mcs/class/corlib/System.Threading/RegisteredWaitHandle.cs

   1 //
   2 // System.Threading.RegisteredWaitHandle.cs
   3 //
   4 // Author:
   5 //   Dick Porter (dick@ximian.com)
   6 //   Lluis Sanchez Gual (lluis@ideary.com)
   7 //
   8 // (C) Ximian, Inc.  http://www.ximian.com
   9 //
  10
  11 //
  12 // Copyright (C) 2004, 2005 Novell, Inc (http://www.novell.com)
  13 //
  14 // Permission is hereby granted, free of charge, to any person obtaining
  15 // a copy of this software and associated documentation files (the
  16 // "Software"), to deal in the Software without restriction, including
  17 // without limitation the rights to use, copy, modify, merge, publish,
  18 // distribute, sublicense, and/or sell copies of the Software, and to
  19 // permit persons to whom the Software is furnished to do so, subject to
  20 // the following conditions:
  21 //
  22 // The above copyright notice and this permission notice shall be
  23 // included in all copies or substantial portions of the Software.
  24 //
  25 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  26 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  27 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  28 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  29 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  30 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  31 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  32 //
  33
  34 using System.Runtime.InteropServices;
  35
  36 namespace System.Threading
  37 {
  38         [ComVisible (true)]
  39         public sealed class RegisteredWaitHandle
  40                 : MarshalByRefObject
  41         {
  42                 WaitHandle _waitObject;
  43                 WaitOrTimerCallback _callback;
  44                 object _state;
  45                 WaitHandle _finalEvent;
  46                 ManualResetEvent _cancelEvent;
  47                 TimeSpan _timeout;
  48                 int _callsInProcess;
  49                 bool _executeOnlyOnce;
  50                 bool _unregistered;
  51
  52                 internal RegisteredWaitHandle (WaitHandle waitObject, WaitOrTimerCallback callback, object state, TimeSpan timeout, bool executeOnlyOnce)
  53                 {
  54                         _waitObject = waitObject;
  55                         _callback = callback;
  56                         _state = state;
  57                         _timeout = timeout;
  58                         _executeOnlyOnce = executeOnlyOnce;
  59                         _finalEvent = null;
  60                         _cancelEvent = new ManualResetEvent (false);
  61                         _callsInProcess = 0;
  62                         _unregistered = false;
  63                 }
  64
  65                 internal void Wait (object state)
  66                 {
  67                         bool release = false;
  68                         try {
  69                                 _waitObject.SafeWaitHandle.DangerousAddRef (ref release);
  70                                 try {
  71                                         WaitHandle[] waits = new WaitHandle[] {_waitObject, _cancelEvent};
  72                                         do {
  73                                                 int signal = WaitHandle.WaitAny (waits, _timeout, false);
  74                                                 if (!_unregistered) {
  75                                                         lock (this) {
  76                                                                 _callsInProcess++;
  77                                                         }
  78                                                         ThreadPool.QueueUserWorkItem (new WaitCallback (DoCallBack), (signal == WaitHandle.WaitTimeout));
  79                                                 }
  80                                         } while (!_unregistered && !_executeOnlyOnce);
  81                                 } catch {
  82                                 }
  83
  84                                 lock (this) {
  85                                         _unregistered = true;
  86                                         if (_callsInProcess == 0 && _finalEvent != null)
  87                                                 NativeEventCalls.SetEvent (_finalEvent.SafeWaitHandle);
  88                                 }
  89                         } catch (ObjectDisposedException) {
  90                                 // Can happen if we called Unregister before we had time to execute Wait
  91                                 if (release)
  92                                         throw;
  93                         } finally {
  94                                 if (release)
  95                                         _waitObject.SafeWaitHandle.DangerousRelease ();
  96                         }
  97                 }
  98
  99                 private void DoCallBack (object timedOut)
 100                 {
 101                         if (_callback != null) {
 102                                 try {
 103                                         _callback (_state, (bool)timedOut);
 104                                 } catch {}
 105                         }
 106
 107                         lock (this)
 108                         {
 109                                 _callsInProcess--;
 110                                 if (_unregistered && _callsInProcess == 0 && _finalEvent != null)
 111                                         NativeEventCalls.SetEvent (_finalEvent.SafeWaitHandle);
 112                         }
 113                 }
 114
 115                 [ComVisible (true)]
 116                 public bool Unregister(WaitHandle waitObject)
 117                 {
 118                         lock (this)
 119                         {
 120                                 if (_unregistered)
 121                                         return false;
 122
 123                                 _finalEvent = waitObject;
 124                                 _unregistered = true;
 125                                 _cancelEvent.Set();
 126
 127                                 return true;
 128                         }
 129                 }
 130         }
 131 }