/**
* Copyright (c) 2002-2011 "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.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import javax.transaction.xa.Xid;
import org.neo4j.kernel.impl.nioneo.store.UnderlyingStorageException;
class MemoryMappedLogBuffer implements LogBuffer
{
private static final int MAPPED_SIZE = 1024 * 1024 * 2;
private final FileChannel fileChannel;
private MappedByteBuffer mappedBuffer = null;
private long mappedStartPosition;
private final ByteBuffer fallbackBuffer;
MemoryMappedLogBuffer( FileChannel fileChannel ) throws IOException
{
this.fileChannel = fileChannel;
mappedStartPosition = fileChannel.position();
getNewMappedBuffer();
fallbackBuffer = ByteBuffer.allocateDirect( 9 + Xid.MAXGTRIDSIZE
+ Xid.MAXBQUALSIZE * 10 );
}
MappedByteBuffer getMappedBuffer()
{
return mappedBuffer;
}
private int mapFail = -1;
private void getNewMappedBuffer()
{
try
{
if ( mappedBuffer != null )
{
mappedStartPosition += mappedBuffer.position();
mappedBuffer.force();
mappedBuffer = null;
}
if ( mapFail > 1000 )
{
mapFail = -1;
}
if ( mapFail > 0 )
{
mapFail++;
return;
}
mappedBuffer = fileChannel.map( MapMode.READ_WRITE,
mappedStartPosition, MAPPED_SIZE );
}
catch ( Throwable t )
{
mapFail = 1;
t.printStackTrace();
}
}
public LogBuffer put( byte b ) throws IOException
{
if ( mappedBuffer == null ||
(MAPPED_SIZE - mappedBuffer.position()) < 1 )
{
getNewMappedBuffer();
if ( mappedBuffer == null )
{
fallbackBuffer.clear();
fallbackBuffer.put( b );
fallbackBuffer.flip();
fileChannel.write( fallbackBuffer, mappedStartPosition );
mappedStartPosition += 1;
return this;
}
}
int pos = mappedBuffer.position();
mappedBuffer.put( b );
return this;
}
public LogBuffer putInt( int i ) throws IOException
{
if ( mappedBuffer == null ||
(MAPPED_SIZE - mappedBuffer.position()) < 4 )
{
getNewMappedBuffer();
if ( mappedBuffer == null )
{
fallbackBuffer.clear();
fallbackBuffer.putInt( i );
fallbackBuffer.flip();
fileChannel.write( fallbackBuffer, mappedStartPosition );
mappedStartPosition += 4;
return this;
}
}
mappedBuffer.putInt( i );
return this;
}
public LogBuffer putLong( long l ) throws IOException
{
if ( mappedBuffer == null ||
(MAPPED_SIZE - mappedBuffer.position()) < 8 )
{
getNewMappedBuffer();
if ( mappedBuffer == null )
{
fallbackBuffer.clear();
fallbackBuffer.putLong( l );
fallbackBuffer.flip();
fileChannel.write( fallbackBuffer, mappedStartPosition );
mappedStartPosition += 8;
return this;
}
}
mappedBuffer.putLong( l );
return this;
}
public LogBuffer putFloat( float f ) throws IOException
{
if ( mappedBuffer == null ||
(MAPPED_SIZE - mappedBuffer.position()) < 4 )
{
getNewMappedBuffer();
if ( mappedBuffer == null )
{
fallbackBuffer.clear();
fallbackBuffer.putFloat( f );
fallbackBuffer.flip();
fileChannel.write( fallbackBuffer, mappedStartPosition );
mappedStartPosition += 4;
return this;
}
}
mappedBuffer.putFloat( f );
return this;
}
public LogBuffer putDouble( double d ) throws IOException
{
if ( mappedBuffer == null ||
(MAPPED_SIZE - mappedBuffer.position()) < 8 )
{
getNewMappedBuffer();
if ( mappedBuffer == null )
{
fallbackBuffer.clear();
fallbackBuffer.putDouble( d );
fallbackBuffer.flip();
fileChannel.write( fallbackBuffer, mappedStartPosition );
mappedStartPosition += 8;
return this;
}
}
mappedBuffer.putDouble( d );
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 > MAPPED_SIZE )
{
bytesToWrite = MAPPED_SIZE;
}
if ( mappedBuffer == null ||
(MAPPED_SIZE - mappedBuffer.position()) < bytesToWrite )
{
getNewMappedBuffer();
if ( mappedBuffer == null )
{
bytesToWrite = bytes.length - offset; // reset
ByteBuffer buf = ByteBuffer.wrap( bytes );
buf.position( offset );
int count = fileChannel.write( buf, mappedStartPosition );
if ( count != bytesToWrite )
{
throw new UnderlyingStorageException( "Failed to write from " +
offset + " expected " + bytesToWrite + " but wrote " +
count );
}
mappedStartPosition += bytesToWrite;
return;
}
}
mappedBuffer.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 > MAPPED_SIZE )
{
charsToWrite = MAPPED_SIZE / 2;
}
if ( mappedBuffer == null ||
(MAPPED_SIZE - mappedBuffer.position()) < (charsToWrite * 2 ) )
{
getNewMappedBuffer();
if ( mappedBuffer == null )
{
int bytesToWrite = ( chars.length - offset ) * 2;
ByteBuffer buf = ByteBuffer.allocate( bytesToWrite );
buf.asCharBuffer().put( chars, offset, chars.length - offset );
buf.limit( chars.length * 2 );
int count = fileChannel.write( buf, mappedStartPosition );
if ( count != bytesToWrite )
{
throw new UnderlyingStorageException( "Failed to write from " +
offset + " expected " + bytesToWrite + " but wrote " +
count );
}
mappedStartPosition += bytesToWrite;
return;
}
}
int oldPos = mappedBuffer.position();
mappedBuffer.asCharBuffer().put( chars, offset, charsToWrite );
mappedBuffer.position( oldPos + (charsToWrite * 2) );
offset += charsToWrite;
if ( offset < chars.length )
{
put( chars, offset );
}
}
void releaseMemoryMapped()
{
if ( mappedBuffer != null )
{
mappedBuffer.force();
mappedBuffer = null;
}
}
public void force() throws IOException
{
if ( mappedBuffer != null )
{
mappedBuffer.force();
}
fileChannel.force( false );
}
public long getFileChannelPosition()
{
if ( mappedBuffer != null )
{
return mappedStartPosition + mappedBuffer.position();
}
return mappedStartPosition;
}
public FileChannel getFileChannel()
{
return fileChannel;
}
}