/*
* 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.nioneo.store;
import java.io.IOException;
import java.nio.channels.FileChannel;
/**
* Persistence window using a {@link MappedByteBuffer} as underlying buffer.
*/
class MappedPersistenceWindow extends LockableWindow
{
private long position = -1;
private Buffer buffer = null;
private int windowSize = -1;
private int recordSize = -1;
private int totalSize = -1;
MappedPersistenceWindow( long position, int recordSize, int totalSize,
FileChannel channel, FileChannel.MapMode mapMode )
{
super( channel );
assert recordSize > 0 : "Record size[" + recordSize
+ "] must be greater then zero";
assert totalSize >= recordSize : "Total size[" + totalSize
+ "] cannot be less than record size[" + recordSize + "]";
assert totalSize >= recordSize : "Total size[" + totalSize
+ "] must mod to zero with record size[" + recordSize + "]";
this.totalSize = totalSize;
windowSize = totalSize / recordSize;
this.recordSize = recordSize;
this.position = position;
buffer = new Buffer( this );
try
{
buffer.setByteBuffer( channel.map( mapMode,
position * recordSize, totalSize ) );
}
catch ( IOException e )
{
this.position = -1;
throw new MappedMemException( "Unable to map pos=" + position +
" recordSize=" + recordSize + " totalSize=" + totalSize, e );
}
}
public Buffer getBuffer()
{
return buffer;
}
public int getRecordSize()
{
return recordSize;
}
public long position()
{
return position;
}
public int size()
{
return windowSize;
}
@Override
public void force()
{
((java.nio.MappedByteBuffer) buffer.getBuffer()).force();
}
public boolean equals( Object o )
{
if ( !(o instanceof MappedPersistenceWindow) )
{
return false;
}
return position() == ((MappedPersistenceWindow) o).position();
}
void unmap()
{
if ( buffer != null )
{
((java.nio.MappedByteBuffer) buffer.getBuffer()).force();
buffer.close();
position = -1;
}
}
private volatile int hashCode = 0;
public int hashCode()
{
if ( hashCode == 0 )
{
hashCode = (int) position();
}
return hashCode;
}
public String toString()
{
return "MappedPersistenceWindow[p=" + position + ",rs=" + recordSize
+ ",ws=" + windowSize + ",ts=" + totalSize + "]";
}
@Override
public void close()
{
buffer.close();
}
public Buffer getOffsettedBuffer( int id )
{
int offset = (int) ((id & 0xFFFFFFFFL) -
buffer.position()) * recordSize;
buffer.setOffset( offset );
return buffer;
}
}