com.ikanow.infinit.e.data_model.custom.InfiniteMongoInputFormat.java Source code

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/*******************************************************************************
 * Copyright 2012 The Infinit.e Open Source Project
 * 
 * Licensed 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 com.ikanow.infinit.e.data_model.custom;

import java.util.List;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.bson.BSONObject;
import org.bson.types.ObjectId;

import com.ikanow.infinit.e.data_model.store.MongoDbManager;
import com.mongodb.BasicDBObject;
import com.mongodb.hadoop.MongoInputFormat;
import com.mongodb.hadoop.input.MongoInputSplit;

public class InfiniteMongoInputFormat extends MongoInputFormat {
    // Just needed to insert a log message that lets me do local debugging...
    @Override
    public RecordReader<Object, BSONObject> createRecordReader(InputSplit split, TaskAttemptContext context) {
        if (!(split instanceof MongoInputSplit))
            throw new IllegalStateException("Creation of a new RecordReader requires a MongoInputSplit instance.");

        final MongoInputSplit mis = (MongoInputSplit) split;

        return new InfiniteMongoRecordReader(mis);
    }

    @Override
    public List<InputSplit> getSplits(JobContext context) {
        final Configuration hadoopConfiguration = context.getConfiguration();
        final InfiniteMongoConfig conf = new InfiniteMongoConfig(hadoopConfiguration);
        List<InputSplit> splits = InfiniteMongoSplitter.calculateSplits(conf);

        if (conf.getSelfMerge() != null) {
            //check if we need to grab existing records and add them to the splits
            final Configuration existingConfiguration = context.getConfiguration();
            existingConfiguration.set("mongo.input.uri", conf.getSelfMerge());
            BasicDBObject query = new BasicDBObject();
            //add on this query to only get items previous to now if no reducer is specified (otherwise
            //we will leak any items we map on the first run back in before this split runs)
            if (context.getNumReduceTasks() == 0)
                query.put("_id", new BasicDBObject(MongoDbManager.lt_, new ObjectId()));
            existingConfiguration.set("mongo.input.query", query.toString());
            final InfiniteMongoConfig existingConf = new InfiniteMongoConfig(existingConfiguration);
            splits.addAll(InfiniteMongoSplitter.calculateSplits(existingConf));
        }
        return splits;
    }
}