/*

 * Copyright (c) 2013, 2016, 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.

 */

/*

 * To use ClassUnloadCommon from a sub-process, see hotspot/test/runtime/logging/ClassLoadUnloadTest.java

 * for an example.

 */

import java.io.File;

import java.net.MalformedURLException;

import java.net.URL;

import java.net.URLClassLoader;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.util.ArrayList;

import java.util.stream.Stream;

public class ClassUnloadCommon {

    public static class TestFailure extends RuntimeException {

        TestFailure(String msg) {

            super(msg);

        }

    }

    public static void failIf(boolean value, String msg) {

        if (value) throw new TestFailure("Test failed: " + msg);

    }

    private static volatile Object dummy = null;

    private static void allocateMemory(int kilobytes) {

        ArrayList<byte[]> l = new ArrayList<>();

        dummy = l;

        for (int i = kilobytes; i > 0; i -= 1) {

            l.add(new byte[1024]);

        }

        l = null;

        dummy = null;

    }

    public static void triggerUnloading() {

        allocateMemory(16 * 1024); // yg size is 8m with cms, force young collection

        System.gc();

    }

    /**

     * Creates a class loader that loads classes from {@code ${test.class.path}}

     * before delegating to the system class loader.

     */

    public static ClassLoader newClassLoader() {

        String cp = System.getProperty("test.class.path", ".");

        URL[] urls = Stream.of(cp.split(File.pathSeparator))

                .map(Paths::get)

                .map(ClassUnloadCommon::toURL)

                .toArray(URL[]::new);

        return new URLClassLoader(urls) {

            @Override

            public Class<?> loadClass(String cn, boolean resolve)

                throws ClassNotFoundException

            {

                synchronized (getClassLoadingLock(cn)) {

                    Class<?> c = findLoadedClass(cn);

                    if (c == null) {

                        try {

                            c = findClass(cn);

                        } catch (ClassNotFoundException e) {

                            c = getParent().loadClass(cn);

                        }

                    }

                    if (resolve) {

                        resolveClass(c);

                    }

                    return c;

                }

            }

        };

    }

    static URL toURL(Path path) {

        try {

            return path.toUri().toURL();

        } catch (MalformedURLException e) {

            throw new RuntimeException(e);

        }

    }

}