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Neo4j kernel is a lightweight, embedded Java database designed to store data structured as graphs rather than tables. For more information, see http://neo4j.org.

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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 .
 */
package org.neo4j.unsafe.impl.batchimport;

import java.util.Arrays;

import org.neo4j.kernel.impl.store.RelationshipStore;
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 org.neo4j.unsafe.impl.batchimport.RecordIdIteration.allIn;

/**
 * Reads from {@link RelationshipStore} and produces batches of startNode,type,endNode values for
 * others to process. The result is one long[] with all values in.
 */
public class ReadRelationshipCountsDataStep extends ReadRecordsStep
{
    private long id = -1;
    private final long highestId;

    public ReadRelationshipCountsDataStep( StageControl control, Configuration config, RelationshipStore store )
    {
        super( control, config, store, allIn( store ) );
        this.highestId = highId - 1;
    }

    @Override
    protected long[] nextBatchOrNull( long ticket, int batchSize )
    {
        if ( id >= highestId )
        {
            return null;
        }

        long[] batch = new long[batchSize*3]; // start node, type, end node = 3
        int i = 0;
        for ( ; i < batchSize && ++id <= highestId; )
        {
            if ( cursor.next( id ) )
            {
                int index = i++ * 3;
                batch[index++] = record.getFirstNode();
                batch[index++] = record.getType();
                batch[index++] = record.getSecondNode();
            }
        }
        return i == batchSize ? batch : Arrays.copyOf( batch, i*3 );
    }

    @Override
    protected long position()
    {
        return doneBatches.get()*batchSize*store.getRecordSize();
    }
}