/*
* Copyright 1998-2009 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
* Access and use of this software shall impose the following obligations
* and understandings on the user. The user is granted the right, without
* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
* documentation for any purpose whatsoever, provided that this entire
* notice appears in all copies of the software, derivative works and
* supporting documentation. Further, UCAR requests that the user credit
* UCAR/Unidata in any publications that result from the use of this
* software or in any product that includes this software. The names UCAR
* and/or Unidata, however, may not be used in any advertising or publicity
* to endorse or promote any products or commercial entity unless specific
* written permission is obtained from UCAR/Unidata. The user also
* understands that UCAR/Unidata is not obligated to provide the user with
* any support, consulting, training or assistance of any kind with regard
* to the use, operation and performance of this software nor to provide
* the user with any updates, revisions, new versions or "bug fixes."
*
* THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
* INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
*/
package ucar.unidata.io;
import java.io.*;
import java.nio.channels.FileChannel;
import java.nio.MappedByteBuffer;
/**
* Use NIO MappedByteBuffer to implement a RandomAccessFile.
* Limited to 2G size. Not currently used - NOT UP TO DATE DO NOT USE
* @author john
*/
class MMapRandomAccessFile extends RandomAccessFile {
private MappedByteBuffer source;
/**
* Constructor for in-memory "files"
* @param location used as a name
* @param mode the open mode
* @throws java.io.IOException on error
*/
MMapRandomAccessFile(String location, String mode ) throws IOException {
super(location, mode, 1);
FileChannel channel = file.getChannel();
source = channel.map( readonly ? FileChannel.MapMode.READ_ONLY : FileChannel.MapMode.READ_WRITE, (long) 0, channel.size());
channel.close();
bufferStart = 0;
dataSize = (int) channel.size();
dataEnd = channel.size();
filePosition = 0;
buffer = null;
endOfFile = false;
}
public void flush() throws IOException {
if (bufferModified) {
source.force();
bufferModified = false;
}
}
public void close() throws IOException {
if (!readonly) flush();
source = null;
}
public long length( ) {
return dataEnd;
}
public void seek( long pos ) {
filePosition = pos;
if( filePosition < dataEnd )
source.position((int) filePosition);
else
endOfFile = true;
}
public void unread( ) {
seek( filePosition-1);
}
public int read() throws IOException {
// If the file position is within the data, return the byte...
if( filePosition < dataEnd ) {
filePosition++;
return source.get() & 0xff;
} else {
return -1;
}
}
protected int readBytes( byte dst[], int offset, int length ) throws IOException {
if( endOfFile ) return -1;
length = (int) Math.min( length, dataEnd - filePosition);
if (length > 0) {
source.get(dst, offset, length);
filePosition += length;
}
return length;
}
public void write( int b ) throws IOException {
source.put( (byte)b);
filePosition++;
bufferModified = true;
}
public void writeBytes( byte dst[], int offset, int length ) throws IOException {
source.put(dst, offset, length);
filePosition += length;
}
}