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RecoveryProtocol.java
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RecoveryProtocol.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.log.segmented;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.SortedMap;
import org.neo4j.coreedge.helper.StatUtil.StatContext;
import org.neo4j.coreedge.raft.log.EntryRecord;
import org.neo4j.coreedge.raft.replication.ReplicatedContent;
import org.neo4j.coreedge.raft.state.ChannelMarshal;
import org.neo4j.coreedge.raft.state.EndOfStreamException;
import org.neo4j.cursor.IOCursor;
import org.neo4j.io.fs.FileSystemAbstraction;
import org.neo4j.io.fs.StoreChannel;
import org.neo4j.kernel.impl.transaction.log.PhysicalFlushableChannel;
import org.neo4j.kernel.impl.transaction.log.ReadAheadChannel;
import org.neo4j.logging.Log;
import org.neo4j.logging.LogProvider;
import static java.util.Collections.emptyList;
/**
* Recovers all the state required for operating the RAFT log and does some simple
* verifications; e.g. checking for gaps, verifying headers.
*/
class RecoveryProtocol
{
private static final SegmentHeader.Marshal headerMarshal = new SegmentHeader.Marshal();
private final FileSystemAbstraction fileSystem;
private final FileNames fileNames;
private final ChannelMarshal<ReplicatedContent> contentMarshal;
private final LogProvider logProvider;
private final Log log;
private final StatContext scanStats;
private long expectedVersion;
private ReaderPool readerPool;
RecoveryProtocol( FileSystemAbstraction fileSystem, FileNames fileNames, ReaderPool readerPool,
ChannelMarshal<ReplicatedContent> contentMarshal, LogProvider logProvider, StatContext scanStats )
{
this.fileSystem = fileSystem;
this.fileNames = fileNames;
this.readerPool = readerPool;
this.contentMarshal = contentMarshal;
this.logProvider = logProvider;
this.log = logProvider.getLog( getClass() );
this.scanStats = scanStats;
}
RecoveryProtocol( FileSystemAbstraction fileSystem, FileNames fileNames, ReaderPool readerPool, ChannelMarshal<ReplicatedContent> marshal, LogProvider logProvider )
{
this( fileSystem, fileNames, readerPool, marshal, logProvider, null );
}
State run() throws IOException, DamagedLogStorageException, DisposedException
{
State state = new State();
SortedMap<Long,File> files = fileNames.getAllFiles( fileSystem, log );
if ( files.entrySet().isEmpty() )
{
state.segments = new Segments( fileSystem, fileNames, readerPool, emptyList(), contentMarshal, logProvider, -1, scanStats );
state.segments.rotate( -1, -1, -1 );
return state;
}
List<SegmentFile> segmentFiles = new ArrayList<>();
long firstVersion = files.firstKey();
expectedVersion = firstVersion;
for ( Map.Entry<Long,File> entry : files.entrySet() )
{
try
{
long fileNameVersion = entry.getKey();
File file = entry.getValue();
SegmentHeader header;
try
{
header = loadHeader( fileSystem, file );
}
catch ( EndOfStreamException e )
{
if ( files.lastKey() != fileNameVersion )
{
throw new DamagedLogStorageException( e, "File with incomplete or no header found: %s", file );
}
header = new SegmentHeader( state.appendIndex, fileNameVersion, state.appendIndex, state.currentTerm );
writeHeader( fileSystem, file, header );
}
SegmentFile segment = new SegmentFile( fileSystem, file, readerPool, fileNameVersion, contentMarshal, logProvider, header, scanStats );
checkVersionStrictlyMonotonic( fileNameVersion );
checkVersionMatches( segment.header().version(), fileNameVersion );
segmentFiles.add( segment );
if ( fileNameVersion == firstVersion )
{
state.prevIndex = segment.header().prevIndex();
state.prevTerm = segment.header().prevTerm();
}
expectedVersion++;
// check term
}
catch ( IOException e )
{
log.error( "Error during recovery", e );
}
}
SegmentFile last = segmentFiles.get( segmentFiles.size() - 1 );
state.segments = new Segments( fileSystem, fileNames, readerPool, segmentFiles, contentMarshal, logProvider, files.lastKey(), scanStats );
state.appendIndex = last.header().prevIndex();
state.currentTerm = last.header().prevTerm();
long firstIndexInLastSegmentFile = last.header().prevIndex() + 1;
try ( IOCursor<EntryRecord> cursor = last.getCursor( firstIndexInLastSegmentFile ) )
{
while ( cursor.next() )
{
EntryRecord entry = cursor.get();
state.appendIndex = entry.logIndex();
state.currentTerm = entry.logEntry().term();
}
}
return state;
}
private static SegmentHeader loadHeader(
FileSystemAbstraction fileSystem,
File file ) throws IOException, EndOfStreamException
{
try ( StoreChannel channel = fileSystem.open( file, "r" ) )
{
return headerMarshal.unmarshal( new ReadAheadChannel<>( channel, SegmentHeader.SIZE ) );
}
}
private static void writeHeader(
FileSystemAbstraction fileSystem,
File file,
SegmentHeader header ) throws IOException
{
try ( StoreChannel channel = fileSystem.open( file, "rw" ) )
{
channel.position( 0 );
PhysicalFlushableChannel writer = new PhysicalFlushableChannel( channel, SegmentHeader.SIZE );
headerMarshal.marshal( header, writer );
writer.prepareForFlush().flush();
}
}
private void checkVersionStrictlyMonotonic( long fileNameVersion ) throws DamagedLogStorageException
{
if ( fileNameVersion != expectedVersion )
{
throw new DamagedLogStorageException( "File versions not strictly monotonic. Expected: %d but found: %d", expectedVersion, fileNameVersion );
}
}
private void checkVersionMatches( long headerVersion, long fileNameVersion ) throws DamagedLogStorageException
{
if ( headerVersion != fileNameVersion )
{
throw new DamagedLogStorageException( "File version does not match header version. Expected: %d but found: %d", headerVersion, fileNameVersion );
}
}
}