modules/hadoop/src/main/java/org/apache/ignite/internal/processors/hadoop/impl/v2/HadoopV2Task.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.ignite.internal.processors.hadoop.impl.v2;

import java.io.IOException;
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.util.ReflectionUtils;
import org.apache.ignite.IgniteCheckedException;
import org.apache.ignite.internal.processors.hadoop.HadoopTask;
import org.apache.ignite.internal.processors.hadoop.HadoopTaskContext;
import org.apache.ignite.internal.processors.hadoop.HadoopTaskInfo;
import org.jetbrains.annotations.Nullable;

/**
 * Extended Hadoop v2 task.
 */
public abstract class HadoopV2Task extends HadoopTask {
    /** Hadoop context. */
    private HadoopV2Context hadoopCtx;

    /**
     * Constructor.
     *
     * @param taskInfo Task info.
     */
    protected HadoopV2Task(HadoopTaskInfo taskInfo) {
        super(taskInfo);
    }

    /** {@inheritDoc} */
    @Override public void run(HadoopTaskContext taskCtx) throws IgniteCheckedException {
        HadoopV2TaskContext ctx = (HadoopV2TaskContext)taskCtx;

        hadoopCtx = new HadoopV2Context(ctx);

        run0(ctx);
    }

    /**
     * Internal task routine.
     *
     * @param taskCtx Task context.
     * @throws IgniteCheckedException
     */
    protected abstract void run0(HadoopV2TaskContext taskCtx) throws IgniteCheckedException;

    /**
     * @return hadoop context.
     */
    protected HadoopV2Context hadoopContext() {
        return hadoopCtx;
    }

    /**
     * Create and configure an OutputFormat instance.
     *
     * @param jobCtx Job context.
     * @return Instance of OutputFormat is specified in job configuration.
     * @throws ClassNotFoundException If specified class not found.
     */
    protected OutputFormat getOutputFormat(JobContext jobCtx) throws ClassNotFoundException {
        return ReflectionUtils.newInstance(jobCtx.getOutputFormatClass(), hadoopContext().getConfiguration());
    }

    /**
     * Put write into Hadoop context and return associated output format instance.
     *
     * @param jobCtx Job context.
     * @return Output format.
     * @throws IgniteCheckedException In case of Grid exception.
     * @throws InterruptedException In case of interrupt.
     */
    protected OutputFormat prepareWriter(JobContext jobCtx)
        throws IgniteCheckedException, InterruptedException {
        try {
            OutputFormat outputFormat = getOutputFormat(jobCtx);

            assert outputFormat != null;

            OutputCommitter outCommitter = outputFormat.getOutputCommitter(hadoopCtx);

            if (outCommitter != null)
                outCommitter.setupTask(hadoopCtx);

            RecordWriter writer = outputFormat.getRecordWriter(hadoopCtx);

            hadoopCtx.writer(writer);

            return outputFormat;
        }
        catch (IOException | ClassNotFoundException e) {
            throw new IgniteCheckedException(e);
        }
    }

    /**
     * Closes writer.
     *
     * @throws Exception If fails and logger hasn't been specified.
     */
    protected void closeWriter() throws Exception {
        RecordWriter writer = hadoopCtx.writer();

        if (writer != null)
            writer.close(hadoopCtx);
    }

    /**
     * Setup task.
     *
     * @param outputFormat Output format.
     * @throws IOException In case of IO exception.
     * @throws InterruptedException In case of interrupt.
     */
    protected void setup(@Nullable OutputFormat outputFormat) throws IOException, InterruptedException {
        if (hadoopCtx.writer() != null) {
            assert outputFormat != null;

            outputFormat.getOutputCommitter(hadoopCtx).setupTask(hadoopCtx);
        }
    }

    /**
     * Commit task.
     *
     * @param outputFormat Output format.
     * @throws IgniteCheckedException In case of Grid exception.
     * @throws IOException In case of IO exception.
     * @throws InterruptedException In case of interrupt.
     */
    protected void commit(@Nullable OutputFormat outputFormat) throws IgniteCheckedException, IOException, InterruptedException {
        if (hadoopCtx.writer() != null) {
            assert outputFormat != null;

            OutputCommitter outputCommitter = outputFormat.getOutputCommitter(hadoopCtx);

            if (outputCommitter.needsTaskCommit(hadoopCtx))
                outputCommitter.commitTask(hadoopCtx);
        }
    }

    /**
     * Abort task.
     *
     * @param outputFormat Output format.
     */
    protected void abort(@Nullable OutputFormat outputFormat) {
        if (hadoopCtx.writer() != null) {
            assert outputFormat != null;

            try {
                outputFormat.getOutputCommitter(hadoopCtx).abortTask(hadoopCtx);
            }
            catch (IOException ignore) {
                // Ignore.
            }
            catch (InterruptedException ignore) {
                Thread.currentThread().interrupt();
            }
        }
    }

    /** {@inheritDoc} */
    @Override public void cancel() {
        hadoopCtx.cancel();
    }
}