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/*
* Copyright (c) 2010, 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
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* @test
* @summary Check that appends are atomic
* @key randomness
*/
import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.io.IOException;
import java.util.Random;
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.TimeUnit;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Files;
import static java.nio.file.StandardOpenOption.*;
public class AtomicAppend {
static final Random rand = new Random();
// Open file for appending, returning FileChannel
static FileChannel newFileChannel(File file) throws IOException {
if (rand.nextBoolean()) {
return new FileOutputStream(file, true).getChannel();
} else {
return FileChannel.open(file.toPath(), APPEND);
}
}
// Open file for append, returning OutputStream
static OutputStream newOutputStream(File file) throws IOException {
if (rand.nextBoolean()) {
return new FileOutputStream(file, true);
} else {
return Files.newOutputStream(file.toPath(), APPEND);
}
}
// write a byte to the given channel
static void write(FileChannel fc, int b) throws IOException {
ByteBuffer buf = ByteBuffer.allocate(1);
buf.put((byte)b);
buf.flip();
if (rand.nextBoolean()) {
ByteBuffer[] bufs = new ByteBuffer[1];
bufs[0] = buf;
fc.write(bufs);
} else {
fc.write(buf);
}
}
public static void main(String[] args) throws Throwable {
final int nThreads = 16;
final int writes = 1000;
final File file = File.createTempFile("foo", null);
try {
ExecutorService pool = Executors.newFixedThreadPool(nThreads);
for (int i = 0; i < nThreads; i++)
pool.execute(new Runnable() { public void run() {
try {
// randomly choose FileChannel or OutputStream
if (rand.nextBoolean()) {
try (FileChannel fc = newFileChannel(file)) {
for (int j=0; j<writes; j++) write(fc, 'x');
}
} else {
try (OutputStream out = newOutputStream(file)) {
for (int j = 0; j<writes; j++) out.write('x');
}
}
} catch (IOException ioe) {
ioe.printStackTrace();
}
}});
pool.shutdown();
pool.awaitTermination(1L, TimeUnit.MINUTES);
if (file.length() != (long) (nThreads * writes))
throw new RuntimeException("File not expected length");
} finally {
file.delete();
}
}
}
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