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

   1 //
   2 // System.Threading.AsyncFlowControl.cs
   3 //
   4 // Author:
   5 //      Sebastien Pouliot  <sebastien@ximian.com>
   6 //
   7 // Copyright (C) 2004-2005 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.InteropServices;
  31 using System.Security;
  32
  33 namespace System.Threading {
  34
  35         internal enum AsyncFlowControlType {
  36                 None,
  37                 Execution,
  38                 Security
  39         }
  40
  41         public struct AsyncFlowControl : IDisposable {
  42                 private Thread _t;
  43                 private AsyncFlowControlType _type;
  44
  45                 internal AsyncFlowControl (Thread t, AsyncFlowControlType type)
  46                 {
  47                         _t = t;
  48                         _type = type;
  49                 }
  50
  51                 public void Undo ()
  52                 {
  53                         if (_t == null) {
  54                                 throw new InvalidOperationException (Locale.GetText (
  55                                         "Can only be called once."));
  56                         }
  57                         switch (_type) {
  58                         case AsyncFlowControlType.Execution:
  59                                 ExecutionContext.RestoreFlow ();
  60                                 break;
  61                         case AsyncFlowControlType.Security:
  62                                 SecurityContext.RestoreFlow ();
  63                                 break;
  64                         }
  65                         _t = null;
  66                 }
  67
  68                 void IDisposable.Dispose ()
  69                 {
  70                         if (_t != null) {
  71                                 Undo ();
  72                                 _t = null;
  73                                 _type = AsyncFlowControlType.None;
  74                         }
  75                 }
  76
  77                 public override int GetHashCode ()
  78                 {
  79                         return(base.GetHashCode ());
  80                 }
  81
  82                 public override bool Equals (object obj)
  83                 {
  84                         if (!(obj is AsyncFlowControl)) {
  85                                 return(false);
  86                         }
  87
  88                         return(obj.Equals (this));
  89                 }
  90
  91                 public bool Equals (AsyncFlowControl obj)
  92                 {
  93                         if (this._t == obj._t &&
  94                             this._type == obj._type) {
  95                                 return(true);
  96                         } else {
  97                                 return(false);
  98                         }
  99                 }
 100
 101                 public static bool operator == (AsyncFlowControl a, AsyncFlowControl b)
 102                 {
 103                         return a.Equals (b);
 104                 }
 105
 106                 public static bool operator != (AsyncFlowControl a, AsyncFlowControl b)
 107                 {
 108                         return !a.Equals (b);
 109                 }
 110         }
 111 }