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

 *

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 *

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

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 * 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")

 * @library /test/lib

 * @build jdk.test.lib.util.FileUtils CleanerTest

 * @modules java.management java.base/sun.nio.ch:+open

 * @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.lang.ref.PhantomReference;

import java.lang.ref.WeakReference;

import java.lang.reflect.Field;

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;

import java.util.HashSet;

import jdk.test.lib.util.FileUtils;

import sun.nio.ch.FileChannelImpl;

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;

        }

        FileUtils.listFileDescriptors(System.out);

        long fdCount0 = unixMxBean.getOpenFileDescriptorCount();

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

        try {

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

                StandardOpenOption.READ, StandardOpenOption.WRITE);

            // Prepare to wait for Channel, FD and Cleaner to be reclaimed

            ReferenceQueue<Object> refQueue = new ReferenceQueue<>();

            HashSet<Reference<?>> pending = new HashSet<>();

            Reference<Object> fcRef = new PhantomReference<>(fc, refQueue);

            pending.add(fcRef);

            Field fdField = FileChannelImpl.class.getDeclaredField("fd");

            fdField.setAccessible(true);

            Object fd = fdField.get(fc);        // get the fd from the channel

            WeakReference<Object> fdWeak = new WeakReference<>(fd, refQueue);

            pending.add(fdWeak);

            Field closerField = FileChannelImpl.class.getDeclaredField("closer");

            closerField.setAccessible(true);

            Object closer = closerField.get(fc);

            System.out.printf("  cleanup: %s, fd: %s, cf: %s%n", fc, fd, closer);

            if (closer != null) {

                WeakReference<Object> closerWeak = new WeakReference<>(closer, refQueue);

                pending.add(closerWeak);

                System.out.printf("    closerWeak: %s%n", closerWeak);

            }

            // Wait for all of the objects being tracked to be reclaimed;

            // The test will timeout if they are not reclaimed within the jtreg timeout

            Reference<?> r;

            while (((r = refQueue.remove(1000L)) != null)

                    || !pending.isEmpty()) {

                System.out.printf("    r: %s, pending: %d%n", r, pending.size());

                if (r != null) {

                    pending.remove(r);

                } else {

                    fc = null;

                    fd = null;

                    closer = null;

                    System.gc();  // attempt to reclaim them

                }

            }

            Reference.reachabilityFence(fc);

            Reference.reachabilityFence(fd);

            Reference.reachabilityFence(closer);

            long fdCount = unixMxBean.getOpenFileDescriptorCount();

            if (fdCount != fdCount0) {

                // Add debugging info about file descriptor changes

                System.out.printf("initial count of open file descriptors: %d%n", fdCount0);

                System.out.printf("final count of open file descriptors: %d%n", fdCount);

                FileUtils.listFileDescriptors(System.out);

            }

        } finally {

            Files.delete(path);

        }

    }

}