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 */ 28 29 import java.io.File; 30 import java.io.FileOutputStream; 31 import java.io.OutputStream; 32 import java.io.IOException; 33 import java.util.Random; 34 import java.util.concurrent.Executors; 35 import java.util.concurrent.ExecutorService; 36 import java.util.concurrent.TimeUnit; 37 import java.nio.ByteBuffer; 38 import java.nio.channels.FileChannel; 39 import java.nio.file.Files; 40 import static java.nio.file.StandardOpenOption.*; 41 42 public class AtomicAppend { 43 static final Random rand = new Random(); 44 45 // Open file for appending, returning FileChannel 46 static FileChannel newFileChannel(File file) throws IOException { 47 if (rand.nextBoolean()) { 48 return new FileOutputStream(file, true).getChannel(); 49 } else { 50 return FileChannel.open(file.toPath(), APPEND); 51 } 52 } 53 54 // Open file for append, returning OutputStream 55 static OutputStream newOutputStream(File file) throws IOException { 56 if (rand.nextBoolean()) { 57 return new FileOutputStream(file, true); 58 } else { 59 return Files.newOutputStream(file.toPath(), APPEND); 60 } 61 } 62 63 // write a byte to the given channel 64 static void write(FileChannel fc, int b) throws IOException { 65 ByteBuffer buf = ByteBuffer.allocate(1); 66 buf.put((byte)b); 67 buf.flip(); 68 if (rand.nextBoolean()) { 69 ByteBuffer[] bufs = new ByteBuffer[1]; 70 bufs[0] = buf; 71 fc.write(bufs); 72 } else { 73 fc.write(buf); 74 } 75 } 76 77 public static void main(String[] args) throws Throwable { 78 final int nThreads = 16; 79 final int writes = 1000; 80 final File file = File.createTempFile("foo", null); 81 try { 82 ExecutorService pool = Executors.newFixedThreadPool(nThreads); 83 for (int i = 0; i < nThreads; i++) 84 pool.execute(new Runnable() { public void run() { 85 try { 86 // randomly choose FileChannel or OutputStream 87 if (rand.nextBoolean()) { 88 try (FileChannel fc = newFileChannel(file)) { 89 for (int j=0; j<writes; j++) write(fc, 'x'); 90 } 91 } else { 92 try (OutputStream out = newOutputStream(file)) { 93 for (int j = 0; j<writes; j++) out.write('x'); 94 } 95 } 96 } catch (IOException ioe) { 97 ioe.printStackTrace(); 98 } 99 }}); 100 pool.shutdown(); 101 pool.awaitTermination(1L, TimeUnit.MINUTES); 102 if (file.length() != (long) (nThreads * writes)) 103 throw new RuntimeException("File not expected length"); 104 } finally { 105 file.delete(); 106 } 107 } 108 }