1/*
2 * Copyright (c) 2007, 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.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23/*
24 * @test
25 * @bug 4405807
26 * @modules java.base/java.util:open
27 * @run main/othervm -Xms10m ReferencesTest
28 * @summary Verify that references from ResourceBundle cache don't prevent
29 * class loader reclamation.
30 */
31
32import java.io.File;
33import java.lang.ref.WeakReference;
34import java.lang.reflect.Field;
35import java.net.URL;
36import java.net.URLClassLoader;
37import java.util.Locale;
38import java.util.Map;
39import java.util.MissingResourceException;
40import java.util.ResourceBundle;
41
42/**
43 * This test relies on the current behavior of the garbage collector and is
44 * therefore no clear indicator of whether the fix for 4405807 works.
45 * If the test fails, it might indicate a regression, or it might just mean
46 * that a less aggressive garbage collector is used.
47 */
48public class ReferencesTest {
49
50    private static final int CLASS_LOADER_COUNT = 20;
51
52    // These two parallel arrays have references to the same class loaders.
53    // The weakLoaders array lets us track whether class loaders are being
54    // reclaimed after the references in the loaders array are nulled out.
55    private static ClassLoader[] loaders = new ClassLoader[CLASS_LOADER_COUNT];
56    private static WeakReference[] weakLoaders = new WeakReference[CLASS_LOADER_COUNT];
57
58    public static void main(String[] args) throws Exception {
59
60        URL testDirectory = new File(System.getProperty("test.classes", ".")).toURL();
61
62        for (int i = 0; i < loaders.length; i++) {
63            URL[] urls = { testDirectory };
64            loaders[i] = new URLClassLoader(urls);
65            weakLoaders[i] = new WeakReference(loaders[i]);
66        }
67
68        // fill the ResourceBundle cache with entries for half the class loaders
69        loadBundles(0, CLASS_LOADER_COUNT / 2);
70
71        report("After loading resource bundles for first half of class loaders: ");
72
73        // release the first half of the class loaders
74        for (int i = 0; i < CLASS_LOADER_COUNT / 2; i++) {
75            loaders[i] = null;
76        }
77
78        System.gc();
79
80        report("After releasing first half of class loaders: ");
81
82        // fill the ResourceBundle cache with entries for second half the class loaders
83        loadBundles(CLASS_LOADER_COUNT / 2, CLASS_LOADER_COUNT);
84
85        report("After loading resource bundles for second half of class loaders: ");
86
87        // release the second half of the class loaders
88        for (int i = CLASS_LOADER_COUNT / 2; i < CLASS_LOADER_COUNT; i++) {
89            loaders[i] = null;
90        }
91
92        System.gc();
93
94        report("After releasing second half of class loaders: ");
95
96        // The garbage collector in Tiger actually has reclaimed all class
97        // loaders at this point, but in order not to become too dependent
98        // on the current behavior, we only require that the first half
99        // has been reclaimed.
100        if (countLoaders(0, CLASS_LOADER_COUNT / 2) > 0) {
101            throw new RuntimeException("Too many class loaders not reclaimed yet.");
102        }
103    }
104
105    private static void report(String when) throws Exception {
106        int first = countLoaders(0, CLASS_LOADER_COUNT / 2);
107        int second = countLoaders(CLASS_LOADER_COUNT / 2, CLASS_LOADER_COUNT);
108
109        Class clazz = ResourceBundle.class;
110        Field cacheList = clazz.getDeclaredField("cacheList");
111        cacheList.setAccessible(true);
112        int cacheSize = ((Map)cacheList.get(clazz)).size();
113
114        System.out.println(when);
115        System.out.println("    " + first + " loaders alive in first half");
116        System.out.println("    " + second + " loaders alive in second half");
117        System.out.println("    " + cacheSize + " entries in resource bundle cache");
118    }
119
120    private static void loadBundles(int start, int end) throws Exception {
121        for (int i = start; i < end; i++) {
122            // There's no resource bundle for NonExistantBundle - this
123            // let's us test the case where a resource bundle is not found,
124            // which in the past created a SoftReference on the value side
125            // of the cache.
126            try {
127                ResourceBundle.getBundle("NonExistantBundle", Locale.US, loaders[i]);
128            } catch (MissingResourceException e) {
129            }
130            // There's a base resource bundle for ReferencesTestBundle - the
131            // normal case.
132            ResourceBundle.getBundle("ReferencesTestBundle", Locale.US, loaders[i]);
133        }
134    }
135
136    private static int countLoaders(int start, int end) {
137        int count = 0;
138        for (int i = start; i < end; i++) {
139            if (weakLoaders[i].get() != null) {
140                count++;
141            }
142        }
143        return count;
144    }
145}
146