test/jdk/java/lang/instrument/ParallelTransformerLoaderAgent.java

/*
 * Copyright (c) 2008, 2021, 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
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import java.io.File;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.instrument.Instrumentation;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.ProtectionDomain;

/**
 *      Test Java Agent
 *
 *      @author Daryl Puryear
 *      @copyright 1999-2004 Wily Technology, Inc.  All rights reserved.
 */
public class ParallelTransformerLoaderAgent {
    private static URL sURL;
    private static ClassLoader sClassLoader;

    public static synchronized ClassLoader getClassLoader() {
        return sClassLoader;
    }

    public static synchronized void generateNewClassLoader() {
        sClassLoader = new URLClassLoader(new URL[]{sURL});
    }

    public static void premain(String agentArgs, Instrumentation instrumentation) throws Exception {
        if (agentArgs == null || agentArgs == "") {
            System.err.println("Error: No jar file name provided, test will not run.");
            return;
        }

        sURL = (new File(agentArgs)).toURI().toURL();
        System.out.println("Using jar file: " + sURL);
        generateNewClassLoader();

        instrumentation.addTransformer(new TestTransformer());
    }

    private static class TestTransformer implements ClassFileTransformer {
        public byte[] transform(ClassLoader loader,
                                String className,
                                Class classBeingRedefined,
                                ProtectionDomain protectionDomain,
                                byte[] classfileBuffer)
                throws IllegalClassFormatException {
            String tName = Thread.currentThread().getName();

            // Load additional classes when called from thread 'TestThread'
            // When a class is loaded during a callback handling the boot loader, we can
            // run into ClassCircularityError if the ClassFileLoadHook is set early enough
            // to catch classes needed during class loading, e.g.
            //          sun.misc.URLClassPath$JarLoader$2.
            // The goal of the test is to stress class loading on the test class loaders.

            if (tName.equals("TestThread") && loader != null) {
                loadClasses(3);
            }
            return null;
        }

        public static void loadClasses(int index) {
            ClassLoader loader = ParallelTransformerLoaderAgent.getClassLoader();
            try {
                Class.forName("TestClass" + index, true, loader);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}