mcs/class/System.Web/System.Web.Caching/OutputCacheModule.cs

   1 //
   2 // System.Web.Caching.OutputCacheModule
   3 //
   4 // Authors:
   5 //  Jackson Harper (jackson@ximian.com)
   6 //
   7 // (C) 2003 Novell, Inc (http://www.novell.com)
   8 //
   9
  10 using System.Web;
  11 using System.Web.Util;
  12
  13 namespace System.Web.Caching {
  14
  15         internal sealed class OutputCacheModule : IHttpModule {
  16
  17                 public OutputCacheModule ()
  18                 {
  19                 }
  20
  21                 public void Dispose ()
  22                 {
  23                 }
  24
  25                 public void Init (HttpApplication app)
  26                 {
  27                         app.AddOnResolveRequestCacheAsync (
  28                                 new BeginEventHandler (OnBeginRequestCache),
  29                                 new EndEventHandler (OnEndRequestCache));
  30
  31                         app.AddOnUpdateRequestCacheAsync (
  32                                 new BeginEventHandler (OnBeginUpdateCache),
  33                                 new EndEventHandler (OnEndUpdateCache));
  34                 }
  35
  36                 IAsyncResult OnBeginRequestCache (object o, EventArgs args, AsyncCallback cb, object data)
  37                 {
  38                         HttpApplication app = (HttpApplication) o;
  39                         HttpContext context = app.Context;
  40
  41                         string vary_key = context.Request.FilePath;
  42                         CachedVaryBy varyby = context.Cache [vary_key] as CachedVaryBy;
  43                         string key;
  44                         CachedRawResponse c;
  45
  46                         if (varyby == null)
  47                                 goto leave;
  48
  49                         key = varyby.CreateKey (vary_key, context);
  50                         c = context.Cache [key] as CachedRawResponse;
  51
  52                         if (c != null && context.Timestamp < c.Policy.Expires) {
  53
  54                                 context.Response.ClearContent ();
  55                                 context.Response.BinaryWrite (c.GetData (), 0, c.ContentLength);
  56
  57                                 context.Response.ClearHeaders ();
  58                                 c.DateHeader.Value = TimeUtil.ToUtcTimeString (DateTime.Now);
  59                                 context.Response.SetCachedHeaders (c.Headers);
  60
  61                                 context.Response.StatusCode = c.StatusCode;
  62                                 context.Response.StatusDescription = c.StatusDescription;
  63
  64                                 app.CompleteRequest ();
  65                         } else if (c != null) {
  66                                 context.Cache.Remove (key);
  67                         }
  68
  69                 leave:
  70                         HttpAsyncResult result = new HttpAsyncResult (cb,this);
  71                         result.Complete (true, o, null);
  72
  73                         return result;
  74                 }
  75
  76                 void OnEndRequestCache (IAsyncResult result)
  77                 {
  78                 }
  79
  80                 IAsyncResult OnBeginUpdateCache (object o, EventArgs args, AsyncCallback cb, object data)
  81                 {
  82                         HttpApplication app = (HttpApplication) o;
  83                         HttpContext context = app.Context;
  84                         HttpAsyncResult result;
  85
  86                         if (context.Response.IsCached && context.Response.StatusCode == 200)
  87                                 DoCacheInsert (context);
  88
  89                         result = new HttpAsyncResult (cb, this);
  90                         result.Complete (true, o, null);
  91                         return result;
  92                 }
  93
  94                 void OnEndUpdateCache (IAsyncResult result)
  95                 {
  96                 }
  97
  98                 private void DoCacheInsert (HttpContext context)
  99                 {
 100                         string vary_key = context.Request.FilePath;
 101                         string key;
 102                         CachedVaryBy varyby = context.Cache [vary_key] as CachedVaryBy;
 103                         CachedRawResponse prev = null;
 104                         bool lookup = true;
 105
 106                         if (varyby == null) {
 107                                 varyby = new CachedVaryBy (context.Response.Cache);
 108                                 context.Cache.InsertPrivate (vary_key, varyby, null,
 109                                                 Cache.NoAbsoluteExpiration, Cache.NoSlidingExpiration,
 110                                                 CacheItemPriority.Normal, null);
 111                                 lookup = false;
 112                         }
 113
 114                         key = varyby.CreateKey (vary_key, context);
 115
 116                         if (lookup)
 117                                 prev = context.Cache [key] as CachedRawResponse;
 118
 119                         if (IsExpired (context, prev)) {
 120                                 CachedRawResponse c = context.Response.GetCachedResponse ();
 121                                 string [] files = new string [0];
 122                                 string [] keys = new string [] { vary_key };
 123
 124                                 context.Cache.InsertPrivate (key, c, new CacheDependency (files, keys),
 125                                                 context.Response.Cache.Expires,
 126                                                 Cache.NoSlidingExpiration,
 127                                                 CacheItemPriority.Normal, null);
 128                         }
 129                 }
 130
 131                 private bool IsExpired (HttpContext context, CachedRawResponse crr)
 132                 {
 133                         if (crr == null || context.Timestamp > crr.Policy.Expires)
 134                                 return true;
 135                         return false;
 136                 }
 137         }
 138 }
 139