org.apache.nutch.fetcher.FetcherOutputFormat.java Source code

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Here is the source code for org.apache.nutch.fetcher.FetcherOutputFormat.java

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/**
 * 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.nutch.fetcher;

import java.io.IOException;

import org.apache.nutch.crawl.CrawlDatum;
import org.apache.nutch.crawl.NutchWritable;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

import org.apache.hadoop.io.MapFile;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.SequenceFile.CompressionType;

import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.InvalidJobConfException;
import org.apache.hadoop.mapred.OutputFormat;
import org.apache.hadoop.mapred.RecordWriter;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.SequenceFileOutputFormat;
import org.apache.hadoop.util.Progressable;

import org.apache.nutch.parse.Parse;
import org.apache.nutch.parse.ParseOutputFormat;
import org.apache.nutch.protocol.Content;

/** Splits FetcherOutput entries into multiple map files. */
public class FetcherOutputFormat implements OutputFormat<Text, NutchWritable> {

    public void checkOutputSpecs(FileSystem fs, JobConf job) throws IOException {
        Path out = FileOutputFormat.getOutputPath(job);
        if ((out == null) && (job.getNumReduceTasks() != 0)) {
            throw new InvalidJobConfException("Output directory not set in JobConf.");
        }
        if (fs == null) {
            fs = out.getFileSystem(job);
        }
        if (fs.exists(new Path(out, CrawlDatum.FETCH_DIR_NAME)))
            throw new IOException("Segment already fetched!");
    }

    public RecordWriter<Text, NutchWritable> getRecordWriter(final FileSystem fs, final JobConf job,
            final String name, final Progressable progress) throws IOException {

        Path out = FileOutputFormat.getOutputPath(job);
        final Path fetch = new Path(new Path(out, CrawlDatum.FETCH_DIR_NAME), name);
        final Path content = new Path(new Path(out, Content.DIR_NAME), name);

        final CompressionType compType = SequenceFileOutputFormat.getOutputCompressionType(job);

        final MapFile.Writer fetchOut = new MapFile.Writer(job, fs, fetch.toString(), Text.class, CrawlDatum.class,
                compType, progress);

        return new RecordWriter<Text, NutchWritable>() {
            private MapFile.Writer contentOut;
            private RecordWriter<Text, Parse> parseOut;

            {
                if (Fetcher.isStoringContent(job)) {
                    contentOut = new MapFile.Writer(job, fs, content.toString(), Text.class, Content.class,
                            compType, progress);
                }

                if (Fetcher.isParsing(job)) {
                    parseOut = new ParseOutputFormat().getRecordWriter(fs, job, name, progress);
                }
            }

            public void write(Text key, NutchWritable value) throws IOException {

                Writable w = value.get();

                if (w instanceof CrawlDatum)
                    fetchOut.append(key, w);
                else if (w instanceof Content)
                    contentOut.append(key, w);
                else if (w instanceof Parse)
                    parseOut.write(key, (Parse) w);
            }

            public void close(Reporter reporter) throws IOException {
                fetchOut.close();
                if (contentOut != null) {
                    contentOut.close();
                }
                if (parseOut != null) {
                    parseOut.close(reporter);
                }
            }

        };

    }
}