/*
* Copyright (c) 2002-2009 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.kernel.impl.transaction.xaframework;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
class DirectMappedLogBuffer implements LogBuffer
{
private static final int BUFFER_SIZE = 1024 * 1024 * 2;
private final FileChannel fileChannel;
private ByteBuffer byteBuffer = null;
private long bufferStartPosition;
DirectMappedLogBuffer( FileChannel fileChannel ) throws IOException
{
this.fileChannel = fileChannel;
bufferStartPosition = fileChannel.position();
byteBuffer = ByteBuffer.allocateDirect( BUFFER_SIZE );
}
private void getNewDirectBuffer() throws IOException
{
byteBuffer.flip();
bufferStartPosition += fileChannel.write( byteBuffer,
bufferStartPosition );
byteBuffer.clear();
}
public LogBuffer put( byte b ) throws IOException
{
if ( byteBuffer == null ||
(BUFFER_SIZE - byteBuffer.position()) < 1 )
{
getNewDirectBuffer();
}
byteBuffer.put( b );
return this;
}
public LogBuffer putInt( int i ) throws IOException
{
if ( byteBuffer == null ||
(BUFFER_SIZE - byteBuffer.position()) < 4 )
{
getNewDirectBuffer();
}
byteBuffer.putInt( i );
return this;
}
public LogBuffer putLong( long l ) throws IOException
{
if ( byteBuffer == null ||
(BUFFER_SIZE - byteBuffer.position()) < 8 )
{
getNewDirectBuffer();
}
byteBuffer.putLong( l );
return this;
}
public LogBuffer put( byte[] bytes ) throws IOException
{
put( bytes, 0 );
return this;
}
private void put( byte[] bytes, int offset ) throws IOException
{
int bytesToWrite = bytes.length - offset;
if ( bytesToWrite > BUFFER_SIZE )
{
bytesToWrite = BUFFER_SIZE;
}
if ( byteBuffer == null ||
(BUFFER_SIZE - byteBuffer.position()) < bytesToWrite )
{
getNewDirectBuffer();
}
byteBuffer.put( bytes, offset, bytesToWrite );
offset += bytesToWrite;
if ( offset < bytes.length )
{
put( bytes, offset );
}
}
public LogBuffer put( char[] chars ) throws IOException
{
put( chars, 0 );
return this;
}
private void put( char[] chars, int offset ) throws IOException
{
int charsToWrite = chars.length - offset;
if ( charsToWrite * 2 > BUFFER_SIZE )
{
charsToWrite = BUFFER_SIZE / 2;
}
if ( byteBuffer == null ||
(BUFFER_SIZE - byteBuffer.position()) < (charsToWrite * 2 ) )
{
getNewDirectBuffer();
}
int oldPos = byteBuffer.position();
byteBuffer.asCharBuffer().put( chars, offset, charsToWrite );
byteBuffer.position( oldPos + (charsToWrite * 2) );
offset += charsToWrite;
if ( offset < chars.length )
{
put( chars, offset );
}
}
public void force() throws IOException
{
getNewDirectBuffer();
fileChannel.force( false );
}
public long getFileChannelPosition()
{
if ( byteBuffer != null )
{
return bufferStartPosition + byteBuffer.position();
}
return bufferStartPosition;
}
public FileChannel getFileChannel()
{
return fileChannel;
}
}