root / trunk / Pithos.Core / Agents / SnapshotDifferencer.cs @ 6ef37eeb
History | View | Annotate | Download (6.8 kB)
1 |
#region |
---|---|
2 |
/* ----------------------------------------------------------------------- |
3 |
* <copyright file="SnapshotDifferencer.cs" company="GRNet"> |
4 |
* |
5 |
* Copyright 2011-2012 GRNET S.A. All rights reserved. |
6 |
* |
7 |
* Redistribution and use in source and binary forms, with or |
8 |
* without modification, are permitted provided that the following |
9 |
* conditions are met: |
10 |
* |
11 |
* 1. Redistributions of source code must retain the above |
12 |
* copyright notice, this list of conditions and the following |
13 |
* disclaimer. |
14 |
* |
15 |
* 2. Redistributions in binary form must reproduce the above |
16 |
* copyright notice, this list of conditions and the following |
17 |
* disclaimer in the documentation and/or other materials |
18 |
* provided with the distribution. |
19 |
* |
20 |
* |
21 |
* THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS |
22 |
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
23 |
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
24 |
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR |
25 |
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
26 |
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
27 |
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
28 |
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
29 |
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
30 |
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
31 |
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
32 |
* POSSIBILITY OF SUCH DAMAGE. |
33 |
* |
34 |
* The views and conclusions contained in the software and |
35 |
* documentation are those of the authors and should not be |
36 |
* interpreted as representing official policies, either expressed |
37 |
* or implied, of GRNET S.A. |
38 |
* </copyright> |
39 |
* ----------------------------------------------------------------------- |
40 |
*/ |
41 |
#endregion |
42 |
using System.Collections.Concurrent; |
43 |
using Pithos.Interfaces; |
44 |
using Pithos.Network; |
45 |
using System; |
46 |
using System.Collections.Generic; |
47 |
using System.Linq; |
48 |
|
49 |
namespace Pithos.Core.Agents |
50 |
{ |
51 |
|
52 |
/// <summary> |
53 |
/// Calculates the differences between two ObjectInfo snapshots. |
54 |
/// </summary> |
55 |
public class SnapshotDifferencer |
56 |
{ |
57 |
/// <summary> |
58 |
/// Contains the previous and current listings. |
59 |
/// Using a separate class for the state simplifies the Post method |
60 |
/// which has to modify the listings |
61 |
/// </summary> |
62 |
private class State |
63 |
{ |
64 |
/// <summary> |
65 |
/// The previous snapshot listing |
66 |
/// </summary> |
67 |
public readonly ObjectInfo[] Previous; |
68 |
|
69 |
/// <summary> |
70 |
/// The current snapshot listing |
71 |
/// </summary> |
72 |
public readonly ObjectInfo[] Current; |
73 |
|
74 |
/// <summary> |
75 |
/// Common objects, lazily evalueated. |
76 |
/// The common objects are used to calculate both the Changed and Unchanged objects |
77 |
/// </summary> |
78 |
public readonly Lazy<IEnumerable<ObjectInfo>> Common; |
79 |
|
80 |
private readonly static ObjectInfo[] Empty = new ObjectInfo[0]; |
81 |
|
82 |
public State(ObjectInfo[] previous, ObjectInfo[] current) |
83 |
{ |
84 |
Previous = previous ?? Empty; |
85 |
Current = current ?? Empty; |
86 |
|
87 |
Common=new Lazy<IEnumerable<ObjectInfo>>(() => |
88 |
Current.Join(Previous, |
89 |
outKey => new { outKey.Account, outKey.Container, outKey.Name }, |
90 |
inKey => new { inKey.Account, inKey.Container, inKey.Name }, |
91 |
(outer, inner) => |
92 |
{ |
93 |
outer.PreviousHash = inner.Hash; |
94 |
return outer; |
95 |
})); |
96 |
} |
97 |
} |
98 |
|
99 |
|
100 |
private State _state; |
101 |
|
102 |
/// <summary> |
103 |
/// The comparer used to identify common objects. |
104 |
/// Objects are considered common when they have the same Account, Container and Name |
105 |
/// </summary> |
106 |
private readonly ObjectInfoComparer _comparer = new ObjectInfoComparer(); |
107 |
|
108 |
/// <summary> |
109 |
/// Default constructor. Initializes the Current and Previous listings to empty lists |
110 |
/// </summary> |
111 |
public SnapshotDifferencer() |
112 |
{ |
113 |
_state = new State(null, null); |
114 |
} |
115 |
|
116 |
/// <summary> |
117 |
/// Posts a new listing |
118 |
/// </summary> |
119 |
/// <param name="list"></param> |
120 |
/// <returns></returns> |
121 |
public SnapshotDifferencer Post(IEnumerable<ObjectInfo> list) |
122 |
{ |
123 |
ObjectInfo[] newCurrent=null; |
124 |
if (list != null) |
125 |
{ |
126 |
//The state field holds the old state |
127 |
var oldState = _state; |
128 |
//Replace any NoModification entries with previous values that have |
129 |
//the same account, container and possibly, folder |
130 |
newCurrent = list.Replace( |
131 |
info => info is NoModificationInfo, |
132 |
noMod => oldState.Current.Where(noMod.CorrespondsTo)) |
133 |
.ToArray(); |
134 |
} |
135 |
//Set the new state |
136 |
_state = new State(_state.Current, newCurrent); |
137 |
|
138 |
return this; |
139 |
} |
140 |
|
141 |
public IEnumerable<ObjectInfo> Deleted |
142 |
{ |
143 |
get { return _state.Previous.Except(_state.Current,_comparer); } |
144 |
} |
145 |
public IEnumerable<ObjectInfo> Created |
146 |
{ |
147 |
get { return _state.Current.Except(_state.Previous,_comparer); } |
148 |
} |
149 |
|
150 |
public IEnumerable<ObjectInfo> Common |
151 |
{ |
152 |
get { return _state.Common.Value; } |
153 |
} |
154 |
|
155 |
public IEnumerable<ObjectInfo> Changed |
156 |
{ |
157 |
get{return Common.Where(i=>i.PreviousHash!=i.Hash);} |
158 |
} |
159 |
public IEnumerable<ObjectInfo> Unchanged |
160 |
{ |
161 |
get{ return Common.Where(i => i.PreviousHash == i.Hash);} |
162 |
} |
163 |
} |
164 |
|
165 |
public class AccountsDifferencer |
166 |
{ |
167 |
readonly ConcurrentDictionary<string, SnapshotDifferencer> _differencers = new ConcurrentDictionary<string, SnapshotDifferencer>(); |
168 |
|
169 |
public ConcurrentDictionary<string, SnapshotDifferencer> Differencers { get { return _differencers; } } |
170 |
|
171 |
public SnapshotDifferencer PostSnapshot(AccountInfo accountInfo, List<ObjectInfo> cleanRemotes) |
172 |
{ |
173 |
SnapshotDifferencer differencer; |
174 |
if (!_differencers.TryGetValue(accountInfo.UserName, out differencer)) |
175 |
{ |
176 |
differencer = new SnapshotDifferencer(); |
177 |
_differencers[accountInfo.UserName] = differencer; |
178 |
} |
179 |
differencer.Post(cleanRemotes); |
180 |
return differencer; |
181 |
} |
182 |
|
183 |
} |
184 |
} |