/**
* 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.crawl;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.io.IOException;
// Commons Logging imports
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapred.*;
import org.apache.hadoop.util.PriorityQueue;
import org.apache.nutch.metadata.Nutch;
import org.apache.nutch.scoring.ScoringFilterException;
import org.apache.nutch.scoring.ScoringFilters;
/** Merge new page entries with existing entries. */
public class CrawlDbReducer implements Reducer<Text, CrawlDatum, Text, CrawlDatum> {
public static final Log LOG = LogFactory.getLog(CrawlDbReducer.class);
private int retryMax;
private CrawlDatum result = new CrawlDatum();
private InlinkPriorityQueue linked = null;
private ScoringFilters scfilters = null;
private boolean additionsAllowed;
private int maxInterval;
private FetchSchedule schedule;
public void configure(JobConf job) {
retryMax = job.getInt("db.fetch.retry.max", 3);
scfilters = new ScoringFilters(job);
additionsAllowed = job.getBoolean(CrawlDb.CRAWLDB_ADDITIONS_ALLOWED, true);
int oldMaxInterval = job.getInt("db.max.fetch.interval", 0);
maxInterval = job.getInt("db.fetch.interval.max", 0 );
if (oldMaxInterval > 0 && maxInterval == 0) maxInterval = oldMaxInterval * FetchSchedule.SECONDS_PER_DAY;
schedule = FetchScheduleFactory.getFetchSchedule(job);
int maxLinks = job.getInt("db.update.max.inlinks", 10000);
linked = new InlinkPriorityQueue(maxLinks);
}
public void close() {}
public void reduce(Text key, Iterator<CrawlDatum> values,
OutputCollector<Text, CrawlDatum> output, Reporter reporter)
throws IOException {
CrawlDatum fetch = new CrawlDatum();
CrawlDatum old = new CrawlDatum();
boolean fetchSet = false;
boolean oldSet = false;
byte[] signature = null;
boolean multiple = false; // avoid deep copy when only single value exists
linked.clear();
org.apache.hadoop.io.MapWritable metaFromParse = null;
while (values.hasNext()) {
CrawlDatum datum = (CrawlDatum)values.next();
if (!multiple && values.hasNext()) multiple = true;
if (CrawlDatum.hasDbStatus(datum)) {
if (!oldSet) {
if (multiple) {
old.set(datum);
} else {
// no need for a deep copy - this is the only value
old = datum;
}
oldSet = true;
} else {
// always take the latest version
if (old.getFetchTime() < datum.getFetchTime()) old.set(datum);
}
continue;
}
if (CrawlDatum.hasFetchStatus(datum)) {
if (!fetchSet) {
if (multiple) {
fetch.set(datum);
} else {
fetch = datum;
}
fetchSet = true;
} else {
// always take the latest version
if (fetch.getFetchTime() < datum.getFetchTime()) fetch.set(datum);
}
continue;
}
switch (datum.getStatus()) { // collect other info
case CrawlDatum.STATUS_LINKED:
CrawlDatum link;
if (multiple) {
link = new CrawlDatum();
link.set(datum);
} else {
link = datum;
}
linked.insert(link);
break;
case CrawlDatum.STATUS_SIGNATURE:
signature = datum.getSignature();
break;
case CrawlDatum.STATUS_PARSE_META:
metaFromParse = datum.getMetaData();
break;
default:
LOG.warn("Unknown status, key: " + key + ", datum: " + datum);
}
}
// copy the content of the queue into a List
// in reversed order
int numLinks = linked.size();
List<CrawlDatum> linkList = new ArrayList<CrawlDatum>(numLinks);
for (int i = numLinks - 1; i >= 0; i--) {
linkList.add(linked.pop());
}
// if it doesn't already exist, skip it
if (!oldSet && !additionsAllowed) return;
// if there is no fetched datum, perhaps there is a link
if (!fetchSet && linkList.size() > 0) {
fetch = linkList.get(0);
fetchSet = true;
}
// still no new data - record only unchanged old data, if exists, and return
if (!fetchSet) {
if (oldSet) {// at this point at least "old" should be present
output.collect(key, old);
} else {
LOG.warn("Missing fetch and old value, signature=" + signature);
}
return;
}
if (signature == null) signature = fetch.getSignature();
long prevModifiedTime = oldSet ? old.getModifiedTime() : 0L;
long prevFetchTime = oldSet ? old.getFetchTime() : 0L;
// initialize with the latest version, be it fetch or link
result.set(fetch);
if (oldSet) {
// copy metadata from old, if exists
if (old.getMetaData().size() > 0) {
result.putAllMetaData(old);
// overlay with new, if any
if (fetch.getMetaData().size() > 0)
result.putAllMetaData(fetch);
}
// set the most recent valid value of modifiedTime
if (old.getModifiedTime() > 0 && fetch.getModifiedTime() == 0) {
result.setModifiedTime(old.getModifiedTime());
}
}
switch (fetch.getStatus()) { // determine new status
case CrawlDatum.STATUS_LINKED: // it was link
if (oldSet) { // if old exists
result.set(old); // use it
} else {
result = schedule.initializeSchedule((Text)key, result);
result.setStatus(CrawlDatum.STATUS_DB_UNFETCHED);
try {
scfilters.initialScore((Text)key, result);
} catch (ScoringFilterException e) {
if (LOG.isWarnEnabled()) {
LOG.warn("Cannot filter init score for url " + key +
", using default: " + e.getMessage());
}
result.setScore(0.0f);
}
}
break;
case CrawlDatum.STATUS_FETCH_SUCCESS: // succesful fetch
case CrawlDatum.STATUS_FETCH_REDIR_TEMP: // successful fetch, redirected
case CrawlDatum.STATUS_FETCH_REDIR_PERM:
case CrawlDatum.STATUS_FETCH_NOTMODIFIED: // successful fetch, notmodified
// determine the modification status
int modified = FetchSchedule.STATUS_UNKNOWN;
if (fetch.getStatus() == CrawlDatum.STATUS_FETCH_NOTMODIFIED) {
modified = FetchSchedule.STATUS_NOTMODIFIED;
} else {
if (oldSet && old.getSignature() != null && signature != null) {
if (SignatureComparator._compare(old.getSignature(), signature) != 0) {
modified = FetchSchedule.STATUS_MODIFIED;
} else {
modified = FetchSchedule.STATUS_NOTMODIFIED;
}
}
}
// set the schedule
result = schedule.setFetchSchedule((Text)key, result, prevFetchTime,
prevModifiedTime, fetch.getFetchTime(), fetch.getModifiedTime(), modified);
// set the result status and signature
if (modified == FetchSchedule.STATUS_NOTMODIFIED) {
result.setStatus(CrawlDatum.STATUS_DB_NOTMODIFIED);
if (oldSet) result.setSignature(old.getSignature());
} else {
switch (fetch.getStatus()) {
case CrawlDatum.STATUS_FETCH_SUCCESS:
result.setStatus(CrawlDatum.STATUS_DB_FETCHED);
break;
case CrawlDatum.STATUS_FETCH_REDIR_PERM:
result.setStatus(CrawlDatum.STATUS_DB_REDIR_PERM);
break;
case CrawlDatum.STATUS_FETCH_REDIR_TEMP:
result.setStatus(CrawlDatum.STATUS_DB_REDIR_TEMP);
break;
default:
LOG.warn("Unexpected status: " + fetch.getStatus() + " resetting to old status.");
if (oldSet) result.setStatus(old.getStatus());
else result.setStatus(CrawlDatum.STATUS_DB_UNFETCHED);
}
result.setSignature(signature);
if (metaFromParse != null) {
for (Entry<Writable, Writable> e : metaFromParse.entrySet()) {
result.getMetaData().put(e.getKey(), e.getValue());
}
}
}
// if fetchInterval is larger than the system-wide maximum, trigger
// an unconditional recrawl. This prevents the page to be stuck at
// NOTMODIFIED state, when the old fetched copy was already removed with
// old segments.
if (maxInterval < result.getFetchInterval())
result = schedule.forceRefetch((Text)key, result, false);
break;
case CrawlDatum.STATUS_SIGNATURE:
if (LOG.isWarnEnabled()) {
LOG.warn("Lone CrawlDatum.STATUS_SIGNATURE: " + key);
}
return;
case CrawlDatum.STATUS_FETCH_RETRY: // temporary failure
if (oldSet) {
result.setSignature(old.getSignature()); // use old signature
}
result = schedule.setPageRetrySchedule((Text)key, result, prevFetchTime,
prevModifiedTime, fetch.getFetchTime());
if (result.getRetriesSinceFetch() < retryMax) {
result.setStatus(CrawlDatum.STATUS_DB_UNFETCHED);
} else {
result.setStatus(CrawlDatum.STATUS_DB_GONE);
}
break;
case CrawlDatum.STATUS_FETCH_GONE: // permanent failure
if (oldSet)
result.setSignature(old.getSignature()); // use old signature
result.setStatus(CrawlDatum.STATUS_DB_GONE);
result = schedule.setPageGoneSchedule((Text)key, result, prevFetchTime,
prevModifiedTime, fetch.getFetchTime());
break;
default:
throw new RuntimeException("Unknown status: " + fetch.getStatus() + " " + key);
}
try {
scfilters.updateDbScore((Text)key, oldSet ? old : null, result, linkList);
} catch (Exception e) {
if (LOG.isWarnEnabled()) {
LOG.warn("Couldn't update score, key=" + key + ": " + e);
}
}
// remove generation time, if any
result.getMetaData().remove(Nutch.WRITABLE_GENERATE_TIME_KEY);
output.collect(key, result);
}
}
class InlinkPriorityQueue extends PriorityQueue<CrawlDatum> {
public InlinkPriorityQueue(int maxSize) {
initialize(maxSize);
}
/** Determines the ordering of objects in this priority queue. **/
protected boolean lessThan(Object arg0, Object arg1) {
CrawlDatum candidate = (CrawlDatum) arg0;
CrawlDatum least = (CrawlDatum) arg1;
return candidate.getScore() > least.getScore();
}
}