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RecoveryRequiredChecker.java
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RecoveryRequiredChecker.java
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/*
* Copyright (c) 2002-2017 "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 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.kernel.impl.recovery;
import java.io.File;
import java.io.IOException;
import org.neo4j.io.fs.FileSystemAbstraction;
import org.neo4j.io.pagecache.PageCache;
import org.neo4j.kernel.impl.logging.LogService;
import org.neo4j.kernel.impl.store.NeoStores;
import org.neo4j.kernel.impl.transaction.log.LogPosition;
import org.neo4j.kernel.impl.transaction.log.LogTailScanner;
import org.neo4j.kernel.impl.transaction.log.PhysicalLogFiles;
import org.neo4j.kernel.impl.transaction.log.ReadableClosablePositionAwareChannel;
import org.neo4j.kernel.impl.transaction.log.entry.LogEntryReader;
import org.neo4j.kernel.impl.transaction.log.entry.VersionAwareLogEntryReader;
import org.neo4j.kernel.recovery.PositionToRecoverFrom;
import static org.neo4j.kernel.recovery.PositionToRecoverFrom.NO_MONITOR;
/**
* An external tool that can determine if a given store will need recovery.
*/
public class RecoveryRequiredChecker
{
private final FileSystemAbstraction fs;
private final PageCache pageCache;
private final LogService logService;
public RecoveryRequiredChecker( FileSystemAbstraction fs, PageCache pageCache, LogService logService )
{
this.fs = fs;
this.pageCache = pageCache;
this.logService = logService;
}
public boolean isRecoveryRequiredAt( File dataDir ) throws IOException
{
// We need config to determine where the logical log files are
if ( !NeoStores.isStorePresent( pageCache, dataDir ) )
{
// No database in the specified directory.
return false;
}
PhysicalLogFiles logFiles = new PhysicalLogFiles( dataDir, fs );
LogEntryReader<ReadableClosablePositionAwareChannel> reader = new VersionAwareLogEntryReader<>();
LogTailScanner tailScanner = new LogTailScanner( logFiles, fs, reader, logService );
return new PositionToRecoverFrom( tailScanner, NO_MONITOR ).get() != LogPosition.UNSPECIFIED;
}
}