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| 1 | /* | ||
| 2 | * Copyright (c) 1997, 2008, 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. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | |||
| 27 | /* | ||
| 28 | * The Original Code is HAT. The Initial Developer of the | ||
| 29 | * Original Code is Bill Foote, with contributions from others | ||
| 30 | * at JavaSoft/Sun. | ||
| 31 | */ | ||
| 32 | |||
| 33 | package com.sun.tools.hat.internal.parser; | ||
| 34 | |||
| 35 | import java.io.IOException; | ||
| 36 | import java.io.RandomAccessFile; | ||
| 37 | import java.nio.MappedByteBuffer; | ||
| 38 | import java.nio.channels.FileChannel; | ||
| 39 | |||
| 40 | /** | ||
| 41 | * Implementation of ReadBuffer using mapped file buffer | ||
| 42 | * | ||
| 43 | * @author A. Sundararajan | ||
| 44 | */ | ||
| 45 | class MappedReadBuffer implements ReadBuffer { | ||
| 46 | private MappedByteBuffer buf; | ||
| 47 | |||
| 48 | MappedReadBuffer(MappedByteBuffer buf) { | ||
| 49 | this.buf = buf; | ||
| 50 | } | ||
| 51 | |||
| 52 | // factory method to create correct ReadBuffer for a given file | ||
| 53 | static ReadBuffer create(RandomAccessFile file) throws IOException { | ||
| 54 | FileChannel ch = file.getChannel(); | ||
| 55 | long size = ch.size(); | ||
| 56 | // if file size is more than 2 GB and when file mapping is | ||
| 57 | // configured (default), use mapped file reader | ||
| 58 | if (canUseFileMap() && (size <= Integer.MAX_VALUE)) { | ||
| 59 | MappedByteBuffer buf; | ||
| 60 | try { | ||
| 61 | buf = ch.map(FileChannel.MapMode.READ_ONLY, 0, size); | ||
| 62 | ch.close(); | ||
| 63 | return new MappedReadBuffer(buf); | ||
| 64 | } catch (IOException exp) { | ||
| 65 | exp.printStackTrace(); | ||
| 66 | System.err.println("File mapping failed, will use direct read"); | ||
| 67 | // fall through | ||
| 68 | } | ||
| 69 | } // else fall through | ||
| 70 | return new FileReadBuffer(file); | ||
| 71 | } | ||
| 72 | |||
| 73 | private static boolean canUseFileMap() { | ||
| 74 | // set jhat.disableFileMap to any value other than "false" | ||
| 75 | // to disable file mapping | ||
| 76 | String prop = System.getProperty("jhat.disableFileMap"); | ||
| 77 | return prop == null || prop.equals("false"); | ||
| 78 | } | ||
| 79 | |||
| 80 | private void seek(long pos) throws IOException { | ||
| 81 | assert pos <= Integer.MAX_VALUE : "position overflow"; | ||
| 82 | buf.position((int)pos); | ||
| 83 | } | ||
| 84 | |||
| 85 | public synchronized void get(long pos, byte[] res) throws IOException { | ||
| 86 | seek(pos); | ||
| 87 | buf.get(res); | ||
| 88 | } | ||
| 89 | |||
| 90 | public synchronized char getChar(long pos) throws IOException { | ||
| 91 | seek(pos); | ||
| 92 | return buf.getChar(); | ||
| 93 | } | ||
| 94 | |||
| 95 | public synchronized byte getByte(long pos) throws IOException { | ||
| 96 | seek(pos); | ||
| 97 | return buf.get(); | ||
| 98 | } | ||
| 99 | |||
| 100 | public synchronized short getShort(long pos) throws IOException { | ||
| 101 | seek(pos); | ||
| 102 | return buf.getShort(); | ||
| 103 | } | ||
| 104 | |||
| 105 | public synchronized int getInt(long pos) throws IOException { | ||
| 106 | seek(pos); | ||
| 107 | return buf.getInt(); | ||
| 108 | } | ||
| 109 | |||
| 110 | public synchronized long getLong(long pos) throws IOException { | ||
| 111 | seek(pos); | ||
| 112 | return buf.getLong(); | ||
| 113 | } | ||
| 114 | } | ||