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//
// EnumerablePartitioner.cs
//
// Author:
// Jérémie "Garuma" Laval <jeremie.laval@gmail.com>
//
// Copyright (c) 2009 Jérémie "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
using System;
using System.Threading;
using System.Threading.Tasks;
using System.Collections.Generic;
namespace System.Collections.Concurrent.Partitioners
{
// 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;
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];
PartitionerState state = new PartitionerState ();
IEnumerator<T> src = source.GetEnumerator ();
bool isSimple = initialPartitionSize == 1 && partitionMultiplier == 1;
for (int i = 0; i < enumerators.Length; i++) {
enumerators[i] = isSimple ? GetPartitionEnumeratorSimple (src, state, i == enumerators.Length - 1) : GetPartitionEnumerator (src, state);
}
return enumerators;
}
// This partitioner that is simpler than the general case (don't use a list) is called in the case
// of initialPartitionSize == partitionMultiplier == 1
IEnumerator<KeyValuePair<long, T>> GetPartitionEnumeratorSimple (IEnumerator<T> src,
PartitionerState state,
bool last)
{
long index = -1;
var value = default (T);
try {
do {
lock (state.SyncLock) {
if (state.Finished)
break;
if (state.Finished = !src.MoveNext ())
break;
index = state.Index++;
value = src.Current;
}
yield return new KeyValuePair<long, T> (index, value);
} while (!state.Finished);
} finally {
if (last)
src.Dispose ();
}
}
IEnumerator<KeyValuePair<long, T>> GetPartitionEnumerator (IEnumerator<T> src, PartitionerState state)
{
int count = initialPartitionSize;
List<T> list = new List<T> ();
while (!state.Finished) {
list.Clear ();
long ind = -1;
lock (state.SyncLock) {
if (state.Finished)
break;
ind = state.Index;
for (int i = 0; i < count; i++) {
if (state.Finished = !src.MoveNext ()) {
if (list.Count == 0)
yield break;
else
break;
}
list.Add (src.Current);
state.Index++;
}
}
for (int i = 0; i < list.Count; i++)
yield return new KeyValuePair<long, T> (ind + i, list[i]);
count *= partitionMultiplier;
}
}
class PartitionerState
{
public bool Finished;
public long Index = 0;
public readonly object SyncLock = new object ();
}
}
}
#endif
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