10230
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1 /*
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2 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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20 * or visit www.oracle.com if you need additional information or have any
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21 * questions.
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22 */
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23
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24 /*
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25 * @test KeepAliveSoftReference
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26 * @summary This test case uses a java.lang.ref.SoftReference referencing a class instance to keep a class alive.
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27 * @library /testlibrary /testlibrary/whitebox /runtime/testlibrary
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28 * @library classes
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29 * @build KeepAliveSoftReference test.Empty
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30 * @build ClassUnloadCommon
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31 * @run main ClassFileInstaller sun.hotspot.WhiteBox
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32 * @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI KeepAliveSoftReference
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33 */
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34
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35 import java.lang.ref.SoftReference;
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36 import sun.hotspot.WhiteBox;
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37
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38 /**
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39 * Test that verifies that classes are not unloaded when specific types of references are kept to them.
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40 */
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41 public class KeepAliveSoftReference {
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42 private static final String className = "test.Empty";
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43 private static final WhiteBox wb = WhiteBox.getWhiteBox();
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44
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45 public static void main(String... args) throws Exception {
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46 ClassLoader cl = ClassUnloadCommon.newClassLoader();
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47 Class<?> c = cl.loadClass(className);
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48 Object o = c.newInstance();
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49 SoftReference<Object> sr = new SoftReference(o);
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50 o = null; c = null; cl = null;
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51
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52 {
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53 boolean isAlive = wb.isClassAlive(className);
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54 System.out.println("testSoftReference (1) alive: " + isAlive);
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55 boolean cleared = (sr.get() == null);
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56 boolean shouldBeAlive = !cleared;
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57 ClassUnloadCommon.failIf(isAlive != shouldBeAlive, "" + isAlive + " != " + shouldBeAlive);
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58 }
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59
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60 ClassUnloadCommon.triggerUnloading();
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61
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62 {
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63 boolean isAlive = wb.isClassAlive(className);
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64 System.out.println("testSoftReference (2) alive: " + isAlive);
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65 boolean cleared = (sr.get() == null);
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66 boolean shouldBeAlive = !cleared;
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67 ClassUnloadCommon.failIf(isAlive != shouldBeAlive, "" + isAlive + " != " + shouldBeAlive);
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68 }
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69 sr.clear();
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70 ClassUnloadCommon.triggerUnloading();
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71
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72 {
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73 boolean isAlive = wb.isClassAlive(className);
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74 System.out.println("testSoftReference (3) alive: " + isAlive);
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75 boolean cleared = (sr.get() == null);
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76 boolean shouldBeAlive = !cleared;
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77 ClassUnloadCommon.failIf(isAlive != shouldBeAlive, "" + isAlive + " != " + shouldBeAlive);
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78 }
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79 }
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80 }
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