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9 changes: 9 additions & 0 deletions conf/nutch-default.xml
Original file line number Diff line number Diff line change
Expand Up @@ -2588,6 +2588,15 @@ visit https://wiki.apache.org/nutch/SimilarityScoringFilter-->
</description>
</property>

<property>
<name>hostdb.deltaExpression</name>
<value></value>
<description>
The expression for calculation of the delta statistics, the differences between of value of hostdb after update(currentHostDatum) and the value before(previousHostDatum). The return value in the KeyValuePair(String,Integer) format is written to the metadata of the hostdb.
For example, {return new ("javafx.util.Pair","FetchedDelta", currentHostDatum.fetched - previousHostDatum.fetched);}
</description>
</property>

<!-- publisher properties
Do not forget to add the name of your publisher implementation
in plugin.includes ex- publish-rabbitmq -->
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2 changes: 1 addition & 1 deletion src/java/org/apache/nutch/hostdb/UpdateHostDb.java
Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,6 @@
import org.apache.nutch.util.NutchConfiguration;
import org.apache.nutch.util.NutchJob;
import org.apache.nutch.util.TimingUtil;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

Expand All @@ -78,6 +77,7 @@ public class UpdateHostDb extends Configured implements Tool {
public static final String HOSTDB_NUMERIC_FIELDS = "hostdb.numeric.fields";
public static final String HOSTDB_STRING_FIELDS = "hostdb.string.fields";
public static final String HOSTDB_PERCENTILES = "hostdb.percentiles";
public static final String HOSTDB_UPDATEDB_DELTA_EXPRESSION = "hostdb.deltaExpression";

private void updateHostDb(Path hostDb, Path crawlDb, Path topHosts,
boolean checkFailed, boolean checkNew, boolean checkKnown,
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13 changes: 7 additions & 6 deletions src/java/org/apache/nutch/hostdb/UpdateHostDbMapper.java
Original file line number Diff line number Diff line change
Expand Up @@ -19,15 +19,14 @@
import java.io.IOException;
import java.lang.invoke.MethodHandles;


import org.apache.commons.lang3.StringUtils;
import org.apache.hadoop.io.FloatWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reporter;

import org.apache.nutch.crawl.CrawlDatum;
import org.apache.nutch.crawl.CrawlDb;
import org.apache.nutch.crawl.NutchWritable;
Expand All @@ -36,7 +35,6 @@
import org.apache.nutch.net.URLNormalizers;
import org.apache.nutch.protocol.ProtocolStatus;
import org.apache.nutch.util.URLUtil;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

Expand All @@ -62,6 +60,7 @@ public class UpdateHostDbMapper
protected URLFilters filters = null;
protected URLNormalizers normalizers = null;

private boolean isDeltaStatisticCalculated = false;
public void close() {}

/**
Expand All @@ -71,7 +70,8 @@ public void configure(JobConf job) {
readingCrawlDb = job.getBoolean("hostdb.reading.crawldb", false);
filter = job.getBoolean(UpdateHostDb.HOSTDB_URL_FILTERING, false);
normalize = job.getBoolean(UpdateHostDb.HOSTDB_URL_NORMALIZING, false);

isDeltaStatisticCalculated = !StringUtils.isEmpty(job.get(UpdateHostDb.HOSTDB_UPDATEDB_DELTA_EXPRESSION));

if (filter)
filters = new URLFilters(job);
if (normalize)
Expand Down Expand Up @@ -212,9 +212,10 @@ public void map(Text key, Writable value,

// If we're also reading CrawlDb entries, reset db_* statistics because
// we're aggregating them from CrawlDB anyway
if (readingCrawlDb) {

if (readingCrawlDb && !isDeltaStatisticCalculated) {
hostDatum.resetStatistics();
}
}

output.collect(key, new NutchWritable(hostDatum));
}
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