mcs/class/System.Web/System.Web.SessionState_2.0/RemoteStateServer.cs

   1 //
   2 // System.Web.SessionState.RemoteStateServer
   3 //
   4 // Author(s):
   5 //  Jackson Harper (jackson@ximian.com)
   6 //  Gonzalo Paniagua (gonzalo@ximian.com)
   7 //  Marek Habersack (grendello@gmail.com)
   8 //
   9 // (C) 2003-2006 Novell, Inc (http://www.novell.com)
  10 //
  11
  12 //
  13 // Permission is hereby granted, free of charge, to any person obtaining
  14 // a copy of this software and associated documentation files (the
  15 // "Software"), to deal in the Software without restriction, including
  16 // without limitation the rights to use, copy, modify, merge, publish,
  17 // distribute, sublicense, and/or sell copies of the Software, and to
  18 // permit persons to whom the Software is furnished to do so, subject to
  19 // the following conditions:
  20 //
  21 // The above copyright notice and this permission notice shall be
  22 // included in all copies or substantial portions of the Software.
  23 //
  24 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  25 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  26 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  27 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  28 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  29 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  30 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  31 //
  32 #if NET_2_0
  33 using System;
  34 using System.Threading;
  35 using System.Web.Caching;
  36
  37 namespace System.Web.SessionState {
  38         class LockableStateServerItem
  39         {
  40                 public StateServerItem item;
  41                 public ReaderWriterLock rwlock;
  42
  43                 public LockableStateServerItem (StateServerItem item)
  44                 {
  45                         this.item = item;
  46                         this.rwlock = new ReaderWriterLock ();
  47                 }
  48         }
  49
  50         internal class RemoteStateServer : MarshalByRefObject {
  51                 const Int32 lockAcquireTimeout = 30000;
  52                 Cache cache;
  53
  54                 internal RemoteStateServer ()
  55                 {
  56                         cache = new Cache ();
  57                 }
  58
  59                 void Insert (string id, LockableStateServerItem item)
  60                 {
  61                         cache.Insert (id, item, null, Cache.NoAbsoluteExpiration, new TimeSpan (0, item.item.Timeout, 0));
  62                 }
  63
  64                 LockableStateServerItem Retrieve (string id)
  65                 {
  66                         return cache [id] as LockableStateServerItem;
  67                 }
  68
  69                 internal void CreateUninitializedItem (string id, int timeout)
  70                 {
  71                         StateServerItem item = new StateServerItem (timeout);
  72                         item.Action = SessionStateActions.InitializeItem;
  73                         LockableStateServerItem cacheItem = new LockableStateServerItem (item);
  74                         Insert (id, cacheItem);
  75                 }
  76
  77                 internal StateServerItem GetItem (string id,
  78                                                   out bool locked,
  79                                                   out TimeSpan lockAge,
  80                                                   out object lockId,
  81                                                   out SessionStateActions actions,
  82                                                   bool exclusive)
  83                 {
  84                         locked = false;
  85                         lockAge = TimeSpan.MinValue;
  86                         lockId = Int32.MinValue;
  87                         actions = SessionStateActions.None;
  88
  89                         LockableStateServerItem item = Retrieve (id);
  90                         if (item == null || item.item.IsAbandoned ())
  91                                 return null;
  92
  93                         try {
  94                                 item.rwlock.AcquireReaderLock (lockAcquireTimeout);
  95                                 if (item.item.Locked) {
  96                                         locked = true;
  97                                         lockAge = DateTime.UtcNow.Subtract (item.item.LockedTime);
  98                                         lockId = item.item.LockId;
  99                                         return null;
 100                                 }
 101
 102                                 item.rwlock.ReleaseReaderLock ();
 103                                 if (exclusive) {
 104                                         item.rwlock.AcquireWriterLock (lockAcquireTimeout);
 105                                         item.item.Locked = true;
 106                                         item.item.LockedTime = DateTime.UtcNow;
 107                                         item.item.LockId++;
 108                                         lockId = item.item.LockId;
 109                                 }
 110                         } catch {
 111                                 throw;
 112                         } finally {
 113                                 if (item.rwlock.IsReaderLockHeld)
 114                                         item.rwlock.ReleaseReaderLock ();
 115
 116                                 if (item.rwlock.IsWriterLockHeld)
 117                                         item.rwlock.ReleaseWriterLock ();
 118                         }
 119
 120                         actions = item.item.Action;
 121                         return item.item;
 122                 }
 123
 124                 internal void Remove (string id, object lockid)
 125                 {
 126                         cache.Remove (id);
 127                 }
 128
 129                 internal void ResetItemTimeout (string id)
 130                 {
 131                         LockableStateServerItem item = Retrieve (id);
 132                         if (item == null)
 133                                 return;
 134                         item.item.Touch ();
 135                 }
 136
 137                 internal void ReleaseItemExclusive (string id, object lockId)
 138                 {
 139                         LockableStateServerItem item = Retrieve (id);
 140                         if (item == null || item.item.LockId != (Int32)lockId)
 141                                 return;
 142
 143                         try {
 144                                 item.rwlock.AcquireWriterLock (lockAcquireTimeout);
 145                                 item.item.Locked = false;
 146                         } catch {
 147                                 throw;
 148                         } finally {
 149                                 if (item.rwlock.IsWriterLockHeld)
 150                                         item.rwlock.ReleaseWriterLock ();
 151                         }
 152                 }
 153
 154                 internal void SetAndReleaseItemExclusive (string id, byte [] collection_data, byte [] sobjs_data,
 155                                                           object lockId, int timeout, bool newItem)
 156                 {
 157                         LockableStateServerItem item = Retrieve (id);
 158                         bool fresh = false;
 159
 160                         if (newItem || item == null) {
 161                                 item = new LockableStateServerItem (new StateServerItem (collection_data, sobjs_data, timeout));
 162                                 item.item.LockId = (Int32)lockId;
 163                                 fresh = true;
 164                         } else {
 165                                 if (item.item.LockId != (Int32)lockId)
 166                                         return;
 167                                 Remove (id, lockId);
 168                         }
 169
 170                         try {
 171                                 item.rwlock.AcquireWriterLock (lockAcquireTimeout);
 172                                 item.item.Locked = false;
 173                                 if (!fresh) {
 174                                         item.item.CollectionData = collection_data;
 175                                         item.item.StaticObjectsData = sobjs_data;
 176                                 }
 177                                 Insert (id, item);
 178                         } catch {
 179                                 throw;
 180                         } finally {
 181                                 if (item.rwlock.IsWriterLockHeld)
 182                                         item.rwlock.ReleaseWriterLock ();
 183                         }
 184                 }
 185
 186                 public override object InitializeLifetimeService ()
 187                 {
 188                         return null; // just in case...
 189                 }
 190         }
 191 }
 192 #endif