com.cloudera.sqoop.mapreduce.DelegatingOutputFormat.java Source code

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Here is the source code for com.cloudera.sqoop.mapreduce.DelegatingOutputFormat.java

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/**
 * Licensed to Cloudera, Inc. under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  Cloudera, Inc. 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 com.cloudera.sqoop.mapreduce;

import java.io.Closeable;
import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.OutputCommitter;
import org.apache.hadoop.mapreduce.OutputFormat;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.util.ReflectionUtils;

import com.cloudera.sqoop.lib.FieldMappable;
import com.cloudera.sqoop.lib.FieldMapProcessor;
import com.cloudera.sqoop.lib.ProcessingException;

/**
 * OutputFormat that produces a RecordReader which instantiates
 * a FieldMapProcessor which will process FieldMappable
 * output keys.
 *
 * <p>The output value is ignored.</p>
 *
 * <p>The FieldMapProcessor implementation may do any arbitrary
 * processing on the object. For example, it may write an object
 * to HBase, etc.</p>
 *
 * <p>If the FieldMapProcessor implementation also implements
 * Closeable, it will be close()'d in the RecordReader's close()
 * method.</p>
 *
 * <p>If the FMP implements Configurable, it will be configured
 * correctly via ReflectionUtils.</p>
 */
public class DelegatingOutputFormat<K extends FieldMappable, V> extends OutputFormat<K, V> {

    /** conf key: the FieldMapProcessor class to instantiate. */
    public static final String DELEGATE_CLASS_KEY = "sqoop.output.delegate.field.map.processor.class";

    @Override
    /** {@inheritDoc} */
    public void checkOutputSpecs(JobContext context) throws IOException, InterruptedException {
        Configuration conf = context.getConfiguration();

        if (null == conf.get(DELEGATE_CLASS_KEY)) {
            throw new IOException("Delegate FieldMapProcessor class is not set.");
        }
    }

    @Override
    /** {@inheritDoc} */
    public OutputCommitter getOutputCommitter(TaskAttemptContext context) throws IOException, InterruptedException {
        return new NullOutputCommitter();
    }

    @Override
    /** {@inheritDoc} */
    public RecordWriter<K, V> getRecordWriter(TaskAttemptContext context) throws IOException {
        try {
            return new DelegatingRecordWriter(context);
        } catch (ClassNotFoundException cnfe) {
            throw new IOException(cnfe);
        }
    }

    /**
     * RecordWriter to write the output to a row in a database table.
     * The actual database updates are executed in a second thread.
     */
    public class DelegatingRecordWriter extends RecordWriter<K, V> {

        private Configuration conf;

        private FieldMapProcessor mapProcessor;

        public DelegatingRecordWriter(TaskAttemptContext context) throws ClassNotFoundException {

            this.conf = context.getConfiguration();

            @SuppressWarnings("unchecked")
            Class<? extends FieldMapProcessor> procClass = (Class<? extends FieldMapProcessor>) conf
                    .getClass(DELEGATE_CLASS_KEY, null);
            this.mapProcessor = ReflectionUtils.newInstance(procClass, this.conf);
        }

        protected Configuration getConf() {
            return this.conf;
        }

        @Override
        /** {@inheritDoc} */
        public void close(TaskAttemptContext context) throws IOException, InterruptedException {
            if (mapProcessor instanceof Closeable) {
                ((Closeable) mapProcessor).close();
            }
        }

        @Override
        /** {@inheritDoc} */
        public void write(K key, V value) throws InterruptedException, IOException {
            try {
                mapProcessor.accept(key);
            } catch (ProcessingException pe) {
                throw new IOException(pe);
            }
        }
    }
}