cascading.scheme.hadoop.SequenceFile.java Source code

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Here is the source code for cascading.scheme.hadoop.SequenceFile.java

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/*
 * Copyright (c) 2007-2015 Concurrent, Inc. All Rights Reserved.
 *
 * Project and contact information: http://www.cascading.org/
 *
 * This file is part of the Cascading project.
 *
 * 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 cascading.scheme.hadoop;

import java.beans.ConstructorProperties;
import java.io.IOException;

import cascading.flow.FlowProcess;
import cascading.scheme.Scheme;
import cascading.scheme.SinkCall;
import cascading.scheme.SourceCall;
import cascading.tap.Tap;
import cascading.tuple.Fields;
import cascading.tuple.Tuple;
import cascading.tuple.TupleEntry;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapred.InputFormat;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.OutputFormat;
import org.apache.hadoop.mapred.RecordReader;
import org.apache.hadoop.mapred.SequenceFileInputFormat;
import org.apache.hadoop.mapred.SequenceFileOutputFormat;

/**
 * A SequenceFile is a type of {@link cascading.scheme.Scheme}, which is a flat file consisting of
 * binary key/value pairs. This is a space and time efficient means to store data.
 */
public class SequenceFile extends Scheme<Configuration, RecordReader, OutputCollector, Object[], Void> {
    /** Protected for use by TempDfs and other subclasses. Not for general consumption. */
    protected SequenceFile() {
        super(null);
    }

    /**
     * Creates a new SequenceFile instance that stores the given field names.
     *
     * @param fields
     */
    @ConstructorProperties({ "fields" })
    public SequenceFile(Fields fields) {
        super(fields, fields);
    }

    @Override
    public void sourceConfInit(FlowProcess<? extends Configuration> flowProcess,
            Tap<Configuration, RecordReader, OutputCollector> tap, Configuration conf) {
        conf.setBoolean("mapred.mapper.new-api", false);
        conf.setClass("mapred.input.format.class", SequenceFileInputFormat.class, InputFormat.class);
    }

    @Override
    public void sinkConfInit(FlowProcess<? extends Configuration> flowProcess,
            Tap<Configuration, RecordReader, OutputCollector> tap, Configuration conf) {
        conf.setBoolean("mapred.mapper.new-api", false);
        conf.setClass("mapred.output.key.class", Tuple.class, Object.class);
        conf.setClass("mapred.output.value.class", Tuple.class, Object.class);
        conf.setClass("mapred.output.format.class", SequenceFileOutputFormat.class, OutputFormat.class);
    }

    @Override
    public void sourcePrepare(FlowProcess<? extends Configuration> flowProcess,
            SourceCall<Object[], RecordReader> sourceCall) {
        Object[] pair = new Object[] { sourceCall.getInput().createKey(), sourceCall.getInput().createValue() };

        sourceCall.setContext(pair);
    }

    @Override
    public boolean source(FlowProcess<? extends Configuration> flowProcess,
            SourceCall<Object[], RecordReader> sourceCall) throws IOException {
        Tuple key = (Tuple) sourceCall.getContext()[0];
        Tuple value = (Tuple) sourceCall.getContext()[1];
        boolean result = sourceCall.getInput().next(key, value);

        if (!result)
            return false;

        TupleEntry entry = sourceCall.getIncomingEntry();

        if (entry.hasTypes())
            entry.setCanonicalTuple(value);
        else
            entry.setTuple(value);

        return true;
    }

    @Override
    public void sourceCleanup(FlowProcess<? extends Configuration> flowProcess,
            SourceCall<Object[], RecordReader> sourceCall) {
        sourceCall.setContext(null);
    }

    @Override
    public void sink(FlowProcess<? extends Configuration> flowProcess, SinkCall<Void, OutputCollector> sinkCall)
            throws IOException {
        sinkCall.getOutput().collect(Tuple.NULL, sinkCall.getOutgoingEntry().getTuple());
    }
}