org.apache.cassandra.hadoop.trackers.CassandraJobConf.java Source code

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Here is the source code for org.apache.cassandra.hadoop.trackers.CassandraJobConf.java

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/**
 * 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.cassandra.hadoop.trackers;

import java.net.InetAddress;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Set;

import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.log4j.Logger;

public class CassandraJobConf extends org.apache.hadoop.mapred.JobConf {
    private static final Logger logger = Logger.getLogger(CassandraJobConf.class);

    public String get(String name, String defaultValue) {
        if (name.equals("mapred.job.tracker") || name.equals("mapreduce.jobtracker.address")) {
            String address = getJobTrackerNode().getHostName() + ":8012";

            return address;
        }

        return super.get(name, defaultValue);
    }

    public String get(String name) {
        if (name.equals("mapred.job.tracker") || name.equals("mapreduce.jobtracker.address"))
            return getJobTrackerNode().getHostName() + ":8012";

        return super.get(name);
    }

    /**
      * Retrives the JobTracker location from the database.
      * If it is not there fallback into the config file and insert it
      * back to the DB.
      * @return the jobtracker address
      */
    public static InetAddress getJobTrackerNode() {
        try {
            InetAddress jobTrackerLocation = TrackerManager.getCurrentJobtrackerLocation();

            if (jobTrackerLocation == null) {
                // Insert it once so that later we can use the data from the DB
                jobTrackerLocation = internalgetJobTrackerNode();
                TrackerManager.insertJobtrackerLocation(jobTrackerLocation);
            }

            return jobTrackerLocation;
        } catch (TrackerManagerException e) {
            throw new RuntimeException(e);
        }
    }

    //Will pick a seed to use as a job tracker in this local dc
    //We can't check for live seeds because if this is a ec2 cluster
    //the seeds might not be up yet :(
    private static InetAddress internalgetJobTrackerNode() {
        //Get this nodes local DC
        String localDC = DatabaseDescriptor.getEndpointSnitch().getDatacenter(FBUtilities.getLocalAddress());

        Set<InetAddress> seeds = DatabaseDescriptor.getSeeds();

        InetAddress[] sortedSeeds = seeds.toArray(new InetAddress[] {});
        Arrays.sort(sortedSeeds, new Comparator<InetAddress>() {
            public int compare(InetAddress a, InetAddress b) {
                return a.getHostAddress().compareTo(b.getHostAddress());
            }
        });

        //Pick a seed in the same DC as this node to be the job tracker
        for (InetAddress seed : sortedSeeds)
            if (DatabaseDescriptor.getEndpointSnitch().getDatacenter(seed).equals(localDC)) {
                logger.info("Chose seed " + seed.getHostAddress() + " as jobtracker");
                return seed;
            }

        throw new RuntimeException("No seeds found in this DC: " + localDC);
    }
}