mcs/class/System.Data.Linq/src/DbLinq/Data/Linq/Implementation/EntityTracker.cs

   1 #region MIT license\r
   2 // \r
   3 // MIT license\r
   4 //\r
   5 // Copyright (c) 2007-2008 Jiri Moudry, Pascal Craponne\r
   6 // \r
   7 // Permission is hereby granted, free of charge, to any person obtaining a copy\r
   8 // of this software and associated documentation files (the "Software"), to deal\r
   9 // in the Software without restriction, including without limitation the rights\r
  10 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell\r
  11 // copies of the Software, and to permit persons to whom the Software is\r
  12 // furnished to do so, subject to the following conditions:\r
  13 // \r
  14 // The above copyright notice and this permission notice shall be included in\r
  15 // all copies or substantial portions of the Software.\r
  16 // \r
  17 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR\r
  18 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,\r
  19 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE\r
  20 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER\r
  21 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,\r
  22 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN\r
  23 // THE SOFTWARE.\r
  24 // \r
  25 #endregion\r
  26 \r
  27 using System;\r
  28 using System.Collections.Generic;\r
  29 using System.Linq;\r
  30 \r
  31 #if MONO_STRICT\r
  32 using System.Data.Linq.Identity;\r
  33 #else\r
  34 using DbLinq.Data.Linq.Identity;\r
  35 #endif\r
  36 \r
  37 #if MONO_STRICT\r
  38 namespace System.Data.Linq.Implementation\r
  39 #else\r
  40 namespace DbLinq.Data.Linq.Implementation\r
  41 #endif\r
  42 {\r
  43     /// <summary>\r
  44     /// List of entities, with their corresponding state (to insert, to watch, to delete)\r
  45     /// </summary>\r
  46     internal class EntityTracker\r
  47     {\r
  48         /// <summary>\r
  49         /// Entities being watched\r
  50         /// </summary>\r
  51         private readonly List<EntityTrack> entities = new List<EntityTrack>();\r
  52 \r
  53         /// <summary>\r
  54         /// Entities currently being watched and to be updated\r
  55         /// </summary>\r
  56         private readonly IDictionary<IdentityKey, EntityTrack> entitiesByKey = new Dictionary<IdentityKey, EntityTrack>();\r
  57 \r
  58         /// lock key, for thread safety\r
  59         private readonly object lockObject = new object();\r
  60 \r
  61         /// <summary>\r
  62         /// Finds an entity tracking info by object reference\r
  63         /// </summary>\r
  64         /// <param name="entity"></param>\r
  65         /// <returns></returns>\r
  66         public EntityTrack FindByReference(object entity)\r
  67         {\r
  68             lock (lockObject)\r
  69                 return (from e in entities where e.Entity == entity select e).FirstOrDefault();\r
  70         }\r
  71 \r
  72         /// <summary>\r
  73         /// Finds entity by key (PK)\r
  74         /// </summary>\r
  75         /// <param name="identityKey"></param>\r
  76         /// <returns></returns>\r
  77         public EntityTrack FindByIdentity(IdentityKey identityKey)\r
  78         {\r
  79             EntityTrack entityTrack;\r
  80             lock (lockObject)\r
  81                 entitiesByKey.TryGetValue(identityKey, out entityTrack);\r
  82             return entityTrack;\r
  83         }\r
  84 \r
  85         /// <summary>\r
  86         /// Returns true if the list contains the entity\r
  87         /// </summary>\r
  88         /// <param name="entity"></param>\r
  89         /// <returns></returns>\r
  90         public bool ContainsReference(object entity)\r
  91         {\r
  92             return FindByReference(entity) == null;\r
  93         }\r
  94 \r
  95         /// <summary>\r
  96         /// Registers an entity to be inserted\r
  97         /// </summary>\r
  98         /// <param name="entity"></param>\r
  99         public void RegisterToInsert(object entity)\r
 100         {\r
 101             if (entity == null)\r
 102                 throw new ArgumentNullException("entity");\r
 103 \r
 104             lock (lockObject)\r
 105             {\r
 106                 var entityTrack = FindByReference(entity);\r
 107                 if (entityTrack == null)\r
 108                 {\r
 109                     entityTrack = new EntityTrack(entity, EntityState.ToInsert);\r
 110                     entities.Add(entityTrack);\r
 111                 }\r
 112                 else\r
 113                 {\r
 114                     switch (entityTrack.EntityState)\r
 115                     {\r
 116                     // if already registered for insert/update, then this is an error\r
 117                     case EntityState.ToInsert:\r
 118                     case EntityState.ToWatch:\r
 119                         throw new InvalidOperationException();\r
 120                     // whenever the object is registered for deletion, the fact of\r
 121                     // registering it for insertion sets it back to watch\r
 122                     case EntityState.ToDelete:\r
 123                         entityTrack.EntityState = EntityState.ToWatch;\r
 124                         entitiesByKey[entityTrack.IdentityKey] = entityTrack;\r
 125                         break;\r
 126                     default:\r
 127                         throw new ArgumentOutOfRangeException();\r
 128                     }\r
 129                 }\r
 130             }\r
 131         }\r
 132 \r
 133         /// <summary>\r
 134         /// Registers an entity to be watched\r
 135         /// </summary>\r
 136         /// <param name="entity"></param>\r
 137         /// <param name="identityKey"></param>\r
 138         public void RegisterToWatch(object entity, IdentityKey identityKey)\r
 139         {\r
 140             lock (lockObject)\r
 141             {\r
 142                 var entityTrack = FindByReference(entity);\r
 143                 Console.WriteLine("# RegisterToWatch({0}, {1})", entity, identityKey);\r
 144                 Console.WriteLine("# entityTrack={0}", entityTrack);\r
 145                 if (entityTrack == null)\r
 146                 {\r
 147                     entityTrack = new EntityTrack(entity, EntityState.ToWatch) { IdentityKey = identityKey };\r
 148                     entities.Add(entityTrack);\r
 149                     entitiesByKey[identityKey] = entityTrack;\r
 150                 }\r
 151                 else\r
 152                 {\r
 153                     Console.WriteLine("# have entityTrack; entityState={0}", entityTrack.EntityState);\r
 154                     // changes the state of the current entity\r
 155                     switch (entityTrack.EntityState)\r
 156                     {\r
 157                     case EntityState.ToInsert:\r
 158                         entityTrack.EntityState = EntityState.ToWatch;\r
 159                         entityTrack.IdentityKey = identityKey;\r
 160                         entitiesByKey[identityKey] = entityTrack;\r
 161                         break;\r
 162                     // watched entities should not be registered again\r
 163                     case EntityState.ToWatch:\r
 164                     case EntityState.ToDelete:\r
 165                         throw new InvalidOperationException();\r
 166                     default:\r
 167                         throw new ArgumentOutOfRangeException();\r
 168                     }\r
 169                 }\r
 170             }\r
 171         }\r
 172 \r
 173         /// <summary>\r
 174         /// Registers entity to be deleted\r
 175         /// </summary>\r
 176         /// <param name="entity"></param>\r
 177         public void RegisterToDelete(object entity)\r
 178         {\r
 179             if (entity == null)\r
 180                 throw new ArgumentNullException("entity");\r
 181 \r
 182             lock (lockObject)\r
 183             {\r
 184                 var entityTrack = FindByReference(entity);\r
 185                 if (entityTrack == null)\r
 186                 {\r
 187                     entityTrack = new EntityTrack(entity, EntityState.ToDelete);\r
 188                     entities.Add(entityTrack);\r
 189                 }\r
 190                 else\r
 191                 {\r
 192                     // changes the state of the current entity\r
 193                     switch (entityTrack.EntityState)\r
 194                     {\r
 195                     // if entity was to be inserted, we just remove it from the list\r
 196                     // as if it never came here\r
 197                     case EntityState.ToInsert:\r
 198                         entities.Remove(entityTrack);\r
 199                         break;\r
 200                     // watched entities are registered to be removed\r
 201                     case EntityState.ToWatch:\r
 202                         entityTrack.EntityState = EntityState.ToDelete;\r
 203                         entitiesByKey.Remove(entityTrack.IdentityKey);\r
 204                         break;\r
 205                     case EntityState.ToDelete:\r
 206                         throw new InvalidOperationException();\r
 207                     default:\r
 208                         throw new ArgumentOutOfRangeException();\r
 209                     }\r
 210                 }\r
 211             }\r
 212         }\r
 213 \r
 214         /// <summary>\r
 215         /// Unregisters the entity after deletion\r
 216         /// </summary>\r
 217         /// <param name="entity"></param>\r
 218         public void RegisterDeleted(object entity)\r
 219         {\r
 220             lock (lockObject)\r
 221             {\r
 222                 // TODO: we could require an index\r
 223                 var entityTrack = FindByReference(entity);\r
 224                 if (entityTrack == null)\r
 225                 {\r
 226                     throw new ArgumentException("entity");\r
 227                 }\r
 228                 // changes the state of the current entity\r
 229                 switch (entityTrack.EntityState)\r
 230                 {\r
 231                 case EntityState.ToDelete:\r
 232                     entities.Remove(entityTrack);\r
 233                     break;\r
 234                 case EntityState.ToInsert:\r
 235                 case EntityState.ToWatch:\r
 236                     throw new InvalidOperationException();\r
 237                 default:\r
 238                     throw new ArgumentOutOfRangeException();\r
 239                 }\r
 240             }\r
 241         }\r
 242 \r
 243         /// <summary>\r
 244         /// Enumerates all registered entities\r
 245         /// </summary>\r
 246         /// <returns></returns>\r
 247         public IEnumerable<EntityTrack> EnumerateAll()\r
 248         {\r
 249             return entities;\r
 250         }\r
 251     }\r
 252 }\r