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 using System.Collections.Concurrent;\r
  43 using System.Diagnostics.Contracts;\r
  44 using Pithos.Interfaces;\r
  45 using Pithos.Network;\r
  46 using System;\r
  47 using System.Collections.Generic;\r
  48 using System.Linq;\r
  49 \r
  50 namespace Pithos.Core.Agents\r
  51 {\r
  52 \r
  53     /// <summary>\r
  54     /// Calculates the differences between two ObjectInfo snapshots.\r
  55     /// </summary>\r
  56     public class SnapshotDifferencer\r
  57     {\r
  58         /// <summary>\r
  59         /// Contains the previous and current listings.\r
  60         /// Using a separate class for the state simplifies the Post method\r
  61         /// which has to modify the listings\r
  62         /// </summary>\r
  63         private class State\r
  64         {\r
  65             /// <summary>\r
  66             /// The previous snapshot listing\r
  67             /// </summary>\r
  68             public readonly ObjectInfo[] Previous;\r
  69 \r
  70             /// <summary>\r
  71             /// The current snapshot listing\r
  72             /// </summary>\r
  73             public readonly ObjectInfo[] Current;\r
  74 \r
  75             public readonly Dictionary<string, ObjectInfo> CurrentDict;\r
  76 \r
  77             public readonly Dictionary<string, ObjectInfo> PreviousDict;\r
  78 \r
  79 \r
  80             /// <summary>\r
  81             /// Common objects, lazily evalueated. \r
  82             /// The common objects are used to calculate both the Changed and Unchanged objects\r
  83             /// </summary>\r
  84             public readonly Lazy<IEnumerable<ObjectInfo>> Common;\r
  85 \r
  86             private readonly static ObjectInfo[] Empty = new ObjectInfo[0];\r
  87 \r
  88             [ContractInvariantMethod]\r
  89             private void StatInvariant()\r
  90             {\r
  91 // ReSharper disable InvocationIsSkipped\r
  92                 Contract.Invariant(Current!=null);\r
  93                 Contract.Invariant(Previous!=null);\r
  94                 Contract.Invariant(CurrentDict!=null);\r
  95                 Contract.Invariant(PreviousDict!=null);\r
  96                 Contract.Invariant(Common!=null);\r
  97 // ReSharper restore InvocationIsSkipped\r
  98             }\r
  99 \r
 100             public State(ObjectInfo[] previous, ObjectInfo[] current)\r
 101             {\r
 102                 Previous = previous ?? Empty;\r
 103                 Current = current ?? Empty;\r
 104                 CurrentDict = Current.ToDictionary(info => info.UUID);\r
 105                 PreviousDict = Previous.ToDictionary(info => info.UUID);\r
 106 \r
 107                 Common=new Lazy<IEnumerable<ObjectInfo>>(() =>\r
 108                     Current.Join(Previous,\r
 109                                 outKey => outKey.UUID,\r
 110                                 inKey => inKey.UUID,\r
 111                                 (outer, inner) =>outer.SetPrevious(inner)));            \r
 112             }\r
 113         }\r
 114 \r
 115 \r
 116         private State _state;\r
 117 \r
 118         /// <summary>\r
 119         /// The comparer used to identify common objects.\r
 120         /// Objects are considered common when they have the same Account, Container and Name\r
 121         /// </summary>\r
 122         private readonly ObjectInfoComparer _comparer = new ObjectInfoComparer();\r
 123 \r
 124         /// <summary>\r
 125         /// Default constructor. Initializes the Current and Previous listings to empty lists\r
 126         /// </summary>\r
 127         public SnapshotDifferencer()\r
 128         {                        \r
 129             _state = new State(null, null);\r
 130         }\r
 131 \r
 132         /// <summary>\r
 133         /// Posts a new listing\r
 134         /// </summary>\r
 135         /// <param name="list"></param>\r
 136         /// <returns></returns>\r
 137         public SnapshotDifferencer Post(IEnumerable<ObjectInfo> list)\r
 138         {\r
 139             ObjectInfo[] newCurrent=null;\r
 140             if (list != null)\r
 141             {\r
 142                 //The state field holds the old state\r
 143                 var oldState = _state;\r
 144                 //Replace any NoModification entries with previous values that have\r
 145                 //the same account, container and possibly, folder\r
 146                 newCurrent = list.Replace(\r
 147                     info => info is NoModificationInfo,\r
 148                     noMod => oldState.Current.Where(noMod.CorrespondsTo))\r
 149                     .ToArray();\r
 150             }\r
 151             //Set the new state\r
 152             _state = new State(_state.Current, newCurrent);\r
 153 \r
 154             return this;\r
 155         }\r
 156         \r
 157         /// <summary>\r
 158         /// Deleted objects are those that existed in the Previous listing\r
 159         /// but are not found in the Current listing, and their UUIDs do not\r
 160         /// appear in the Current listing (ie they were not renamed/moved)\r
 161         /// </summary>\r
 162         public IEnumerable<ObjectInfo> Deleted\r
 163         {\r
 164             get { return _state.Previous.Except(_state.Current,_comparer)\r
 165                 .Where(info=>!_state.CurrentDict.ContainsKey(info.UUID)); }\r
 166         }\r
 167 \r
 168         /// <summary>\r
 169         /// Created objects are those that exist in the Current listing\r
 170         /// but are not found in the Previous listing, and their UUIDs do not\r
 171         /// appear in the Previous listing (ie they were not renamed/moved)\r
 172         /// </summary>\r
 173         public IEnumerable<ObjectInfo> Created\r
 174         {\r
 175             get { return _state.Current.Except(_state.Previous,_comparer)\r
 176                 .Where(info=>!_state.PreviousDict.ContainsKey(info.UUID)); }\r
 177         }\r
 178                 \r
 179         public IEnumerable<ObjectInfo> Common\r
 180         {\r
 181             get { return _state.Common.Value; }\r
 182         }\r
 183 \r
 184         public IEnumerable<ObjectInfo> Changed\r
 185         {\r
 186             get\r
 187             {\r
 188                 return Common.Where(i => i.PreviousHash != i.Hash && (i.Previous == null ||  i.Uri == i.Previous.Uri));}\r
 189         }\r
 190         public IEnumerable<ObjectInfo> Unchanged\r
 191         {\r
 192             get{ return Common.Where(i => i.PreviousHash == i.Hash);}\r
 193         }\r
 194 \r
 195         public IEnumerable<ObjectInfo>  Moved\r
 196         {\r
 197             get\r
 198             {\r
 199                                 \r
 200                 return _state.Current.Join(_state.Previous,\r
 201                                     outer => outer.UUID,\r
 202                                     inner => inner.UUID,\r
 203                                     (outer, inner) => (outer.Name == inner.Name ? null : outer.SetPrevious(inner)))\r
 204                     .Where(t => t != null);                \r
 205             }\r
 206         }\r
 207     }\r
 208 \r
 209     public class AccountsDifferencer\r
 210     {\r
 211         readonly ConcurrentDictionary<string, SnapshotDifferencer> _differencers = new ConcurrentDictionary<string, SnapshotDifferencer>();\r
 212 \r
 213         public ConcurrentDictionary<string, SnapshotDifferencer> Differencers { get { return _differencers; } }\r
 214 \r
 215         public SnapshotDifferencer PostSnapshot(AccountInfo accountInfo, List<ObjectInfo> cleanRemotes)\r
 216         {\r
 217             SnapshotDifferencer differencer;\r
 218             if (!_differencers.TryGetValue(accountInfo.UserName, out differencer))\r
 219             {\r
 220                 differencer = new SnapshotDifferencer();\r
 221                 _differencers[accountInfo.UserName] = differencer;\r
 222             }\r
 223             differencer.Post(cleanRemotes);\r
 224             return differencer;\r
 225         }\r
 226 \r
 227     }\r
 228 }\r