com.wibidata.wibidota.DotaMaxAccountId.java Source code

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Here is the source code for com.wibidata.wibidota.DotaMaxAccountId.java

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/* Copyright 2013 WibiData, Inc.
*
* See the NOTICE file distributed with this work for additional
* information regarding copyright ownership.
*
* 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.wibidata.wibidota;

import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.HashMap;

/**
 * A Map Reduce job built to find the maximum value the 'account id' field can take in the
 * raw  dota-matches JSON
 */
public class DotaMaxAccountId extends Configured implements Tool {
    private static final Logger LOG = LoggerFactory.getLogger(DotaMaxAccountId.class);

    public static class Map extends Mapper<LongWritable, Text, Text, LongWritable> {

        private final static JsonParser PARSER = new JsonParser();

        private static long max = Long.MIN_VALUE;

        public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
            try {
                JsonObject matchData = PARSER.parse(value.toString()).getAsJsonObject();
                for (JsonElement playerElem : matchData.get("players").getAsJsonArray()) {
                    JsonObject playerData = playerElem.getAsJsonObject();
                    JsonElement acccountElem = playerData.get("account_id");
                    if (acccountElem != null) {
                        long accountId = acccountElem.getAsLong();
                        // 4294967295L indicates anonymous and so can be ignored
                        if (accountId != 4294967295L && accountId > max) {
                            context.write(new Text("account_id"), new LongWritable(accountId));
                            max = accountId;
                        }
                    }
                }

            } catch (IllegalStateException e) {
                // Ignore
            }
        }
    }

    /**
     * Reducer that continues to search for the max value
     */
    public static class TakeMax extends Reducer<Text, LongWritable, Text, LongWritable> {

        public void reduce(Text key, Iterable<LongWritable> values, Context context)
                throws IOException, InterruptedException {
            StringBuilder out = new StringBuilder();
            long max = Long.MIN_VALUE;
            for (LongWritable id : values) {
                if (id.get() > max) {
                    max = id.get();
                }
            }
            context.write(key, new LongWritable(max));
        }
    }

    public static void main(String args[]) throws Exception {
        Configuration conf = new Configuration();
        int res = ToolRunner.run(conf, new DotaMaxAccountId(), args);
        System.exit(res);
    }

    public final int run(final String[] args) throws Exception {
        Job job = new Job(super.getConf(), "Dota Max Builder");
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(LongWritable.class);

        job.setMapperClass(DotaMaxAccountId.Map.class);
        job.setCombinerClass(DotaMaxAccountId.TakeMax.class);
        job.setReducerClass(DotaMaxAccountId.TakeMax.class);

        job.setJarByClass(DotaMaxAccountId.class);

        job.setInputFormatClass(TextInputFormat.class);
        job.setOutputFormatClass(TextOutputFormat.class);

        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        if (job.waitForCompletion(true)) {
            return 0;
        } else {
            return -1;
        }
    }

}