/*

 * Copyright (c) 2007, 2018, 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

 * 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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 */

import java.io.File;

import java.io.FileDescriptor;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.RandomAccessFile;

import java.lang.management.ManagementFactory;

import java.lang.management.OperatingSystemMXBean;

import java.lang.ref.Cleaner;

import java.lang.ref.Reference;

import java.lang.ref.ReferenceQueue;

import java.lang.ref.WeakReference;

import java.lang.reflect.Field;

import java.nio.file.Path;

import java.util.ArrayDeque;

import java.util.HashSet;

import com.sun.management.UnixOperatingSystemMXBean;

import jdk.test.lib.util.FileUtils;

/**

 * @test

 * @bug 8080225

 * @library /test/lib

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

 * @modules java.base/java.io:open

 * @summary Test to ensure that an unclosed and unreferenced RandomAccessFile closes the fd

 * @run main/othervm UnreferencedRAFClosesFd

 */

public class UnreferencedRAFClosesFd {

    static final String FILE_NAME = "empty.txt";

    /* standalone interface */

    public static void main(String argv[]) throws Exception {

        File inFile= new File(System.getProperty("test.dir", "."), FILE_NAME);

        inFile.createNewFile();

        inFile.deleteOnExit();

        FileUtils.listFileDescriptors(System.out);

        long fdCount0 = getFdCount();

        String name = inFile.getPath();

        RandomAccessFile raf;

        try {

            // raf is explicitly *not* closed to allow cleaner to work

            raf = new RandomAccessFile(name, "rw");

        } catch (FileNotFoundException e) {

            System.out.println("Unexpected exception " + e);

            throw(e);

        }

        FileDescriptor fd = raf.getFD();

        Field fdField = FileDescriptor.class.getDeclaredField("cleanup");

        fdField.setAccessible(true);

        Cleaner.Cleanable cleanup = (Cleaner.Cleanable)fdField.get(fd);

        // Prepare to wait for FOS, FD, Cleanup to be reclaimed

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

        HashSet<Reference<?>> pending = new HashSet<>(3);

        pending.add(new WeakReference<>(cleanup, queue));

        pending.add(new WeakReference<>(raf, queue));

        pending.add(new WeakReference<>(fd, queue));

        Reference<?> r;

        while (((r = queue.remove(10L)) != null)

                || !pending.isEmpty()) {

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

            if (r != null) {

                pending.remove(r);

            } else {

                cleanup = null;

                raf = null;

                fd = null;

                System.gc();  // attempt to reclaim the RAF, cleanup, and fd

            }

        }

        // Keep these variables in scope as gc roots

        Reference.reachabilityFence(cleanup);

        Reference.reachabilityFence(fd);

        Reference.reachabilityFence(raf);

        Reference.reachabilityFence(pending);

        // Check the final count of open file descriptors

        long fdCount = getFdCount();

        if (fdCount != fdCount0) {

            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);

        }

    }

    // Get the count of open file descriptors, or -1 if not available

    private static long getFdCount() {

        OperatingSystemMXBean mxBean = ManagementFactory.getOperatingSystemMXBean();

        return  (mxBean instanceof UnixOperatingSystemMXBean)

                ? ((UnixOperatingSystemMXBean) mxBean).getOpenFileDescriptorCount()

                : -1L;

    }

}