/*

 * Copyright (c) 2017, 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 TestStringDedupStress

 * @summary Test Shenandoah string deduplication implementation

 * @key gc

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

 * @library /test/lib

 * @modules java.base/jdk.internal.misc:open

 * @modules java.base/java.lang:open

 *          java.management

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -DtargetStrings=3000000

 *                   -Xlog:gc

 *                   TestStringDedupStress

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -XX:ShenandoahGCHeuristics=aggressive -DtargetStrings=2000000

 *                   -Xlog:gc

 *                   TestStringDedupStress

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -XX:ShenandoahGCHeuristics=aggressive -XX:+ShenandoahOOMDuringEvacALot -DtargetStrings=2000000

 *                   -Xlog:gc

 *                    TestStringDedupStress

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -XX:ShenandoahGCHeuristics=static -DtargetStrings=4000000

 *                   -Xlog:gc

 *                   TestStringDedupStress

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -XX:ShenandoahGCHeuristics=compact

 *                   -Xlog:gc

 *                   TestStringDedupStress

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -XX:ShenandoahGCMode=passive -XX:+ShenandoahDegeneratedGC

 *                   -Xlog:gc

 *                   TestStringDedupStress

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -XX:ShenandoahGCMode=passive -XX:-ShenandoahDegeneratedGC

 *                   -Xlog:gc

 *                   TestStringDedupStress

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -XX:ShenandoahGCMode=traversal

 *                   -Xlog:gc

 *                   TestStringDedupStress

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -XX:ShenandoahUpdateRefsEarly=off -DtargetStrings=3000000

 *                   -Xlog:gc

 *                   TestStringDedupStress

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -XX:ShenandoahGCHeuristics=compact -XX:ShenandoahUpdateRefsEarly=off -DtargetStrings=2000000

 *                   -Xlog:gc

 *                   TestStringDedupStress

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -XX:ShenandoahGCHeuristics=aggressive -XX:ShenandoahUpdateRefsEarly=off -DtargetStrings=2000000

 *                   -Xlog:gc

 *                   TestStringDedupStress

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -XX:ShenandoahGCHeuristics=static -XX:ShenandoahUpdateRefsEarly=off

 *                   -Xlog:gc

 *                   TestStringDedupStress

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -XX:ShenandoahGCHeuristics=aggressive -XX:ShenandoahUpdateRefsEarly=off -XX:+ShenandoahOOMDuringEvacALot -DtargetStrings=2000000

 *                   -Xlog:gc

 *                   TestStringDedupStress

 *

 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseStringDeduplication -Xmx1g -Xlog:gc+stats

 *                   -XX:ShenandoahGCMode=traversal -XX:+ShenandoahOOMDuringEvacALot -DtargetStrings=2000000

 *                   -Xlog:gc

 *                   TestStringDedupStress

 */

import java.lang.management.*;

import java.lang.reflect.*;

import java.util.*;

import sun.misc.*;

public class TestStringDedupStress {

    private static Field valueField;

    private static Unsafe unsafe;

    private static final int TARGET_STRINGS = Integer.getInteger("targetStrings", 2_500_000);

    private static final long MAX_REWRITE_GC_CYCLES = 6;

    private static final long MAX_REWRITE_TIME = 30*1000; // ms

    private static final int UNIQUE_STRINGS = 20;

    static {

        try {

            Field field = Unsafe.class.getDeclaredField("theUnsafe");

            field.setAccessible(true);

            unsafe = (Unsafe) field.get(null);

            valueField = String.class.getDeclaredField("value");

            valueField.setAccessible(true);

        } catch (Exception e) {

            throw new RuntimeException(e);

        }

    }

    private static Object getValue(String string) {

        try {

            return valueField.get(string);

        } catch (Exception e) {

            throw new RuntimeException(e);

        }

    }

    static class StringAndId {

        private String str;

        private int id;

        public StringAndId(String str, int id) {

            this.str = str;

            this.id = id;

        }

        public String str() {

            return str;

        }

        public int id() {

            return id;

        }

    }

    // Generate uniqueStrings number of strings

    private static void generateStrings(ArrayList<StringAndId> strs, int uniqueStrings) {

        Random rn = new Random();

        for (int u = 0; u < uniqueStrings; u++) {

            int n = rn.nextInt(uniqueStrings);

            strs.add(new StringAndId("Unique String " + n, n));

        }

    }

    private static int verifyDedupString(ArrayList<StringAndId> strs) {

        Map<Object, StringAndId> seen = new HashMap<>(TARGET_STRINGS*2);

        int total = 0;

        int dedup = 0;

        for (StringAndId item : strs) {

            total++;

            StringAndId existingItem = seen.get(getValue(item.str()));

            if (existingItem == null) {

                seen.put(getValue(item.str()), item);

            } else {

                if (item.id() != existingItem.id() ||

                        !item.str().equals(existingItem.str())) {

                    System.out.println("StringDedup error:");

                    System.out.println("id: " + item.id() + " != " + existingItem.id());

                    System.out.println("or String: " + item.str() + " != " + existingItem.str());

                    throw new RuntimeException("StringDedup Test failed");

                } else {

                    dedup++;

                }

            }

        }

        System.out.println("Dedup: " + dedup + "/" + total + " unique: " + (total - dedup));

        return (total - dedup);

    }

    static volatile ArrayList<StringAndId> astrs = new ArrayList<>();

    static GarbageCollectorMXBean gcCycleMBean;

    public static void main(String[] args) {

        Random rn = new Random();

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

            if ("Shenandoah Cycles".equals(bean.getName())) {

                gcCycleMBean = bean;

                break;

            }

        }

        if (gcCycleMBean == null) {

            throw new RuntimeException("Can not find Shenandoah GC cycle mbean");

        }

        // Generate roughly TARGET_STRINGS strings, only UNIQUE_STRINGS are unique

        int genIters = TARGET_STRINGS / UNIQUE_STRINGS;

        for (int index = 0; index < genIters; index++) {

            generateStrings(astrs, UNIQUE_STRINGS);

        }

        long cycleBeforeRewrite = gcCycleMBean.getCollectionCount();

        long timeBeforeRewrite = System.currentTimeMillis();

        long loop = 1;

        while (true) {

            int arrSize = astrs.size();

            int index = rn.nextInt(arrSize);

            StringAndId item = astrs.get(index);

            int n = rn.nextInt(UNIQUE_STRINGS);

            item.str = "Unique String " + n;

            item.id = n;

            if (loop++ % 1000 == 0) {

                // enough GC cycles for rewritten strings to be deduplicated

                if (gcCycleMBean.getCollectionCount() - cycleBeforeRewrite >= MAX_REWRITE_GC_CYCLES) {

                    break;

                }

                // enough time is spent waiting for GC to happen

                if (System.currentTimeMillis() - timeBeforeRewrite >= MAX_REWRITE_TIME) {

                    break;

                }

            }

        }

        verifyDedupString(astrs);

    }

}