/*

 * Copyright (c) 2014, 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.

 *

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 */

/*

 * @test TestEagerReclaimHumongousRegionsWithRefs

 * @bug 8048179

 * @summary Test to make sure that eager reclaim of humongous objects that have previously

 * been referenced by other old gen regions work. We simply try to fill

 * up the heap with humongous objects and create a remembered set entry from an object by

 * referencing that we know is in the old gen. After changing this reference, the object

 * should still be eagerly reclaimable to avoid Full GC.

 * @key gc

 * @library /test/lib

 * @modules java.base/jdk.internal.misc

 *          java.management

 */

import java.util.regex.Pattern;

import java.util.regex.Matcher;

import java.util.LinkedList;

import jdk.test.lib.process.OutputAnalyzer;

import jdk.test.lib.process.ProcessTools;

import static jdk.test.lib.Asserts.*;

class RefHolder {

  Object ref;

}

class ReclaimRegionFast {

    public static final int M = 1024*1024;

    public static LinkedList<Object> garbageList = new LinkedList<Object>();

    public static void genGarbage() {

        for (int i = 0; i < 32*1024; i++) {

            garbageList.add(new int[100]);

        }

        garbageList.clear();

    }

    // A large object referenced by a static.

    static int[] filler = new int[10 * M];

    // Old gen object referencing the large object, generating remembered

    // set entries.

    static RefHolder fromOld = new RefHolder();

    public static void main(String[] args) {

        int[] large = new int[M];

        Object ref_from_stack = large;

        for (int i = 0; i < 100; i++) {

            // A large object that will be reclaimed eagerly.

            large = new int[6*M];

            fromOld.ref = large;

            genGarbage();

        }

        // Keep the reference to the first object alive.

        System.out.println(ref_from_stack);

    }

}

public class TestEagerReclaimHumongousRegionsWithRefs {

    public static void main(String[] args) throws Exception {

        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(

            "-XX:+UseG1GC",

            "-Xms128M",

            "-Xmx128M",

            "-Xmn16M",

            "-Xlog:gc",

            ReclaimRegionFast.class.getName());

        Pattern p = Pattern.compile("Full GC");

        OutputAnalyzer output = new OutputAnalyzer(pb.start());

        int found = 0;

        Matcher m = p.matcher(output.getStdout());

        while (m.find()) {

            found++;

        }

        System.out.println("Issued " + found + " Full GCs");

        assertLessThan(found, 10, "Found that " + found + " Full GCs were issued. This is larger than the bound. Eager reclaim of objects once referenced from old gen seems to not work at all");

        output.shouldHaveExitValue(0);

    }

}