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ReadRelationshipRecordsBackwardsStep.java
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ReadRelationshipRecordsBackwardsStep.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 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.unsafe.impl.batchimport;
import org.neo4j.kernel.impl.store.RelationshipStore;
import org.neo4j.kernel.impl.store.id.validation.IdValidator;
import org.neo4j.kernel.impl.store.record.RelationshipRecord;
import org.neo4j.unsafe.impl.batchimport.staging.ReadRecordsStep;
import org.neo4j.unsafe.impl.batchimport.staging.StageControl;
import static java.lang.Math.min;
/**
* Reads from {@link RelationshipStore} backwards and produces batches of {@link RelationshipRecord} for others
* to process.
*/
public class ReadRelationshipRecordsBackwardsStep extends ReadRecordsStep<RelationshipRecord>
{
private final long firstRelationshipId;
private long id;
public ReadRelationshipRecordsBackwardsStep( StageControl control, Configuration config,
RelationshipStore store, long firstRelationshipId )
{
super( control, config, store );
this.firstRelationshipId = firstRelationshipId;
this.id = highId;
}
@Override
protected Object nextBatchOrNull( long ticket, int batchSize )
{
int size = (int) min( batchSize, id-firstRelationshipId );
RelationshipRecord[] batch = new RelationshipRecord[size];
boolean seenReservedId = false;
for ( int i = 0; i < size; i++ )
{
cursor.next( --id );
RelationshipRecord newRecord = record.clone();
batch[i] = newRecord;
seenReservedId |= IdValidator.isReservedId( newRecord.getId() );
}
batch = removeRecordWithReservedId( batch, seenReservedId );
return batch.length > 0 ? batch : null;
}
@Override
protected long position()
{
return (highId - id) * store.getRecordSize();
}
}