//
// ListPartitioner.cs
//
// Author:
// Jrmie "Garuma" Laval <jeremie.laval@gmail.com>
//
// Copyright (c) 2009 Jrmie "Garuma" Laval
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
using System;
using System.Collections.Generic;
#if NET_4_0 || BOOTSTRAP_NET_4_0
namespace System.Collections.Concurrent{
// Represent a Range partitioner
internal class ListPartitioner<T> : OrderablePartitioner<T>
{
IList<T> source;
readonly bool chunking = Environment.GetEnvironmentVariable ("PLINQ_PARTITIONING_HINT") == "chunking";
public ListPartitioner (IList<T> source) : base (true, true, true)
{
this.source = source;
}
public override IList<IEnumerator<KeyValuePair<long, T>>> GetOrderablePartitions (int partitionCount)
{
if (partitionCount <= 0)
throw new ArgumentOutOfRangeException ("partitionCount");
IEnumerator<KeyValuePair<long, T>>[] enumerators
= new IEnumerator<KeyValuePair<long, T>>[partitionCount];
int count = source.Count / partitionCount;
if (count <= 1)
count = 1;
for (int i = 0; i < enumerators.Length; i++) {
if (chunking) {
const int step = 64;
enumerators[i] = GetEnumeratorForRange (i * step, enumerators.Length, source.Count, step);
continue;
}
if (i != enumerators.Length - 1)
enumerators[i] = GetEnumeratorForRange (i * count, i * count + count);
else
enumerators[i] = GetEnumeratorForRange (i * count, source.Count);
}
return enumerators;
}
IEnumerator<KeyValuePair<long, T>> GetEnumeratorForRange (int startIndex, int lastIndex)
{
if (startIndex >= source.Count)
return GetEmpty ();
return GetEnumeratorForRangeInternal (startIndex, lastIndex);
}
IEnumerator<KeyValuePair<long, T>> GetEnumeratorForRange (int startIndex, int stride, int count, int step)
{
if (startIndex >= source.Count)
return GetEmpty ();
return GetEnumeratorForRangeInternal (startIndex, stride, count, step);
}
IEnumerator<KeyValuePair<long, T>> GetEmpty ()
{
yield break;
}
IEnumerator<KeyValuePair<long, T>> GetEnumeratorForRangeInternal (int startIndex, int lastIndex)
{
for (int i = startIndex; i < lastIndex; i++) {
yield return new KeyValuePair<long, T> (i, source[i]);
}
}
IEnumerator<KeyValuePair<long, T>> GetEnumeratorForRangeInternal (int startIndex, int stride, int count, int step)
{
for (int i = startIndex; i < count; i += stride * step) {
for (int j = i; j < i + step && j < count; j++) {
yield return new KeyValuePair<long, T> (j, source[j]);
}
}
}
}
}
#endif
|