fetcher.java

nutch0.8源码

      } 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)
    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());

    // 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);              // run the Fetcher

  }
}