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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 *

 * 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,

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 *

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 */

/*

 * @test

 * @bug     4530538

 * @summary Basic unit test of memory management testing:

 *          1) setUsageThreshold() and getUsageThreshold()

 *          2) test low memory detection on the old generation.

 *

 * @author  Mandy Chung

 *

 * @build LowMemoryTest MemoryUtil

 * @run main/othervm/timeout=600 LowMemoryTest

 */

import java.lang.management.*;

import java.util.*;

import javax.management.*;

import javax.management.openmbean.CompositeData;

public class LowMemoryTest {

    private static MemoryPoolMXBean mpool = null;

    private static boolean trace = false;

    private static boolean testFailed = false;

    private static final int NUM_TRIGGERS = 5;

    private static final int NUM_CHUNKS = 2;

    private static long chunkSize;

    static class SensorListener implements NotificationListener {

        public void handleNotification(Notification notif, Object handback) {

            String type = notif.getType();

            if (type.equals(MemoryNotificationInfo.MEMORY_THRESHOLD_EXCEEDED) ||

                type.equals(MemoryNotificationInfo.

                    MEMORY_COLLECTION_THRESHOLD_EXCEEDED)) {

                MemoryNotificationInfo minfo = MemoryNotificationInfo.

                    from((CompositeData) notif.getUserData());

                MemoryUtil.printMemoryNotificationInfo(minfo, type);

                listenerInvoked = true;

            }

        }

    }

    static class TestListener implements NotificationListener {

        private int triggers = 0;

        public void handleNotification(Notification notif, Object handback) {

            MemoryNotificationInfo minfo = MemoryNotificationInfo.

                from((CompositeData) notif.getUserData());

            count[triggers] = minfo.getCount();

            usedMemory[triggers] = minfo.getUsage().getUsed();

            triggers++;

        }

        public void checkResult() throws Exception {

            if (triggers != NUM_TRIGGERS) {

                throw new RuntimeException("Unexpected number of triggers = " +

                    triggers + " but expected to be " + NUM_TRIGGERS);

            }

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

                if (count[i] != i+1) {

                    throw new RuntimeException("Unexpected count of" +

                        " notification #" + i +

                        " count = " + count[i] +

                        " but expected to be " + (i+1));

                }

                if (usedMemory[i] < newThreshold) {

                    throw new RuntimeException("Used memory = " +

                        usedMemory[i] + " is less than the threshold = " +

                        newThreshold);

                }

            }

        }

    }

    private static long newThreshold;

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

        if (args.length > 0 && args[0].equals("trace")) {

            trace = true;

        }

        // Find the Old generation which supports low memory detection

        ListIterator iter = pools.listIterator();

        while (iter.hasNext()) {

            MemoryPoolMXBean p = (MemoryPoolMXBean) iter.next();

            if (p.getType() == MemoryType.HEAP &&

                    p.isUsageThresholdSupported()) {

                mpool = p;

                if (trace) {

                    System.out.println("Selected memory pool for low memory " +

                        "detection.");

                    MemoryUtil.printMemoryPool(mpool);

                }

                break;

            }

        }

        TestListener listener = new TestListener();

        SensorListener l2 = new SensorListener();

        NotificationEmitter emitter = (NotificationEmitter) mm;

        emitter.addNotificationListener(listener, null, null);

        emitter.addNotificationListener(l2, null, null);

        Thread allocator = new AllocatorThread();

        Thread sweeper = new SweeperThread();

        // Now set threshold

        MemoryUsage mu = mpool.getUsage();

        chunkSize = (mu.getMax() - mu.getUsed()) / 20;

        newThreshold = mu.getUsed() + (chunkSize * NUM_CHUNKS);

        System.out.println("Setting threshold for " + mpool.getName() +

            " from " + mpool.getUsageThreshold() + " to " + newThreshold +

            ".  Current used = " + mu.getUsed());

        mpool.setUsageThreshold(newThreshold);

        if (mpool.getUsageThreshold() != newThreshold) {

            throw new RuntimeException("TEST FAILED: " +

                "Threshold for Memory pool " + mpool.getName() +

                "is " + mpool.getUsageThreshold() + " but expected to be" +

                newThreshold);

        }

        allocator.start();

        sweeper.start();

        try {

            allocator.join();

            sweeper.join();

        } catch (InterruptedException e) {

            testFailed = true;

        }

        listener.checkResult();

        if (testFailed)

            throw new RuntimeException("TEST FAILED.");

        System.out.println("Test passed.");

    }

    private static void goSleep(long ms) {

        try {

            Thread.sleep(ms);

        } catch (InterruptedException e) {

            testFailed = true;

        }

    }

    static class AllocatorThread extends Thread {

        public void doTask() {

            int iterations = 0;

            int numElements = (int) (chunkSize / 4); // minimal object size

                iterations++;

                if (trace) {

                    System.out.println("   Iteration " + iterations +

                        ": before allocation " +

                        mpool.getUsage().getUsed());

                }

                Object[] o = new Object[numElements];

                if (iterations <= NUM_CHUNKS) {

                    // only hold a reference to the first NUM_CHUNKS

                    // allocated objects

                    objectPool.add(o);

                }

                if (trace) {

                    System.out.println("               " +

                        "  after allocation " +

                        mpool.getUsage().getUsed());

                }

                goSleep(100);

            }

        }

        public void run() {

            for (int i = 1; i <= NUM_TRIGGERS; i++) {

                doTask();

                }

            }

        }

    }

    static class SweeperThread extends Thread {

        private void doTask() {

            for (; mpool.getUsage().getUsed() >=

                       mpool.getUsageThreshold();) {

                // clear all allocated objects and invoke GC

                objectPool.clear();

                mm.gc();

                goSleep(100);

            }

        }

        public void run() {

            for (int i = 1; i <= NUM_TRIGGERS; i++) {

                doTask();

                listenerInvoked = false;

                if (testFailed) return;

            }

        }

    }

}