/*

 * Copyright (c) 2018, Red Hat, Inc. All rights reserved.

 *

 * 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.

 *

 */

/*

 * @test TestRefprocSanity

 * @summary Test that null references/referents work fine

 * @key gc

 * @requires vm.gc.Shenandoah & !vm.graal.enabled

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -Xmx1g -Xms1g                                                             TestRefprocSanity

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -Xmx1g -Xms1g -XX:+ShenandoahVerify                                       TestRefprocSanity

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -Xmx1g -Xms1g                       -XX:ShenandoahGCHeuristics=aggressive TestRefprocSanity

 */

import java.lang.ref.*;

public class TestRefprocSanity {

    static final long TARGET_MB = Long.getLong("target", 10_000); // 10 Gb allocation

    static final int WINDOW = 10_000;

    static final Reference<MyObject>[] refs = new Reference[WINDOW];

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

        long count = TARGET_MB * 1024 * 1024 / 32;

        int rIdx = 0;

        ReferenceQueue rq = new ReferenceQueue();

        for (int c = 0; c < WINDOW; c++) {

            refs[c] = select(c, new MyObject(c), rq);

        }

        for (int c = 0; c < count; c++) {

            verifyRefAt(rIdx);

            refs[rIdx] = select(c, new MyObject(rIdx), rq);

            rIdx++;

            if (rIdx >= WINDOW) {

                rIdx = 0;

            }

            while (rq.poll() != null); // drain

        }

    }

    static Reference<MyObject> select(int v, MyObject ext, ReferenceQueue rq) {

        switch (v % 10) {

            case 0:  return new SoftReference<MyObject>(null);

            case 1:  return new SoftReference<MyObject>(null, rq);

            case 2:  return new SoftReference<MyObject>(ext);

            case 3:  return new SoftReference<MyObject>(ext, rq);

            case 4:  return new WeakReference<MyObject>(null);

            case 5:  return new WeakReference<MyObject>(null, rq);

            case 6:  return new WeakReference<MyObject>(ext);

            case 7:  return new WeakReference<MyObject>(ext, rq);

            case 8:  return new PhantomReference<MyObject>(null, rq);

            case 9:  return new PhantomReference<MyObject>(ext, rq);

            default: throw new IllegalStateException();

        }

    }

    static void verifyRefAt(int idx) {

        Reference<MyObject> ref = refs[idx];

        MyObject mo = ref.get();

        if (mo != null && mo.x != idx) {

            throw new IllegalStateException("Referent tag is incorrect: " + mo.x + ", should be " + idx);

        }

    }

    static class MyObject {

        final int x;

        public MyObject(int x) {

            this.x = x;

        }

    }

}