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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 | +} | |