src/org/apache/pig/backend/hadoop/executionengine/mapReduceLayer/MapReducePOStoreImpl.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.pig.backend.hadoop.executionengine.mapReduceLayer;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.OutputFormat;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.TaskInputOutputContext;
import org.apache.pig.StoreFuncInterface;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POStore;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POStoreImpl;
import org.apache.pig.backend.hadoop.executionengine.shims.HadoopShims;
import org.apache.pig.tools.pigstats.PigStatsUtil;
import org.apache.pig.tools.pigstats.PigStatusReporter;
/**
 * This class is used to have a POStore write to DFS via a output
 * collector/record writer. It sets up a modified job configuration to
 * force a write to a specific subdirectory of the main output
 * directory. This is done so that multiple output directories can be
 * used in the same job.
 */
public class MapReducePOStoreImpl extends POStoreImpl {

    private TaskAttemptContext context;
    private PigStatusReporter reporter;
    private RecordWriter<?,?> writer;

    public MapReducePOStoreImpl(TaskInputOutputContext<?,?,?,?> context) {
        // get a copy of the Configuration so that changes to the
        // configuration below (like setting the output location) do
        // not affect the caller's copy
        Configuration outputConf = new Configuration(context.getConfiguration());
        reporter = PigStatusReporter.getInstance();
        reporter.setContext(new MRTaskContext(context));

        // make a copy of the Context to use here - since in the same
        // task (map or reduce) we could have multiple stores, we should
        // make this copy so that the same context does not get over-written
        // by the different stores.

        this.context = HadoopShims.createTaskAttemptContext(outputConf,
                context.getTaskAttemptID());
    }

    @Override
    public StoreFuncInterface createStoreFunc(POStore store)
            throws IOException {

        StoreFuncInterface storeFunc = store.getStoreFunc();

        // call the setStoreLocation on the storeFunc giving it the
        // Job. Typically this will result in the OutputFormat of the
        // storeFunc storing the output location in the Configuration
        // in the Job. The PigOutFormat.setLocation() method will merge
        // this modified Configuration into the configuration of the
        // Context we have
        PigOutputFormat.setLocation(context, store);
        OutputFormat<?,?> outputFormat = storeFunc.getOutputFormat();

        // create a new record writer
        try {
            writer = outputFormat.getRecordWriter(context);
        } catch (InterruptedException e) {
            throw new IOException(e);
        }

        storeFunc.prepareToWrite(writer);

        return storeFunc;
    }

    @Override
    public void tearDown() throws IOException {
        if (writer != null) {
            try {
                writer.close(context);
            } catch (InterruptedException e) {
                throw new IOException(e);
            }
            writer = null;
        }
    }

    @Override
    public void cleanUp() throws IOException {
        if (writer != null) {
            try {
                writer.close(context);
            } catch (InterruptedException e) {
                throw new IOException(e);
            }
            writer = null;
        }
    }

    public void incrRecordCounter(String name, long incr) {
        reporter.incrCounter(PigStatsUtil.MULTI_STORE_COUNTER_GROUP, name, incr);
    }
}