org.apache.nutch.crawl.GeneratorReducer.java Source code

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Here is the source code for org.apache.nutch.crawl.GeneratorReducer.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
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package org.apache.nutch.crawl;

import java.io.IOException;
import java.net.MalformedURLException;
import java.util.HashMap;
import java.util.Map;

import org.apache.avro.util.Utf8;
import org.apache.gora.mapreduce.GoraReducer;
import org.apache.gora.query.Query;
import org.apache.gora.query.Result;
import org.apache.gora.store.DataStore;
import org.apache.hadoop.conf.Configuration;
import org.apache.nutch.crawl.GeneratorJob.SelectorEntry;
import org.apache.nutch.fetcher.FetcherJob.FetcherMapper;
import org.apache.nutch.storage.Mark;
import org.apache.nutch.storage.WebPage;
import org.apache.nutch.util.TableUtil;
import org.apache.nutch.util.URLUtil;

/**
 * Reduce class for generate
 * 
 * The #reduce() method write a random integer to all generated URLs. This
 * random number is then used by {@link FetcherMapper}.
 * 
 */
public class GeneratorReducer extends GoraReducer<SelectorEntry, WebPage, String, WebPage> {

    private long limit;
    private long maxCount;
    protected static long count = 0;
    private boolean byDomain = false;
    private Map<String, Integer> hostCountMap = new HashMap<String, Integer>();
    private Utf8 batchId;

    @Override
    protected void reduce(SelectorEntry key, Iterable<WebPage> values, Context context)
            throws IOException, InterruptedException {
        for (WebPage page : values) {
            if (count >= limit) {
                return;
            }
            if (maxCount > 0) {
                String hostordomain;
                if (byDomain) {
                    hostordomain = URLUtil.getDomainName(key.url);
                } else {
                    hostordomain = URLUtil.getHost(key.url);
                }

                Integer hostCount = hostCountMap.get(hostordomain);
                if (hostCount == null) {
                    hostCountMap.put(hostordomain, 0);
                    hostCount = 0;
                }
                if (hostCount >= maxCount) {
                    return;
                }
                hostCountMap.put(hostordomain, hostCount + 1);
            }

            Mark.GENERATE_MARK.putMark(page, batchId);
            page.setBatchId(batchId);
            try {
                context.write(TableUtil.reverseUrl(key.url), page);
            } catch (MalformedURLException e) {
                context.getCounter("Generator", "MALFORMED_URL").increment(1);
                continue;
            }
            context.getCounter("Generator", "GENERATE_MARK").increment(1);
            count++;
        }
    }

    @Override
    protected void setup(Context context) throws IOException, InterruptedException {
        Configuration conf = context.getConfiguration();
        long totalLimit = conf.getLong(GeneratorJob.GENERATOR_TOP_N, Long.MAX_VALUE);
        if (totalLimit == Long.MAX_VALUE) {
            limit = Long.MAX_VALUE;
        } else {
            limit = totalLimit / context.getNumReduceTasks();
        }
        maxCount = conf.getLong(GeneratorJob.GENERATOR_MAX_COUNT, -2);
        batchId = new Utf8(conf.get(GeneratorJob.BATCH_ID));
        String countMode = conf.get(GeneratorJob.GENERATOR_COUNT_MODE, GeneratorJob.GENERATOR_COUNT_VALUE_HOST);
        if (countMode.equals(GeneratorJob.GENERATOR_COUNT_VALUE_DOMAIN)) {
            byDomain = true;
        }

    }

}