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
132
133
|
/*
* Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package nsk.share;
import java.util.Stack;
/**
* Finalizer performs object finalization when virtual mashine shuts down.
* Finalizer is a thread that acts as a VM shutdown hook.
* This thread will be activated as VM shuts down because of
* invocation of <code>exit()</code> or termination. After activation
* Finalizer just calls <code>finalizeAtExit()</code> method of the specified object.
* The finalizable object should implement interface <code>Finalizable</code>.
*
* @see Finalizable
*/
public class Finalizer {
/** Finalizer thread to register as a VM shutdown hook. */
private static FinalizerThread finalizerThread = null;
/** An object to finalize. */
private Finalizable object;
/**
* Create finalizer for the specified object.
*/
public Finalizer(Finalizable object) {
this.object = object;
}
/**
* Register finalizer for finalization at VM shutdown.
*/
public void activate() {
if (finalizerThread == null) {
finalizerThread = new FinalizerThread("FinalizerThread for Finalizable objects");
finalizerThread.activate();
}
finalizerThread.add(object);
}
/**
* Unregister finalizer for finalization at VM shutdown.
*/
public void deactivate() {
if (finalizerThread == null)
return;
finalizerThread.remove(object);
}
/**
* Static inner thread that is registered as a VM shutdown hook
* and performs finalization of all registered finalizable objects.
*/
private static class FinalizerThread extends Thread {
/** Stack of objects registered for finalization. */
private Stack<Object> objects = new Stack<Object>();
/** Make new instance of FinalizerThread with given thread name. */
public FinalizerThread(String threadName) {
super(threadName);
}
/**
* Push an object to the stack of registered objects.
*/
public void add(Finalizable object) {
objects.push(object);
}
/**
* Remove an object from the stack of registered objects.
*/
public void remove(Finalizable object) {
objects.remove(object);
}
/**
* Register finalizer thread as a VM shutdown hook.
*/
public void activate() {
Runtime.getRuntime().addShutdownHook( this );
}
/**
* Unregister finalizer thread as a VM shutdown hook.
*/
public void deactivate() {
Runtime.getRuntime().removeShutdownHook( this );
}
/**
* Pop all registered objects from the stack and finalize them.
*/
public void run() {
while (!objects.empty()) {
Finalizable object = (Finalizable)objects.pop();
try {
object.finalizeAtExit();
} catch (ThreadDeath e) {
throw e;
} catch (Throwable ex) {
ex.printStackTrace();
}
}
}
} // end of FinalizerThread
} // end of Finalizer
|
