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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.crunch.examples;

import java.io.Serializable;

import org.apache.crunch.DoFn;
import org.apache.crunch.Emitter;
import org.apache.crunch.PCollection;
import org.apache.crunch.PObject;
import org.apache.crunch.PTable;
import org.apache.crunch.Pipeline;
import org.apache.crunch.PipelineResult;
import org.apache.crunch.fn.Aggregators;
import org.apache.crunch.impl.mr.MRPipeline;
import org.apache.crunch.types.writable.Writables;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

public class TotalWordCount extends Configured implements Tool, Serializable {
  public int run(String[] args) throws Exception {
    if (args.length != 1) {
      System.err.println();
      System.err.println("Usage: " + this.getClass().getName() + " [generic options] input");
      System.err.println();
      GenericOptionsParser.printGenericCommandUsage(System.err);
      return 1;
    }
    // Create an object to coordinate pipeline creation and execution.
    Pipeline pipeline = new MRPipeline(TotalWordCount.class, getConf());
    // Reference a given text file as a collection of Strings.
    PCollection lines = pipeline.readTextFile(args[0]);

    // Define a function that splits each line in a PCollection of Strings into
    // a
    // PCollection made up of the individual words in the file.
    PCollection numberOfWords = lines.parallelDo(new DoFn() {
      public void process(String line, Emitter emitter) {
        emitter.emit((long)line.split("\\s+").length);
      }
    }, Writables.longs()); // Indicates the serialization format

    // The aggregate method groups a collection into a single PObject.
    PObject totalCount = numberOfWords.aggregate(Aggregators.SUM_LONGS()).first();

    // Execute the pipeline as a MapReduce.
    PipelineResult result = pipeline.run();

    System.out.println("Total number of words: " + totalCount.getValue());
    
    pipeline.done();

    return result.succeeded() ? 0 : 1;
  }

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