/*

 * 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 TestChurnNotifications

 * @summary Check that MX notifications are reported for all cycles

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

 *

 * @run main/othervm -Xmx128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCMode=passive            -XX:+ShenandoahDegeneratedGC -Dprecise=true  TestChurnNotifications

 * @run main/othervm -Xmx128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCMode=passive            -XX:-ShenandoahDegeneratedGC -Dprecise=true  TestChurnNotifications

 *

 * @run main/othervm -Xmx128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=aggressive   -Dprecise=false TestChurnNotifications

 *

 * @run main/othervm -Xmx128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=adaptive     -Dprecise=false TestChurnNotifications

 * @run main/othervm -Xmx128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=static       -Dprecise=false TestChurnNotifications

 * @run main/othervm -Xmx128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=compact      -Dprecise=false TestChurnNotifications

 * @run main/othervm -Xmx128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCMode=traversal          -Dprecise=false TestChurnNotifications

 */

import java.util.*;

import java.util.concurrent.atomic.*;

import javax.management.*;

import java.lang.management.*;

import javax.management.openmbean.*;

import com.sun.management.GarbageCollectionNotificationInfo;

public class TestChurnNotifications {

    static final long HEAP_MB = 128;                           // adjust for test configuration above

    static final long TARGET_MB = Long.getLong("target", 8_000); // 8 Gb allocation

    // Should we track the churn precisely?

    // Precise tracking is only reliable when GC is fully stop-the-world. Otherwise,

    // we cannot tell, looking at heap used before/after, what was the GC churn.

    static final boolean PRECISE = Boolean.getBoolean("precise");

    static final long M = 1024 * 1024;

    static volatile Object sink;

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

        final AtomicLong churnBytes = new AtomicLong();

        NotificationListener listener = new NotificationListener() {

            @Override

            public void handleNotification(Notification n, Object o) {

                if (n.getType().equals(GarbageCollectionNotificationInfo.GARBAGE_COLLECTION_NOTIFICATION)) {

                    GarbageCollectionNotificationInfo info = GarbageCollectionNotificationInfo.from((CompositeData) n.getUserData());

                    Map<String, MemoryUsage> mapBefore = info.getGcInfo().getMemoryUsageBeforeGc();

                    Map<String, MemoryUsage> mapAfter = info.getGcInfo().getMemoryUsageAfterGc();

                    MemoryUsage before = mapBefore.get("Shenandoah");

                    MemoryUsage after = mapAfter.get("Shenandoah");

                    if ((before != null) && (after != null)) {

                        long diff = before.getUsed() - after.getUsed();

                        if (diff > 0) {

                            churnBytes.addAndGet(diff);

                        }

                    }

                }

            }

        };

        for (GarbageCollectorMXBean bean : ManagementFactory.getGarbageCollectorMXBeans()) {

            ((NotificationEmitter) bean).addNotificationListener(listener, null, null);

        }

        final int size = 100_000;

        long count = TARGET_MB * 1024 * 1024 / (16 + 4 * size);

        long mem = count * (16 + 4 * size);

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

            sink = new int[size];

        }

        System.gc();

        Thread.sleep(1000);

        long actual = churnBytes.get();

        long minExpected = PRECISE ? (mem - HEAP_MB * 1024 * 1024) : 1;

        long maxExpected = mem + HEAP_MB * 1024 * 1024;

        String msg = "Expected = [" + minExpected / M + "; " + maxExpected / M + "] (" + mem / M + "), actual = " + actual / M;

        if (minExpected < actual && actual < maxExpected) {

            System.out.println(msg);

        } else {

            throw new IllegalStateException(msg);

        }

    }

}