WriteUsingMR.java

/* 
 * 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 parquet.proto.utils;

import com.google.protobuf.Message;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
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.lib.input.TextInputFormat;
import parquet.Log;
import parquet.proto.ProtoParquetOutputFormat;
import parquet.proto.TestUtils;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import static java.lang.Thread.sleep;

/**
 * Writes data to parquet file using MapReduce job.
 */
public class WriteUsingMR {

  private static final Log LOG = Log.getLog(WriteUsingMR.class);
  Configuration conf = new Configuration();
  private static List<Message> inputMessages;
  Path outputPath;

  public Configuration getConfiguration() {
    return conf;
  }

  public static class WritingMapper extends Mapper<LongWritable, Text, Void, Message> {

    public void run(Context context) throws IOException, InterruptedException {
      if (inputMessages == null || inputMessages.size() == 0) {
        throw new RuntimeException("No mock data given");
      } else {
        for (Message msg : inputMessages) {
          context.write(null, msg);
          LOG.debug("Reading msg from mock writing mapper" + msg);
        }
      }
    }
  }

  public Path write(Message... messages) throws Exception {

    synchronized (WriteUsingMR.class) {

      outputPath = TestUtils.someTemporaryFilePath();

      Path inputPath = TestUtils.someTemporaryFilePath();
      FileSystem fileSystem = inputPath.getFileSystem(conf);
      fileSystem.create(inputPath);

      inputMessages = Collections.unmodifiableList(Arrays.asList(messages));

      final Job job = new Job(conf, "write");

      // input not really used
      TextInputFormat.addInputPath(job, inputPath);
      job.setInputFormatClass(TextInputFormat.class);

      job.setMapperClass(WritingMapper.class);
      job.setNumReduceTasks(0);

      job.setOutputFormatClass(ProtoParquetOutputFormat.class);
      ProtoParquetOutputFormat.setOutputPath(job, outputPath);
      ProtoParquetOutputFormat.setProtobufClass(job, TestUtils.inferRecordsClass(messages));

      waitForJob(job);

      inputMessages = null;
      return outputPath;
    }
  }

  static void waitForJob(Job job) throws Exception {
    job.submit();
    while (!job.isComplete()) {
      LOG.debug("waiting for job " + job.getJobName());
      sleep(50);
    }
    LOG.debug("status for job " + job.getJobName() + ": " + (job.isSuccessful() ? "SUCCESS" : "FAILURE"));
    if (!job.isSuccessful()) {
      throw new RuntimeException("job failed " + job.getJobName());
    }
  }
}