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                 bool _locked;
  51                 [NonSerialized]
  52                 int _lockCount = 0;
  53
  54                 [NonSerialized]
  55                 Mutex _mutex = new Mutex (false);
  56                 [NonSerialized]
  57                 Thread _ownerThread;
  58
  59                 public SynchronizationAttribute ()
  60                 : this (REQUIRES_NEW, false)
  61                 {
  62                 }
  63
  64                 public SynchronizationAttribute (bool reEntrant)
  65                 : this (REQUIRES_NEW, reEntrant)
  66                 {
  67                 }
  68
  69                 public SynchronizationAttribute (int flag)
  70                 : this (flag, false)
  71                 {
  72                 }
  73
  74                 public SynchronizationAttribute (int flag, bool reEntrant)
  75                 : base ("Synchronization")
  76                 {
  77                         if (flag != NOT_SUPPORTED && flag != REQUIRED && flag != REQUIRES_NEW && flag != SUPPORTED)
  78                                 throw new ArgumentException ("flag");
  79
  80                         _bReEntrant = reEntrant;
  81                         _flavor = flag;
  82                 }
  83
  84                 public virtual bool IsReEntrant
  85                 {
  86                         get { return _bReEntrant; }
  87                 }
  88
  89                 public virtual bool Locked
  90                 {
  91                         get
  92                         {
  93                                 return _locked;
  94                         }
  95
  96                         set
  97                         {
  98                                 if (value)
  99                                 {
 100                                         _mutex.WaitOne ();
 101                                         lock (this)
 102                                         {
 103                                                 _lockCount++;
 104                                                 if (_lockCount > 1)
 105                                                         ReleaseLock (); // Thread already had the lock
 106
 107                                                 _ownerThread = Thread.CurrentThread;
 108                                         }
 109                                 }
 110                                 else
 111                                 {
 112                                         lock (this)
 113                                         {
 114                                                 while (_lockCount > 0 && _ownerThread == Thread.CurrentThread)
 115                                                 {
 116                                                         _lockCount--;
 117                                                         _mutex.ReleaseMutex ();
 118                                                         _ownerThread = null;
 119                                                 }
 120                                         }
 121                                 }
 122                         }
 123                 }
 124
 125                 internal void AcquireLock ()
 126                 {
 127                         _mutex.WaitOne ();
 128
 129                         lock (this)
 130                         {
 131                                 _ownerThread = Thread.CurrentThread;
 132                                 _lockCount++;
 133                         }
 134                 }
 135
 136                 internal void ReleaseLock ()
 137                 {
 138                         lock (this)
 139                         {
 140                                 if (_lockCount > 0 && _ownerThread == Thread.CurrentThread) {
 141                                         _lockCount--;
 142                                         _mutex.ReleaseMutex ();
 143                                         _ownerThread = null;
 144                                 }
 145                         }
 146                 }
 147
 148                 [System.Runtime.InteropServices.ComVisible (true)]
 149                 public override void GetPropertiesForNewContext (IConstructionCallMessage ctorMsg)
 150                 {
 151                         if (_flavor != NOT_SUPPORTED) {
 152                                 ctorMsg.ContextProperties.Add (this);
 153                         }
 154                 }
 155
 156                 public virtual IMessageSink GetClientContextSink (IMessageSink nextSink)
 157                 {
 158                         return new SynchronizedClientContextSink (nextSink, this);
 159                 }
 160
 161                 public virtual IMessageSink GetServerContextSink (IMessageSink nextSink)
 162                 {
 163                         return new SynchronizedServerContextSink (nextSink, this);
 164                 }
 165
 166                 [System.Runtime.InteropServices.ComVisible (true)]
 167                 public override bool IsContextOK (Context ctx, IConstructionCallMessage msg)
 168                 {
 169                         SynchronizationAttribute prop = ctx.GetProperty ("Synchronization") as SynchronizationAttribute;
 170                         switch (_flavor)
 171                         {
 172                                 case NOT_SUPPORTED: return (prop == null);
 173                                 case REQUIRED: return (prop != null);
 174                                 case REQUIRES_NEW: return false;
 175                                 case SUPPORTED: return true;
 176                         }
 177                         return false;
 178                 }
 179
 180                 internal static void ExitContext ()
 181                 {
 182                         if (Thread.CurrentContext.IsDefaultContext) return;
 183                         SynchronizationAttribute prop = Thread.CurrentContext.GetProperty ("Synchronization") as SynchronizationAttribute;
 184                         if (prop == null) return;
 185                         prop.Locked = false;
 186                 }
 187
 188                 internal static void EnterContext ()
 189                 {
 190                         if (Thread.CurrentContext.IsDefaultContext) return;
 191                         SynchronizationAttribute prop = Thread.CurrentContext.GetProperty ("Synchronization") as SynchronizationAttribute;
 192                         if (prop == null) return;
 193                         prop.Locked = true;
 194                 }
 195         }
 196
 197         internal class SynchronizedClientContextSink: IMessageSink
 198         {
 199                 IMessageSink _next;
 200                 SynchronizationAttribute _att;
 201
 202                 public SynchronizedClientContextSink (IMessageSink next, SynchronizationAttribute att)
 203                 {
 204                         _att = att;
 205                         _next = next;
 206                 }
 207
 208                 public IMessageSink NextSink
 209                 {
 210                         get { return _next; }
 211                 }
 212
 213                 public IMessageCtrl AsyncProcessMessage (IMessage msg, IMessageSink replySink)
 214                 {
 215                         if (_att.IsReEntrant)
 216                         {
 217                                 _att.ReleaseLock();     // Unlock when leaving the context
 218                                 replySink = new SynchronizedContextReplySink (replySink, _att, true);
 219                         }
 220                         return _next.AsyncProcessMessage (msg, replySink);
 221                 }
 222
 223                 public IMessage SyncProcessMessage (IMessage msg)
 224                 {
 225                         if (_att.IsReEntrant)
 226                                 _att.ReleaseLock ();    // Unlock when leaving the context
 227
 228                         try
 229                         {
 230                                 return _next.SyncProcessMessage (msg);
 231                         }
 232                         finally
 233                         {
 234                                 if (_att.IsReEntrant)
 235                                         _att.AcquireLock ();
 236                         }
 237                 }
 238         }
 239
 240         internal class SynchronizedServerContextSink: IMessageSink
 241         {
 242                 IMessageSink _next;
 243                 SynchronizationAttribute _att;
 244
 245                 public SynchronizedServerContextSink (IMessageSink next, SynchronizationAttribute att)
 246                 {
 247                         _att = att;
 248                         _next = next;
 249                 }
 250
 251                 public IMessageSink NextSink
 252                 {
 253                         get { return _next; }
 254                 }
 255
 256                 public IMessageCtrl AsyncProcessMessage (IMessage msg, IMessageSink replySink)
 257                 {
 258                         _att.AcquireLock ();
 259                         replySink = new SynchronizedContextReplySink (replySink, _att, false);
 260                         return _next.AsyncProcessMessage (msg, replySink);
 261                 }
 262
 263                 public IMessage SyncProcessMessage (IMessage msg)
 264                 {
 265                         _att.AcquireLock ();
 266                         try
 267                         {
 268                                 return _next.SyncProcessMessage (msg);
 269                         }
 270                         finally
 271                         {
 272                                 _att.ReleaseLock ();
 273                         }
 274                 }
 275         }
 276
 277         internal class SynchronizedContextReplySink: IMessageSink
 278         {
 279                 IMessageSink _next;
 280                 bool _newLock;
 281                 SynchronizationAttribute _att;
 282
 283                 public SynchronizedContextReplySink (IMessageSink next, SynchronizationAttribute att, bool newLock)
 284                 {
 285                         _newLock = newLock;
 286                         _next = next;
 287                         _att = att;
 288                 }
 289
 290                 public IMessageSink NextSink
 291                 {
 292                         get { return _next; }
 293                 }
 294
 295                 public IMessageCtrl AsyncProcessMessage (IMessage msg, IMessageSink replySink)
 296                 {
 297                         // Never called
 298                         throw new NotSupportedException ();
 299                 }
 300
 301                 public IMessage SyncProcessMessage (IMessage msg)
 302                 {
 303                         if (_newLock) _att.AcquireLock ();
 304                         else _att.ReleaseLock ();
 305
 306                         try
 307                         {
 308                                 return _next.SyncProcessMessage (msg);
 309                         }
 310                         finally
 311                         {
 312                                 if (_newLock)
 313                                         _att.ReleaseLock ();
 314                         }
 315                 }
 316         }
 317 }
 318