mcs/class/System.Web.Mvc/System.Web.Mvc/ActionMethodSelectorCache.cs

   1 /* ****************************************************************************\r
   2  *\r
   3  * Copyright (c) Microsoft Corporation. All rights reserved.\r
   4  *\r
   5  * This software is subject to the Microsoft Public License (Ms-PL). \r
   6  * A copy of the license can be found in the license.htm file included \r
   7  * in this distribution.\r
   8  *\r
   9  * You must not remove this notice, or any other, from this software.\r
  10  *\r
  11  * ***************************************************************************/\r
  12 \r
  13 namespace System.Web.Mvc {\r
  14     using System;\r
  15     using System.Collections.Generic;\r
  16     using System.Threading;\r
  17 \r
  18     internal sealed class ActionMethodSelectorCache {\r
  19 \r
  20         private ReaderWriterLock _rwLock = new ReaderWriterLock();\r
  21         private Dictionary<Type, ActionMethodSelector> _selectorDictionary = new Dictionary<Type, ActionMethodSelector>();\r
  22 \r
  23         // This method could potentially return multiple selectors for the same controllerType due to\r
  24         // upgrading the lock from reader to writer, but the dictionary won't be corrupted as a result.\r
  25         public ActionMethodSelector GetSelector(Type controllerType) {\r
  26             ActionMethodSelector selector;\r
  27 \r
  28             _rwLock.AcquireReaderLock(Timeout.Infinite);\r
  29             try {\r
  30                 if (_selectorDictionary.TryGetValue(controllerType, out selector)) {\r
  31                     return selector;\r
  32                 }\r
  33             }\r
  34             finally {\r
  35                 _rwLock.ReleaseReaderLock();\r
  36             }\r
  37 \r
  38             // if we got this far, the selector was not in the cache\r
  39             selector = new ActionMethodSelector(controllerType);\r
  40             _rwLock.AcquireWriterLock(Timeout.Infinite);\r
  41             try {\r
  42                 _selectorDictionary[controllerType] = selector;\r
  43                 return selector;\r
  44             }\r
  45             finally {\r
  46                 _rwLock.ReleaseWriterLock();\r
  47             }\r
  48         }\r
  49 \r
  50     }\r
  51 }\r