io/FileOutputStream/UnreferencedFOSClosesFd.java

/*
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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
 * @modules java.base/java.io:open
 * @library /test/lib
 * @build jdk.test.lib.util.FileUtils UnreferencedFOSClosesFd
 * @bug 6524062
 * @summary Test to ensure that the fd is closed if left unreferenced
 * @run main/othervm UnreferencedFOSClosesFd
 */
import java.io.File;
import java.io.FileDescriptor;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;
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 java.util.concurrent.atomic.AtomicInteger;

import com.sun.management.UnixOperatingSystemMXBean;

import jdk.test.lib.util.FileUtils;

public class UnreferencedFOSClosesFd {

    static final String FILE_NAME = "empty.txt";

    /**
     * Subclass w/ no overrides; not close.
     * Cleanup should be via the Cleaner.
     */
    public static class StreamOverrides extends FileOutputStream {

        protected final AtomicInteger closeCounter;

        public StreamOverrides(String name) throws FileNotFoundException {
            super(name);
            closeCounter = new AtomicInteger(0);
        }

        final AtomicInteger closeCounter() {
            return closeCounter;
        }
    }

    /**
     * Subclass overrides close.
     * Cleanup should be via AltFinalizer calling close().
     */
    public static class StreamOverridesClose extends StreamOverrides {

        public StreamOverridesClose(String name) throws FileNotFoundException {
            super(name);
        }

        public void close() throws IOException {
            closeCounter.incrementAndGet();
            super.close();
        }
    }

    /**
     * Subclass overrides finalize and close.
     * Cleanup should be via the Cleaner.
     */
    public static class StreamOverridesFinalize extends StreamOverrides {

        public StreamOverridesFinalize(String name) throws FileNotFoundException {
            super(name);
        }

        @SuppressWarnings({"deprecation","removal"})
        protected void finalize() throws IOException, Throwable {
            super.finalize();
        }
    }

    /**
     * Subclass overrides finalize and close.
     * Cleanup should be via the Cleaner.
     */
    public static class StreamOverridesFinalizeClose extends StreamOverridesClose {

        public StreamOverridesFinalizeClose(String name) throws FileNotFoundException {
            super(name);
        }

        @SuppressWarnings({"deprecation","removal"})
        protected void finalize() throws IOException, Throwable {
            super.finalize();
        }
    }

    /**
     * Main runs each test case and reports number of failures.
     */
    public static void main(String argv[]) throws Exception {

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

        String name = inFile.getPath();

        FileUtils.listFileDescriptors(System.out);
        long fdCount0 = getFdCount();

        int failCount = 0;
        failCount += test(new FileOutputStream(name));

        failCount += test(new StreamOverrides(name));

        failCount += test(new StreamOverridesClose(name));

        failCount += test(new StreamOverridesFinalize(name));

        failCount += test(new StreamOverridesFinalizeClose(name));

        if (failCount > 0) {
            throw new AssertionError("Failed test count: " + failCount);
        }

        // 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;
    }

    private static int test(FileOutputStream fos) throws Exception {

        try {
            System.out.printf("%nTesting %s%n", fos.getClass().getName());

            // Prepare to wait for FOS to be reclaimed
            ReferenceQueue<Object> queue = new ReferenceQueue<>();
            HashSet<Reference<?>> pending = new HashSet<>();
            WeakReference<FileOutputStream> msWeak = new WeakReference<>(fos, queue);
            pending.add(msWeak);

            FileDescriptor fd = fos.getFD();
            WeakReference<FileDescriptor> fdWeak = new WeakReference<>(fd, queue);
            pending.add(fdWeak);

            Field fdField = FileDescriptor.class.getDeclaredField("fd");
            fdField.setAccessible(true);
            int ffd = fdField.getInt(fd);

            Field cleanupField = FileDescriptor.class.getDeclaredField("cleanup");
            cleanupField.setAccessible(true);
            Object cleanup = cleanupField.get(fd);
            System.out.printf("  cleanup: %s, ffd: %d, cf: %s%n", cleanup, ffd, cleanupField);
            if (cleanup == null) {
                throw new RuntimeException("cleanup should not be null");
            }

            WeakReference<Object> cleanupWeak = new WeakReference<>(cleanup, queue);
            pending.add(cleanupWeak);
            System.out.printf("    fdWeak: %s%n    msWeak: %s%n    cleanupWeak: %s%n",
                    fdWeak, msWeak, cleanupWeak);

            AtomicInteger closeCounter = fos instanceof StreamOverrides
                    ? ((StreamOverrides) fos).closeCounter() : null;

            Reference<?> r;
            while (((r = queue.remove(1000L)) != null)
                    || !pending.isEmpty()) {
                System.out.printf("    r: %s, pending: %d%n",
                        r, pending.size());
                if (r != null) {
                    pending.remove(r);
                } else {
                    fos = null;
                    fd = null;
                    cleanup = null;
                    System.gc();  // attempt to reclaim them
                }
            }
            Reference.reachabilityFence(fd);
            Reference.reachabilityFence(fos);
            Reference.reachabilityFence(cleanup);

            // Confirm the correct number of calls to close depending on the cleanup type
            if (closeCounter != null && closeCounter.get() > 0) {
                throw new RuntimeException("Close should not have been called: count: " + closeCounter);
            }
        } catch (Exception ex) {
            ex.printStackTrace(System.out);
            return 1;
        }
        return 0;
    }
}