110 lines
3.9 KiB
Java
110 lines
3.9 KiB
Java
/*
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* Copyright (c) 2010, 2018, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* @test
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* @summary Check that appends are atomic
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* @key randomness
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*/
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import java.io.File;
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import java.io.FileOutputStream;
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import java.io.OutputStream;
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import java.io.IOException;
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import java.util.Random;
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import java.util.concurrent.Executors;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.TimeUnit;
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import java.nio.ByteBuffer;
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import java.nio.channels.FileChannel;
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import java.nio.file.Files;
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import static java.nio.file.StandardOpenOption.*;
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public class AtomicAppend {
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static final Random rand = new Random();
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// Open file for appending, returning FileChannel
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static FileChannel newFileChannel(File file) throws IOException {
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if (rand.nextBoolean()) {
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return new FileOutputStream(file, true).getChannel();
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} else {
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return FileChannel.open(file.toPath(), APPEND);
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}
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}
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// Open file for append, returning OutputStream
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static OutputStream newOutputStream(File file) throws IOException {
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if (rand.nextBoolean()) {
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return new FileOutputStream(file, true);
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} else {
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return Files.newOutputStream(file.toPath(), APPEND);
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}
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}
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// write a byte to the given channel
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static void write(FileChannel fc, int b) throws IOException {
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ByteBuffer buf = ByteBuffer.allocate(1);
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buf.put((byte)b);
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buf.flip();
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if (rand.nextBoolean()) {
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ByteBuffer[] bufs = new ByteBuffer[1];
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bufs[0] = buf;
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fc.write(bufs);
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} else {
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fc.write(buf);
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}
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}
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public static void main(String[] args) throws Throwable {
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final int nThreads = 16;
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final int writes = 1000;
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final File file = File.createTempFile("foo", null);
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try {
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ExecutorService pool = Executors.newFixedThreadPool(nThreads);
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for (int i = 0; i < nThreads; i++)
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pool.execute(new Runnable() { public void run() {
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try {
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// randomly choose FileChannel or OutputStream
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if (rand.nextBoolean()) {
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try (FileChannel fc = newFileChannel(file)) {
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for (int j=0; j<writes; j++) write(fc, 'x');
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}
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} else {
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try (OutputStream out = newOutputStream(file)) {
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for (int j = 0; j<writes; j++) out.write('x');
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}
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}
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} catch (IOException ioe) {
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ioe.printStackTrace();
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}
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}});
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pool.shutdown();
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pool.awaitTermination(1L, TimeUnit.MINUTES);
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if (file.length() != (long) (nThreads * writes))
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throw new RuntimeException("File not expected length");
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} finally {
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file.delete();
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}
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}
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}
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