1 /*

     2  * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.

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

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  */

    23 

    24 /*

    25  * @test

    26  * @bug 8209824

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

    28  *          and prevIndex in ThreadLocal.ThreadLocalMap are not touched

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

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

    31  * @run testng ReplaceStaleEntry

    32  */

    33 

    34 import java.lang.reflect.Field;

    35 import java.util.HashMap;

    36 import java.util.Map;

    37 

    38 import static org.testng.Assert.assertEquals;

    39 import org.testng.annotations.BeforeClass;

    40 import org.testng.annotations.Test;

    41 

    42 public class ReplaceStaleEntry {

    43 

    44     public static int INITIAL_CAPACITY;

    45 

    46     @BeforeClass

    47     public static void setup() throws Exception {

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

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

    50         f.setAccessible(true);

    51         INITIAL_CAPACITY = f.getInt(null);

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

    53     }

    54 

    55     /**

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

    57      * triggered too as it's called by replaceStaleEntry.

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

    59      * map's entry table. The code below

    60      *  1. first occupies the entries

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

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

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

    64      * thread locals, also trigger rehash of the map.

    65      */

    66     @Test

    67     public static void test() {

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

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

    70             int loop = INITIAL_CAPACITY * j;

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

    72                 ThreadLocal l = new ThreadLocal<Integer>();

    73                 l.set(i);

    74                 locals.put(i, l);

    75             }

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

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

    78             });

    79             locals.clear();

    80             System.gc();

    81         }

    82     }

    83 }