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OnDiskTermState.java
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OnDiskTermState.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.term;
import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.function.Supplier;
import org.neo4j.coreedge.raft.log.RaftStorageException;
import org.neo4j.coreedge.raft.state.StatePersister;
import org.neo4j.coreedge.raft.state.StateRecoveryManager;
import org.neo4j.coreedge.raft.state.vote.InMemoryVoteState;
import org.neo4j.io.fs.FileSystemAbstraction;
import org.neo4j.kernel.internal.DatabaseHealth;
import org.neo4j.kernel.lifecycle.LifecycleAdapter;
public class OnDiskTermState extends LifecycleAdapter implements TermState
{
public static final String FILENAME = "term.";
public static final String DIRECTORY_NAME = "term-state";
private final ByteBuffer workingBuffer;
private InMemoryTermState inMemoryTermState;
private final StatePersister<InMemoryTermState> statePersister;
public OnDiskTermState( FileSystemAbstraction fileSystemAbstraction, File stateDir,
int numberOfEntriesBeforeRotation, Supplier<DatabaseHealth> databaseHealthSupplier )
throws IOException
{
File fileA = new File( stateDir, FILENAME + "a" );
File fileB = new File( stateDir, FILENAME + "b" );
workingBuffer = ByteBuffer.allocate( InMemoryVoteState.InMemoryVoteStateMarshal
.NUMBER_OF_BYTES_PER_VOTE );
TermStateRecoveryManager recoveryManager =
new TermStateRecoveryManager( fileSystemAbstraction, new InMemoryTermState.InMemoryTermStateMarshal() );
final StateRecoveryManager.RecoveryStatus recoveryStatus = recoveryManager.recover( fileA, fileB );
this.inMemoryTermState = recoveryManager.readLastEntryFrom( fileSystemAbstraction, recoveryStatus
.previouslyActive() );
this.statePersister = new StatePersister<>( fileA, fileB, fileSystemAbstraction, numberOfEntriesBeforeRotation,
workingBuffer, new InMemoryTermState.InMemoryTermStateMarshal(), recoveryStatus.previouslyInactive(),
databaseHealthSupplier );
}
@Override
public void shutdown() throws Throwable
{
statePersister.close();
}
@Override
public long currentTerm()
{
return inMemoryTermState.currentTerm();
}
@Override
public void update( long newTerm ) throws RaftStorageException
{
inMemoryTermState.failIfInvalid( newTerm );
try
{
if ( needsToWriteToDisk( newTerm ) )
{
InMemoryTermState tempState = new InMemoryTermState( inMemoryTermState );
tempState.update( newTerm );
statePersister.persistStoreData( tempState );
inMemoryTermState = tempState;
}
}
catch ( IOException e )
{
throw new RaftStorageException( e );
}
}
private boolean needsToWriteToDisk( long newTerm )
{
return newTerm > inMemoryTermState.currentTerm();
}
}