code.grnet.gr Git - pithos-ms-client/blob - trunk/Pithos.Core/Agents/SnapshotDifferencer.cs

   1 #region\r
   2 /* -----------------------------------------------------------------------\r
   3  * <copyright file="SnapshotDifferencer.cs" company="GRNet">\r
   4  * \r
   5  * Copyright 2011-2012 GRNET S.A. All rights reserved.\r
   6  *\r
   7  * Redistribution and use in source and binary forms, with or\r
   8  * without modification, are permitted provided that the following\r
   9  * conditions are met:\r
  10  *\r
  11  *   1. Redistributions of source code must retain the above\r
  12  *      copyright notice, this list of conditions and the following\r
  13  *      disclaimer.\r
  14  *\r
  15  *   2. Redistributions in binary form must reproduce the above\r
  16  *      copyright notice, this list of conditions and the following\r
  17  *      disclaimer in the documentation and/or other materials\r
  18  *      provided with the distribution.\r
  19  *\r
  20  *\r
  21  * THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS\r
  22  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED\r
  23  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR\r
  24  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR\r
  25  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,\r
  26  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT\r
  27  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF\r
  28  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED\r
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT\r
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN\r
  31  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE\r
  32  * POSSIBILITY OF SUCH DAMAGE.\r
  33  *\r
  34  * The views and conclusions contained in the software and\r
  35  * documentation are those of the authors and should not be\r
  36  * interpreted as representing official policies, either expressed\r
  37  * or implied, of GRNET S.A.\r
  38  * </copyright>\r
  39  * -----------------------------------------------------------------------\r
  40  */\r
  41 #endregion\r
  42 \r
  43 using System;\r
  44 using System.Collections.Concurrent;\r
  45 using System.Diagnostics.Contracts;\r
  46 using Pithos.Interfaces;\r
  47 using Pithos.Network;\r
  48 using System.Collections.Generic;\r
  49 using System.Linq;\r
  50 \r
  51 namespace Pithos.Core.Agents\r
  52 {\r
  53 \r
  54     /// <summary>\r
  55     /// Calculates the differences between two ObjectInfo snapshots.\r
  56     /// </summary>\r
  57     public class SnapshotDifferencer\r
  58     {\r
  59         /// <summary>\r
  60         /// Contains the previous and current listings.\r
  61         /// Using a separate class for the state simplifies the Post method\r
  62         /// which has to modify the listings\r
  63         /// </summary>\r
  64         private class State\r
  65         {\r
  66             /// <summary>\r
  67             /// The previous snapshot listing\r
  68             /// </summary>\r
  69             public readonly ObjectInfo[] Previous;\r
  70 \r
  71             /// <summary>\r
  72             /// The current snapshot listing\r
  73             /// </summary>\r
  74             public readonly ObjectInfo[] Current;\r
  75 \r
  76             public readonly Dictionary<string, ObjectInfo> CurrentDict;\r
  77 \r
  78             public readonly Dictionary<string, ObjectInfo> PreviousDict;\r
  79 \r
  80 \r
  81             /// <summary>\r
  82             /// Common objects, lazily evalueated. \r
  83             /// The common objects are used to calculate both the Changed and Unchanged objects\r
  84             /// </summary>\r
  85             public readonly IEnumerable<ObjectInfo> Common;\r
  86 \r
  87             private readonly static ObjectInfo[] Empty = new ObjectInfo[0];\r
  88 \r
  89             [ContractInvariantMethod]\r
  90             private void StatInvariant()\r
  91             {\r
  92 // ReSharper disable InvocationIsSkipped\r
  93                 Contract.Invariant(Current!=null);\r
  94                 Contract.Invariant(Previous!=null);\r
  95                 Contract.Invariant(CurrentDict!=null);\r
  96                 Contract.Invariant(PreviousDict!=null);\r
  97                 Contract.Invariant(Common!=null);\r
  98 // ReSharper restore InvocationIsSkipped\r
  99             }\r
 100 \r
 101             public State(ObjectInfo[] previous, ObjectInfo[] current)\r
 102             {\r
 103                 Previous = previous ?? Empty;\r
 104                 Current = current ?? Empty;\r
 105                 CurrentDict = Current.ToDictionary(info => info.UUID);\r
 106                 PreviousDict = Previous.ToDictionary(info => info.UUID);\r
 107 \r
 108                 //Attach the previous version to the current listings\r
 109                 foreach (var info in Current)\r
 110                 {\r
 111                     ObjectInfo prev;\r
 112                     if (PreviousDict.TryGetValue(info.UUID, out prev))\r
 113                         info.SetPrevious(prev);\r
 114                 }\r
 115 \r
 116                 Common=Current.Where(c=>c.Previous !=null);\r
 117             }\r
 118         }\r
 119 \r
 120 \r
 121         private State _state;\r
 122 \r
 123         /// <summary>\r
 124         /// Default constructor. Initializes the Current and Previous listings to empty lists\r
 125         /// </summary>\r
 126         public SnapshotDifferencer()\r
 127         {                        \r
 128             _state = new State(null, null);\r
 129         }\r
 130 \r
 131         /// <summary>\r
 132         /// Posts a new listing\r
 133         /// </summary>\r
 134         /// <param name="list"></param>\r
 135         /// <returns></returns>\r
 136         public SnapshotDifferencer Post(IEnumerable<ObjectInfo> list)\r
 137         {\r
 138             ObjectInfo[] newCurrent=null;\r
 139             if (list != null)\r
 140             {\r
 141                 //The state field holds the old state\r
 142                 var oldState = _state;\r
 143                 //Replace any NoModification entries with previous values that have\r
 144                 //the same account, container and possibly, folder\r
 145                 newCurrent = list.Replace(\r
 146                     info => info is NoModificationInfo,\r
 147                     noMod => oldState.Current.Where(noMod.CorrespondsTo))\r
 148                     .ToArray();\r
 149             }\r
 150             //Set the new state\r
 151             _state = new State(_state.Current, newCurrent);\r
 152 \r
 153             return this;\r
 154         }\r
 155         \r
 156         /// <summary>\r
 157         /// Deleted objects are those that existed in the Previous listing\r
 158         /// but are not found in the Current listing\r
 159         /// </summary>\r
 160         public IEnumerable<ObjectInfo> Deleted\r
 161         {\r
 162             get { return _state.Previous\r
 163                 .Where(info=>!_state.CurrentDict.ContainsKey(info.UUID)); }\r
 164         }\r
 165 \r
 166         /// <summary>\r
 167         /// Created objects are those that exist in the Current listing\r
 168         /// but are not found in the Previous listing \r
 169         /// </summary>\r
 170         public IEnumerable<ObjectInfo> Created\r
 171         {\r
 172             get { return _state.Current\r
 173                 .Where(info=>!_state.PreviousDict.ContainsKey(info.UUID)); }\r
 174         }\r
 175                 \r
 176         public IEnumerable<ObjectInfo> Common\r
 177         {\r
 178             get { return _state.Common; }\r
 179         }\r
 180 \r
 181         public IEnumerable<ObjectInfo> Changed\r
 182         {\r
 183             get\r
 184             {\r
 185                 return Common.Where(info => \r
 186                     //The hash is different\r
 187                     info.PreviousHash != info.Hash \r
 188                     //And the Uri is unchanged or there is no previous version\r
 189                     && (info.Previous == null ||  info.Uri == info.Previous.Uri));\r
 190             }\r
 191         }\r
 192 \r
 193         /// <summary>\r
 194         /// Unchanged objects have the same current and previous hash\r
 195         /// </summary>\r
 196         public IEnumerable<ObjectInfo> Unchanged\r
 197         {\r
 198             get{ return Common.Where(i => i.PreviousHash == i.Hash);}\r
 199         }\r
 200 \r
 201         /// <summary>\r
 202         /// Moved objects have a previous version with a different name\r
 203         /// </summary>\r
 204         public IEnumerable<ObjectInfo>  Moved\r
 205         {\r
 206             get\r
 207             {                                \r
 208                 return Common.Where(info=>\r
 209                     //A previous version exists\r
 210                     info.Previous!= null \r
 211                     //and the Uri is different\r
 212                     && info.Uri!=info.Previous.Uri);                    \r
 213             }\r
 214         }\r
 215     }\r
 216 \r
 217     public class AccountsDifferencer\r
 218     {\r
 219         readonly ConcurrentDictionary<Uri, SnapshotDifferencer> _differencers = new ConcurrentDictionary<Uri, SnapshotDifferencer>();\r
 220 \r
 221         public ConcurrentDictionary<Uri, SnapshotDifferencer> Differencers { get { return _differencers; } }\r
 222 \r
 223         public SnapshotDifferencer PostSnapshot(AccountInfo accountInfo, List<ObjectInfo> cleanRemotes)\r
 224         {\r
 225             SnapshotDifferencer differencer;\r
 226             if (!_differencers.TryGetValue(accountInfo.AccountKey, out differencer))\r
 227             {\r
 228                 differencer = new SnapshotDifferencer();\r
 229                 _differencers[accountInfo.AccountKey] = differencer;\r
 230             }\r
 231             differencer.Post(cleanRemotes);\r
 232             return differencer;\r
 233         }\r
 234 \r
 235     }\r
 236 }\r