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 //
   9
  10 //
  11 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  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
  33 using System.Threading;
  34 using System.Runtime.Remoting.Messaging;
  35 using System.Runtime.Remoting.Activation;
  36
  37 namespace System.Runtime.Remoting.Contexts
  38 {
  39         [AttributeUsage(AttributeTargets.Class)]
  40         [Serializable]
  41         [MonoTODO ("Fix serialization compatibility with MS.NET")]
  42         public class SynchronizationAttribute: ContextAttribute, IContributeClientContextSink, IContributeServerContextSink
  43         {
  44                 public const int NOT_SUPPORTED = 1;
  45                 public const int SUPPORTED = 2;
  46                 public const int REQUIRED = 4;
  47                 public const int REQUIRES_NEW = 8;
  48
  49                 bool _isReentrant;
  50                 bool _locked;
  51                 int _flag;
  52                 int _lockCount = 0;
  53
  54                 Mutex _mutex = new Mutex (false);
  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                         _isReentrant = reEntrant;
  79                         _flag = flag;
  80                 }
  81
  82                 public virtual bool IsReEntrant
  83                 {
  84                         get { return _isReentrant; }
  85                 }
  86
  87                 public virtual bool Locked
  88                 {
  89                         get
  90                         {
  91                                 return _locked;
  92                         }
  93
  94                         set
  95                         {
  96                                 if (value)
  97                                 {
  98                                         _mutex.WaitOne ();
  99                                         lock (this)
 100                                         {
 101                                                 _lockCount++;
 102                                                 if (_lockCount > 1)
 103                                                         ReleaseLock (); // Thread already had the lock
 104
 105                                                 _ownerThread = Thread.CurrentThread;
 106                                         }
 107                                 }
 108                                 else
 109                                 {
 110                                         lock (this)
 111                                         {
 112                                                 while (_lockCount > 0 && _ownerThread == Thread.CurrentThread)
 113                                                 {
 114                                                         _lockCount--;
 115                                                         _mutex.ReleaseMutex ();
 116                                                         _ownerThread = null;
 117                                                 }
 118                                         }
 119                                 }
 120                         }
 121                 }
 122
 123                 internal void AcquireLock ()
 124                 {
 125                         _mutex.WaitOne ();
 126
 127                         lock (this)
 128                         {
 129                                 _ownerThread = Thread.CurrentThread;
 130                                 _lockCount++;
 131                         }
 132                 }
 133
 134                 internal void ReleaseLock ()
 135                 {
 136                         lock (this)
 137                         {
 138                                 if (_lockCount > 0 && _ownerThread == Thread.CurrentThread) {
 139                                         _lockCount--;
 140                                         _mutex.ReleaseMutex ();
 141                                         _ownerThread = null;
 142                                 }
 143                         }
 144                 }
 145
 146                 public override void GetPropertiesForNewContext (IConstructionCallMessage ctorMsg)
 147                 {
 148                         if (_flag != NOT_SUPPORTED) {
 149                                 ctorMsg.ContextProperties.Add (this);
 150                         }
 151                 }
 152
 153                 public virtual IMessageSink GetClientContextSink (IMessageSink nextSink)
 154                 {
 155                         return new SynchronizedClientContextSink (nextSink, this);
 156                 }
 157
 158                 public virtual IMessageSink GetServerContextSink (IMessageSink nextSink)
 159                 {
 160                         return new SynchronizedServerContextSink (nextSink, this);
 161                 }
 162
 163                 public override bool IsContextOK (Context ctx, IConstructionCallMessage msg)
 164                 {
 165                         SynchronizationAttribute prop = ctx.GetProperty ("Synchronization") as SynchronizationAttribute;
 166                         switch (_flag)
 167                         {
 168                                 case NOT_SUPPORTED: return (prop == null);
 169                                 case REQUIRED: return (prop != null);
 170                                 case REQUIRES_NEW: return false;
 171                                 case SUPPORTED: return true;
 172                         }
 173                         return false;
 174                 }
 175
 176                 internal static void ExitContext ()
 177                 {
 178                         if (Thread.CurrentContext.IsDefaultContext) return;
 179                         SynchronizationAttribute prop = Thread.CurrentContext.GetProperty ("Synchronization") as SynchronizationAttribute;
 180                         if (prop == null) return;
 181                         prop.Locked = false;
 182                 }
 183
 184                 internal static void EnterContext ()
 185                 {
 186                         if (Thread.CurrentContext.IsDefaultContext) return;
 187                         SynchronizationAttribute prop = Thread.CurrentContext.GetProperty ("Synchronization") as SynchronizationAttribute;
 188                         if (prop == null) return;
 189                         prop.Locked = true;
 190                 }
 191         }
 192
 193         internal class SynchronizedClientContextSink: IMessageSink
 194         {
 195                 IMessageSink _next;
 196                 SynchronizationAttribute _att;
 197
 198                 public SynchronizedClientContextSink (IMessageSink next, SynchronizationAttribute att)
 199                 {
 200                         _att = att;
 201                         _next = next;
 202                 }
 203
 204                 public IMessageSink NextSink
 205                 {
 206                         get { return _next; }
 207                 }
 208
 209                 public IMessageCtrl AsyncProcessMessage (IMessage msg, IMessageSink replySink)
 210                 {
 211                         if (_att.IsReEntrant)
 212                         {
 213                                 _att.ReleaseLock();     // Unlock when leaving the context
 214                                 replySink = new SynchronizedContextReplySink (replySink, _att, true);
 215                         }
 216                         return _next.AsyncProcessMessage (msg, replySink);
 217                 }
 218
 219                 public IMessage SyncProcessMessage (IMessage msg)
 220                 {
 221                         if (_att.IsReEntrant)
 222                                 _att.ReleaseLock ();    // Unlock when leaving the context
 223
 224                         try
 225                         {
 226                                 return _next.SyncProcessMessage (msg);
 227                         }
 228                         finally
 229                         {
 230                                 if (_att.IsReEntrant)
 231                                         _att.AcquireLock ();
 232                         }
 233                 }
 234         }
 235
 236         internal class SynchronizedServerContextSink: IMessageSink
 237         {
 238                 IMessageSink _next;
 239                 SynchronizationAttribute _att;
 240
 241                 public SynchronizedServerContextSink (IMessageSink next, SynchronizationAttribute att)
 242                 {
 243                         _att = att;
 244                         _next = next;
 245                 }
 246
 247                 public IMessageSink NextSink
 248                 {
 249                         get { return _next; }
 250                 }
 251
 252                 public IMessageCtrl AsyncProcessMessage (IMessage msg, IMessageSink replySink)
 253                 {
 254                         _att.AcquireLock ();
 255                         replySink = new SynchronizedContextReplySink (replySink, _att, false);
 256                         return _next.AsyncProcessMessage (msg, replySink);
 257                 }
 258
 259                 public IMessage SyncProcessMessage (IMessage msg)
 260                 {
 261                         _att.AcquireLock ();
 262                         try
 263                         {
 264                                 return _next.SyncProcessMessage (msg);
 265                         }
 266                         finally
 267                         {
 268                                 _att.ReleaseLock ();
 269                         }
 270                 }
 271         }
 272
 273         internal class SynchronizedContextReplySink: IMessageSink
 274         {
 275                 IMessageSink _next;
 276                 bool _newLock;
 277                 SynchronizationAttribute _att;
 278
 279                 public SynchronizedContextReplySink (IMessageSink next, SynchronizationAttribute att, bool newLock)
 280                 {
 281                         _newLock = newLock;
 282                         _next = next;
 283                         _att = att;
 284                 }
 285
 286                 public IMessageSink NextSink
 287                 {
 288                         get { return _next; }
 289                 }
 290
 291                 public IMessageCtrl AsyncProcessMessage (IMessage msg, IMessageSink replySink)
 292                 {
 293                         // Never called
 294                         throw new NotSupportedException ();
 295                 }
 296
 297                 public IMessage SyncProcessMessage (IMessage msg)
 298                 {
 299                         if (_newLock) _att.AcquireLock ();
 300                         else _att.ReleaseLock ();
 301
 302                         try
 303                         {
 304                                 return _next.SyncProcessMessage (msg);
 305                         }
 306                         finally
 307                         {
 308                                 if (_newLock)
 309                                         _att.ReleaseLock ();
 310                         }
 311                 }
 312         }
 313 }
 314