/*

 * Copyright (c) 2019, 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 8209824

 * @summary per latest JDK code coverage report, 2 methods replaceStaleEntry

 *          and prevIndex in ThreadLocal.ThreadLocalMap are not touched

 *          by any JDK regression tests, this is to trigger the code paths.

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

 * @run testng ReplaceStaleEntry

 */

import java.lang.reflect.Field;

import java.util.HashMap;

import java.util.Map;

import static org.testng.Assert.assertEquals;

import org.testng.annotations.BeforeClass;

import org.testng.annotations.Test;

public class ReplaceStaleEntry {

    public static int INITIAL_CAPACITY;

    @BeforeClass

    public static void setup() throws Exception {

        Class<?> clazz = Class.forName("java.lang.ThreadLocal$ThreadLocalMap");

        Field f = clazz.getDeclaredField("INITIAL_CAPACITY");

        f.setAccessible(true);

        INITIAL_CAPACITY = f.getInt(null);

        System.out.println("INITIAL_CAPACITY: " + INITIAL_CAPACITY);

    }

    /**

     * This test triggers the code path to replaceStaleEntry, so as prevIndex is

     * triggered too as it's called by replaceStaleEntry.

     * The code paths must be triggered by reusing an already used entry in the

     * map's entry table. The code below

     *  1. first occupies the entries

     *  2. then expunges the entries by removing strong references to thread locals

     *  3. then reuse some of entries by adding more thread locals to the thread

     * and, the above steps are run for several times by adding more and more

     * thread locals, also trigger rehash of the map.

     */

    @Test

    public static void test() {

        Map<Integer, ThreadLocal> locals = new HashMap<>();

        for (int j = 1; j < 32; j *= 2) {

            int loop = INITIAL_CAPACITY * j;

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

                ThreadLocal l = new ThreadLocal<Integer>();

                l.set(i);

                locals.put(i, l);

            }

            locals.keySet().stream().forEach(i -> {

                assertEquals((int)locals.get(i).get(), (int)i, "Unexpected thread local value!");

            });

            locals.clear();

            System.gc();

        }

    }

}