src/java/org/apache/hcatalog/data/transfer/impl/HCatOutputFormatWriter.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 org.apache.hcatalog.data.transfer.impl;

import java.io.IOException;
import java.util.Iterator;
import java.util.Map;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.JobStatus.State;
import org.apache.hadoop.mapreduce.OutputCommitter;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.TaskAttemptID;
import org.apache.hcatalog.common.ErrorType;
import org.apache.hcatalog.common.HCatException;
import org.apache.hcatalog.data.HCatRecord;
import org.apache.hcatalog.data.transfer.HCatWriter;
import org.apache.hcatalog.data.transfer.WriteEntity;
import org.apache.hcatalog.data.transfer.WriterContext;
import org.apache.hcatalog.data.transfer.state.StateProvider;
import org.apache.hcatalog.mapreduce.HCatOutputFormat;
import org.apache.hcatalog.mapreduce.OutputJobInfo;
import org.apache.hcatalog.shims.HCatHadoopShims;

/**
 * This writer writes via {@link HCatOutputFormat}
 *
 */
public class HCatOutputFormatWriter extends HCatWriter {

    public HCatOutputFormatWriter(WriteEntity we, Map<String, String> config) {
        super(we, config);
    }

    public HCatOutputFormatWriter(Configuration config, StateProvider sp) {
        super(config, sp);
    }

    @Override
    public WriterContext prepareWrite() throws HCatException {
        OutputJobInfo jobInfo = OutputJobInfo.create(we.getDbName(),
            we.getTableName(), we.getPartitionKVs());
        Job job;
        try {
            job = new Job(conf);
            HCatOutputFormat.setOutput(job, jobInfo);
            HCatOutputFormat.setSchema(job, HCatOutputFormat.getTableSchema(job));
            HCatOutputFormat outFormat = new HCatOutputFormat();
            outFormat.checkOutputSpecs(job);
            outFormat.getOutputCommitter(HCatHadoopShims.Instance.get().createTaskAttemptContext
                (job.getConfiguration(), HCatHadoopShims.Instance.get().createTaskAttemptID())).setupJob(job);
        } catch (IOException e) {
            throw new HCatException(ErrorType.ERROR_NOT_INITIALIZED, e);
        } catch (InterruptedException e) {
            throw new HCatException(ErrorType.ERROR_NOT_INITIALIZED, e);
        }
        WriterContext cntxt = new WriterContext();
        cntxt.setConf(job.getConfiguration());
        return cntxt;
    }

    @Override
    public void write(Iterator<HCatRecord> recordItr) throws HCatException {

        int id = sp.getId();
        setVarsInConf(id);
        HCatOutputFormat outFormat = new HCatOutputFormat();
        TaskAttemptContext cntxt = HCatHadoopShims.Instance.get().createTaskAttemptContext
            (conf, new TaskAttemptID(HCatHadoopShims.Instance.get().createTaskID(), id));
        OutputCommitter committer = null;
        RecordWriter<WritableComparable<?>, HCatRecord> writer;
        try {
            committer = outFormat.getOutputCommitter(cntxt);
            committer.setupTask(cntxt);
            writer = outFormat.getRecordWriter(cntxt);
            while (recordItr.hasNext()) {
                HCatRecord rec = recordItr.next();
                writer.write(null, rec);
            }
            writer.close(cntxt);
            if (committer.needsTaskCommit(cntxt)) {
                committer.commitTask(cntxt);
            }
        } catch (IOException e) {
            if (null != committer) {
                try {
                    committer.abortTask(cntxt);
                } catch (IOException e1) {
                    throw new HCatException(ErrorType.ERROR_INTERNAL_EXCEPTION, e1);
                }
            }
            throw new HCatException("Failed while writing", e);
        } catch (InterruptedException e) {
            if (null != committer) {
                try {
                    committer.abortTask(cntxt);
                } catch (IOException e1) {
                    throw new HCatException(ErrorType.ERROR_INTERNAL_EXCEPTION, e1);
                }
            }
            throw new HCatException("Failed while writing", e);
        }
    }

    @Override
    public void commit(WriterContext context) throws HCatException {
        try {
            new HCatOutputFormat().getOutputCommitter(HCatHadoopShims.Instance.get().createTaskAttemptContext
                (context.getConf(), HCatHadoopShims.Instance.get().createTaskAttemptID()))
                .commitJob(HCatHadoopShims.Instance.get().createJobContext(context.getConf(), null));
        } catch (IOException e) {
            throw new HCatException(ErrorType.ERROR_NOT_INITIALIZED, e);
        } catch (InterruptedException e) {
            throw new HCatException(ErrorType.ERROR_NOT_INITIALIZED, e);
        }
    }

    @Override
    public void abort(WriterContext context) throws HCatException {
        try {
            new HCatOutputFormat().getOutputCommitter(HCatHadoopShims.Instance.get().createTaskAttemptContext
                (context.getConf(), HCatHadoopShims.Instance.get().createTaskAttemptID()))
                .abortJob(HCatHadoopShims.Instance.get().createJobContext(context.getConf(), null), State.FAILED);
        } catch (IOException e) {
            throw new HCatException(ErrorType.ERROR_NOT_INITIALIZED, e);
        } catch (InterruptedException e) {
            throw new HCatException(ErrorType.ERROR_NOT_INITIALIZED, e);
        }
    }

    private void setVarsInConf(int id) {

        // Following two config keys are required by FileOutputFormat to work
        // correctly.
        // In usual case of Hadoop, JobTracker will set these before launching
        // tasks.
        // Since there is no jobtracker here, we set it ourself.
        conf.setInt("mapred.task.partition", id);
        conf.set("mapred.task.id", "attempt__0000_r_000000_" + id);
    }
}