1 /*
   2  * Copyright (c) 2017, 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 import java.io.*;
  25 import java.nio.ByteBuffer;
  26 import java.nio.CharBuffer;
  27 import java.nio.channels.*;
  28 import java.nio.channels.FileChannel;
  29 import java.nio.file.Paths;
  30 import java.nio.file.Path;
  31 import java.nio.file.Files;
  32 import java.nio.file.FileStore;
  33 import java.nio.file.StandardOpenOption;
  34 import com.sun.nio.file.ExtendedOpenOption;
  35 
  36 public class DirectIO {
  37 
  38     private static final int SIZE = 4096;
  39 
  40     static {
  41         System.loadLibrary("DirectIO");
  42     }
  43 
  44     private static void testWrite(Path p) throws Exception {
  45         FileChannel fc = FileChannel.open(p, StandardOpenOption.WRITE,
  46                 ExtendedOpenOption.DIRECT);
  47         FileStore fs = Files.getFileStore(p);
  48         int alignment = (int)fs.getBlockSize();
  49         ByteBuffer src = ByteBuffer.allocateDirect(SIZE + alignment -1)
  50                                    .alignedSlice(alignment);
  51         for (int j = 0; j < SIZE; j++) {
  52             src.put((byte)0);
  53         }
  54         src.flip();
  55         try {
  56             fc.write(src);
  57         } finally {
  58             fc.close();
  59         }
  60     }
  61 
  62     private static void testRead(Path p) throws Exception {
  63         FileChannel fc = FileChannel.open(p, ExtendedOpenOption.DIRECT);
  64         FileStore fs = Files.getFileStore(p);
  65         int alignment = (int)fs.getBlockSize();
  66 
  67         ByteBuffer dest = ByteBuffer.allocateDirect(SIZE + alignment - 1)
  68                                     .alignedSlice(alignment);
  69         fc.read(dest);
  70 
  71         fc.close();
  72     }
  73 
  74     private static boolean isFileInCache(Path p) {
  75         String path = p.toString();
  76         return isFileInCache0(SIZE, path);
  77     }
  78 
  79     private static native boolean isFileInCache0(int size, String path);
  80 
  81     public static void main(String[] args) throws Exception {
  82         Path p = Files.createTempFile(Paths.get(
  83                 System.getProperty("test.dir", ".")), "test", null);
  84         testWrite(p);
  85         if (isFileInCache(p)) {
  86             throw new RuntimeException("DirectIO is not working properly with "
  87                                        + "write. File still exists in cache!");
  88         }
  89         testRead(p);
  90         if (isFileInCache(p)) {
  91             throw new RuntimeException("DirectIO is not working properly with "
  92                                        + "read. File still exists in cache!");
  93         }
  94         Files.delete(p);
  95     }
  96 }