1 /* 2 * Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 /* 25 * @test 26 * @summary Check that appends are atomic 27 * @key randomness 28 */ 29 30 import java.io.File; 31 import java.io.FileOutputStream; 32 import java.io.OutputStream; 33 import java.io.IOException; 34 import java.util.Random; 35 import java.util.concurrent.Executors; 36 import java.util.concurrent.ExecutorService; 37 import java.util.concurrent.TimeUnit; 38 import java.nio.ByteBuffer; 39 import java.nio.channels.FileChannel; 40 import java.nio.file.Files; 41 import static java.nio.file.StandardOpenOption.*; 42 43 public class AtomicAppend { 44 static final Random rand = new Random(); 45 46 // Open file for appending, returning FileChannel 47 static FileChannel newFileChannel(File file) throws IOException { 48 if (rand.nextBoolean()) { 49 return new FileOutputStream(file, true).getChannel(); 50 } else { 51 return FileChannel.open(file.toPath(), APPEND); 52 } 53 } 54 55 // Open file for append, returning OutputStream 56 static OutputStream newOutputStream(File file) throws IOException { 57 if (rand.nextBoolean()) { 58 return new FileOutputStream(file, true); 59 } else { 60 return Files.newOutputStream(file.toPath(), APPEND); 61 } 62 } 63 64 // write a byte to the given channel 65 static void write(FileChannel fc, int b) throws IOException { 66 ByteBuffer buf = ByteBuffer.allocate(1); 67 buf.put((byte)b); 68 buf.flip(); 69 if (rand.nextBoolean()) { 70 ByteBuffer[] bufs = new ByteBuffer[1]; 71 bufs[0] = buf; 72 fc.write(bufs); 73 } else { 74 fc.write(buf); 75 } 76 } 77 78 public static void main(String[] args) throws Throwable { 79 final int nThreads = 16; 80 final int writes = 1000; 81 final File file = File.createTempFile("foo", null); 82 try { 83 ExecutorService pool = Executors.newFixedThreadPool(nThreads); 84 for (int i = 0; i < nThreads; i++) 85 pool.execute(new Runnable() { public void run() { 86 try { 87 // randomly choose FileChannel or OutputStream 88 if (rand.nextBoolean()) { 89 try (FileChannel fc = newFileChannel(file)) { 90 for (int j=0; j<writes; j++) write(fc, 'x'); 91 } 92 } else { 93 try (OutputStream out = newOutputStream(file)) { 94 for (int j = 0; j<writes; j++) out.write('x'); 95 } 96 } 97 } catch (IOException ioe) { 98 ioe.printStackTrace(); 99 } 100 }}); 101 pool.shutdown(); 102 pool.awaitTermination(1L, TimeUnit.MINUTES); 103 if (file.length() != (long) (nThreads * writes)) 104 throw new RuntimeException("File not expected length"); 105 } finally { 106 file.delete(); 107 } 108 } 109 }