToString ()
 219                 {
 220                         return NameHelper.GetName (this, dataflowBlockOptions);
 221                 }
 222         }
 223 }