com.moz.fiji.mapreduce.produce.impl.FijiProducers.java Source code

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Here is the source code for com.moz.fiji.mapreduce.produce.impl.FijiProducers.java

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/**
 * (c) Copyright 2012 WibiData, Inc.
 *
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * Licensed 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.moz.fiji.mapreduce.produce.impl;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.util.ReflectionUtils;

import com.moz.fiji.annotations.ApiAudience;
import com.moz.fiji.mapreduce.framework.FijiConfKeys;
import com.moz.fiji.mapreduce.produce.FijiProducer;
import com.moz.fiji.mapreduce.produce.FijiProducerOutputException;
import com.moz.fiji.schema.FijiColumnName;
import com.moz.fiji.schema.layout.FijiTableLayout;
import com.moz.fiji.schema.layout.FijiTableLayout.LocalityGroupLayout.FamilyLayout;

/** Utility methods for working with <code>FijiProducer</code>s. */
@ApiAudience.Private
public final class FijiProducers {
    /** Disable the constructor for this utility class. */
    private FijiProducers() {
    }

    /**
     * Creates an instance of the producer specified by the
     * {@link org.apache.hadoop.conf.Configuration}.
     *
     * <p>The configuration would have stored the producer name only if
     * it was configured by a FijiProduceJobBuilder, so don't try calling this
     * method with any old Configuration object.</p>
     *
     * @param conf The job configuration.
     * @return a brand-spankin'-new FijiProducer instance.
     * @throws IOException If the producer name cannot be instantiated from the configuration.
     */
    public static FijiProducer create(Configuration conf) throws IOException {
        final Class<? extends FijiProducer> producerClass = conf.getClass(FijiConfKeys.FIJI_PRODUCER_CLASS, null,
                FijiProducer.class);
        if (null == producerClass) {
            throw new IOException("Producer class could not be found in configuration.");
        }
        return ReflectionUtils.newInstance(producerClass, conf);
    }

    /**
     * Loads a FijiProducer class by name.
     *
     * @param className Fully qualified name of the class to load.
     * @return the loaded class.
     * @throws ClassNotFoundException if the class is not found.
     * @throws ClassCastException if the class is not a FijiGatherer.
     */
    public static Class<? extends FijiProducer> forName(String className) throws ClassNotFoundException {
        return Class.forName(className).asSubclass(FijiProducer.class);
    }

    /**
     * Makes sure the producer's requested output column exists in the
     * fiji table layout.
     *
     * @param producer The producer whose output column should be validated.
     * @param tableLayout The layout of the table to validate the output column against.
     * @throws FijiProducerOutputException If the output column cannot be written to.
     */
    public static void validateOutputColumn(FijiProducer producer, FijiTableLayout tableLayout)
            throws FijiProducerOutputException {
        final String outputColumn = producer.getOutputColumn();
        if (null == outputColumn) {
            throw new FijiProducerOutputException(
                    String.format("Producer '%s' must specify an output column by overridding getOutputColumn().",
                            producer.getClass().getName()));
        }

        final FijiColumnName columnName = new FijiColumnName(outputColumn);
        final FamilyLayout family = tableLayout.getFamilyMap().get(columnName.getFamily());
        if (null == family) {
            throw new FijiProducerOutputException(
                    String.format("Producer '%s' specifies unknown output column family '%s' in table '%s'.",
                            producer.getClass().getName(), columnName.getFamily(), tableLayout.getName()));
        }

        // When writing to a particular column qualifier of a group, make sure it exists:
        if (columnName.isFullyQualified() && family.isGroupType()
                && !family.getColumnMap().containsKey(columnName.getQualifier())) {
            throw new FijiProducerOutputException(
                    String.format("Producer '%s' specifies unknown column '%s' in table '%s'.",
                            producer.getClass().getName(), columnName, tableLayout.getName()));
        }
    }
}