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

   1 // BatchBlock.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 BatchBlock<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 int batchSize;
  43                 int batchCount;
  44                 MessageOutgoingQueue<T[]> outgoing;
  45                 TargetBuffer<T[]> targets = new TargetBuffer<T[]> ();
  46                 DataflowMessageHeader headers = DataflowMessageHeader.NewValid ();
  47
  48                 public BatchBlock (int batchSize) : this (batchSize, defaultOptions)
  49                 {
  50
  51                 }
  52
  53                 public BatchBlock (int batchSize, DataflowBlockOptions dataflowBlockOptions)
  54                 {
  55                         if (dataflowBlockOptions == null)
  56                                 throw new ArgumentNullException ("dataflowBlockOptions");
  57
  58                         this.batchSize = batchSize;
  59                         this.dataflowBlockOptions = dataflowBlockOptions;
  60                         this.messageBox = new PassingMessageBox<T> (messageQueue, compHelper, () => outgoing.IsCompleted, BatchProcess, dataflowBlockOptions);
  61                         this.outgoing = new MessageOutgoingQueue<T[]> (compHelper, () => messageQueue.IsCompleted);
  62                         this.vault = new MessageVault<T[]> ();
  63                 }
  64
  65                 public DataflowMessageStatus OfferMessage (DataflowMessageHeader messageHeader,
  66                                                            T messageValue,
  67                                                            ISourceBlock<T> source,
  68                                                            bool consumeToAccept)
  69                 {
  70                         return messageBox.OfferMessage (this, messageHeader, messageValue, source, consumeToAccept);
  71                 }
  72
  73                 public IDisposable LinkTo (ITargetBlock<T[]> target, bool unlinkAfterOne)
  74                 {
  75                         var result = targets.AddTarget (target, unlinkAfterOne);
  76                         outgoing.ProcessForTarget (target, this, false, ref headers);
  77
  78                         return result;
  79                 }
  80
  81                 public T[] ConsumeMessage (DataflowMessageHeader messageHeader, ITargetBlock<T[]> target, out bool messageConsumed)
  82                 {
  83                         return vault.ConsumeMessage (messageHeader, target, out messageConsumed);
  84                 }
  85
  86                 public void ReleaseReservation (DataflowMessageHeader messageHeader, ITargetBlock<T[]> target)
  87                 {
  88                         vault.ReleaseReservation (messageHeader, target);
  89                 }
  90
  91                 public bool ReserveMessage (DataflowMessageHeader messageHeader, ITargetBlock<T[]> target)
  92                 {
  93                         return vault.ReserveMessage (messageHeader, target);
  94                 }
  95
  96                 public bool TryReceive (Predicate<T[]> filter, out T[] item)
  97                 {
  98                         return TryReceive (filter, out item);
  99                 }
 100
 101                 public bool TryReceiveAll (out IList<T[]> items)
 102                 {
 103                         return outgoing.TryReceiveAll (out items);
 104                 }
 105
 106                 public void TriggerBatch ()
 107                 {
 108                         int earlyBatchSize;
 109                         do {
 110                                 earlyBatchSize = batchCount;
 111                                 if (earlyBatchSize == 0)
 112                                         return;
 113                         } while (Interlocked.CompareExchange (ref batchCount, 0, earlyBatchSize) != earlyBatchSize);
 114
 115                         MakeBatch (targets.Current, earlyBatchSize);
 116                 }
 117
 118                 // TODO: there can be out-of-order processing of message elements if two collections
 119                 // are triggered and work side by side. See if it's a problem or not.
 120                 void BatchProcess ()
 121                 {
 122                         ITargetBlock<T[]> target = targets.Current;
 123                         int current = Interlocked.Increment (ref batchCount);
 124
 125                         if (current % batchSize != 0)
 126                                 return;
 127
 128                         Interlocked.Add (ref batchCount, -current);
 129
 130                         MakeBatch (target, batchSize);
 131                 }
 132
 133                 void MakeBatch (ITargetBlock<T[]> target, int size)
 134                 {
 135                         T[] batch = new T[size];
 136                         for (int i = 0; i < size; ++i)
 137                                 messageQueue.TryTake (out batch[i]);
 138
 139                         if (target == null)
 140                                 outgoing.AddData (batch);
 141                         else
 142                                 target.OfferMessage (headers.Increment (), batch, this, false);
 143
 144                         if (!outgoing.IsEmpty && targets.Current != null)
 145                                 outgoing.ProcessForTarget (targets.Current, this, false, ref headers);
 146                 }
 147
 148                 public void Complete ()
 149                 {
 150                         messageBox.Complete ();
 151                 }
 152
 153                 public void Fault (Exception ex)
 154                 {
 155                         compHelper.Fault (ex);
 156                 }
 157
 158                 public Task Completion {
 159                         get {
 160                                 return compHelper.Completion;
 161                         }
 162                 }
 163
 164                 public int OutputCount {
 165                         get {
 166                                 return outgoing.Count;
 167                         }
 168                 }
 169         }
 170 }
 171