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 * Copyright (c) 2017, 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

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 *

 * 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.

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package org.graalvm.util.test;

import static org.junit.Assert.assertEquals;

import jdk.internal.vm.compiler.collections.EconomicMap;

import jdk.internal.vm.compiler.collections.Equivalence;

import org.graalvm.compiler.serviceprovider.JavaVersionUtil;

import org.graalvm.util.ObjectSizeEstimate;

import org.junit.Assume;

import org.junit.Test;

public class CollectionSizeTest {

    /**

     * Tests the memory size of an empty map and a map with only one or two entries.

     */

    @Test

    public void testSize() {

        Assume.assumeTrue("Not working in JDK9 due to module visibility.", JavaVersionUtil.JAVA_SPEC <= 8);

        EconomicMap<Object, Object> map = EconomicMap.create(Equivalence.IDENTITY);

        assertEquals(49, ObjectSizeEstimate.forObject(map).getTotalBytes());

        Integer value = 1;

        map.put(value, value);

        assertEquals(153, ObjectSizeEstimate.forObject(map).getTotalBytes());

        Integer secondValue = 2;

        map.put(secondValue, secondValue);

        assertEquals(153 + 20, ObjectSizeEstimate.forObject(map).getTotalBytes());

    }

    /**

     * Tests whether the map actually compresses the entries array when a large number of entries

     * are deleted.

     */

    @Test

    public void testCompress() {

        Assume.assumeTrue("Not working in JDK9 due to module visibility.", JavaVersionUtil.JAVA_SPEC <= 8);

        EconomicMap<Object, Object> map = EconomicMap.create();

        // Measuring size of map with one entry.

        Object firstValue = 0;

        map.put(firstValue, firstValue);

        ObjectSizeEstimate afterFirstValue = ObjectSizeEstimate.forObject(map);

        // Add 999 more entries.

        for (int i = 1; i < 1000; ++i) {

            Object value = i;

            map.put(value, value);

        }

        ObjectSizeEstimate beforeRemove = ObjectSizeEstimate.forObject(map);

        // Remove 999 first entries.

        for (int i = 0; i < 999; ++i) {

            map.removeKey(i);

        }

        ObjectSizeEstimate afterRemove = ObjectSizeEstimate.forObject(map);

        // Check that size is same size as with one entry.

        assertEquals(afterFirstValue, afterRemove);

        // Add 999 new entries.

        for (int i = 0; i < 999; ++i) {

            Object value = i;

            map.put(value, value);

        }

        ObjectSizeEstimate afterAdd = ObjectSizeEstimate.forObject(map);

        // Check that entries array is same size again.

        assertEquals(beforeRemove.getPointerCount(), afterAdd.getPointerCount());

    }

}