src/Boo.Lang/Runtime/DispatcherCache.cs

   1 #region license
   2 // Copyright (c) 2003, 2004, 2005 Rodrigo B. de Oliveira (rbo@acm.org)
   3 // All rights reserved.
   4 //
   5 // Redistribution and use in source and binary forms, with or without modification,
   6 // are permitted provided that the following conditions are met:
   7 //
   8 //     * Redistributions of source code must retain the above copyright notice,
   9 //     this list of conditions and the following disclaimer.
  10 //     * Redistributions in binary form must reproduce the above copyright notice,
  11 //     this list of conditions and the following disclaimer in the documentation
  12 //     and/or other materials provided with the distribution.
  13 //     * Neither the name of Rodrigo B. de Oliveira nor the names of its
  14 //     contributors may be used to endorse or promote products derived from this
  15 //     software without specific prior written permission.
  16 //
  17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  18 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  19 // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  20 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
  21 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  23 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  24 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  25 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26 // THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27 #endregion
  28
  29
  30 using System.Collections.Generic;
  31
  32 namespace Boo.Lang.Runtime
  33 {
  34         public class DispatcherCache
  35         {
  36                 public delegate Dispatcher DispatcherFactory();
  37
  38                 private static Dictionary<DispatcherKey, Dispatcher> _cache =
  39                         new Dictionary<DispatcherKey, Dispatcher>(DispatcherKey.EqualityComparer);
  40
  41                 /// <summary>
  42                 /// Gets a dispatcher from the cache if available otherwise
  43                 /// invokes factory to produce one and then cache it.
  44                 /// </summary>
  45                 /// <param name="key">the dispatcher key</param>
  46                 /// <param name="factory">function to produce a dispatcher in case one it's not yet available</param>
  47                 /// <returns></returns>
  48                 public Dispatcher Get(DispatcherKey key, DispatcherFactory factory)
  49                 {
  50                         Dispatcher dispatcher;
  51                         if (!_cache.TryGetValue(key, out dispatcher))
  52                         {
  53                                 lock (_cache)
  54                                 {
  55                                         if (!_cache.TryGetValue(key, out dispatcher))
  56                                         {
  57                                                 dispatcher = factory();
  58                                                 _cache.Add(key, dispatcher);
  59                                         }
  60                                 }
  61                         }
  62                         return dispatcher;
  63                 }
  64
  65                 /// <summary>
  66                 /// Removes all Dispatchers from the cache.
  67                 /// </summary>
  68                 public void Clear()
  69                 {
  70                         lock (_cache)
  71                         {
  72                                 _cache.Clear();
  73                         }
  74                 }
  75         }
  76 }