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

   1 //
   2 // System.Threading.CompressedStackSwitcher structure
   3 //
   4 // Author:
   5 //      Sebastien Pouliot  <sebastien@ximian.com>
   6 //
   7 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 using System.Globalization;
  30 using System.Runtime.ConstrainedExecution;
  31 using System.Runtime.InteropServices;
  32
  33 namespace System.Threading {
  34
  35         [ComVisibleAttribute (false)]
  36         public struct CompressedStackSwitcher : IDisposable {
  37
  38                 private CompressedStack _cs;
  39                 private Thread _t;
  40
  41                 internal CompressedStackSwitcher (CompressedStack cs, Thread t)
  42                 {
  43                         _cs = cs;
  44                         _t = t;
  45                 }
  46
  47                 public override bool Equals (object obj)
  48                 {
  49                         if (obj == null)
  50                                 return false;
  51
  52                         if (obj is CompressedStackSwitcher)
  53                                 return op_Equality (this, (CompressedStackSwitcher)obj);
  54
  55                         return false;
  56                 }
  57
  58                 public override int GetHashCode ()
  59                 {
  60                         // documented as always the same for all instances
  61                         return typeof (CompressedStackSwitcher).GetHashCode ();
  62                         // Microsoft seems to return 1404280835 every time
  63                         // (even between executions).
  64                 }
  65
  66                 [ReliabilityContract (Consistency.WillNotCorruptState, Cer.MayFail)]
  67                 public void Undo ()
  68                 {
  69                         if ((_cs != null) && (_t != null)) {
  70                                 lock (_cs) {
  71                                         if ((_cs != null) && (_t != null)) {
  72                                                 _t.SetCompressedStack (_cs);
  73                                         }
  74                                         _t = null;
  75                                         _cs = null;
  76                                 }
  77                         }
  78                 }
  79
  80                 public static bool op_Equality (CompressedStackSwitcher c1, CompressedStackSwitcher c2)
  81                 {
  82                         if (c1._cs == null)
  83                                 return (c2._cs == null);
  84                         if (c2._cs == null)
  85                                 return false;
  86
  87                         if (c1._t.ManagedThreadId != c2._t.ManagedThreadId)
  88                                 return false;
  89                         return c1._cs.Equals (c2._cs);
  90                 }
  91
  92                 public static bool op_Inequality (CompressedStackSwitcher c1, CompressedStackSwitcher c2)
  93                 {
  94                         return !op_Equality (c1, c2);
  95                 }
  96
  97                 void IDisposable.Dispose ()
  98                 {
  99                         Undo ();
 100                 }
 101         }
 102 }