/*
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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.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * questions.
 */

/* @test
 * @bug 7176630 7074436
 * @summary Check for short writes on SocketChannels configured in blocking mode
 * @key randomness
 */

import java.net.*;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.concurrent.*;
import java.util.Random;
import java.util.zip.CRC32;

public class ShortWrite {

    static final Random rand = new Random();

    /**
     * Returns a checksum on the remaining bytes in the given buffers.
     */
    static long computeChecksum(ByteBuffer... bufs) {
        CRC32 crc32 = new CRC32();
        for (int i=0; i<bufs.length; i++)
            crc32.update(bufs[i]);
        return crc32.getValue();
    }

    /**
     * A task that reads the expected number of bytes and returns the CRC32
     * of those bytes.
     */
    static class Reader implements Callable<Long> {
        final SocketChannel sc;
        final ByteBuffer buf;

        Reader(SocketChannel sc, int expectedSize) {
            this.sc = sc;
            this.buf = ByteBuffer.allocate(expectedSize);
        }

        public Long call() throws Exception {
            while (buf.hasRemaining()) {
                int n = sc.read(buf);
                if (n == -1)
                    throw new RuntimeException("Premature EOF encountered");
            }
            buf.flip();
            return computeChecksum(buf);
        }
    }

    /**
     * Exercise write(ByteBuffer) with given number of bytes.
     */
    static void test1(ExecutorService pool,
                      SocketChannel source,
                      SocketChannel sink,
                      int size)
        throws Exception
    {
        System.out.println("write(ByteBuffer), size=" + size);

        // random bytes in the buffer
        ByteBuffer buf = ByteBuffer.allocate(size);
        rand.nextBytes(buf.array());

        // submit task to read the bytes
        Future<Long> result = pool.submit(new Reader(sink, size));

        // write the bytes
        int n = source.write(buf);
        if (n != size)
            throw new RuntimeException("Short write detected");

        // check the bytes that were received match
        buf.rewind();
        long expected = computeChecksum(buf);
        long actual = result.get();
        if (actual != expected)
            throw new RuntimeException("Checksum did not match");
    }

    /**
     * Exercise write(ByteBuffer[]) with buffers of the given sizes.
     */
    static void testN(ExecutorService pool,
                      SocketChannel source,
                      SocketChannel sink,
                      int... sizes)
        throws Exception
    {
        System.out.print("write(ByteBuffer[]), sizes=");
        for (int size: sizes)
            System.out.print(size + " ");
        System.out.println();

        int total = 0;
        int len = sizes.length;
        ByteBuffer[] bufs = new ByteBuffer[len];
        for (int i=0; i<len; i++) {
            int size = sizes[i];
            ByteBuffer buf = ByteBuffer.allocate(size);
            rand.nextBytes(buf.array());
            bufs[i] = buf;
            total += size;
        }

        // submit task to read the bytes
        Future<Long> result = pool.submit(new Reader(sink, total));

        // write the bytes
        long n = source.write(bufs);
        if (n != total)
            throw new RuntimeException("Short write detected");

        // check the bytes that were received match
        for (int i=0; i<len; i++)
            bufs[i].rewind();
        long expected = computeChecksum(bufs);
        long actual = result.get();
        if (actual != expected)
            throw new RuntimeException("Checksum did not match");
    }

    public static void main(String[] args) throws Exception {
        ExecutorService pool = Executors.newSingleThreadExecutor();
        try {
            try (ServerSocketChannel ssc = ServerSocketChannel.open()) {
                ssc.bind(new InetSocketAddress(0));
                InetAddress lh = InetAddress.getLocalHost();
                int port = ssc.socket().getLocalPort();
                SocketAddress sa = new InetSocketAddress(lh, port);

                try (SocketChannel source = SocketChannel.open(sa);
                     SocketChannel sink = ssc.accept())
                {
                    // Exercise write(BufferBuffer) on sizes around 128k
                    int BOUNDARY = 128 * 1024;
                    for (int size=(BOUNDARY-2); size<=(BOUNDARY+2); size++) {
                        test1(pool, source, sink, size);
                    }

                    // Exercise write(BufferBuffer) on random sizes
                    for (int i=0; i<20; i++) {
                        int size = rand.nextInt(1024*1024);
                        test1(pool, source, sink, size);
                    }

                    // Exercise write(BufferBuffer[]) on sizes around 128k
                    for (int i=BOUNDARY-2; i<=BOUNDARY+2; i++) {
                        testN(pool, source, sink, i);
                        testN(pool, source, sink, 0, i);
                        testN(pool, source, sink, i, 0);
                        for (int j=BOUNDARY-2; j<=BOUNDARY+2; j++) {
                            testN(pool, source, sink, i, j);
                            testN(pool, source, sink, 0, i, j);
                            testN(pool, source, sink, i, 0, j);
                            testN(pool, source, sink, i, j, 0);
                            for (int k=BOUNDARY-2; k<=BOUNDARY+2; k++) {
                                testN(pool, source, sink, i, j, k);
                                testN(pool, source, sink, 0, i, j, k);
                                testN(pool, source, sink, i, 0, j, k);
                                testN(pool, source, sink, i, j, 0, k);
                                testN(pool, source, sink, i, j, k, 0);
                            }
                        }
                    }

                    // Exercise write(BufferBuffer[]) on random sizes
                    // (assumes IOV_MAX >= 8)
                    for (int i=0; i<20; i++) {
                        int n = rand.nextInt(9);
                        int[] sizes = new int[n];
                        for (int j=0; j<n; j++) {
                            sizes[j] = rand.nextInt(1024*1024);
                        }
                        testN(pool, source, sink, sizes);
                    }
                }
            }

        } finally {
            pool.shutdown();
        }
    }
}