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HPROF heap dump parser
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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 1997-2010 Oracle and/or its affiliates. All rights reserved.
 *
 * Oracle and Java are registered trademarks of Oracle and/or its affiliates.
 * Other names may be trademarks of their respective owners.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common
 * Development and Distribution License("CDDL") (collectively, the
 * "License"). You may not use this file except in compliance with the
 * License. You can obtain a copy of the License at
 * http://www.netbeans.org/cddl-gplv2.html
 * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the
 * specific language governing permissions and limitations under the
 * License.  When distributing the software, include this License Header
 * Notice in each file and include the License file at
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 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the GPL Version 2 section of the License file that
 * accompanied this code. If applicable, add the following below the
 * License Header, with the fields enclosed by brackets [] replaced by
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 * Contributor(s):
 * The Original Software is NetBeans. The Initial Developer of the Original
 * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
 * Microsystems, Inc. All Rights Reserved.
 *
 * If you wish your version of this file to be governed by only the CDDL
 * or only the GPL Version 2, indicate your decision by adding
 * "[Contributor] elects to include this software in this distribution
 * under the [CDDL or GPL Version 2] license." If you do not indicate a
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 * to extend the choice of license to its licensees as provided above.
 * However, if you add GPL Version 2 code and therefore, elected the GPL
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package org.netbeans.lib.profiler.heap;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;


/**
 *
 * @author Tomas Hurka
 */
class HprofLongMappedByteBuffer extends HprofByteBuffer {
    //~ Static fields/initializers -----------------------------------------------------------------------------------------------

    private static int BUFFER_SIZE_BITS = 30;
    private static long BUFFER_SIZE = 1L << BUFFER_SIZE_BITS;
    private static int BUFFER_SIZE_MASK = (int) ((BUFFER_SIZE) - 1);
    private static int BUFFER_EXT = 32 * 1024;

    //~ Instance fields ----------------------------------------------------------------------------------------------------------

    private MappedByteBuffer[] dumpBuffer;

    //~ Constructors -------------------------------------------------------------------------------------------------------------

    HprofLongMappedByteBuffer(File dumpFile) throws IOException {
        FileInputStream fis = new FileInputStream(dumpFile);
        FileChannel channel = fis.getChannel();
        length = channel.size();
        dumpBuffer = new MappedByteBuffer[(int) (((length + BUFFER_SIZE) - 1) / BUFFER_SIZE)];

        for (int i = 0; i < dumpBuffer.length; i++) {
            long position = i * BUFFER_SIZE;
            long size = Math.min(BUFFER_SIZE + BUFFER_EXT, length - position);
            dumpBuffer[i] = channel.map(FileChannel.MapMode.READ_ONLY, position, size);
        }

        channel.close();
        readHeader();
    }

    //~ Methods ------------------------------------------------------------------------------------------------------------------

    char getChar(long index) {
        return dumpBuffer[getBufferIndex(index)].getChar(getBufferOffset(index));
    }

    double getDouble(long index) {
        return dumpBuffer[getBufferIndex(index)].getDouble(getBufferOffset(index));
    }

    float getFloat(long index) {
        return dumpBuffer[getBufferIndex(index)].getFloat(getBufferOffset(index));
    }

    int getInt(long index) {
        return dumpBuffer[getBufferIndex(index)].getInt(getBufferOffset(index));
    }

    long getLong(long index) {
        return dumpBuffer[getBufferIndex(index)].getLong(getBufferOffset(index));
    }

    short getShort(long index) {
        return dumpBuffer[getBufferIndex(index)].getShort(getBufferOffset(index));
    }

    // delegate to MappedByteBuffer
    byte get(long index) {
        return dumpBuffer[getBufferIndex(index)].get(getBufferOffset(index));
    }

    synchronized void get(long position, byte[] chars) {
        MappedByteBuffer buffer = dumpBuffer[getBufferIndex(position)];
        buffer.position(getBufferOffset(position));
        buffer.get(chars);
    }

    private int getBufferIndex(long index) {
        return (int) (index >> BUFFER_SIZE_BITS);
    }

    private int getBufferOffset(long index) {
        return (int) (index & BUFFER_SIZE_MASK);
    }
    
    public String toString() {
        return "Long memory mapped file strategy";
    }
}