com.moz.fiji.mapreduce.impl.FijiTableContextFactory.java Source code

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Here is the source code for com.moz.fiji.mapreduce.impl.FijiTableContextFactory.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.impl;

import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.TaskInputOutputContext;

import com.moz.fiji.annotations.ApiAudience;
import com.moz.fiji.mapreduce.FijiTableContext;
import com.moz.fiji.mapreduce.framework.FijiConfKeys;

/** Instantiates a FijiTableContext according to a configuration. */
@ApiAudience.Private
public final class FijiTableContextFactory {

    /**
     * Instantiates the configured FijiTableContext.
     *
     * @param taskContext Hadoop task context.
     * @return the configured FijiTableContext.
     * @throws IOException on I/O error.
     */
    public static FijiTableContext create(TaskInputOutputContext taskContext) throws IOException {
        final Configuration conf = taskContext.getConfiguration();
        final String className = conf.get(FijiConfKeys.FIJI_TABLE_CONTEXT_CLASS);
        if (className == null) {
            throw new IOException(String.format("FijiTableContext class missing from configuration (key '%s').",
                    FijiConfKeys.FIJI_TABLE_CONTEXT_CLASS));
        }

        Throwable throwable = null;
        try {
            final Class<?> genericClass = Class.forName(className);
            final Class<? extends FijiTableContext> klass = genericClass.asSubclass(FijiTableContext.class);
            final Constructor<? extends FijiTableContext> constructor = klass
                    .getConstructor(TaskInputOutputContext.class);
            final FijiTableContext context = constructor.newInstance(taskContext);
            return context;
        } catch (ClassCastException cce) {
            throwable = cce;
        } catch (ClassNotFoundException cnfe) {
            throwable = cnfe;
        } catch (NoSuchMethodException nsme) {
            throwable = nsme;
        } catch (InvocationTargetException ite) {
            throwable = ite;
        } catch (IllegalAccessException iae) {
            throwable = iae;
        } catch (InstantiationException ie) {
            throwable = ie;
        }
        throw new IOException(String.format("Error instantiating FijiTableWriter class '%s': %s.", className,
                throwable.getMessage()), throwable);
    }

    /** Utility class cannot be instantiated. */
    private FijiTableContextFactory() {
    }
}