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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

 *

 * @library /lib/testlibrary/

 * @build jdk.testlibrary.* LowMemoryTest MemoryUtil RunUtil

 * @run main/timeout=600 LowMemoryTest

 */

import java.lang.management.*;

import java.util.*;

import java.util.concurrent.Phaser;

import javax.management.*;

import javax.management.openmbean.CompositeData;

public class LowMemoryTest {

    private static final MemoryMXBean mm = ManagementFactory.getMemoryMXBean();

    private static final List<MemoryPoolMXBean> pools = ManagementFactory.getMemoryPoolMXBeans();

    private static final Phaser phaser = new Phaser(2);

    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 final int YOUNG_GEN_SIZE = 8 * 1024 * 1024;

    private static long chunkSize;

    /**

     * Run the test multiple times with different GC versions.

     * First with default command line specified by the framework.

     * Then with GC versions specified by the test.

     */

    public static void main(String a[]) throws Throwable {

        final String main = "LowMemoryTest$TestMain";

        // Use a low young gen size to ensure that the

        // allocated objects are put in the old gen.

        final String nmFlag = "-Xmn" + YOUNG_GEN_SIZE;

        // Using large pages will change the young gen size,

        // make sure we don't use them for this test.

        final String lpFlag = "-XX:-UseLargePages";

        // Prevent G1 from selecting a large heap region size,

        // since that would change the young gen size.

        final String g1Flag = "-XX:G1HeapRegionSize=1m";

        RunUtil.runTestClearGcOpts(main, nmFlag, lpFlag, "-XX:+UseSerialGC");

        RunUtil.runTestClearGcOpts(main, nmFlag, lpFlag, "-XX:+UseParallelGC");

        RunUtil.runTestClearGcOpts(main, nmFlag, lpFlag, "-XX:+UseG1GC", g1Flag);

        RunUtil.runTestClearGcOpts(main, nmFlag, lpFlag, "-XX:+UseConcMarkSweepGC");

    }

    private static volatile boolean listenerInvoked = false;

    static class SensorListener implements NotificationListener {

        @Override

        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;

        private final long[] count = new long[NUM_TRIGGERS * 2];

        private final long[] usedMemory = new long[NUM_TRIGGERS * 2];

        @Override

        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 {

                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;

    private static class TestMain {

        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();

            // The chunk size needs to be larger than YOUNG_GEN_SIZE,

            // otherwise we will get intermittent failures when objects

            // end up in the young gen instead of the old gen.

            final long epsilon = 1024;

            chunkSize = YOUNG_GEN_SIZE + epsilon;

            MemoryUsage mu = mpool.getUsage();

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

            // Sanity check. Make sure the new threshold isn't too large.

            // Tweak the test if this fails.

            final long headRoom = chunkSize * 2;

            final long max = mu.getMax();

            if (max != -1 && newThreshold > max - headRoom) {

                throw new RuntimeException("TEST FAILED: newThreshold: " + newThreshold +

                        " is too near the maximum old gen size: " + max +

                        " used: " + mu.getUsed() + " headRoom: " + headRoom);

            }

            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();

            // Force Allocator start first

            phaser.arriveAndAwaitAdvance();

            sweeper.start();

            try {

                allocator.join();

                // Wait until AllocatorThread's done

                phaser.arriveAndAwaitAdvance();

                sweeper.join();

            } catch (InterruptedException e) {

                System.out.println("Unexpected exception:" + e);

                testFailed = true;

            }

            listener.checkResult();

            if (testFailed)

                throw new RuntimeException("TEST FAILED.");

            System.out.println(RunUtil.successMessage);

        }

    }

    private static void goSleep(long ms) {

        try {

            Thread.sleep(ms);

        } catch (InterruptedException e) {

            System.out.println("Unexpected exception:" + e);

            testFailed = true;

        }

    }

    private static final List<Object> objectPool = new ArrayList<>();

    static class AllocatorThread extends Thread {

        public void doTask() {

            int iterations = 0;

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

            while (!listenerInvoked || mpool.getUsage().getUsed() < mpool.getUsageThreshold()) {

                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);

            }

        }

        @Override

        public void run() {

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

                // Sync with SweeperThread's second phase.

                phaser.arriveAndAwaitAdvance();

                System.out.println("AllocatorThread is doing task " + i +

                    " phase " + phaser.getPhase());

                doTask();

                // Sync with SweeperThread's first phase.

                phaser.arriveAndAwaitAdvance();

                System.out.println("AllocatorThread done task " + i +

                    " phase " + phaser.getPhase());

                if (testFailed) {

                    return;

                }

            }

        }

    }

    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);

            }

        }

        @Override

        public void run() {

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

                // Sync with AllocatorThread's first phase.

                phaser.arriveAndAwaitAdvance();

                System.out.println("SweepThread is doing task " + i +

                    " phase " + phaser.getPhase());

                doTask();

                listenerInvoked = false;

                // Sync with AllocatorThread's second phase.

                phaser.arriveAndAwaitAdvance();

                System.out.println("SweepThread done task " + i +

                    " phase " + phaser.getPhase());

                if (testFailed) return;

            }

        }

    }

}