    1   /* FrontierScheduler
    2    *
    3    * $Id: FrontierScheduler.java 4671 2006-09-26 23:47:15Z paul_jack $
    4    *
    5    * Created on June 6, 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   */
    26  package org.archive.crawler.postprocessor;
    27
    28
    29  import java.util.logging.Level;
    30  import java.util.logging.Logger;
    31
    32  import org.archive.crawler.datamodel.CandidateURI;
    33  import org.archive.crawler.datamodel.CrawlURI;
    34  import org.archive.crawler.datamodel.FetchStatusCodes;
    35  import org.archive.crawler.framework.Processor;
    36
    37  /***
    38   * 'Schedule' with the Frontier CandidateURIs being carried by the passed
    39   * CrawlURI.
    40   * Adds either prerequisites or whatever is in CrawlURI outlinks to the
    41   * Frontier.  Run a Scoper ahead of this processor so only links that
    42   * are in-scope get scheduled.
    43   * @author stack
    44   */
    45  public class FrontierScheduler extends Processor
    46  implements FetchStatusCodes {
    47
    48      private static final long serialVersionUID = -5178775477602250542L;
    49
    50      private static Logger LOGGER =
    51          Logger.getLogger(FrontierScheduler.class.getName());
    52
    53      /***
    54       * @param name Name of this filter.
    55       */
    56      public FrontierScheduler(String name) {
    57          super(name, "FrontierScheduler. 'Schedule' with the Frontier " +
    58              "any CandidateURIs carried by the passed CrawlURI. " +
    59              "Run a Scoper before this " +
    60              "processor so links that are not in-scope get bumped from the " +
    61              "list of links (And so those in scope get promoted from Link " +
    62              "to CandidateURI).");
    63      }
    64
    65      protected void innerProcess(final CrawlURI curi) {
    66          if (LOGGER.isLoggable(Level.FINEST)) {
    67              LOGGER.finest(getName() + " processing " + curi);
    68          }
    69
    70          // Handle any prerequisites when S_DEFERRED for prereqs
    71          if (curi.hasPrerequisiteUri() && curi.getFetchStatus() == S_DEFERRED) {
    72              handlePrerequisites(curi);
    73              return;
    74          }
    75
    76          synchronized(this) {
    77              for (CandidateURI cauri: curi.getOutCandidates()) {
    78                  schedule(cauri);
    79              }
    80          }
    81      }
    82
    83      protected void handlePrerequisites(CrawlURI curi) {
    84          schedule((CandidateURI)curi.getPrerequisiteUri());
    85      }
    86
    87      /***
    88       * Schedule the given {@link CandidateURI CandidateURI} with the Frontier.
    89       * @param caUri The CandidateURI to be scheduled.
    90       */
    91      protected void schedule(CandidateURI caUri) {
    92          getController().getFrontier().schedule(caUri);
    93      }
    94  }