class/System.Core/System.Linq/ParallelQueryEnumerator.cs

   1 //
   2 // ParallelEnumerator.cs
   3 //
   4 // Author:
   5 //       Jérémie "Garuma" Laval <jeremie.laval@gmail.com>
   6 //
   7 // Copyright (c) 2010 Jérémie "Garuma" Laval
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining a copy
  10 // of this software and associated documentation files (the "Software"), to deal
  11 // in the Software without restriction, including without limitation the rights
  12 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  13 // copies of the Software, and to permit persons to whom the Software is
  14 // furnished to do so, subject to the following conditions:
  15 //
  16 // The above copyright notice and this permission notice shall be included in
  17 // all copies or substantial portions of the Software.
  18 //
  19 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  22 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  23 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  24 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  25 // THE SOFTWARE.
  26
  27 using System;
  28 using System.Threading;
  29 using System.Collections;
  30 using System.Collections.Generic;
  31 using System.Collections.Concurrent;
  32
  33 #if NET_4_0
  34
  35 namespace System.Linq
  36 {
  37         internal class ParallelQueryEnumerator<T> : IEnumerator<T>
  38         {
  39                 readonly int DefaultBufferSize = ParallelExecuter.GetBestWorkerNumber () * 50;
  40
  41                 BlockingCollection<T> buffer;
  42                 IEnumerator<T> loader;
  43                 QueryOptions options;
  44                 OrderingEnumerator<T> ordEnumerator;
  45
  46                 T current;
  47
  48                 Action waitAction;
  49
  50                 internal ParallelQueryEnumerator (QueryBaseNode<T> node)
  51                 {
  52                         this.options = ParallelExecuter.CheckQuery (node);
  53                         Setup ();
  54
  55                         // Launch adding to the buffer asynchronously via Tasks
  56                         if (options.BehindOrderGuard.Value) {
  57                                 waitAction = ParallelExecuter.ProcessAndCallback (node,
  58                                                                                   (e, i) => ordEnumerator.Add (e),
  59                                                                                   (i) => ordEnumerator.EndParticipation (),
  60                                                                                   ordEnumerator.Stop,
  61                                                                                   options);
  62                         } else {
  63                                 waitAction = ParallelExecuter.ProcessAndCallback (node,
  64                                                                                   buffer.Add,
  65                                                                                   buffer.CompleteAdding,
  66                                                                                   options);
  67                         }
  68
  69                         if (options.Options.HasValue && options.Options.Value == ParallelMergeOptions.FullyBuffered)
  70                                 waitAction ();
  71                 }
  72
  73                 void Setup ()
  74                 {
  75                         if (!options.BehindOrderGuard.Value) {
  76                                 if (options.Options.HasValue && (options.Options.Value == ParallelMergeOptions.NotBuffered
  77                                                                  || options.Options.Value == ParallelMergeOptions.FullyBuffered)) {
  78                                         buffer = new BlockingCollection<T> ();
  79                                 } else {
  80                                         buffer = new BlockingCollection<T> (DefaultBufferSize);
  81                                 }
  82
  83                                 IEnumerable<T> source = buffer.GetConsumingEnumerable (options.Token);
  84
  85                                 loader = source.GetEnumerator ();
  86                         } else {
  87                                 loader = ordEnumerator = new OrderingEnumerator<T> (options.PartitionCount);
  88                         }
  89                 }
  90
  91                 public void Dispose ()
  92                 {
  93
  94                 }
  95
  96                 public void Reset ()
  97                 {
  98                         throw new NotSupportedException ();
  99                 }
 100
 101                 public bool MoveNext ()
 102                 {
 103                         // If there are no stuff in the buffer
 104                         // but CompleteAdding hasn't been called,
 105                         // MoveNext blocks until further results are produced
 106                         if (!loader.MoveNext ())
 107                                 return false;
 108
 109                         current = loader.Current;
 110                         return true;
 111                 }
 112
 113                 public T Current {
 114                         get {
 115                                 return current;
 116                         }
 117                 }
 118
 119                 object IEnumerator.Current {
 120                         get {
 121                                 return current;
 122                         }
 123                 }
 124         }
 125 }
 126 #endif