/*

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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.

 *

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 */

/* @test

 * @bug 8147615

 * @summary Test whether an unreferenced FileChannel is actually cleaned

 * @requires (os.family == "linux") | (os.family == "mac") | (os.family == "solaris") | (os.family == "aix")

 * @modules java.management

 * @run main/othervm CleanerTest

 */

import com.sun.management.UnixOperatingSystemMXBean;

import java.lang.management.ManagementFactory;

import java.lang.management.OperatingSystemMXBean;

import java.lang.ref.PhantomReference;

import java.lang.ref.Reference;

import java.lang.ref.ReferenceQueue;

import java.nio.channels.FileChannel;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.StandardOpenOption;

public class CleanerTest {

    public static void main(String[] args) throws Throwable {

        OperatingSystemMXBean mxBean =

            ManagementFactory.getOperatingSystemMXBean();

        UnixOperatingSystemMXBean unixMxBean = null;

        if (mxBean instanceof UnixOperatingSystemMXBean) {

            unixMxBean = (UnixOperatingSystemMXBean)mxBean;

        } else {

            System.out.println("Non-Unix system: skipping test.");

            return;

        }

        Path path = Paths.get(System.getProperty("test.dir", "."), "junk");

        try {

            FileChannel fc = FileChannel.open(path, StandardOpenOption.CREATE,

                StandardOpenOption.READ, StandardOpenOption.WRITE);

            ReferenceQueue refQueue = new ReferenceQueue();

            Reference fcRef = new PhantomReference(fc, refQueue);

            long fdCount0 = unixMxBean.getOpenFileDescriptorCount();

            fc = null;

            // Perform repeated GCs until the reference has been enqueued.

            do {

                Thread.sleep(1);

                System.gc();

            } while (refQueue.poll() == null);

            // Loop until the open file descriptor count has been decremented.

            while (unixMxBean.getOpenFileDescriptorCount() > fdCount0 - 1) {

                Thread.sleep(1);

            }

            long fdCount = unixMxBean.getOpenFileDescriptorCount();

            if (fdCount != fdCount0 - 1) {

                throw new RuntimeException("FD count expected " +

                    (fdCount0 - 1) + "; actual " + fdCount);

            }

        } finally {

            Files.delete(path);

        }

    }

}