InversionOfControl/Castle.MicroKernel/Lifestyle/PerWebRequestLifestyleManager.cs

   1 // Copyright 2004-2008 Castle Project - http://www.castleproject.org/
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License");
   4 // you may not use this file except in compliance with the License.
   5 // You may obtain a copy of the License at
   6 //
   7 //     http://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS,
  11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 // See the License for the specific language governing permissions and
  13 // limitations under the License.
  14
  15 namespace Castle.MicroKernel.Lifestyle
  16 {
  17         using System;
  18         using System.Collections;
  19         using System.Configuration;
  20         using System.Web;
  21
  22         /// <summary>
  23         /// Implements a Lifestyle Manager for Web Apps that
  24         /// create at most one object per web request.
  25         /// </summary>
  26         [Serializable]
  27         public class PerWebRequestLifestyleManager : AbstractLifestyleManager
  28         {
  29                 private string PerRequestObjectID = "PerRequestLifestyleManager_" + Guid.NewGuid().ToString();
  30
  31                 #region ILifestyleManager Members
  32
  33                 public override object Resolve(CreationContext context)
  34                 {
  35                         HttpContext current = HttpContext.Current;
  36
  37                         if (current == null)
  38                                 throw new InvalidOperationException(
  39                                         "HttpContext.Current is null.  PerWebRequestLifestyle can only be used in ASP.Net");
  40
  41                         if (current.Items[PerRequestObjectID] == null)
  42                         {
  43                                 if (!PerWebRequestLifestyleModule.Initialized)
  44                                 {
  45                                         string message = "Looks like you forgot to register the http module " +
  46                                                          typeof(PerWebRequestLifestyleModule).FullName +
  47                                                          "\r\nAdd '<add name=\"PerRequestLifestyle\" type=\"Castle.MicroKernel.Lifestyle.PerWebRequestLifestyleModule, Castle.MicroKernel\" />' " +
  48                                                          "to the <httpModules> section on your web.config";
  49
  50                                         throw new ConfigurationErrorsException(message);
  51                                 }
  52
  53                                 object instance = base.Resolve(context);
  54                                 current.Items[PerRequestObjectID] = instance;
  55                                 PerWebRequestLifestyleModule.RegisterForEviction(this, instance);
  56                         }
  57
  58                         return current.Items[PerRequestObjectID];
  59                 }
  60
  61                 public override void Release(object instance)
  62                 {
  63                         // Since this method is called by the kernel when an external
  64                         // request to release the component is made, it must do nothing
  65                         // to ensure the component is available during the duration of
  66                         // the web request.  An internal Evict method is provided to
  67                         // allow the actual releasing of the component at the end of
  68                         // the web request.
  69                 }
  70
  71                 internal void Evict(object instance)
  72                 {
  73                         base.Release(instance);
  74                 }
  75
  76                 public override void Dispose()
  77                 {
  78                 }
  79
  80                 #endregion
  81         }
  82
  83         #region PerWebRequestLifestyleModule
  84
  85         public class PerWebRequestLifestyleModule : IHttpModule
  86         {
  87                 private static bool initialized;
  88
  89                 private const string PerRequestEvict = "PerRequestLifestyleManager_Evict";
  90
  91                 public void Init(HttpApplication context)
  92                 {
  93                         initialized = true;
  94                         context.EndRequest += new EventHandler(Application_EndRequest);
  95                 }
  96
  97                 public void Dispose()
  98                 {
  99                 }
 100
 101                 internal static void RegisterForEviction(PerWebRequestLifestyleManager manager, object instance)
 102                 {
 103                         HttpContext context = HttpContext.Current;
 104
 105                         IDictionary candidates = (IDictionary) context.Items[PerRequestEvict];
 106
 107                         if (candidates == null)
 108                         {
 109                                 candidates = new Hashtable();
 110                                 context.Items[PerRequestEvict] = candidates;
 111                         }
 112
 113                         candidates.Add(manager, instance);
 114                 }
 115
 116                 protected void Application_EndRequest(Object sender, EventArgs e)
 117                 {
 118                         HttpApplication application = (HttpApplication) sender;
 119                         IDictionary candidates = (IDictionary) application.Context.Items[PerRequestEvict];
 120
 121                         if (candidates != null)
 122                         {
 123                                 foreach(DictionaryEntry candidate in candidates)
 124                                 {
 125                                         PerWebRequestLifestyleManager manager =
 126                                                 (PerWebRequestLifestyleManager) candidate.Key;
 127                                         manager.Evict(candidate.Value);
 128                                 }
 129
 130                                 application.Context.Items.Remove(PerRequestEvict);
 131                         }
 132                 }
 133
 134                 internal static bool Initialized
 135                 {
 136                         get { return initialized; }
 137                 }
 138         }
 139
 140         #endregion
 141 }