/**
* Copyright 2005 The Apache Software Foundation
*
* 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 org.apache.nutch.fetcher;
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.fs.*;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.mapred.*;
import org.apache.nutch.crawl.CrawlDatum;
import org.apache.nutch.crawl.SignatureFactory;
import org.apache.nutch.metadata.Metadata;
import org.apache.nutch.net.*;
import org.apache.nutch.protocol.*;
import org.apache.nutch.parse.*;
import org.apache.nutch.scoring.ScoringFilters;
import org.apache.nutch.util.*;
/** The fetcher. Most of the work is done by plugins. */
public class Fetcher extends Configured implements MapRunnable {
public static final Log LOG = LogFactory.getLog(Fetcher.class);
public static final String SIGNATURE_KEY = "nutch.content.digest";
public static final String SEGMENT_NAME_KEY = "nutch.segment.name";
public static final String SCORE_KEY = "nutch.crawl.score";
public static class InputFormat extends SequenceFileInputFormat {
/** Don't split inputs, to keep things polite. */
public FileSplit[] getSplits(FileSystem fs, JobConf job, int nSplits)
throws IOException {
Path[] files = listPaths(fs, job);
FileSplit[] splits = new FileSplit[files.length];
for (int i = 0; i < files.length; i++) {
splits[i] = new FileSplit(files[i], 0, fs.getLength(files[i]));
}
return splits;
}
}
private RecordReader input;
private OutputCollector output;
private Reporter reporter;
private String segmentName;
private int activeThreads;
private int maxRedirect;
private long start = System.currentTimeMillis(); // start time of fetcher run
private long lastRequestStart = start;
private long bytes; // total bytes fetched
private int pages; // total pages fetched
private int errors; // total pages errored
private boolean storingContent;
private boolean parsing;
private class FetcherThread extends Thread {
private Configuration conf;
private URLFilters urlFilters;
private ScoringFilters scfilters;
private ParseUtil parseUtil;
private UrlNormalizer normalizer;
private ProtocolFactory protocolFactory;
public FetcherThread(Configuration conf) {
this.setDaemon(true); // don't hang JVM on exit
this.setName("FetcherThread"); // use an informative name
this.conf = conf;
this.urlFilters = new URLFilters(conf);
this.scfilters = new ScoringFilters(conf);
this.parseUtil = new ParseUtil(conf);
this.protocolFactory = new ProtocolFactory(conf);
this.normalizer = new UrlNormalizerFactory(conf).getNormalizer();
}
public void run() {
synchronized (Fetcher.this) {activeThreads++;} // count threads
try {
UTF8 key = new UTF8();
CrawlDatum datum = new CrawlDatum();
while (true) {
// TODO : NUTCH-258 ...
// If something bad happened, then exit
// if (conf.getBoolean("fetcher.exit", false)) {
// break;
// ]
try { // get next entry from input
if (!input.next(key, datum)) {
break; // at eof, exit
}
} catch (IOException e) {
if (LOG.isFatalEnabled()) {
e.printStackTrace(LogUtil.getFatalStream(LOG));
LOG.fatal("fetcher caught:"+e.toString());
}
break;
}
synchronized (Fetcher.this) {
lastRequestStart = System.currentTimeMillis();
}
// url may be changed through redirects.
UTF8 url = new UTF8();
url.set(key);
try {
if (LOG.isInfoEnabled()) { LOG.info("fetching " + url); }
// fetch the page
boolean redirecting;
int redirectCount = 0;
do {
if (LOG.isDebugEnabled()) {
LOG.debug("redirectCount=" + redirectCount);
}
redirecting = false;
Protocol protocol = this.protocolFactory.getProtocol(url.toString());
ProtocolOutput output = protocol.getProtocolOutput(url, datum);
ProtocolStatus status = output.getStatus();
Content content = output.getContent();
ParseStatus pstatus = null;
switch(status.getCode()) {
case ProtocolStatus.SUCCESS: // got a page
pstatus = output(url, datum, content, CrawlDatum.STATUS_FETCH_SUCCESS);
updateStatus(content.getContent().length);
if (pstatus != null && pstatus.isSuccess() &&
pstatus.getMinorCode() == ParseStatus.SUCCESS_REDIRECT) {
String newUrl = pstatus.getMessage();
newUrl = normalizer.normalize(newUrl);
newUrl = this.urlFilters.filter(newUrl);
if (newUrl != null && !newUrl.equals(url.toString())) {
url = new UTF8(newUrl);
redirecting = true;
redirectCount++;
if (LOG.isDebugEnabled()) {
LOG.debug(" - content redirect to " + url);
}
} else if (LOG.isDebugEnabled()) {
LOG.debug(" - content redirect skipped: " +
(newUrl != null ? "to same url" : "filtered"));
}
}
break;
case ProtocolStatus.MOVED: // redirect
case ProtocolStatus.TEMP_MOVED:
String newUrl = status.getMessage();
newUrl = normalizer.normalize(newUrl);
newUrl = this.urlFilters.filter(newUrl);
if (newUrl != null && !newUrl.equals(url.toString())) {
url = new UTF8(newUrl);
redirecting = true;
redirectCount++;
if (LOG.isDebugEnabled()) {
LOG.debug(" - protocol redirect to " + url);
}
} else if (LOG.isDebugEnabled()) {
LOG.debug(" - protocol redirect skipped: " +
(newUrl != null ? "to same url" : "filtered"));
}
break;
case ProtocolStatus.EXCEPTION:
logError(url, status.getMessage());
case ProtocolStatus.RETRY: // retry
datum.setRetriesSinceFetch(datum.getRetriesSinceFetch()+1);
output(url, datum, null, CrawlDatum.STATUS_FETCH_RETRY);
break;
case ProtocolStatus.GONE: // gone
case ProtocolStatus.NOTFOUND:
case ProtocolStatus.ACCESS_DENIED:
case ProtocolStatus.ROBOTS_DENIED:
case ProtocolStatus.NOTMODIFIED:
output(url, datum, null, CrawlDatum.STATUS_FETCH_GONE);
break;
default:
if (LOG.isWarnEnabled()) {
LOG.warn("Unknown ProtocolStatus: " + status.getCode());
}
output(url, datum, null, CrawlDatum.STATUS_FETCH_GONE);
}
if (redirecting && redirectCount >= maxRedirect) {
if (LOG.isInfoEnabled()) {
LOG.info(" - redirect count exceeded " + url);
}
output(url, datum, null, CrawlDatum.STATUS_FETCH_GONE);
}
} while (redirecting && (redirectCount < maxRedirect));
} catch (Throwable t) { // unexpected exception
logError(url, t.toString());
output(url, datum, null, CrawlDatum.STATUS_FETCH_RETRY);
}
}
} catch (Throwable e) {
if (LOG.isFatalEnabled()) {
e.printStackTrace(LogUtil.getFatalStream(LOG));
LOG.fatal("fetcher caught:"+e.toString());
}
} finally {
synchronized (Fetcher.this) {activeThreads--;} // count threads
}
}
private void logError(UTF8 url, String message) {
if (LOG.isInfoEnabled()) {
LOG.info("fetch of " + url + " failed with: " + message);
}
synchronized (Fetcher.this) { // record failure
errors++;
}
}
private ParseStatus output(UTF8 key, CrawlDatum datum,
Content content, int status) {
datum.setStatus(status);
datum.setFetchTime(System.currentTimeMillis());
if (content == null) {
String url = key.toString();
content = new Content(url, url, new byte[0], "", new Metadata(), this.conf);
}
Metadata metadata = content.getMetadata();
// add segment to metadata
metadata.set(SEGMENT_NAME_KEY, segmentName);
// add score to content metadata so that ParseSegment can pick it up.
try {
scfilters.passScoreBeforeParsing(key, datum, content);
} catch (Exception e) {
if (LOG.isWarnEnabled()) {
e.printStackTrace(LogUtil.getWarnStream(LOG));
LOG.warn("Couldn't pass score, url " + key + " (" + e + ")");
}
}
Parse parse = null;
if (parsing && status == CrawlDatum.STATUS_FETCH_SUCCESS) {
ParseStatus parseStatus;
try {
parse = this.parseUtil.parse(content);
parseStatus = parse.getData().getStatus();
} catch (Exception e) {
parseStatus = new ParseStatus(e);
}
if (!parseStatus.isSuccess()) {
if (LOG.isWarnEnabled()) {
LOG.warn("Error parsing: " + key + ": " + parseStatus);
}
parse = parseStatus.getEmptyParse(getConf());
}
// Calculate page signature. For non-parsing fetchers this will
// be done in ParseSegment
byte[] signature = SignatureFactory.getSignature(getConf()).calculate(content, parse);
metadata.set(SIGNATURE_KEY, StringUtil.toHexString(signature));
datum.setSignature(signature);
// Ensure segment name and score are in parseData metadata
parse.getData().getContentMeta().set(SEGMENT_NAME_KEY, segmentName);
parse.getData().getContentMeta().set(SIGNATURE_KEY, StringUtil.toHexString(signature));
try {
scfilters.passScoreAfterParsing(key, content, parse);
} catch (Exception e) {
if (LOG.isWarnEnabled()) {
e.printStackTrace(LogUtil.getWarnStream(LOG));
LOG.warn("Couldn't pass score, url " + key + " (" + e + ")");
}
}
}
try {
output.collect
(key,
new FetcherOutput(datum,
storingContent ? content : null,
parse != null ? new ParseImpl(parse) : null));
} catch (IOException e) {
if (LOG.isFatalEnabled()) {
e.printStackTrace(LogUtil.getFatalStream(LOG));
LOG.fatal("fetcher caught:"+e.toString());
}
}
if (parse != null) return parse.getData().getStatus();
else return null;
}
}
public Fetcher() { super(null); }
public Fetcher(Configuration conf) { super(conf); }
private synchronized void updateStatus(int bytesInPage) throws IOException {
pages++;
bytes += bytesInPage;
}
private void reportStatus() throws IOException {
String status;
synchronized (this) {
long elapsed = (System.currentTimeMillis() - start)/1000;
status =
pages+" pages, "+errors+" errors, "
+ Math.round(((float)pages*10)/elapsed)/10.0+" pages/s, "
+ Math.round(((((float)bytes)*8)/1024)/elapsed)+" kb/s, ";
}
reporter.setStatus(status);
}
public void configure(JobConf job) {
setConf(job);
this.segmentName = job.get(SEGMENT_NAME_KEY);
this.storingContent = isStoringContent(job);
this.parsing = isParsing(job);
// if (job.getBoolean("fetcher.verbose", false)) {
// LOG.setLevel(Level.FINE);
// }
}
public void close() {}
public static boolean isParsing(Configuration conf) {
return conf.getBoolean("fetcher.parse", true);
}
public static boolean isStoringContent(Configuration conf) {
return conf.getBoolean("fetcher.store.content", true);
}
public void run(RecordReader input, OutputCollector output,
Reporter reporter) throws IOException {
this.input = input;
this.output = output;
this.reporter = reporter;
this.maxRedirect = getConf().getInt("http.redirect.max", 3);
int threadCount = getConf().getInt("fetcher.threads.fetch", 10);
if (LOG.isInfoEnabled()) { LOG.info("Fetcher: threads: " + threadCount); }
for (int i = 0; i < threadCount; i++) { // spawn threads
new FetcherThread(getConf()).start();
}
// select a timeout that avoids a task timeout
long timeout = getConf().getInt("mapred.task.timeout", 10*60*1000)/2;
do { // wait for threads to exit
try {
Thread.sleep(1000);
} catch (InterruptedException e) {}
reportStatus();
// some requests seem to hang, despite all intentions
synchronized (this) {
if ((System.currentTimeMillis() - lastRequestStart) > timeout) {
if (LOG.isWarnEnabled()) {
LOG.warn("Aborting with "+activeThreads+" hung threads.");
}
return;
}
}
} while (activeThreads > 0);
}
public void fetch(Path segment, int threads, boolean parsing)
throws IOException {
if (LOG.isInfoEnabled()) {
LOG.info("Fetcher: starting");
LOG.info("Fetcher: segment: " + segment);
}
JobConf job = new NutchJob(getConf());
job.setJobName("fetch " + segment);
job.setInt("fetcher.threads.fetch", threads);
job.set(SEGMENT_NAME_KEY, segment.getName());
job.setBoolean("fetcher.parse", parsing);
// for politeness, don't permit parallel execution of a single task
job.setSpeculativeExecution(false);
job.setInputPath(new Path(segment, CrawlDatum.GENERATE_DIR_NAME));
job.setInputFormat(InputFormat.class);
job.setInputKeyClass(UTF8.class);
job.setInputValueClass(CrawlDatum.class);
job.setMapRunnerClass(Fetcher.class);
job.setOutputPath(segment);
job.setOutputFormat(FetcherOutputFormat.class);
job.setOutputKeyClass(UTF8.class);
job.setOutputValueClass(FetcherOutput.class);
JobClient.runJob(job);
if (LOG.isInfoEnabled()) { LOG.info("Fetcher: done"); }
}
/** Run the fetcher. */
public static void main(String[] args) throws Exception {
String usage = "Usage: Fetcher <segment> [-threads n] [-noParsing]";
if (args.length < 1) {
System.err.println(usage);
System.exit(-1);
}
Path segment = new Path(args[0]);
Configuration conf = NutchConfiguration.create();
int threads = conf.getInt("fetcher.threads.fetch", 10);
boolean parsing = true;
for (int i = 1; i < args.length; i++) { // parse command line
if (args[i].equals("-threads")) { // found -threads option
threads = Integer.parseInt(args[++i]);
} else if (args[i].equals("-noParsing")) parsing = false;
}
conf.setInt("fetcher.threads.fetch", threads);
if (!parsing) {
conf.setBoolean("fetcher.parse", parsing);
}
Fetcher fetcher = new Fetcher(conf); // make a Fetcher
fetcher.fetch(segment, threads, parsing); // run the Fetcher
}
}