1 /*
2 * Copyright (c) 2011, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 /*
27 * To change this template, choose Tools | Templates
28 * and open the template in the editor.
29 */
30
31 package com.sun.webkit;
32
33 import java.lang.ref.ReferenceQueue;
34 import java.lang.ref.WeakReference;
35 import java.util.Arrays;
36 import java.util.Collection;
37 import java.util.HashSet;
38 import java.util.Set;
39 import java.util.concurrent.LinkedBlockingQueue;
40
41 /**
42 * This class is used for registering and disposing the native
43 * data associated with java objects.
44 *
45 * The object can register itself by calling the addRecord method and
46 * providing a descendant of the DisposerRecord class with overridden
47 * dispose() method.
48 *
49 * When the object becomes unreachable, the dispose() method
50 * of the associated DisposerRecord object will be called.
51 *
52 * @see DisposerRecord
53 */
54 public final class Disposer implements Runnable {
55 private static final ReferenceQueue queue = new ReferenceQueue();
56 private static final Disposer disposerInstance = new Disposer();
57 private static final Set<WeakDisposerRecord> records =
58 new HashSet<WeakDisposerRecord>();
59
60 static {
61 Thread t = new Thread(disposerInstance, "Disposer");
62 t.setDaemon(true);
63 t.setPriority(Thread.MAX_PRIORITY);
64 t.start();
65 }
66
67 /**
68 * Registers the object and the native data for later disposal.
69 * @param target Object to be registered
70 * @param rec the associated DisposerRecord object
71 * @see DisposerRecord
72 */
73 public static void addRecord(Object target, DisposerRecord rec) {
74 disposerInstance.add(target, rec);
75 }
76
77 /**
78 * Performs the actual registration of the target object to be disposed.
79 * @param target Object to be registered
80 * @param rec the associated DisposerRecord object
81 * @see DisposerRecord
82 */
83 private synchronized void add(Object target, DisposerRecord rec) {
84 records.add(new WeakDisposerRecord(target, rec));
85 }
86
87 public void run() {
88 while (true) {
89 try {
90 WeakDisposerRecord obj = (WeakDisposerRecord) queue.remove();
91 obj.clear();
92 DisposerRunnable.getInstance().enqueue(obj);
93 } catch (Exception e) {
94 System.out.println("Exception while removing reference: " + e);
95 e.printStackTrace();
96 }
97 }
98 }
99
100 private static final class DisposerRunnable implements Runnable {
101 private static final DisposerRunnable theInstance = new DisposerRunnable();
102
103 private static DisposerRunnable getInstance() {
104 return theInstance;
105 }
106
107 private boolean isRunning = false;
108 private final Object disposerLock = new Object();
109 private final LinkedBlockingQueue<WeakDisposerRecord> disposerQueue
110 = new LinkedBlockingQueue<WeakDisposerRecord>();
111
112 private void enqueueAll(Collection<WeakDisposerRecord> objs) {
113 synchronized (disposerLock) {
114 disposerQueue.addAll(objs);
115 if (!isRunning) {
116 Invoker.getInvoker().invokeOnEventThread(this);
117 isRunning = true;
118 }
119 }
120 }
121
122 private void enqueue(WeakDisposerRecord obj) {
123 enqueueAll(Arrays.asList(obj));
124 }
125
126 @Override public void run() {
127 while (true) {
128 WeakDisposerRecord obj;
129 synchronized (disposerLock) {
130 obj = disposerQueue.poll();
131 if (obj == null) {
132 isRunning = false;
133 break;
134 }
135 }
136 // Check if the object has not yet been removed & disposed.
137 if (records.contains(obj)) {
138 records.remove(obj);
139 obj.dispose();
140 }
141 }
142 }
143 }
144
145 public static class WeakDisposerRecord
146 extends WeakReference
147 implements DisposerRecord
148 {
149 protected WeakDisposerRecord(Object referent) {
150 super(referent, Disposer.queue);
151 this.record = null;
152 }
153
154 private WeakDisposerRecord(Object referent, DisposerRecord record) {
155 super(referent, Disposer.queue);
156 this.record = record;
157 }
158
159 private final DisposerRecord record;
160
161 @Override
162 public void dispose() {
163 record.dispose();
164 }
165 }
166 }