/*

 * Copyright (c) 2017, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

import java.lang.instrument.ClassFileTransformer;

import java.lang.instrument.Instrumentation;

import java.lang.instrument.IllegalClassFormatException;

import java.security.ProtectionDomain;

public class GCDuringDumpTransformer implements ClassFileTransformer {

    static int n = 0;

    public byte[] transform(ClassLoader loader, String name, Class<?> classBeingRedefined,

                            ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException {

        n++;

        System.out.println("dump time loading: " + name + " in loader: " + loader);

        System.out.println("making garbage: " + n);

        try {

            makeGarbage();

        } catch (Throwable t) {

            t.printStackTrace();

            try {

                Thread.sleep(200); // let GC to have a chance to run

            } catch (Throwable t2) {}

        }

        System.out.println("making garbage: done");

        return null;

    }

    private static Instrumentation savedInstrumentation;

    public static void premain(String agentArguments, Instrumentation instrumentation) {

        System.out.println("ClassFileTransformer.premain() is called");

        instrumentation.addTransformer(new GCDuringDumpTransformer(), /*canRetransform=*/true);

        savedInstrumentation = instrumentation;

    }

    public static Instrumentation getInstrumentation() {

        return savedInstrumentation;

    }

    public static void agentmain(String args, Instrumentation inst) throws Exception {

        premain(args, inst);

    }

    public static void makeGarbage() {

        for (int x=0; x<10; x++) {

            Object[] a = new Object[10000];

        }

    }

}