/*
 * Copyright (c) 2011, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * Portions Copyright (c) 2011 IBM Corporation
 */

/*
 * @test
 * @bug 7031076
 * @summary Allow stale InputStreams from ZipFiles to be GC'd
 * @author Neil Richards <neil.richards@ngmr.net>, <neil_richards@uk.ibm.com>
 */
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Random;
import java.util.Set;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import java.util.zip.ZipOutputStream;

public class ClearStaleZipFileInputStreams {
    private static final int ZIP_ENTRY_NUM = 5;

    private static final byte[][] data;

    static {
        data = new byte[ZIP_ENTRY_NUM][];
        Random r = new Random();
        for (int i = 0; i < ZIP_ENTRY_NUM; i++) {
            data[i] = new byte[1000];
            r.nextBytes(data[i]);
        }
    }

    private static File createTestFile(int compression) throws Exception {
        File tempZipFile =
            File.createTempFile("test-data" + compression, ".zip");
        tempZipFile.deleteOnExit();

        try (FileOutputStream fos = new FileOutputStream(tempZipFile);
                ZipOutputStream zos = new ZipOutputStream(fos)) {
            zos.setLevel(compression);
            for (int i = 0; i < ZIP_ENTRY_NUM; i++) {
                String text = "Entry" + i;
                ZipEntry entry = new ZipEntry(text);
                zos.putNextEntry(entry);
                try {
                    zos.write(data[i], 0, data[i].length);
                } finally {
                    zos.closeEntry();
                }
            }
        }

        return tempZipFile;
    }

    private static final class GcInducingThread extends Thread {
        private final int sleepMillis;
        private boolean keepRunning = true;

        public GcInducingThread(final int sleepMillis) {
            this.sleepMillis = sleepMillis;
        }

        public synchronized void run() {
            while (keepRunning) {
                System.gc();
                try {
                    wait(sleepMillis);
                } catch (InterruptedException e) {
                    System.out.println("GCing thread unexpectedly interrupted");
                    return;
                }
            }
        }

        public synchronized void shutDown() {
            keepRunning = false;
            notifyAll();
        }
    }

    public static void main(String[] args) throws Exception {
        GcInducingThread gcThread = new GcInducingThread(500);
        gcThread.start();
        try {
            runTest(ZipOutputStream.DEFLATED);
            runTest(ZipOutputStream.STORED);
        } finally {
            gcThread.shutDown();
            gcThread.join();
        }
    }

    private static void runTest(int compression) throws Exception {
        ReferenceQueue<InputStream> rq = new ReferenceQueue<>();

        System.out.println("Testing with a zip file with compression level = "
                + compression);
        File f = createTestFile(compression);
        try (ZipFile zf = new ZipFile(f)) {
            Set<Object> refSet = createTransientInputStreams(zf, rq);

            System.out.println("Waiting for 'stale' input streams from ZipFile to be GC'd ...");
            System.out.println("(The test will hang on failure)");
            while (false == refSet.isEmpty()) {
                refSet.remove(rq.remove());
            }
            System.out.println("Test PASSED.");
            System.out.println();
        } finally {
            f.delete();
        }
    }

    private static Set<Object> createTransientInputStreams(ZipFile zf,
            ReferenceQueue<InputStream> rq) throws Exception {
        Enumeration<? extends ZipEntry> zfe = zf.entries();
        Set<Object> refSet = new HashSet<>();

        while (zfe.hasMoreElements()) {
            InputStream is = zf.getInputStream(zfe.nextElement());
            refSet.add(new WeakReference<InputStream>(is, rq));
        }

        return refSet;
    }
}