| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.tinkerpop.gremlin.hadoop.structure.io; |
| |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.io.NullWritable; |
| import org.apache.hadoop.mapreduce.InputFormat; |
| import org.apache.hadoop.mapreduce.InputSplit; |
| import org.apache.hadoop.mapreduce.JobID; |
| import org.apache.hadoop.mapreduce.RecordReader; |
| import org.apache.hadoop.mapreduce.TaskAttemptID; |
| import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; |
| import org.apache.hadoop.mapreduce.task.JobContextImpl; |
| import org.apache.hadoop.mapreduce.task.TaskAttemptContextImpl; |
| import org.apache.tinkerpop.gremlin.hadoop.Constants; |
| import org.apache.tinkerpop.gremlin.hadoop.structure.HadoopGraph; |
| import org.apache.tinkerpop.gremlin.hadoop.structure.util.ConfUtil; |
| import org.apache.tinkerpop.gremlin.structure.Element; |
| import org.apache.tinkerpop.gremlin.structure.io.Storage; |
| |
| import java.io.IOException; |
| import java.util.Iterator; |
| import java.util.LinkedList; |
| import java.util.List; |
| import java.util.Queue; |
| import java.util.UUID; |
| |
| /** |
| * @author Marko A. Rodriguez (http://markorodriguez.com) |
| */ |
| public abstract class HadoopElementIterator<E extends Element> implements Iterator<E>, AutoCloseable { |
| |
| protected final HadoopGraph graph; |
| protected final Queue<RecordReader<NullWritable, VertexWritable>> readers = new LinkedList<>(); |
| |
| public HadoopElementIterator(final HadoopGraph graph) { |
| try { |
| this.graph = graph; |
| final Configuration configuration = ConfUtil.makeHadoopConfiguration(this.graph.configuration()); |
| final InputFormat<NullWritable, VertexWritable> inputFormat = ConfUtil.getReaderAsInputFormat(configuration); |
| if (inputFormat instanceof FileInputFormat) { |
| final Storage storage = FileSystemStorage.open(configuration); |
| if (!this.graph.configuration().containsKey(Constants.GREMLIN_HADOOP_INPUT_LOCATION)) |
| return; // there is no input location and thus, no data (empty graph) |
| if (!Constants.getSearchGraphLocation(this.graph.configuration().getInputLocation(), storage).isPresent()) |
| return; // there is no data at the input location (empty graph) |
| configuration.set(Constants.MAPREDUCE_INPUT_FILEINPUTFORMAT_INPUTDIR, Constants.getSearchGraphLocation(this.graph.configuration().getInputLocation(), storage).get()); |
| } |
| final List<InputSplit> splits = inputFormat.getSplits(new JobContextImpl(configuration, new JobID(UUID.randomUUID().toString(), 1))); |
| for (final InputSplit split : splits) { |
| this.readers.add(inputFormat.createRecordReader(split, new TaskAttemptContextImpl(configuration, new TaskAttemptID()))); |
| } |
| } catch (final Exception e) { |
| throw new IllegalStateException(e.getMessage(), e); |
| } |
| } |
| |
| @Override |
| public void close() { |
| try { |
| for (final RecordReader reader : this.readers) { |
| reader.close(); |
| } |
| } catch (final IOException e) { |
| throw new IllegalStateException(e.getMessage(), e); |
| } |
| } |
| } |