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 * 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
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 * questions.
 */

/**
 * @test TestPeriodicCollection
 * @requires vm.gc.G1
 * @summary Verify that heap shrinks when the application is idle.
 * @library /test/lib /
 * @modules java.base/jdk.internal.misc
 * @modules java.management/sun.management
 * @build sun.hotspot.WhiteBox
 * @run driver ClassFileInstaller sun.hotspot.WhiteBox
 *                                sun.hotspot.WhiteBox$WhiteBoxPermission
 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xbootclasspath/a:. -Xms32M -Xmx128M -XX:MinHeapFreeRatio=5 -XX:MaxHeapFreeRatio=25 -XX:+UseG1GC -XX:G1PeriodicGCInterval=3000 -XX:+G1PeriodicGCInvokesConcurrent -Xlog:gc,gc+periodic=debug,gc+ergo+heap=debug TestPeriodicCollection
 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xbootclasspath/a:. -Xms32M -Xmx128M -XX:MinHeapFreeRatio=5 -XX:MaxHeapFreeRatio=25 -XX:+UseG1GC -XX:G1PeriodicGCInterval=3000 -XX:-G1PeriodicGCInvokesConcurrent -Xlog:gc,gc+periodic=debug,gc+ergo+heap=debug TestPeriodicCollection
 */

import com.sun.management.HotSpotDiagnosticMXBean;

import gc.testlibrary.Helpers;

import java.lang.management.ManagementFactory;
import java.lang.management.MemoryUsage;
import java.util.ArrayList;
import java.util.List;
import java.text.NumberFormat;
import static jdk.test.lib.Asserts.*;

import sun.hotspot.WhiteBox;

public class TestPeriodicCollection {

    public static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio";
    public static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio";

    private static final List<List<byte[]>> garbage = new ArrayList();

    private static final long TOTAL_MEMORY = Runtime.getRuntime().totalMemory();
    private static final long MAX_MEMORY = Runtime.getRuntime().maxMemory();
    private static final int IDLE_TIME = 10 * 1000;

    private static final int ARR_SIZE = 64 * 1024; // 64k
    private static final int LISTS_COUNT = 10;
    private static final int ARR_COUNT = (int) ((TOTAL_MEMORY / ARR_SIZE) / LISTS_COUNT);

    public static void main(String[] args) {
        if (ARR_COUNT == 0) {
            System.out.println("Skipped. Heap is too small");
            return;
        }

        if (TOTAL_MEMORY + ARR_SIZE * ARR_COUNT > MAX_MEMORY) {
            System.out.println("Skipped. Initial heap size is too close to max heap size.");
            return;
        }

        new TestPeriodicCollection().test();
    }

    private final void test() {
        WhiteBox.getWhiteBox().fullGC();

        MemoryUsagePrinter.printMemoryUsage("init");

        allocate();
        MemoryUsagePrinter.printMemoryUsage("allocated");
        MemoryUsage muFull = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();

        garbage.clear();
        try {
            Thread.sleep(IDLE_TIME);
        } catch (InterruptedException ie) {
            System.err.println("Skipped. Failed to wait for idle collection");
        }
        MemoryUsagePrinter.printMemoryUsage("free");
        MemoryUsage muFree = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();

        assertLessThan(muFree.getCommitted(), muFull.getCommitted(), String.format(
                "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n"
                + "%s = %s%n%s = %s",
                MIN_FREE_RATIO_FLAG_NAME,
                ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
                    .getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(),
                MAX_FREE_RATIO_FLAG_NAME,
                ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
                    .getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue()
        ));
    }

    private void allocate() {

        for (int i = 0; i < LISTS_COUNT; i++) {
            List<byte[]> stuff = new ArrayList();
            allocateList(stuff, ARR_COUNT, ARR_SIZE);
            MemoryUsagePrinter.printMemoryUsage("allocate #" + (i+1));
            garbage.add(stuff);
        }
    }

    private static void allocateList(List garbage, int count, int size) {
        for (int i = 0; i < count; i++) {
            garbage.add(new byte[size]);
        }
    }
}

/**
 * Prints memory usage to standard output
 */
class MemoryUsagePrinter {

    public static final NumberFormat NF = Helpers.numberFormatter();

    public static void printMemoryUsage(String label) {
        MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
        float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted();
        System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n",
                label,
                NF.format(memusage.getInit()),
                NF.format(memusage.getUsed()),
                NF.format(memusage.getCommitted()),
                freeratio * 100
        );
    }
}