//
// EnumerablePartitioner.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.
#if NET_4_0 || BOOTSTRAP_NET_4_0
using System;
using System.Threading.Tasks;
using System.Collections.Generic;
namespace System.Collections.Concurrent{
// Represent a chunk partitioner
internal class EnumerablePartitioner<T> : OrderablePartitioner<T>
{
IEnumerable<T> source;
const int InitialPartitionSize = 1;
const int PartitionMultiplier = 2;
int initialPartitionSize;
int partitionMultiplier;
int index = 0;
readonly object syncLock = new object ();
public EnumerablePartitioner (IEnumerable<T> source)
: this (source, InitialPartitionSize, PartitionMultiplier)
{
}
// This is used to get striped partitionning (for Take and Skip for instance
public EnumerablePartitioner (IEnumerable<T> source, int initialPartitionSize, int partitionMultiplier)
: base (true, false, true)
{
this.source = source;
this.initialPartitionSize = initialPartitionSize;
this.partitionMultiplier = partitionMultiplier;
}
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];
IEnumerator<T> src = source.GetEnumerator ();
for (int i = 0; i < enumerators.Length; i++) {
enumerators[i] = GetPartitionEnumerator (src);
}
return enumerators;
}
IEnumerator<KeyValuePair<long, T>> GetPartitionEnumerator (IEnumerator<T> src)
{
int count = initialPartitionSize;
List<T> list = new List<T> ();
while (true) {
list.Clear ();
int ind = -1;
lock (syncLock) {
ind = index;
for (int i = 0; i < count; i++) {
if (!src.MoveNext ()) {
if (list.Count == 0)
yield break;
else
break;
}
list.Add (src.Current);
index++;
}
}
for (int i = 0; i < list.Count; i++)
yield return new KeyValuePair<long, T> (ind + i, list[i]);
count *= partitionMultiplier;
}
}
}
}
#endif
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