/*

 * Copyright (c) 2003, 2018, 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.

 *

 * 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

 * @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

 *

 * @requires vm.gc == "null"

 * @requires vm.opt.ExplicitGCInvokesConcurrent != "true"

 * @requires vm.opt.DisableExplicitGC != "true"

 * @library /lib/testlibrary/ /test/lib

 *

 * @build jdk.testlibrary.* LowMemoryTest MemoryUtil RunUtil

 * @build sun.hotspot.WhiteBox

 * @run driver ClassFileInstaller sun.hotspot.WhiteBox sun.hotspot.WhiteBox$WhiteBoxPermission

 * @run main/othervm/timeout=600 -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xbootclasspath/a:. LowMemoryTest

 */

import java.lang.management.*;

import java.util.*;

import java.util.concurrent.Phaser;

import javax.management.*;

import javax.management.openmbean.CompositeData;

import jdk.testlibrary.JDKToolFinder;

import jdk.testlibrary.Utils;

import sun.hotspot.code.Compiler;

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;

    private static final String classMain = "LowMemoryTest$TestMain";

    /**

     * 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 {

        // 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";

        // Runs the test collecting subprocess I/O while it's running.

        traceTest(classMain + ", -XX:+UseSerialGC", nmFlag, lpFlag, "-XX:+UseSerialGC");

        traceTest(classMain + ", -XX:+UseParallelGC", nmFlag, lpFlag, "-XX:+UseParallelGC");

        traceTest(classMain + ", -XX:+UseG1GC", nmFlag, lpFlag, "-XX:+UseG1GC", g1Flag);

        if (!Compiler.isGraalEnabled()) { // Graal does not support CMS

            traceTest(classMain + ", -XX:+UseConcMarkSweepGC", nmFlag, lpFlag, "-XX:+UseConcMarkSweepGC");

        }

    }

    /*

     * Creating command-line for running subprocess JVM:

     *

     * JVM command line is like:

     * {test_jdk}/bin/java {defaultopts} -cp {test.class.path} {testopts} main

     *

     * {defaultopts} are the default java options set by the framework.

     *

     * @param testOpts java options specified by the test.

     */

    private static List<String> buildCommandLine(String... testOpts) {

        List<String> opts = new ArrayList<>();

        opts.add(JDKToolFinder.getJDKTool("java"));

        opts.addAll(Arrays.asList(Utils.getTestJavaOpts()));

        opts.add("-cp");

        opts.add(System.getProperty("test.class.path", "test.class.path"));

        opts.add("-Xlog:gc*=debug");

        opts.addAll(Arrays.asList(testOpts));

        opts.add(classMain);

        return opts;

    }

    /**

     * Runs LowMemoryTest$TestMain with the passed options and redirects subprocess

     * standard I/O to the current (parent) process. This provides a trace of what

     * happens in the subprocess while it is runnning (and before it terminates).

     *

     * @param prefixName the prefix string for redirected outputs

     * @param testOpts java options specified by the test.

     */

    private static void traceTest(String prefixName,

                                  String... testOpts)

                throws Throwable {

        // Building command-line

        List<String> opts = buildCommandLine(testOpts);

        // We activate all tracing in subprocess

        opts.add("trace");

        // Launch separate JVM subprocess

        String[] optsArray = opts.toArray(new String[0]);

        ProcessBuilder pb = new ProcessBuilder(optsArray);

        System.out.println("\n========= Tracing of subprocess " + prefixName + " =========");

        Process p = ProcessTools.startProcess(prefixName, pb);

        // Handling end of subprocess

        try {

            int exitCode = p.waitFor();

            if (exitCode != 0) {

                throw new RuntimeException(

                    "Subprocess unexpected exit value of [" + exitCode + "]. Expected 0.\n");

            }

        } catch (InterruptedException e) {

            throw new RuntimeException("Parent process interrupted with exception : \n " + e + " :" );

        }

     }

    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 boolean isRelaxed = false;

        private int triggers = 0;

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

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

        public TestListener() {

            isRelaxed = ManagementFactory.getRuntimeMXBean().getInputArguments().contains("-XX:+UseConcMarkSweepGC");

        }

        @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 {

            if (!checkValue(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 (!checkValue(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 boolean checkValue(int value, int target) {

            return checkValue((long)value, target);

        }

        private boolean checkValue(long value, int target) {

            if (!isRelaxed) {

                return value == target;

            } else {

                return value >= target;

            }

        }

    }

    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() {

            int iterations = 0;

            if (trace) {

                System.out.println("SweeperThread clearing allocated objects.");

            }

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

                       mpool.getUsageThreshold();) {

                // clear all allocated objects and invoke GC

                objectPool.clear();

                mm.gc();

                if (trace) {

                    iterations++;

                    System.out.println("SweeperThread called " + iterations +

                        " time(s) MemoryMXBean.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("SweeperThread is doing task " + i +

                    " phase " + phaser.getPhase());

                doTask();

                listenerInvoked = false;

                // Sync with AllocatorThread's second phase.

                phaser.arriveAndAwaitAdvance();

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

                    " phase " + phaser.getPhase());

                if (testFailed) return;

            }

        }

    }

}