Example usage for org.apache.hadoop.mapreduce Job getMapOutputValueClass

Introduction

In this page you can find the example usage for org.apache.hadoop.mapreduce Job getMapOutputValueClass.

Prototype

public Class<?> getMapOutputValueClass()

Source Link

Document

Get the value class for the map output data.

Usage

From source file:org.kiji.mapreduce.framework.MapReduceJobBuilder.java

License:Apache License

/**
 * Configures the MapReduce reducer for the job.
 *
 * @param job The Hadoop MR job.//from  w  w  w  .  jav a 2s .  c om
 * @throws IOException If there is an error.
 */
protected void configureReducer(Job job) throws IOException {
    final KijiReducer<?, ?, ?, ?> reducer = getReducer();
    if (null == reducer) {
        LOG.info("No reducer provided. This will be a map-only job");
        job.setNumReduceTasks(0);

        // Set the job output key/value classes based on what the map output key/value classes were
        // since this a map-only job.
        job.setOutputKeyClass(job.getMapOutputKeyClass());
        Schema mapOutputKeySchema = AvroJob.getMapOutputKeySchema(job.getConfiguration());
        if (null != mapOutputKeySchema) {
            AvroJob.setOutputKeySchema(job, mapOutputKeySchema);
        }
        job.setOutputValueClass(job.getMapOutputValueClass());
        Schema mapOutputValueSchema = AvroJob.getMapOutputValueSchema(job.getConfiguration());
        if (null != mapOutputValueSchema) {
            AvroJob.setOutputValueSchema(job, mapOutputValueSchema);
        }
        return;
    }
    if (reducer instanceof Configurable) {
        ((Configurable) reducer).setConf(job.getConfiguration());
    }
    job.setReducerClass(reducer.getClass());

    // Set output key class.
    Class<?> outputKeyClass = reducer.getOutputKeyClass();
    job.setOutputKeyClass(outputKeyClass);
    Schema outputKeyWriterSchema = AvroMapReduce.getAvroKeyWriterSchema(reducer);
    if (AvroKey.class.isAssignableFrom(outputKeyClass)) {
        if (null == outputKeyWriterSchema) {
            throw new JobConfigurationException("Using AvroKey output, but a writer schema was not provided. "
                    + "Did you forget to implement AvroKeyWriter in your KijiReducer?");
        }
        AvroJob.setOutputKeySchema(job, outputKeyWriterSchema);
    } else if (null != outputKeyWriterSchema) {
        throw new JobConfigurationException(
                reducer.getClass().getName() + ".getAvroKeyWriterSchema() returned a non-null Schema"
                        + " but the output key class was not AvroKey.");
    }

    // Set output value class.
    Class<?> outputValueClass = reducer.getOutputValueClass();
    job.setOutputValueClass(outputValueClass);
    Schema outputValueWriterSchema = AvroMapReduce.getAvroValueWriterSchema(reducer);
    if (AvroValue.class.isAssignableFrom(outputValueClass)) {
        if (null == outputValueWriterSchema) {
            throw new JobConfigurationException("Using AvroValue output, but a writer schema was not provided. "
                    + "Did you forget to implement AvroValueWriter in your KijiReducer?");
        }
        AvroJob.setOutputValueSchema(job, outputValueWriterSchema);
    } else if (null != outputValueWriterSchema) {
        throw new JobConfigurationException(
                reducer.getClass().getName() + ".getAvroValueWriterSchema() returned a non-null Schema"
                        + " but the output value class was not AvroValue.");
    }
}