1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
//
// System.WeakReference.cs
//
// Author:
// Ajay kumar Dwivedi (adwiv@yahoo.com)
//
//
// Copyright (C) 2004 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System.Runtime.Serialization;
using System.Runtime.InteropServices;
namespace System
{
[Serializable]
#if NET_2_0
[ComVisible (true)]
#endif
public class WeakReference : ISerializable
{
//Fields
private bool isLongReference;
private GCHandle gcHandle;
// Helper method for constructors
//Should not be called from any other method.
private void AllocateHandle (Object target)
{
if (isLongReference) {
gcHandle = GCHandle.Alloc (target, GCHandleType.WeakTrackResurrection);
}
else {
gcHandle = GCHandle.Alloc (target, GCHandleType.Weak);
}
}
//Constructors
#if NET_2_1
protected WeakReference ()
{
}
#endif
public WeakReference (object target)
: this (target, false)
{
}
public WeakReference (object target, bool trackResurrection)
{
isLongReference = trackResurrection;
AllocateHandle (target);
}
protected WeakReference (SerializationInfo info, StreamingContext context)
{
if (info == null)
throw new ArgumentNullException ("info");
isLongReference = info.GetBoolean ("TrackResurrection");
Object target = info.GetValue ("TrackedObject", typeof (System.Object));
AllocateHandle (target);
}
// Properties
public virtual bool IsAlive {
get {
//Target property takes care of the exception
return (Target != null);
}
}
public virtual object Target {
get {
//Exception is thrown by gcHandle's Target
return gcHandle.Target;
}
set
{
gcHandle.Target = value;
}
}
public virtual bool TrackResurrection {
get {
return isLongReference;
}
}
//Methods
~WeakReference ()
{
gcHandle.Free ();
}
public virtual void GetObjectData (SerializationInfo info, StreamingContext context)
{
if (info == null)
throw new ArgumentNullException ("info");
info.AddValue ("TrackResurrection", TrackResurrection);
try {
info.AddValue ("TrackedObject", Target);
} catch (Exception) {
info.AddValue ("TrackedObject", null);
}
}
}
}
|
