    1   /* Extractor
    2   *
    3   * $Id: Extractor.java 4497 2006-08-15 01:31:35Z stack-sf $
    4   *
    5   * Created on Sep 22, 2005
    6   *
    7   * Copyright (C) 2005 Internet Archive.
    8   *
    9   * This file is part of the Heritrix web crawler (crawler.archive.org).
    10  *
    11  * Heritrix is free software; you can redistribute it and/or modify
    12  * it under the terms of the GNU Lesser Public License as published by
    13  * the Free Software Foundation; either version 2.1 of the License, or
    14  * any later version.
    15  *
    16  * Heritrix is distributed in the hope that it will be useful,
    17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
    18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    19  * GNU Lesser Public License for more details.
    20  *
    21  * You should have received a copy of the GNU Lesser Public License
    22  * along with Heritrix; if not, write to the Free Software
    23  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    24  */
    25  package org.archive.crawler.extractor;
    26
    27  import java.util.logging.Level;
    28  import java.util.logging.Logger;
    29
    30  import org.archive.crawler.datamodel.CrawlURI;
    31  import org.archive.crawler.framework.Processor;
    32
    33  /***
    34   * Convenience shared superclass for Extractor Processors.
    35   *
    36   * Currently only wraps Extractor-specific extract() action with
    37   * a StackOverflowError catch/log/proceed handler, so that any
    38   * extractors that recurse too deep on problematic input will
    39   * only suffer a local error, and other normal CrawlURI processing
    40   * can continue. See:
    41   *  [ 1122836 ] Localize StackOverflowError in Extractors
    42   *  http://sourceforge.net/tracker/index.php?func=detail&aid=1122836&group_id=73833&atid=539099
    43   *
    44   * This class could also become home to common utility features
    45   * of extractors, like a running tally of the URIs examined/discovered,
    46   * etc.
    47   *
    48   * @author gojomo
    49   */
    50  public abstract class Extractor extends Processor {
    51      private static final Logger logger = Logger
    52          .getLogger(Extractor.class.getName());
    53
    54      /***
    55       * Passthrough constructor.
    56       *
    57       * @param name
    58       * @param description
    59       */
    60      public Extractor(String name, String description) {
    61          super(name, description);
    62          // TODO Auto-generated constructor stub
    63      }
    64
    65      public void innerProcess(CrawlURI curi) {
    66          try {
    67              extract(curi);
    68          } catch (NullPointerException npe) {
    69              // both annotate (to highlight in crawl log) & add as local-error
    70              curi.addAnnotation("err=" + npe.getClass().getName());
    71              curi.addLocalizedError(getName(), npe, "");
    72              // also log as warning
    73              logger.log(Level.WARNING, getName() + ": NullPointerException",
    74                  npe);
    75          } catch (StackOverflowError soe) {
    76              // both annotate (to highlight in crawl log) & add as local-error
    77              curi.addAnnotation("err=" + soe.getClass().getName());
    78              curi.addLocalizedError(getName(), soe, "");
    79              // also log as warning
    80              logger.log(Level.WARNING, getName() + ": StackOverflowError", soe);
    81          } catch (java.nio.charset.CoderMalfunctionError cme) {
    82              // See http://sourceforge.net/tracker/index.php?func=detail&aid=1540222&group_id=73833&atid=539099
    83              // Both annotate (to highlight in crawl log) & add as local-error
    84              curi.addAnnotation("err=" + cme.getClass().getName());
    85              curi.addLocalizedError(getName(), cme, ""); // <-- Message field ignored when logging.
    86              logger.log(Level.WARNING, getName() + ": CoderMalfunctionError",
    87                  cme);
    88          }
    89      }
    90
    91      protected abstract void extract(CrawlURI curi);
    92  }