244 lines
9.0 KiB
Java
244 lines
9.0 KiB
Java
/*
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* Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* @test
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* @summary verify if the hidden class is unloaded when the class loader is GC'ed
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* @modules jdk.compiler
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* @library /test/lib/
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* @build jdk.test.lib.util.ForceGC
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* @run testng/othervm UnloadingTest
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*/
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import java.io.IOException;
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import java.lang.invoke.MethodHandles.Lookup;
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import java.lang.ref.Reference;
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import java.lang.ref.WeakReference;
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import java.lang.reflect.Method;
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import java.net.MalformedURLException;
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import java.net.URL;
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import java.net.URLClassLoader;
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import java.nio.file.Files;
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import java.nio.file.Path;
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import java.nio.file.Paths;
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import java.util.concurrent.atomic.AtomicInteger;
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import jdk.test.lib.util.ForceGC;
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import jdk.test.lib.compiler.CompilerUtils;
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import jdk.test.lib.Utils;
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import org.testng.annotations.BeforeTest;
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import org.testng.annotations.Test;
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import static java.lang.invoke.MethodHandles.lookup;
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import static java.lang.invoke.MethodHandles.Lookup.ClassOption.*;
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import static org.testng.Assert.*;
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public class UnloadingTest {
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private static final Path CLASSES_DIR = Paths.get("classes");
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private static byte[] hiddenClassBytes;
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@BeforeTest
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static void setup() throws IOException {
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Path src = Paths.get(Utils.TEST_SRC, "src", "LookupHelper.java");
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if (!CompilerUtils.compile(src, CLASSES_DIR)) {
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throw new RuntimeException("Compilation of the test failed: " + src);
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}
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hiddenClassBytes = Files.readAllBytes(CLASSES_DIR.resolve("LookupHelper.class"));
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}
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/*
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* Test that a hidden class is unloaded while the loader remains strongly reachable
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*/
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@Test
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public void unloadable() throws Exception {
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TestLoader loader = new TestLoader();
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Class<?> helper = Class.forName("LookupHelper", true, loader);
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Method m = helper.getMethod("getLookup");
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Lookup lookup = (Lookup)m.invoke(null);
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HiddenClassUnloader unloader = createHiddenClass(lookup, false);
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// the hidden class should be unloaded
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unloader.unload();
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// loader is strongly reachable
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Reference.reachabilityFence(loader);
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}
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/*
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* Test that a hidden class is not unloaded when the loader is strongly reachable
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*/
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@Test
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public void notUnloadable() throws Exception {
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TestLoader loader = new TestLoader();
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Class<?> helper = Class.forName("LookupHelper", true, loader);
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Method m = helper.getMethod("getLookup");
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Lookup lookup = (Lookup)m.invoke(null);
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HiddenClassUnloader unloader = createHiddenClass(lookup, true);
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assertFalse(unloader.tryUnload()); // hidden class is not unloaded
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// loader is strongly reachable
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Reference.reachabilityFence(loader);
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}
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/*
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* Create a nest of two hidden classes.
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* They can be unloaded even the loader is strongly reachable
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*/
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@Test
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public void hiddenClassNest() throws Exception {
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TestLoader loader = new TestLoader();
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Class<?> helper = Class.forName("LookupHelper", true, loader);
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Method m = helper.getMethod("getLookup");
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Lookup lookup = (Lookup)m.invoke(null);
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HiddenClassUnloader[] unloaders = createNestOfTwoHiddenClasses(lookup, false, false);
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// keep a strong reference to the nest member class
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Class<?> member = unloaders[1].weakRef.get();
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assertTrue(member != null);
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// nest host and member will not be unloaded
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assertFalse(unloaders[0].tryUnload());
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assertFalse(unloaders[1].tryUnload());
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// clear the reference to the nest member
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Reference.reachabilityFence(member);
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member = null;
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// nest host and member will be unloaded
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unloaders[0].unload();
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unloaders[1].unload();
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// loader is strongly reachable
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Reference.reachabilityFence(loader);
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}
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/*
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* Create a nest with a hidden class nest host and strong nest member.
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* Test that both are not unloaded
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*/
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@Test
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public void hiddenClassNestStrongMember() throws Exception {
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TestLoader loader = new TestLoader();
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Class<?> helper = Class.forName("LookupHelper", true, loader);
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Method m = helper.getMethod("getLookup");
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Lookup lookup = (Lookup)m.invoke(null);
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HiddenClassUnloader[] unloaders = createNestOfTwoHiddenClasses(lookup, false, true);
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assertFalse(unloaders[0].tryUnload()); // nest host cannot be unloaded
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assertFalse(unloaders[1].tryUnload()); // nest member cannot be unloaded
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// loader is strongly reachable
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Reference.reachabilityFence(loader);
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}
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/*
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* Create a nest with a strong hidden nest host and a hidden class member.
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* The nest member can be unloaded whereas the nest host will not be unloaded.
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*/
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@Test
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public void hiddenClassNestStrongHost() throws Exception {
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TestLoader loader = new TestLoader();
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Class<?> helper = Class.forName("LookupHelper", true, loader);
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Method m = helper.getMethod("getLookup");
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Lookup lookup = (Lookup)m.invoke(null);
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HiddenClassUnloader[] unloaders = createNestOfTwoHiddenClasses(lookup, true, false);
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assertFalse(unloaders[0].tryUnload()); // nest host cannot be unloaded
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unloaders[1].unload();
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// loader is strongly reachable
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Reference.reachabilityFence(loader);
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}
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/*
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* Create a HiddenClassUnloader that holds a weak reference to the newly created
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* hidden class.
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*/
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static HiddenClassUnloader createHiddenClass(Lookup lookup, boolean strong) throws Exception {
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Class<?> hc;
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if (strong) {
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hc = lookup.defineHiddenClass(hiddenClassBytes, false, STRONG).lookupClass();
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} else {
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hc = lookup.defineHiddenClass(hiddenClassBytes, false).lookupClass();
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}
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assertTrue(hc.getClassLoader() == lookup.lookupClass().getClassLoader());
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return new HiddenClassUnloader(hc);
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}
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/*
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* Create an array of HiddenClassUnloader with two elements: the first element
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* is for the nest host and the second element is for the nest member.
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*/
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static HiddenClassUnloader[] createNestOfTwoHiddenClasses(Lookup lookup, boolean strongHost, boolean strongMember) throws Exception {
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Lookup hostLookup;
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if (strongHost) {
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hostLookup = lookup.defineHiddenClass(hiddenClassBytes, false, STRONG);
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} else {
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hostLookup = lookup.defineHiddenClass(hiddenClassBytes, false);
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}
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Class<?> host = hostLookup.lookupClass();
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Class<?> member;
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if (strongMember) {
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member = hostLookup.defineHiddenClass(hiddenClassBytes, false, NESTMATE, STRONG).lookupClass();
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} else {
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member = hostLookup.defineHiddenClass(hiddenClassBytes, false, NESTMATE).lookupClass();
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}
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assertTrue(member.getNestHost() == host);
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return new HiddenClassUnloader[] { new HiddenClassUnloader(host), new HiddenClassUnloader(member) };
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}
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static class HiddenClassUnloader {
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private final WeakReference<Class<?>> weakRef;
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private HiddenClassUnloader(Class<?> hc) {
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assertTrue(hc.isHidden());
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this.weakRef = new WeakReference<>(hc);
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}
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void unload() {
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// Force garbage collection to trigger unloading of class loader
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// and native library.
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if (!ForceGC.wait(() -> weakRef.refersTo(null))) {
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throw new RuntimeException("loader " + " not unloaded!");
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}
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}
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boolean tryUnload() {
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return ForceGC.waitFor(() -> weakRef.refersTo(null), 2000L);
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}
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}
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static class TestLoader extends URLClassLoader {
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static URL[] toURLs() {
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try {
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return new URL[] { CLASSES_DIR.toUri().toURL() };
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} catch (MalformedURLException e) {
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throw new Error(e);
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}
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}
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static AtomicInteger counter = new AtomicInteger();
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TestLoader() {
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super("testloader-" + counter.addAndGet(1), toURLs(), ClassLoader.getSystemClassLoader());
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}
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}
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}
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