/*

 * Copyright (c) 2013, 2019, 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.

 */

package gc.metaspace;

/*

 * @test G1AddMetaspaceDependency

 * @bug 8010196

 * @requires vm.gc.G1

 * @library /

 * @summary Checks that we don't get locking problems when adding metaspace dependencies with the G1 update buffer monitor

 * @run main/othervm -XX:+UseG1GC -XX:G1UpdateBufferSize=1 gc.metaspace.G1AddMetaspaceDependency

 */

import java.io.InputStream;

public class G1AddMetaspaceDependency {

  static byte[] getClassBytes(String name) {

    byte[] b = null;

    try (InputStream is = ClassLoader.getSystemResourceAsStream(name)) {

      byte[] tmp = new byte[is.available()];

      is.read(tmp);

      b = tmp;

    } finally {

      if (b == null) {

        throw new RuntimeException("Unable to load class file");

      }

      return b;

    }

  }

  static final String a_name = A.class.getName();

  static final String b_name = B.class.getName();

  public static void main(String... args) throws Exception {

    final byte[] a_bytes = getClassBytes(a_name.replace('.', '/') + ".class");

    final byte[] b_bytes = getClassBytes(b_name.replace('.', '/') + ".class");

    for (int i = 0; i < 1000; i += 1) {

      runTest(a_bytes, b_bytes);

    }

  }

  static class Loader extends ClassLoader {

    private final String myClass;

    private final byte[] myBytes;

    private final String friendClass;

    private final ClassLoader friendLoader;

    Loader(String myClass, byte[] myBytes,

           String friendClass, ClassLoader friendLoader) {

      this.myClass = myClass;

      this.myBytes = myBytes;

      this.friendClass = friendClass;

      this.friendLoader = friendLoader;

    }

    Loader(String myClass, byte[] myBytes) {

      this(myClass, myBytes, null, null);

    }

    @Override

    public Class<?> loadClass(String name) throws ClassNotFoundException {

      Class<?> c = findLoadedClass(name);

      if (c != null) {

        return c;

      }

      if (name.equals(friendClass)) {

        return friendLoader.loadClass(name);

      }

      if (name.equals(myClass)) {

        c = defineClass(name, myBytes, 0, myBytes.length);

        resolveClass(c);

        return c;

      }

      return findSystemClass(name);

    }

  }

  private static void runTest(final byte[] a_bytes, final byte[] b_bytes) throws Exception {

    Loader a_loader = new Loader(a_name, a_bytes);

    Loader b_loader = new Loader(b_name, b_bytes, a_name, a_loader);

    Loader c_loader = new Loader(b_name, b_bytes, a_name, a_loader);

    Loader d_loader = new Loader(b_name, b_bytes, a_name, a_loader);

    Loader e_loader = new Loader(b_name, b_bytes, a_name, a_loader);

    Loader f_loader = new Loader(b_name, b_bytes, a_name, a_loader);

    Loader g_loader = new Loader(b_name, b_bytes, a_name, a_loader);

    b_loader.loadClass(b_name);

    c_loader.loadClass(b_name);

    d_loader.loadClass(b_name);

    e_loader.loadClass(b_name);

    f_loader.loadClass(b_name);

    g_loader.loadClass(b_name);

  }

  public class A {

  }

  class B extends A {

  }

}