mcs/class/corlib/System.Runtime.Remoting.Contexts/SynchronizationAttribute.cs

   1 //
   2 // System.Runtime.Remoting.Contexts.SynchronizationAttribute.cs
   3 //
   4 // Author:
   5 //   Lluis Sanchez Gual (lluis@ximian.com)
   6 //
   7 // (C) Novell, Inc.  http://www.ximian.com
   8 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
   9 //
  10 // Permission is hereby granted, free of charge, to any person obtaining
  11 // a copy of this software and associated documentation files (the
  12 // "Software"), to deal in the Software without restriction, including
  13 // without limitation the rights to use, copy, modify, merge, publish,
  14 // distribute, sublicense, and/or sell copies of the Software, and to
  15 // permit persons to whom the Software is furnished to do so, subject to
  16 // the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be
  19 // included in all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28 //
  29
  30 using System.Threading;
  31 using System.Runtime.Remoting.Messaging;
  32 using System.Runtime.Remoting.Activation;
  33
  34 namespace System.Runtime.Remoting.Contexts
  35 {
  36         [AttributeUsage(AttributeTargets.Class)]
  37         [Serializable]
  38         [System.Runtime.InteropServices.ComVisible (true)]
  39         public class SynchronizationAttribute: ContextAttribute, IContributeClientContextSink, IContributeServerContextSink
  40         {
  41                 public const int NOT_SUPPORTED = 1;
  42                 public const int SUPPORTED = 2;
  43                 public const int REQUIRED = 4;
  44                 public const int REQUIRES_NEW = 8;
  45
  46                 bool _bReEntrant;
  47                 int _flavor;
  48
  49                 [NonSerialized]
  50                 int _lockCount;
  51
  52                 [NonSerialized]
  53                 Mutex _mutex = new Mutex (false);
  54                 [NonSerialized]
  55                 Thread _ownerThread;
  56
  57                 public SynchronizationAttribute ()
  58                 : this (REQUIRES_NEW, false)
  59                 {
  60                 }
  61
  62                 public SynchronizationAttribute (bool reEntrant)
  63                 : this (REQUIRES_NEW, reEntrant)
  64                 {
  65                 }
  66
  67                 public SynchronizationAttribute (int flag)
  68                 : this (flag, false)
  69                 {
  70                 }
  71
  72                 public SynchronizationAttribute (int flag, bool reEntrant)
  73                 : base ("Synchronization")
  74                 {
  75                         if (flag != NOT_SUPPORTED && flag != REQUIRED && flag != REQUIRES_NEW && flag != SUPPORTED)
  76                                 throw new ArgumentException ("flag");
  77
  78                         _bReEntrant = reEntrant;
  79                         _flavor = flag;
  80                 }
  81
  82                 public virtual bool IsReEntrant
  83                 {
  84                         get { return _bReEntrant; }
  85                 }
  86
  87                 public virtual bool Locked
  88                 {
  89                         get
  90                         {
  91                                 return _lockCount > 0;
  92                         }
  93
  94                         set
  95                         {
  96                                 if (value)
  97                                 {
  98                                         AcquireLock ();
  99                                         lock (this)
 100                                         {
 101                                                 if (_lockCount > 1)
 102                                                         ReleaseLock (); // Thread already had the lock
 103                                         }
 104                                 }
 105                                 else
 106                                 {
 107                                         lock (this)
 108                                         {
 109                                                 while (_lockCount > 0 && _ownerThread == Thread.CurrentThread) {
 110                                                         ReleaseLock ();
 111                                                 }
 112                                         }
 113                                 }
 114                         }
 115                 }
 116
 117                 internal void AcquireLock ()
 118                 {
 119                         _mutex.WaitOne ();
 120
 121                         lock (this)
 122                         {
 123                                 _ownerThread = Thread.CurrentThread;
 124                                 _lockCount++;
 125                         }
 126                 }
 127
 128                 internal void ReleaseLock ()
 129                 {
 130                         lock (this)
 131                         {
 132                                 if (_lockCount > 0 && _ownerThread == Thread.CurrentThread) {
 133                                         _lockCount--;
 134                                         _mutex.ReleaseMutex ();
 135                                         if (_lockCount == 0) {
 136                                                 _ownerThread = null;
 137                                         }
 138                                 }
 139                         }
 140                 }
 141
 142                 [System.Runtime.InteropServices.ComVisible (true)]
 143                 public override void GetPropertiesForNewContext (IConstructionCallMessage ctorMsg)
 144                 {
 145                         if (_flavor != NOT_SUPPORTED) {
 146                                 ctorMsg.ContextProperties.Add (this);
 147                         }
 148                 }
 149
 150                 public virtual IMessageSink GetClientContextSink (IMessageSink nextSink)
 151                 {
 152                         return new SynchronizedClientContextSink (nextSink, this);
 153                 }
 154
 155                 public virtual IMessageSink GetServerContextSink (IMessageSink nextSink)
 156                 {
 157                         return new SynchronizedServerContextSink (nextSink, this);
 158                 }
 159
 160                 [System.Runtime.InteropServices.ComVisible (true)]
 161                 public override bool IsContextOK (Context ctx, IConstructionCallMessage msg)
 162                 {
 163                         SynchronizationAttribute prop = ctx.GetProperty ("Synchronization") as SynchronizationAttribute;
 164                         switch (_flavor)
 165                         {
 166                                 case NOT_SUPPORTED: return (prop == null);
 167                                 case REQUIRED: return (prop != null);
 168                                 case REQUIRES_NEW: return false;
 169                                 case SUPPORTED: return true;
 170                         }
 171                         return false;
 172                 }
 173
 174                 internal static void ExitContext ()
 175                 {
 176                         if (Thread.CurrentContext.IsDefaultContext) return;
 177                         SynchronizationAttribute prop = Thread.CurrentContext.GetProperty ("Synchronization") as SynchronizationAttribute;
 178                         if (prop == null) return;
 179                         prop.Locked = false;
 180                 }
 181
 182                 internal static void EnterContext ()
 183                 {
 184                         if (Thread.CurrentContext.IsDefaultContext) return;
 185                         SynchronizationAttribute prop = Thread.CurrentContext.GetProperty ("Synchronization") as SynchronizationAttribute;
 186                         if (prop == null) return;
 187                         prop.Locked = true;
 188                 }
 189         }
 190
 191         internal class SynchronizedClientContextSink: IMessageSink
 192         {
 193                 IMessageSink _next;
 194                 SynchronizationAttribute _att;
 195
 196                 public SynchronizedClientContextSink (IMessageSink next, SynchronizationAttribute att)
 197                 {
 198                         _att = att;
 199                         _next = next;
 200                 }
 201
 202                 public IMessageSink NextSink
 203                 {
 204                         get { return _next; }
 205                 }
 206
 207                 public IMessageCtrl AsyncProcessMessage (IMessage msg, IMessageSink replySink)
 208                 {
 209                         if (_att.IsReEntrant)
 210                         {
 211                                 _att.ReleaseLock();     // Unlock when leaving the context
 212                                 replySink = new SynchronizedContextReplySink (replySink, _att, true);
 213                         }
 214                         return _next.AsyncProcessMessage (msg, replySink);
 215                 }
 216
 217                 public IMessage SyncProcessMessage (IMessage msg)
 218                 {
 219                         if (_att.IsReEntrant)
 220                                 _att.ReleaseLock ();    // Unlock when leaving the context
 221
 222                         try
 223                         {
 224                                 return _next.SyncProcessMessage (msg);
 225                         }
 226                         finally
 227                         {
 228                                 if (_att.IsReEntrant)
 229                                         _att.AcquireLock ();
 230                         }
 231                 }
 232         }
 233
 234         internal class SynchronizedServerContextSink: IMessageSink
 235         {
 236                 IMessageSink _next;
 237                 SynchronizationAttribute _att;
 238
 239                 public SynchronizedServerContextSink (IMessageSink next, SynchronizationAttribute att)
 240                 {
 241                         _att = att;
 242                         _next = next;
 243                 }
 244
 245                 public IMessageSink NextSink
 246                 {
 247                         get { return _next; }
 248                 }
 249
 250                 public IMessageCtrl AsyncProcessMessage (IMessage msg, IMessageSink replySink)
 251                 {
 252                         _att.AcquireLock ();
 253                         replySink = new SynchronizedContextReplySink (replySink, _att, false);
 254                         return _next.AsyncProcessMessage (msg, replySink);
 255                 }
 256
 257                 public IMessage SyncProcessMessage (IMessage msg)
 258                 {
 259                         _att.AcquireLock ();
 260                         try
 261                         {
 262                                 return _next.SyncProcessMessage (msg);
 263                         }
 264                         finally
 265                         {
 266                                 _att.ReleaseLock ();
 267                         }
 268                 }
 269         }
 270
 271         internal class SynchronizedContextReplySink: IMessageSink
 272         {
 273                 IMessageSink _next;
 274                 bool _newLock;
 275                 SynchronizationAttribute _att;
 276
 277                 public SynchronizedContextReplySink (IMessageSink next, SynchronizationAttribute att, bool newLock)
 278                 {
 279                         _newLock = newLock;
 280                         _next = next;
 281                         _att = att;
 282                 }
 283
 284                 public IMessageSink NextSink
 285                 {
 286                         get { return _next; }
 287                 }
 288
 289                 public IMessageCtrl AsyncProcessMessage (IMessage msg, IMessageSink replySink)
 290                 {
 291                         // Never called
 292                         throw new NotSupportedException ();
 293                 }
 294
 295                 public IMessage SyncProcessMessage (IMessage msg)
 296                 {
 297                         if (_newLock) _att.AcquireLock ();
 298                         else _att.ReleaseLock ();
 299
 300                         try
 301                         {
 302                                 return _next.SyncProcessMessage (msg);
 303                         }
 304                         finally
 305                         {
 306                                 if (_newLock)
 307                                         _att.ReleaseLock ();
 308                         }
 309                 }
 310         }
 311 }
 312