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OnDiskVoteState.java
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OnDiskVoteState.java
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/*
* Copyright (c) 2002-2016 "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.coreedge.raft.state.vote;
import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import org.neo4j.coreedge.server.CoreMember;
import org.neo4j.coreedge.raft.log.RaftStorageException;
import org.neo4j.coreedge.raft.membership.CoreMarshal;
import org.neo4j.io.fs.FileSystemAbstraction;
import org.neo4j.io.fs.StoreChannel;
import org.neo4j.kernel.lifecycle.LifecycleAdapter;
public class OnDiskVoteState extends LifecycleAdapter implements VoteState<CoreMember>
{
private final StoreChannel channel;
private final CoreMarshal coreMemberMarshal = new CoreMarshal();
private CoreMember votedFor;
public OnDiskVoteState( FileSystemAbstraction fileSystem, File directory )
{
try
{
channel = fileSystem.open( new File( directory, "vote.state" ), "rw" );
votedFor = readVote();
}
catch ( IOException e )
{
throw new RuntimeException( e );
}
}
@Override
public void shutdown() throws Throwable
{
channel.force( false );
channel.close();
}
@Override
public CoreMember votedFor()
{
return votedFor;
}
@Override
public void update( CoreMember votedFor ) throws RaftStorageException
{
try
{
if ( votedFor == null )
{
channel.truncate( 0 );
}
else
{
ByteBuf byteBuf = Unpooled.buffer();
coreMemberMarshal.marshal( votedFor, byteBuf );
ByteBuffer buffer = byteBuf.nioBuffer();
channel.writeAll( buffer, 0 );
}
channel.force( false );
}
catch ( IOException e )
{
throw new RaftStorageException( "Failed to update votedFor", e );
}
this.votedFor = votedFor;
}
private CoreMember readVote() throws IOException
{
if ( channel.size() == 0 )
{
return null;
}
ByteBuffer buffer = ByteBuffer.allocate( (int) channel.size() );
channel.read( buffer, 0 );
buffer.flip();
return coreMemberMarshal.unmarshal( Unpooled.wrappedBuffer( buffer ) );
}
}