mcs/class/System.Core/System.Linq.Parallel.QueryNodes/QueryStartNode.cs

   1 //
   2 // QueryStartNode.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 #if NET_4_0
  28 using System;
  29 using System.Collections;
  30 using System.Collections.Generic;
  31 using System.Collections.Concurrent;
  32 using System.Threading;
  33 using System.Threading.Tasks;
  34
  35 namespace System.Linq.Parallel.QueryNodes
  36 {
  37         internal interface QueryStartNode : IVisitableNode {
  38                 int Count { get; }
  39         }
  40
  41         internal class QueryStartNode<T> : QueryBaseNode<T>, QueryStartNode
  42         {
  43                 readonly IEnumerable<T> source;
  44                 readonly Partitioner<T> customPartitioner;
  45
  46                 internal QueryStartNode (IEnumerable<T> source)
  47                 {
  48                         if (source == null)
  49                                 throw new ArgumentNullException ("source");
  50
  51                         this.source = source;
  52                 }
  53
  54                 internal QueryStartNode (Partitioner<T> custom)
  55                 {
  56                         if (custom == null)
  57                                 throw new ArgumentNullException ("custom");
  58
  59                         this.customPartitioner = custom;
  60                 }
  61
  62                 // If possible, this property will return the number of element the query
  63                 // is going to process. If that number if pretty low, executing the query
  64                 // sequentially is better
  65                 public int Count {
  66                         get {
  67                                 if (source == null)
  68                                         return -1;
  69
  70                                 ICollection coll = source as ICollection;
  71                                 return coll == null ? -1 : coll.Count;
  72                         }
  73                 }
  74
  75                 public override void Visit (INodeVisitor visitor)
  76                 {
  77                         visitor.Visit ((QueryStartNode)this);
  78                 }
  79
  80                 internal override IEnumerable<T> GetSequential ()
  81                 {
  82                         if (source != null)
  83                                 return source;
  84
  85                         return WrapHelper.Wrap (customPartitioner.GetPartitions (1))[0];
  86                 }
  87
  88                 internal override IList<IEnumerable<T>> GetEnumerables (QueryOptions options)
  89                 {
  90                         if (customPartitioner != null) {
  91                                 return WrapHelper.Wrap (customPartitioner.GetPartitions (options.PartitionCount));
  92                         }
  93
  94                         Partitioner<T> partitioner
  95                                 = (options.UseStrip) ? ParallelPartitioner.CreateForStrips (source, 1) : ParallelPartitioner.CreateBest (source);
  96
  97                         return WrapHelper.Wrap (partitioner.GetPartitions (options.PartitionCount));
  98                 }
  99
 100                 internal override IList<IEnumerable<KeyValuePair<long, T>>> GetOrderedEnumerables (QueryOptions options)
 101                 {
 102                         OrderablePartitioner<T> partitioner = null;
 103                         if (customPartitioner != null) {
 104                                 partitioner = customPartitioner as OrderablePartitioner<T>;
 105                                 if (partitioner == null)
 106                                         throw new InvalidOperationException ("The partitionner you are using doesn't support ordered partitionning");
 107                         } else {
 108                                 partitioner =
 109                                         (options.UseStrip) ? ParallelPartitioner.CreateForStrips (source, 1) : ParallelPartitioner.CreateBest (source);
 110                         }
 111
 112                         options.PartitionerSettings = Tuple.Create (partitioner.KeysOrderedAcrossPartitions,
 113                                                                     partitioner.KeysOrderedInEachPartition,
 114                                                                     partitioner.KeysNormalized);
 115
 116                         // We only support one style of partitioning at the moment.
 117                         // Standard partitioners follow this style.
 118                         if (options.UseStrip && (!partitioner.KeysOrderedInEachPartition || partitioner.KeysOrderedAcrossPartitions))
 119                                 throw new NotImplementedException ("Partitioner must have KeysOrderedInEachPartition "
 120                                                                    + "and !KeysOrderedAcrossPartitions"
 121                                                                    + "to be used with indexed operators");
 122
 123                         return WrapHelper.Wrap (partitioner.GetOrderablePartitions (options.PartitionCount));
 124                 }
 125         }
 126 }
 127 #endif