| /* |
| * Copyright (c) 2010, 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. |
| */ |
| |
| /* |
| * @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(); |
| } |
| } |
| } |