NodeFirstRelationshipStage.java

/*
 * 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.unsafe.impl.batchimport;

import org.neo4j.kernel.impl.store.NodeStore;
import org.neo4j.kernel.impl.store.record.NodeRecord;
import org.neo4j.kernel.impl.store.record.RelationshipGroupRecord;
import org.neo4j.unsafe.impl.batchimport.cache.NodeRelationshipCache;
import org.neo4j.unsafe.impl.batchimport.cache.NodeType;
import org.neo4j.unsafe.impl.batchimport.staging.Stage;

/**
 * Updates {@link NodeRecord node records} with relationship/group chain heads after relationship import. Steps:
 *
 * <ol>
 * <li>{@link ReadNodeRecordsByCacheStep} looks at {@link NodeRelationshipCache} for which nodes have had
 * relationships imported and loads those {@link NodeRecord records} from store.</li>
 * <li>{@link RecordProcessorStep} / {@link NodeFirstRelationshipProcessor} uses {@link NodeRelationshipCache}
 * to update each {@link NodeRecord#setNextRel(long)}. For dense nodes {@link RelationshipGroupRecord group records}
 * are created and set as {@link NodeRecord#setNextRel(long)}.</li>
 * <li>{@link UpdateRecordsStep} writes the updated records back into store.</li>
 * </ol>
 */
public class NodeFirstRelationshipStage extends Stage
{
    public NodeFirstRelationshipStage( String topic, Configuration config, NodeStore nodeStore,
            NodeRelationshipCache cache )
    {
        super( "Node --> Relationship" + topic, config );
        add( new ReadNodeRecordsByCacheStep( control(), config, nodeStore, cache, NodeType.NODE_TYPE_SPARSE ) );
        add( new RecordProcessorStep<>( control(), "LINK", config,
                new NodeFirstRelationshipProcessor( cache ), false ) );
        add( new UpdateRecordsStep<>( control(), config, nodeStore ) );
    }
}