2 // EnumerablePartitioner.cs
5 // Jérémie "Garuma" Laval <jeremie.laval@gmail.com>
7 // Copyright (c) 2009 Jérémie "Garuma" Laval
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:
16 // The above copyright notice and this permission notice shall be included in
17 // all copies or substantial portions of the Software.
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
30 using System
.Threading
;
31 using System
.Threading
.Tasks
;
32 using System
.Collections
.Generic
;
34 namespace System
.Collections
.Concurrent
.Partitioners
36 // Represent a chunk partitioner
37 internal class EnumerablePartitioner
<T
> : OrderablePartitioner
<T
>
39 IEnumerable
<T
> source
;
41 const int InitialPartitionSize
= 1;
42 const int PartitionMultiplier
= 2;
44 int initialPartitionSize
;
45 int partitionMultiplier
;
47 public EnumerablePartitioner (IEnumerable
<T
> source
)
48 : this (source
, InitialPartitionSize
, PartitionMultiplier
)
53 // This is used to get striped partitionning (for Take and Skip for instance
54 public EnumerablePartitioner (IEnumerable
<T
> source
, int initialPartitionSize
, int partitionMultiplier
)
55 : base (true, false, true)
58 this.initialPartitionSize
= initialPartitionSize
;
59 this.partitionMultiplier
= partitionMultiplier
;
62 public override IList
<IEnumerator
<KeyValuePair
<long, T
>>> GetOrderablePartitions (int partitionCount
)
64 if (partitionCount
<= 0)
65 throw new ArgumentOutOfRangeException ("partitionCount");
67 IEnumerator
<KeyValuePair
<long, T
>>[] enumerators
68 = new IEnumerator
<KeyValuePair
<long, T
>>[partitionCount
];
70 PartitionerState state
= new PartitionerState ();
71 IEnumerator
<T
> src
= source
.GetEnumerator ();
72 bool isSimple
= initialPartitionSize
== 1 && partitionMultiplier
== 1;
74 for (int i
= 0; i
< enumerators
.Length
; i
++) {
75 enumerators
[i
] = isSimple
? GetPartitionEnumeratorSimple (src
, state
, i
== enumerators
.Length
- 1) : GetPartitionEnumerator (src
, state
);
81 // This partitioner that is simpler than the general case (don't use a list) is called in the case
82 // of initialPartitionSize == partitionMultiplier == 1
83 IEnumerator
<KeyValuePair
<long, T
>> GetPartitionEnumeratorSimple (IEnumerator
<T
> src
,
84 PartitionerState state
,
88 var value = default (T
);
92 lock (state
.SyncLock
) {
95 if (state
.Finished
= !src
.MoveNext ())
98 index
= state
.Index
++;
102 yield return new KeyValuePair
<long, T
> (index
, value);
103 } while (!state
.Finished
);
110 IEnumerator
<KeyValuePair
<long, T
>> GetPartitionEnumerator (IEnumerator
<T
> src
, PartitionerState state
)
112 int count
= initialPartitionSize
;
113 List
<T
> list
= new List
<T
> ();
115 while (!state
.Finished
) {
119 lock (state
.SyncLock
) {
125 for (int i
= 0; i
< count
; i
++) {
126 if (state
.Finished
= !src
.MoveNext ()) {
133 list
.Add (src
.Current
);
138 for (int i
= 0; i
< list
.Count
; i
++)
139 yield return new KeyValuePair
<long, T
> (ind
+ i
, list
[i
]);
141 count
*= partitionMultiplier
;
145 class PartitionerState
147 public bool Finished
;
148 public long Index
= 0;
149 public readonly object SyncLock
= new object ();