ParallelBatchImporter.java

/*
 * Copyright (c) 2002-2018 "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 java.io.File;
import java.io.IOException;

import org.neo4j.io.fs.FileSystemAbstraction;
import org.neo4j.io.pagecache.PageCache;
import org.neo4j.kernel.configuration.Config;
import org.neo4j.kernel.impl.logging.LogService;
import org.neo4j.kernel.impl.store.format.RecordFormats;
import org.neo4j.kernel.lifecycle.LifecycleAdapter;
import org.neo4j.unsafe.impl.batchimport.input.Input;
import org.neo4j.unsafe.impl.batchimport.staging.ExecutionMonitor;
import org.neo4j.unsafe.impl.batchimport.store.BatchingNeoStores;

import static org.neo4j.unsafe.impl.batchimport.ImportLogic.instantiateNeoStores;

/**
 * {@link BatchImporter} which tries to exercise as much of the available resources to gain performance.
 * Or rather ensure that the slowest resource (usually I/O) is fully saturated and that enough work is
 * being performed to keep that slowest resource saturated all the time.
 * <p>
 * Overall goals: split up processing cost by parallelizing. Keep CPUs busy, keep I/O busy and writing sequentially.
 * I/O is only allowed to be read to and written from sequentially, any random access drastically reduces performance.
 * Goes through multiple stages where each stage has one or more steps executing in parallel, passing
 * batches between these steps through each stage, i.e. passing batches downstream.
 */
public class ParallelBatchImporter extends LifecycleAdapter implements BatchImporter
{
    private final PageCache externalPageCache;
    private final File storeDir;
    private final FileSystemAbstraction fileSystem;
    private final Configuration config;
    private final LogService logService;
    private final Config dbConfig;
    private final RecordFormats recordFormats;
    private final ExecutionMonitor executionMonitor;
    private final AdditionalInitialIds additionalInitialIds;
    private final ImportLogic.Monitor monitor;

    public ParallelBatchImporter( File storeDir, FileSystemAbstraction fileSystem, PageCache externalPageCache,
            Configuration config, LogService logService, ExecutionMonitor executionMonitor,
            AdditionalInitialIds additionalInitialIds, Config dbConfig, RecordFormats recordFormats, ImportLogic.Monitor monitor )
    {
        this.externalPageCache = externalPageCache;
        this.storeDir = storeDir;
        this.fileSystem = fileSystem;
        this.config = config;
        this.logService = logService;
        this.dbConfig = dbConfig;
        this.recordFormats = recordFormats;
        this.executionMonitor = executionMonitor;
        this.additionalInitialIds = additionalInitialIds;
        this.monitor = monitor;
    }

    @Override
    public void doImport( Input input ) throws IOException
    {
        try ( BatchingNeoStores store = instantiateNeoStores( fileSystem, storeDir, externalPageCache, recordFormats,
                      config, logService, additionalInitialIds, dbConfig );
              ImportLogic logic = new ImportLogic( storeDir, fileSystem, store, config, logService,
                      executionMonitor, recordFormats, monitor ) )
        {
            store.createNew();
            logic.initialize( input );

            logic.importNodes();
            logic.prepareIdMapper();
            logic.importRelationships();
            logic.calculateNodeDegrees();
            logic.linkRelationshipsOfAllTypes();
            logic.defragmentRelationshipGroups();
            logic.buildCountsStore();

            store.success();
        }
    }
}