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 using System;
  33 using System.Threading;
  34 using System.Web.Caching;
  35
  36 namespace System.Web.SessionState {
  37         class LockableStateServerItem
  38         {
  39                 public StateServerItem item;
  40                 public ReaderWriterLock rwlock;
  41
  42                 public LockableStateServerItem (StateServerItem item)
  43                 {
  44                         this.item = item;
  45                         this.rwlock = new ReaderWriterLock ();
  46                 }
  47         }
  48
  49         internal class RemoteStateServer : MarshalByRefObject {
  50                 const Int32 lockAcquireTimeout = 30000;
  51                 Cache cache;
  52
  53                 internal RemoteStateServer ()
  54                 {
  55                         cache = new Cache ();
  56                 }
  57
  58                 void Insert (string id, LockableStateServerItem item)
  59                 {
  60                         cache.Insert (id, item, null, Cache.NoAbsoluteExpiration, new TimeSpan (0, item.item.Timeout, 0));
  61                 }
  62
  63                 LockableStateServerItem Retrieve (string id)
  64                 {
  65                         return cache [id] as LockableStateServerItem;
  66                 }
  67
  68                 internal void CreateUninitializedItem (string id, int timeout)
  69                 {
  70                         StateServerItem item = new StateServerItem (timeout);
  71                         item.Action = SessionStateActions.InitializeItem;
  72                         LockableStateServerItem cacheItem = new LockableStateServerItem (item);
  73                         Insert (id, cacheItem);
  74                 }
  75
  76                 internal StateServerItem GetItem (string id,
  77                                                   out bool locked,
  78                                                   out TimeSpan lockAge,
  79                                                   out object lockId,
  80                                                   out SessionStateActions actions,
  81                                                   bool exclusive)
  82                 {
  83                         locked = false;
  84                         lockAge = TimeSpan.MinValue;
  85                         lockId = Int32.MinValue;
  86                         actions = SessionStateActions.None;
  87
  88                         LockableStateServerItem item = Retrieve (id);
  89                         if (item == null || item.item.IsAbandoned ())
  90                                 return null;
  91
  92                         try {
  93                                 item.rwlock.AcquireReaderLock (lockAcquireTimeout);
  94                                 if (item.item.Locked) {
  95                                         locked = true;
  96                                         lockAge = DateTime.UtcNow.Subtract (item.item.LockedTime);
  97                                         lockId = item.item.LockId;
  98                                         return null;
  99                                 }
 100
 101                                 item.rwlock.ReleaseReaderLock ();
 102                                 if (exclusive) {
 103                                         item.rwlock.AcquireWriterLock (lockAcquireTimeout);
 104                                         item.item.Locked = true;
 105                                         item.item.LockedTime = DateTime.UtcNow;
 106                                         item.item.LockId++;
 107                                         lockId = item.item.LockId;
 108                                 }
 109                         } catch {
 110                                 throw;
 111                         } finally {
 112                                 if (item.rwlock.IsReaderLockHeld)
 113                                         item.rwlock.ReleaseReaderLock ();
 114
 115                                 if (item.rwlock.IsWriterLockHeld)
 116                                         item.rwlock.ReleaseWriterLock ();
 117                         }
 118
 119                         actions = item.item.Action;
 120                         return item.item;
 121                 }
 122
 123                 internal void Remove (string id, object lockid)
 124                 {
 125                         cache.Remove (id);
 126                 }
 127
 128                 internal void ResetItemTimeout (string id)
 129                 {
 130                         LockableStateServerItem item = Retrieve (id);
 131                         if (item == null)
 132                                 return;
 133                         item.item.Touch ();
 134                 }
 135
 136                 internal void ReleaseItemExclusive (string id, object lockId)
 137                 {
 138                         LockableStateServerItem item = Retrieve (id);
 139                         if (item == null || item.item.LockId != (Int32)lockId)
 140                                 return;
 141
 142                         try {
 143                                 item.rwlock.AcquireWriterLock (lockAcquireTimeout);
 144                                 item.item.Locked = false;
 145                         } catch {
 146                                 throw;
 147                         } finally {
 148                                 if (item.rwlock.IsWriterLockHeld)
 149                                         item.rwlock.ReleaseWriterLock ();
 150                         }
 151                 }
 152
 153                 internal void SetAndReleaseItemExclusive (string id, byte [] collection_data, byte [] sobjs_data,
 154                                                           object lockId, int timeout, bool newItem)
 155                 {
 156                         LockableStateServerItem item = Retrieve (id);
 157                         bool fresh = false;
 158
 159                         if (newItem || item == null) {
 160                                 item = new LockableStateServerItem (new StateServerItem (collection_data, sobjs_data, timeout));
 161                                 item.item.LockId = (Int32)lockId;
 162                                 fresh = true;
 163                         } else {
 164                                 if (item.item.LockId != (Int32)lockId)
 165                                         return;
 166                                 Remove (id, lockId);
 167                         }
 168
 169                         try {
 170                                 item.rwlock.AcquireWriterLock (lockAcquireTimeout);
 171                                 item.item.Locked = false;
 172                                 if (!fresh) {
 173                                         item.item.CollectionData = collection_data;
 174                                         item.item.StaticObjectsData = sobjs_data;
 175                                 }
 176                                 Insert (id, item);
 177                         } catch {
 178                                 throw;
 179                         } finally {
 180                                 if (item.rwlock.IsWriterLockHeld)
 181                                         item.rwlock.ReleaseWriterLock ();
 182                         }
 183                 }
 184
 185                 public override object InitializeLifetimeService ()
 186                 {
 187                         return null; // just in case...
 188                 }
 189         }
 190 }