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