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VoteState.java
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VoteState.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.IOException;
import org.neo4j.coreedge.raft.state.ChannelMarshal;
import org.neo4j.coreedge.raft.state.EndOfStreamException;
import org.neo4j.coreedge.raft.state.SafeStateMarshal;
import org.neo4j.coreedge.server.MemberId;
import org.neo4j.storageengine.api.ReadableChannel;
import org.neo4j.storageengine.api.WritableChannel;
public class VoteState
{
private MemberId votedFor;
private long term = -1;
public VoteState()
{
}
private VoteState( MemberId votedFor, long term )
{
this.term = term;
this.votedFor = votedFor;
}
public MemberId votedFor()
{
return votedFor;
}
public boolean update( MemberId votedFor, long term )
{
if ( termChanged( term ) )
{
this.votedFor = votedFor;
this.term = term;
return true;
}
else
{
if ( this.votedFor == null )
{
if ( votedFor != null )
{
this.votedFor = votedFor;
return true;
}
}
else if ( !this.votedFor.equals( votedFor ) )
{
throw new IllegalArgumentException( "Can only vote once per term." );
}
return false;
}
}
private boolean termChanged( long term )
{
return term != this.term;
}
public long term()
{
return term;
}
public static class Marshal extends SafeStateMarshal<VoteState>
{
private final ChannelMarshal<MemberId> memberMarshal;
public Marshal( ChannelMarshal<MemberId> memberMarshal )
{
this.memberMarshal = memberMarshal;
}
@Override
public void marshal( VoteState state, WritableChannel channel ) throws IOException
{
channel.putLong( state.term );
memberMarshal.marshal( state.votedFor(), channel );
}
@Override
public VoteState unmarshal0( ReadableChannel channel ) throws IOException, EndOfStreamException
{
final long term = channel.getLong();
final MemberId member = memberMarshal.unmarshal( channel );
return new VoteState( member, term );
}
@Override
public VoteState startState()
{
return new VoteState();
}
@Override
public long ordinal( VoteState state )
{
return state.term();
}
}
@Override
public String toString()
{
return "VoteState{" +
"votedFor=" + votedFor +
", term=" + term +
'}';
}
}